fix(ui): Strip Silence opens with the values it last had (#1382) (#1396)

Strip Silence always opened at -48 dB / 50 / 5 / 20 ms. Its four values are
now kept for the session next to the strip names and written back each frame
the window is shown, so Escape, Cancel, Strip, Extract, Separate and the
Rename round trip all keep them.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -41,3 +41,4 @@ jobs:
       AZURE_SIGNING_ENDPOINT: ${{ secrets.AZURE_SIGNING_ENDPOINT }}
       AZURE_SIGNING_ACCOUNT: ${{ secrets.AZURE_SIGNING_ACCOUNT }}
       AZURE_CERT_PROFILE: ${{ secrets.AZURE_CERT_PROFILE }}
+      LINUX_SIGNING_KEY: ${{ secrets.LINUX_SIGNING_KEY }}

Cargo.lock

@@ -1422,6 +1422,19 @@ dependencies = [
  "winit",
 ]
 
+[[package]]
+name = "egui_extras"
+version = "0.37.0"
+source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"
+dependencies = [
+ "ahash",
+ "egui",
+ "enum-map",
+ "itertools 0.15.0",
+ "log",
+ "profiling",
+]
+
 [[package]]
 name = "egui_glow"
 version = "0.37.0"
@@ -1475,6 +1488,26 @@ version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "66b7e2430c6dff6a955451e2cfc438f09cea1965a9d6f87f7e3b90decc014099"
 
+[[package]]
+name = "enum-map"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4532960034c15ba2f55e9eee631040ecc473c32e6c4b200828c759840f13a06"
+dependencies = [
+ "enum-map-derive",
+]
+
+[[package]]
+name = "enum-map-derive"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7127272f64b3e098f7d81f350d672081b879bff896d219c42370dc858b1af9ff"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.9",
+]
+
 [[package]]
 name = "enumflags2"
 version = "0.7.12"
@@ -4374,6 +4407,7 @@ dependencies = [
  "clap",
  "clap_complete",
  "clap_mangen",
+ "log",
  "same-file",
  "serde",
  "serde_json",
@@ -4489,6 +4523,7 @@ dependencies = [
  "craft-ui",
  "craft-update",
  "egui",
+ "egui_extras",
  "egui_kittest",
  "image",
  "log",
@@ -6509,11 +6544,6 @@ name = "egui_demo_lib"
 version = "0.37.0"
 source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"
 
-[[patch.unused]]
-name = "egui_extras"
-version = "0.37.0"
-source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"
-
 [[patch.unused]]
 name = "egui_inspection"
 version = "0.37.0"

Cargo.toml

@@ -60,6 +60,8 @@ craft-update = { version = "=0.1.0", git = "https://github.com/storytold/craft-l
 # ui
 craft-ui = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "c5a1cbfb5f9049f9270955caffb5bee5997aebf7", features = ["serde"] }
 egui = { version = "0.37" }
+# Resizable table columns (About ▸ Contributors / Models); no image loaders.
+egui_extras = { version = "0.37", default-features = false }
 eframe = { version = "0.37", default-features = false }
 # Monotonic clock on native and the browser (the `web_time::Instant` panics-free equivalent).
 web-time = "1.1"

README.md

@@ -228,7 +228,8 @@ soundcraft-cli mcp --automation-read-root DIR --automation-write-root DIR
 
 See [`docs/cli.md`](docs/cli.md) for the command-line tool (subcommands, exit codes, environment
 variables, man pages and completions), [`docs/control-protocol.md`](docs/control-protocol.md) and
-[`docs/mcp.md`](docs/mcp.md). `soundcraft-cli commands` lists every command.
+[`docs/mcp.md`](docs/mcp.md). `soundcraft-cli commands` lists every command (`--json` for each
+one's parameters and details, as JSON).
 
 Open **SoundCraft › Session Audio Health** to check loaded audio availability, sample-rate
 mismatches and clip source bounds across all playlists, including alternate takes. The report

apps/soundcraft-cli/Cargo.toml

@@ -25,6 +25,7 @@ soundcraft-dsp.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 thiserror.workspace = true
+log.workspace = true
 clap.workspace = true
 same-file.workspace = true
 

apps/soundcraft-cli/src/args.rs

@@ -168,6 +168,12 @@ pub(crate) struct CommandsArgs {
     /// Only the commands whose id, or label in any case, contains this text
     #[arg(value_parser = NonEmptyStringValueParser::new())]
     pub(crate) filter: Option<String>,
+    /// Print a JSON array of each command's details, as describe prints them
+    #[arg(long)]
+    pub(crate) json: bool,
+    /// One line of JSON instead of pretty-printed
+    #[arg(long, requires = "json")]
+    pub(crate) compact: bool,
 }
 
 /// Print one engine command's details as JSON

apps/soundcraft-cli/src/catalog.rs

@@ -7,11 +7,15 @@ use std::io::Write;
 pub(crate) fn commands(args: &CommandsArgs, out: &mut dyn Write) {
     let filter = args.filter.clone().unwrap_or_default();
     let e = Engine::default();
-    for c in soundcraft_engine::command_specs() {
-        if !filter.is_empty() && !c.id.contains(&filter) && !c.label.to_ascii_lowercase().contains(&filter.to_ascii_lowercase()) {
-            continue;
-        }
-        let i = c.info(&e);
+    let infos = soundcraft_engine::command_specs()
+        .iter()
+        .filter(|c| filter.is_empty() || c.id.contains(&filter) || c.label.to_ascii_lowercase().contains(&filter.to_ascii_lowercase()))
+        .map(|c| c.info(&e));
+    if args.json {
+        print_json(out, &infos.collect::<Vec<_>>(), args.compact);
+        return;
+    }
+    for i in infos {
         outln!(out, "{:<36} {:<34} {}", i.id, i.label, i.menu.join(" > "));
     }
 }

apps/soundcraft-cli/src/convert.rs

@@ -15,6 +15,7 @@ pub(crate) fn convert(args: &ConvertArgs, out: &mut dyn Write) -> Result<(), Cli
     let bytes = std::fs::read(input).map_err(|source| CliError::File { path: input.clone(), source })?;
     let ext = input.extension().and_then(std::ffi::OsStr::to_str);
     let (info, mut buf) = soundcraft_audio_io::decode(&bytes, ext).map_err(|source| CliError::Audio { path: input.clone(), source })?;
+    let source_rate = buf.sample_rate;
     if let Some(rate) = rate {
         buf.channels = soundcraft_dsp::offline::resample(&buf.channels, buf.sample_rate, rate);
         buf.sample_rate = rate;
@@ -30,13 +31,28 @@ pub(crate) fn convert(args: &ConvertArgs, out: &mut dyn Write) -> Result<(), Cli
     let Some(format) = soundcraft_audio_io::FileFormat::from_write_extension(&out_ext) else {
         return Err(ConvertError::OutputFormat { output: output.clone(), ext: out_ext }.into());
     };
-    let opts = soundcraft_audio_io::EncodeOptions { format, bit_depth, dither, bwf: None };
+    // A BWF source keeps its `bext` (written for WAV output only). The time reference counts
+    // samples, so it moves to the output rate.
+    let bwf = info.bwf.map(|mut b| {
+        b.time_reference = at_rate(b.time_reference, source_rate, buf.sample_rate);
+        b
+    });
+    let opts = soundcraft_audio_io::EncodeOptions { format, bit_depth, dither, bwf };
     let bytes = soundcraft_audio_io::encode(&buf, &opts).map_err(|source| CliError::Audio { path: output.clone(), source })?;
     write_replacing(&args.write_path(), &bytes).map_err(|source| CliError::File { path: output.clone(), source })?;
     outln!(out, "wrote {} ({} ch, {} Hz, {:.2} s)", output.display(), buf.num_channels(), buf.sample_rate, buf.duration_secs());
     Ok(())
 }
 
+/// The sample position `pos` at `from` Hz as the nearest sample at `to` Hz.
+fn at_rate(pos: u64, from: u32, to: u32) -> u64 {
+    if from == 0 || from == to {
+        return pos;
+    }
+    let scaled = (u128::from(pos) * u128::from(to) + u128::from(from) / 2) / u128::from(from);
+    u64::try_from(scaled).unwrap_or(u64::MAX)
+}
+
 /// Writes `bytes` to a new file next to `target`, flushes it and renames it over `target`, so `target`
 /// (the input, for --in-place) holds either its old or its new contents. The new file is removed when
 /// writing or renaming fails.

apps/soundcraft-cli/src/lib.rs

@@ -11,6 +11,7 @@ mod catalog;
 mod convert;
 mod error;
 mod info;
+pub mod logger;
 mod mcp;
 mod session;
 

apps/soundcraft-cli/src/logger.rs

@@ -0,0 +1,49 @@
+//! The command line's logger. Without one, every `log::warn!` and `log::error!` in the workspace
+//! was dropped: a plugin that failed to load just vanished from `engine.clap_plugins`, and nothing
+//! said why. Warnings and errors now go to standard error as `warning: <message>` and
+//! `error: <message>`, like the CLI's own errors; standard output keeps only the results.
+//! `RUST_LOG` stays a desktop app variable (docs/cli.md), so the level is fixed.
+
+use std::io::Write;
+
+struct StderrLogger;
+
+impl log::Log for StderrLogger {
+    fn enabled(&self, metadata: &log::Metadata<'_>) -> bool {
+        metadata.level() <= log::Level::Warn
+    }
+
+    fn log(&self, record: &log::Record<'_>) {
+        if self.enabled(record.metadata()) {
+            // A closed standard error is not worth failing a command over.
+            let _ = std::io::stderr().write_all(line(record.level(), &record.args().to_string()).as_bytes());
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+/// One record as the CLI prints it.
+fn line(level: log::Level, message: &str) -> String {
+    let label = if level == log::Level::Error { "error" } else { "warning" };
+    format!("{label}: {}\n", message.strip_suffix('\n').unwrap_or(message))
+}
+
+/// Installs the logger. Once per process: `main` calls it, not `run`, which tests call many times.
+pub fn install() {
+    static LOGGER: StderrLogger = StderrLogger;
+    if log::set_logger(&LOGGER).is_ok() {
+        log::set_max_level(log::LevelFilter::Warn);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn records_print_like_the_cli_errors() {
+        assert_eq!(line(log::Level::Warn, "cannot load CLAP plugin x.clap: bad file\n"), "warning: cannot load CLAP plugin x.clap: bad file\n");
+        assert_eq!(line(log::Level::Error, "panic: boom"), "error: panic: boom\n");
+    }
+}

apps/soundcraft-cli/src/main.rs

@@ -3,6 +3,7 @@
 #![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
 
 fn main() {
+    soundcraft_cli::logger::install();
     // `args_os`, not `args`: a non-Unicode argument must reach clap, not panic before anything is printed.
     let code = soundcraft_cli::run(std::env::args_os().skip(1), &mut std::io::stdout(), &mut std::io::stderr());
     // The subcommand's engine and its plugin instances are gone by now. This is process teardown,

apps/soundcraft-cli/tests/convert.rs

@@ -5,7 +5,7 @@
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use soundcraft_audio_io::{AudioBuffer, BitDepth, EncodeOptions, FileFormat};
+use soundcraft_audio_io::{AudioBuffer, BitDepth, BwfInfo, EncodeOptions, FileFormat};
 
 fn tmpdir(tag: &str) -> PathBuf {
     let dir = std::env::temp_dir().join(format!("sc-cli-convert-{tag}-{}", std::process::id()));
@@ -93,3 +93,31 @@ fn convert_dithers_when_reducing_depth_unless_told_not_to() {
     assert!(steps16(&plain).iter().all(|s| *s == 0.0), "--no-dither still dithered");
     let _ = std::fs::remove_dir_all(&dir);
 }
+
+#[test]
+fn convert_keeps_the_bwf_time_stamp() {
+    let dir = tmpdir("bext");
+    let src = dir.join("take.wav");
+    // 01:00:00:00 at 48 kHz.
+    let bwf = BwfInfo {
+        description: "take 3".into(),
+        originator: "recorder".into(),
+        origination_date: "2026-11-03".into(),
+        origination_time: "10:00:00".into(),
+        time_reference: 172_800_000,
+        ..Default::default()
+    };
+    let buf = AudioBuffer::new(48_000, 1, 4800);
+    let opts = EncodeOptions { format: FileFormat::Wav, bit_depth: BitDepth::Int24, dither: false, bwf: Some(bwf.clone()) };
+    std::fs::write(&src, soundcraft_audio_io::encode(&buf, &opts).unwrap()).unwrap();
+    let bext = |p: &Path| soundcraft_audio_io::probe(&std::fs::read(p).unwrap(), None).unwrap().bwf;
+
+    let out = dir.join("16.wav");
+    convert(&src, &out, &["--bit-depth", "16"]);
+    assert_eq!(bext(&out), Some(bwf.clone()));
+    // Resampled, the stamp still points at 01:00:00:00: 158,760,000 samples at 44.1 kHz.
+    let out = dir.join("44k.wav");
+    convert(&src, &out, &["--rate", "44100"]);
+    assert_eq!(bext(&out), Some(BwfInfo { time_reference: 158_760_000, ..bwf }));
+    let _ = std::fs::remove_dir_all(&dir);
+}

apps/soundcraft-cli/tests/it/behaviour.rs

@@ -88,6 +88,25 @@ fn assert_refused(got: &Invoke, port: u16) {
     assert!(got.stderr.starts_with(&prefix) && got.stderr.contains(" (os error ") && got.stderr.ends_with(")\n"), "{}", got.stderr);
 }
 
+// ---- logging ----
+
+/// Warnings SoundCraft logs (a plugin that fails to load, a backup it can't write) go to standard
+/// error. Without a logger they were dropped.
+#[test]
+fn logged_warnings_reach_standard_error() {
+    let dir = sandbox("log");
+    let first = invoke(&dir, &["run", "--save", "s.scraft"]);
+    assert_eq!(first.code, 0, "{}", first.stderr);
+    // A file where the backups folder should go: the next save that changes the session can't
+    // back the old one up.
+    std::fs::write(dir.join("Backups"), b"not a folder").unwrap();
+    let again = invoke(&dir, &["run", "--in", "s.scraft", "--cmd", r#"track.new={"count":1}"#, "--save", "s.scraft", "--in-place"]);
+    assert_eq!(again.code, 0, "{}", again.stderr);
+    assert!(again.stderr.contains("warning: no backup of"), "{}", again.stderr);
+    assert!(!again.stdout.contains("no backup"), "results only on standard output: {}", again.stdout);
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
 // ---- unknown flags ----
 
 #[test]

apps/soundcraft-cli/tests/it/cli.rs

@@ -253,3 +253,31 @@ fn script_bounce_without_range_covers_the_session() {
     assert!((secs - 19.2).abs() < 0.01, "bounced {secs} s: {stdout}");
     let _ = std::fs::remove_dir_all(base);
 }
+
+/// `commands --json` lists every command with the details `describe` prints for one (#744).
+#[test]
+fn commands_json_lists_what_describe_prints() {
+    let json = |o: &Output| -> Value {
+        assert!(o.status.success(), "{}", String::from_utf8_lossy(&o.stderr));
+        serde_json::from_slice(&o.stdout).unwrap()
+    };
+    let all = json(&run(&["commands", "--json"]));
+    let all = all.as_array().unwrap();
+    let table = run(&["commands"]);
+    assert_eq!(all.len(), String::from_utf8_lossy(&table.stdout).lines().count());
+    let bounce = json(&run(&["describe", "file.bounce_mix"]));
+    assert!(all.contains(&bounce), "{bounce}");
+    assert!(all.iter().all(|c| c["id"].is_string() && c["params"].is_string() && c["menu"].is_array()));
+    // The filter applies, and --compact prints one line.
+    let compact = run(&["commands", "bounce", "--json", "--compact"]);
+    assert_eq!(String::from_utf8_lossy(&compact.stdout).lines().count(), 1);
+    let some = json(&compact);
+    let some = some.as_array().unwrap();
+    assert!(some.contains(&bounce) && some.len() < all.len(), "{some:?}");
+    // No match is an empty list, still JSON.
+    assert_eq!(json(&run(&["commands", "zzzzqq", "--json"])), Value::Array(Vec::new()));
+    // --compact shapes JSON output only.
+    let bad = run(&["commands", "--compact"]);
+    assert_eq!(bad.status.code(), Some(2));
+    assert!(String::from_utf8_lossy(&bad.stderr).contains("--json"), "{}", String::from_utf8_lossy(&bad.stderr));
+}

apps/soundcraft-cli/tests/it/run.rs

@@ -151,7 +151,7 @@ fn every_subcommand_has_help_listing_its_arguments() {
         ),
         ("run", "run [OPTIONS]", &["--cmd <ID[=JSON]>"]),
         ("script", "script [OPTIONS] <FILE>", &["<FILE>", "--keep-going"]),
-        ("commands", "commands [FILTER]", &["[FILTER]"]),
+        ("commands", "commands [OPTIONS] [FILTER]", &["[FILTER]", "--json", "--compact"]),
         ("describe", "describe [OPTIONS] <ID>", &["<ID>", "--compact"]),
         (
             "app",

crates/clap-host/src/ffi.rs

@@ -27,6 +27,7 @@ use clap_sys::ext::note_ports::{CLAP_EXT_NOTE_PORTS, clap_note_port_info, clap_p
 use clap_sys::ext::params::{
     CLAP_EXT_PARAMS, clap_host_params, clap_param_clear_flags, clap_param_info, clap_param_rescan_flags, clap_plugin_params,
 };
+use clap_sys::ext::render::{CLAP_EXT_RENDER, CLAP_RENDER_OFFLINE, CLAP_RENDER_REALTIME, clap_plugin_render};
 use clap_sys::ext::state::{CLAP_EXT_STATE, clap_host_state, clap_plugin_state};
 use clap_sys::factory::plugin_factory::{CLAP_PLUGIN_FACTORY_ID, clap_plugin_factory};
 use clap_sys::fixedpoint::{CLAP_BEATTIME_FACTOR, CLAP_SECTIME_FACTOR};

crates/clap-host/src/ffi/bundle.rs

@@ -7,6 +7,7 @@ use super::{
     clap_host, clap_plugin_audio_ports, clap_plugin_entry, clap_plugin_factory, clap_plugin_gui, clap_plugin_latency, clap_plugin_note_ports,
     clap_plugin_params, clap_plugin_state, clap_version_is_compatible, read_cstr, scan,
 };
+use super::{CLAP_EXT_RENDER, clap_plugin_render};
 
 // ---- loaded binaries -----------------------------------------------------------------------
 
@@ -42,6 +43,16 @@ fn loaded() -> &'static Mutex<HashMap<PathBuf, Arc<Bundle>>> {
     L.get_or_init(|| Mutex::new(HashMap::new()))
 }
 
+/// A libloading error with the system's reason. libloading's own text is only "dlopen failed"
+/// (or "dlsym failed", "LoadLibraryExW failed"); the reason (`dlerror`, the Windows error) is its
+/// source.
+fn with_reason(e: &libloading::Error) -> String {
+    match std::error::Error::source(e) {
+        Some(why) => format!("{e}: {why}"),
+        None => e.to_string(),
+    }
+}
+
 impl Bundle {
     /// Loads (once per path, then cached for the life of the process) and initialises a `.clap`.
     pub fn load(path: &Path) -> Result<Arc<Bundle>, ClapError> {
@@ -59,12 +70,12 @@ impl Bundle {
         let exe = scan::bundle_executable(path).ok_or_else(|| err("no loadable binary".into()))?;
         // SAFETY: loading a shared library runs its static initialisers. That is inherent to
         // hosting plugins; we only load files found in CLAP plugin folders or named explicitly.
-        let lib = unsafe { libloading::Library::new(&exe) }.map_err(|e| err(e.to_string()))?;
+        let lib = unsafe { libloading::Library::new(&exe) }.map_err(|e| err(with_reason(&e)))?;
         // SAFETY: `clap_entry` is the CLAP-mandated exported data symbol of type
         // `const clap_plugin_entry`; the symbol's address is therefore a `*const clap_plugin_entry`.
         let entry: *const clap_plugin_entry = match unsafe { lib.get::<*const clap_plugin_entry>(b"clap_entry\0") } {
             Ok(sym) => *sym,
-            Err(e) => return Err(err(format!("not a CLAP plugin: {e}"))),
+            Err(e) => return Err(err(format!("not a CLAP plugin (no clap_entry): {}", with_reason(&e)))),
         };
         if entry.is_null() {
             return Err(err("null clap_entry".into()));
@@ -178,6 +189,7 @@ impl Bundle {
             latency: std::ptr::null(),
             notes: std::ptr::null(),
             state_ext: std::ptr::null(),
+            render: std::ptr::null(),
             gui: Arc::new(GuiLink::default()),
             raw: Vec::with_capacity(EVENT_CAP),
             out_params: Vec::with_capacity(EVENT_CAP),
@@ -205,6 +217,7 @@ impl Bundle {
         inst.latency = inst.extension::<clap_plugin_latency>(CLAP_EXT_LATENCY);
         inst.notes = inst.extension::<clap_plugin_note_ports>(CLAP_EXT_NOTE_PORTS);
         inst.state_ext = inst.extension::<clap_plugin_state>(CLAP_EXT_STATE);
+        inst.render = inst.extension::<clap_plugin_render>(CLAP_EXT_RENDER);
         let gui = inst.extension::<clap_plugin_gui>(CLAP_EXT_GUI);
         inst.gui = Arc::new(GuiLink {
             inner: Mutex::new(GuiInner { plugin, gui, state: inst.state_ext, alive: true, created: false, visible: false, window: None }),

crates/clap-host/src/ffi/gui.rs

@@ -17,9 +17,11 @@ pub(crate) fn on_main_thread() -> bool {
     unsafe { pthread_main_np() == 1 }
 }
 
+/// True on the process's main thread: Rust names it "main", and the app runs its UI there (the
+/// rule `hostwin` and the VST3 host use). CLAP makes `clap.gui` main-thread only on every platform.
 #[cfg(not(target_os = "macos"))]
 pub(crate) fn on_main_thread() -> bool {
-    true
+    std::thread::current().name() == Some("main")
 }
 
 /// The windowing API of this platform.

crates/clap-host/src/ffi/instance.rs

@@ -8,6 +8,7 @@ use super::{
     clap_plugin, clap_plugin_audio_ports, clap_plugin_latency, clap_plugin_note_ports, clap_plugin_params, clap_plugin_state, clap_process,
     read_name,
 };
+use super::{CLAP_RENDER_OFFLINE, CLAP_RENDER_REALTIME, clap_plugin_render};
 
 // ---- audio buffers -------------------------------------------------------------------------
 
@@ -99,6 +100,7 @@ pub(crate) struct Instance {
     pub(super) latency: *const clap_plugin_latency,
     pub(super) notes: *const clap_plugin_note_ports,
     pub(super) state_ext: *const clap_plugin_state,
+    pub(super) render: *const clap_plugin_render,
     pub(super) gui: Arc<GuiLink>,
     pub(super) raw: Vec<RawEvent>,
     /// Parameter values the plugin reported through output events in the current `process`.
@@ -158,6 +160,16 @@ impl Instance {
         unsafe { load(self.plugin, &stream) }
     }
 
+    /// `clap_plugin_render.set`: offline (no realtime pressure) or realtime. `false` without the
+    /// extension or when the plugin can't switch.
+    pub fn set_render_mode(&self, offline: bool) -> bool {
+        // SAFETY: the extension pointer, when non-null, points to a static vtable in the plugin.
+        let Some(set) = (unsafe { self.render.as_ref() }).and_then(|r| r.set) else { return false };
+        let mode = if offline { CLAP_RENDER_OFFLINE } else { CLAP_RENDER_REALTIME };
+        // SAFETY: valid instance, called from the thread that owns it.
+        unsafe { set(self.plugin, mode) }
+    }
+
     /// Runs `on_main_thread` if the plugin asked for a callback.
     pub fn service_callback(&mut self) {
         if self.state.callback.swap(false, Ordering::Relaxed)

crates/clap-host/src/lib.rs

@@ -262,4 +262,17 @@ mod tests {
         assert!(instantiate("clap:does.not.exist").is_err());
         let _ = std::fs::remove_dir_all(&d);
     }
+
+    /// A binary the system refuses to load reports the system's reason (missing library, wrong
+    /// glibc, not an ELF file), not just "dlopen failed".
+    #[test]
+    fn a_binary_that_does_not_load_says_why() {
+        let d = fresh_private_dir("soundcraft-clap-reason");
+        let f = d.join("garbage.clap");
+        std::fs::write(&f, b"\x7fELF this is not a plugin \x00\x01\x02").unwrap();
+        let msg = load_bundle(&f).err().map(|e| e.to_string()).unwrap_or_default();
+        let reason = msg.split_once("failed: ").map_or("", |(_, r)| r.trim());
+        assert!(!reason.is_empty(), "no reason in: {msg}");
+        let _ = std::fs::remove_dir_all(&d);
+    }
 }

crates/clap-host/src/plugin.rs

@@ -178,6 +178,11 @@ impl Plugin for ClapPlugin {
         }
     }
 
+    fn set_offline(&mut self, offline: bool) {
+        // `clap.render`: plugins without it render the same way either way.
+        self.inst.set_render_mode(offline);
+    }
+
     fn reset(&mut self) {
         self.inst.reset();
         self.queue.retain(|e| matches!(e, Event::Param { .. }));

crates/clap-host/src/scan.rs

@@ -150,7 +150,9 @@ mod tests {
     fn tmp(name: &str) -> PathBuf {
         let d = std::env::temp_dir().join(format!("soundcraft-clap-scan-{name}-{}", std::process::id()));
         let _ = std::fs::remove_dir_all(&d);
-        std::fs::create_dir_all(&d).unwrap();
+        // Created exclusively: a folder still there after the cleanup (someone else's) would
+        // let a link inside it redirect the test's writes.
+        std::fs::create_dir(&d).unwrap();
         d
     }
 

crates/clap-host/tests/editor_main_thread.rs

@@ -5,6 +5,7 @@
 mod common;
 
 use soundcraft_dsp::Plugin;
+use std::sync::Mutex;
 
 const GAIN: &str = "clap:org.soundcraft.test.gain";
 
@@ -14,12 +15,31 @@ fn block(p: &mut Box<dyn Plugin>) -> Vec<Vec<f32>> {
     io
 }
 
+/// The warnings logged, to tell which way the host went.
+static WARNINGS: Mutex<Vec<String>> = Mutex::new(Vec::new());
+
+struct Warnings;
+
+impl log::Log for Warnings {
+    fn enabled(&self, m: &log::Metadata) -> bool {
+        m.level() <= log::Level::Warn
+    }
+    fn log(&self, r: &log::Record) {
+        if self.enabled(r.metadata()) {
+            WARNINGS.lock().unwrap().push(r.args().to_string());
+        }
+    }
+    fn flush(&self) {}
+}
+
 fn main() {
     // nextest lists custom-harness tests with `--list`; each binary here is one test.
     if std::env::args().any(|a| a == "--list") {
         println!("editor_main_thread: test");
         return;
     }
+    log::set_logger(&Warnings).expect("logger");
+    log::set_max_level(log::LevelFilter::Warn);
     common::fixture_dir();
     let mut p = soundcraft_clap_host::create(GAIN).expect("fixture");
     p.prepare(48_000.0, 64, 2);
@@ -32,6 +52,26 @@ fn main() {
     // block and is reported (in SoundCraft units) by idle.
     let io = block(&mut p);
     assert!((io[0][10] - 0.25).abs() < 1e-6, "{}", io[0][10]);
+    // Only the main thread drives the editor, on every platform (#901). Another thread, named or
+    // not, is refused: it neither takes the edit idle reports nor closes or reopens the editor.
+    for name in [None, Some("soundcraft-ui")] {
+        let mut other = p.editor().expect("editor handle");
+        let thread = match name {
+            Some(n) => std::thread::Builder::new().name(n.to_string()),
+            None => std::thread::Builder::new(),
+        };
+        let seen = thread
+            .spawn(move || {
+                let edits = other.idle();
+                other.close();
+                (edits, other.open().map_err(|e| e.contains("main thread")))
+            })
+            .expect("spawn")
+            .join()
+            .expect("no panic");
+        assert_eq!(seen, (Vec::new(), Err(true)), "{name:?}");
+        assert!(ed.is_open(), "{name:?}");
+    }
     assert_eq!(ed.idle(), vec![("7".to_string(), 0.25)]);
     assert!(ed.idle().is_empty(), "drained");
     ed.close();
@@ -49,5 +89,17 @@ fn main() {
     assert!(ed.open().is_err());
     assert!(ed.idle().is_empty());
     ed.close();
+    // #901: a plugin dropped on another thread with its editor open (an audio callback dropped
+    // by the device's thread) does not destroy the editor there, clap.gui being main-thread only:
+    // it warns and leaves it.
+    let mut p = soundcraft_clap_host::create(GAIN).expect("fixture");
+    p.prepare(48_000.0, 64, 2);
+    let mut ed = p.editor().expect("editor handle");
+    ed.open().expect("open on the main thread");
+    std::thread::Builder::new().name("audio".into()).spawn(move || drop(p)).expect("spawn").join().expect("no panic");
+    let left = "clap: editor still open while its plugin is destroyed off the main thread";
+    assert!(WARNINGS.lock().unwrap().iter().any(|w| w == left), "{:?}", WARNINGS.lock().unwrap());
+    assert!(!ed.is_open());
+    assert!(ed.open().is_err());
     println!("editor_main_thread: ok");
 }

crates/clap-host/tests/fixture/src/lib.rs

@@ -9,7 +9,8 @@
 //! - `org.soundcraft.test.wide16`, `.wide17ports`, `.wide65ch`: effects advertising wide layouts
 //!   (16 ports of 64 channels, 17 ports of 2 channels, one port of 65 channels per direction).
 //!   `process` writes 1.0 into every output channel it was given when the host's buffers match the
-//!   advertised layout, -1.0 when they do not.
+//!   advertised layout (2.0 once the host set the offline render mode through `clap.render`), -1.0
+//!   when they do not.
 //!
 //! The gain plugin also implements `clap.state` (gain and mode as two little-endian f64s) and a
 //! floating-only `clap.gui` without a real window: showing it "edits" the gain to 0.25 in the GUI,
@@ -27,6 +28,7 @@ use clap_sys::ext::latency::*;
 use clap_sys::ext::log::*;
 use clap_sys::ext::note_ports::*;
 use clap_sys::ext::params::*;
+use clap_sys::ext::render::*;
 use clap_sys::factory::plugin_factory::*;
 use clap_sys::host::clap_host;
 use clap_sys::id::clap_id;
@@ -100,8 +102,12 @@ struct Fx {
     active: bool,
     processing: bool,
     gui_created: bool,
+    /// The thread that created the GUI (the host's main thread).
+    gui_thread: Option<std::thread::ThreadId>,
     gui_visible: bool,
     gui_edit_pending: bool,
+    /// `clap.render` set the offline mode (wide fixtures only).
+    offline: bool,
 }
 
 unsafe fn fx<'a>(p: *const clap_plugin) -> &'a mut Fx {
@@ -126,7 +132,10 @@ unsafe extern "C" fn init(p: *const clap_plugin) -> bool {
 }
 
 unsafe extern "C" fn destroy(p: *const clap_plugin) {
-    assert!(!unsafe { fx(p) }.gui_created, "plugin destroyed with its GUI alive");
+    let f = unsafe { fx(p) };
+    // A host destroying the plugin off the GUI's thread can't destroy the GUI there (clap.gui is
+    // main-thread only), so it may leave it; on the GUI's thread it must destroy it first.
+    assert!(!f.gui_created || f.gui_thread != Some(std::thread::current().id()), "plugin destroyed with its GUI alive");
     let data = unsafe { (*p).plugin_data } as *mut Fx;
     drop(unsafe { Box::from_raw(data) });
 }
@@ -189,8 +198,8 @@ fn apply(f: &mut Fx, h: &clap_event_header) {
     }
 }
 
-/// Fill every output channel with 1.0 when all ports have the wide layout, else -1.0.
-unsafe fn fill_wide(pr: &clap_process, ports: u32, channels: u32, n: usize) {
+/// Fill every output channel with `fit` when all ports have the wide layout, else -1.0.
+unsafe fn fill_wide(pr: &clap_process, ports: u32, channels: u32, n: usize, fit: f32) {
     let fits = |bufs: *const clap_audio_buffer, n: u32| {
         n == ports && (0..n as usize).all(|i| unsafe { &*bufs.add(i) }.channel_count == channels)
     };
@@ -200,7 +209,7 @@ unsafe fn fill_wide(pr: &clap_process, ports: u32, channels: u32, n: usize) {
         for c in 0..out.channel_count as usize {
             let o = unsafe { *out.data32.add(c) };
             for i in 0..n {
-                unsafe { *o.add(i) = if ok { 1.0 } else { -1.0 } };
+                unsafe { *o.add(i) = if ok { fit } else { -1.0 } };
             }
         }
     }
@@ -252,7 +261,7 @@ unsafe extern "C" fn process(p: *const clap_plugin, pr: *const clap_process) ->
     let ev = unsafe { &*pr.in_events };
     let count = unsafe { (ev.size.unwrap())(pr.in_events) };
     if let Some((ports, channels)) = f.wide {
-        unsafe { fill_wide(pr, ports, channels, n) };
+        unsafe { fill_wide(pr, ports, channels, n, if f.offline { 2.0 } else { 1.0 }) };
         return CLAP_PROCESS_CONTINUE;
     }
     if pr.audio_outputs_count != 1 {
@@ -488,6 +497,7 @@ unsafe extern "C" fn gui_create(p: *const clap_plugin, _api: *const c_char, floa
     let f = unsafe { fx(p) };
     assert!(floating && !f.gui_created, "create");
     f.gui_created = true;
+    f.gui_thread = Some(std::thread::current().id());
     true
 }
 
@@ -543,6 +553,17 @@ static GUI: clap_plugin_gui = clap_plugin_gui {
     hide: Some(gui_hide),
 };
 
+unsafe extern "C" fn render_hard_realtime(_p: *const clap_plugin) -> bool {
+    false
+}
+
+unsafe extern "C" fn render_set(p: *const clap_plugin, mode: clap_plugin_render_mode) -> bool {
+    unsafe { fx(p) }.offline = mode == CLAP_RENDER_OFFLINE;
+    true
+}
+
+static RENDER: clap_plugin_render = clap_plugin_render { has_hard_realtime_requirement: Some(render_hard_realtime), set: Some(render_set) };
+
 unsafe extern "C" fn get_extension(p: *const clap_plugin, id: *const c_char) -> *const c_void {
     let id = unsafe { CStr::from_ptr(id) };
     let synth = unsafe { fx(p) }.synth;
@@ -558,6 +579,8 @@ unsafe extern "C" fn get_extension(p: *const clap_plugin, id: *const c_char) ->
         &STATE as *const _ as *const c_void
     } else if id == CLAP_EXT_GUI && !synth {
         &GUI as *const _ as *const c_void
+    } else if id == CLAP_EXT_RENDER && unsafe { fx(p) }.wide.is_some() {
+        &RENDER as *const _ as *const c_void
     } else {
         std::ptr::null()
     }
@@ -621,8 +644,10 @@ unsafe extern "C" fn factory_create(_f: *const clap_plugin_factory, host: *const
         active: false,
         processing: false,
         gui_created: false,
+        gui_thread: None,
         gui_visible: false,
         gui_edit_pending: false,
+        offline: false,
     });
     let raw = Box::into_raw(b);
     unsafe {

crates/clap-host/tests/it/fixture_e2e.rs

@@ -130,6 +130,19 @@ fn layouts_beyond_the_host_limits_are_rejected_not_truncated() {
     }
 }
 
+#[test]
+fn offline_renders_set_the_render_mode() {
+    fixture_dir();
+    for (offline, want) in [(false, 1.0), (true, 2.0)] {
+        let mut p = soundcraft_clap_host::create("clap:org.soundcraft.test.wide16").unwrap();
+        p.set_offline(offline);
+        p.prepare(44_100.0, 64, 2);
+        let mut io = vec![vec![0.5f32; 64]; 2];
+        p.process(&mut io, 64);
+        assert!(io.iter().flatten().all(|&x| x == want), "offline {offline}: {:?}", &io[0][..4]);
+    }
+}
+
 #[test]
 fn many_instances_create_and_drop_cleanly() {
     fixture_dir();
@@ -202,14 +215,12 @@ fn state_reader_reads_while_another_thread_processes() {
 #[test]
 fn editors_refuse_to_open_off_the_main_thread() {
     fixture_dir();
-    // Test threads are never the process main thread.
+    // Test threads are never the process main thread, on any platform (#901).
     let mut p = soundcraft_clap_host::create(GAIN).unwrap();
     let mut ed = p.editor().expect("the gain fixture has clap.gui");
-    if cfg!(target_os = "macos") {
-        assert!(ed.open().unwrap_err().contains("main thread"));
-        assert!(p.open_editor().is_err());
-        assert!(!ed.is_open());
-    }
+    assert!(ed.open().unwrap_err().contains("main thread"));
+    assert!(p.open_editor().is_err());
+    assert!(!ed.is_open());
     ed.close();
     p.close_editor();
 }

crates/dsp/src/lib.rs

@@ -195,6 +195,11 @@ pub struct Transport {
 pub trait Plugin: Send {
     fn info(&self) -> &'static PluginInfo;
     fn prepare(&mut self, sample_rate: f32, max_block: usize, channels: usize);
+    /// The plugin renders offline (a bounce: faster or slower than realtime, no deadline) rather
+    /// than in realtime. Hosted plugins pass it on (VST3 `processMode`, CLAP `clap.render`): some
+    /// use better algorithms then, or wait for what they load instead of playing on without it.
+    /// Called before `prepare`; plugins are realtime until told otherwise.
+    fn set_offline(&mut self, _offline: bool) {}
     fn reset(&mut self);
     /// Sets a parameter (clamped into range; NaN becomes the default). `false` if `id` is unknown.
     fn set_param(&mut self, id: &str, value: f32) -> bool;

crates/engine/src/autosave.rs

@@ -212,6 +212,11 @@ impl Autosave {
         let audio_dir = self.dir.join("Audio Files");
         let mut s = session.clone();
         let mut copies = BTreeMap::new();
+        // Copies made in this write, by the audio they hold: sources sharing one decoded buffer
+        // (a session may name one file under many ids) share one file.
+        let mut written: BTreeMap<*const SourceAudio, String> = BTreeMap::new();
+        // Copies still to make, written once the size is checked; their numbers are taken then too.
+        let (mut fresh, mut next) = (Vec::new(), self.next);
         for src in &mut s.sources {
             let file = if Path::new(&src.path).is_absolute() { Some(PathBuf::from(&src.path)) } else { base.as_ref().map(|b| b.join(&src.path)) };
             let audio = s.pool.get(src.id);
@@ -222,26 +227,37 @@ impl Autosave {
                 continue;
             }
             let Some(audio) = audio else { continue };
-            let name = match self.copies.remove(&src.id) {
-                Some((copy, name)) if copy.upgrade().is_some_and(|a| Arc::ptr_eq(&a, audio)) => name,
+            let name = match self.copies.get(&src.id) {
+                Some((copy, name)) if copy.upgrade().is_some_and(|a| Arc::ptr_eq(&a, audio)) => name.clone(),
+                _ if written.contains_key(&Arc::as_ptr(audio)) => written.get(&Arc::as_ptr(audio)).cloned().unwrap_or_default(),
                 _ => {
-                    let name = format!("{} {}.wav", sanitize_name(&src.name), self.next);
-                    self.next += 1;
-                    let opts = EncodeOptions { format: FileFormat::Wav, bit_depth: BitDepth::Float32, dither: false, bwf: None };
-                    let bytes = soundcraft_audio_io::encode(&audio.buffer, &opts).map_err(|err| EngineError::Io(err.to_string()))?;
-                    create_folder(&audio_dir).and_then(|()| write_synced(&audio_dir.join(&name), &bytes)).map_err(|err| io_error(&audio_dir, err))?;
+                    let name = format!("{} {}.wav", sanitize_name(&src.name), next);
+                    next += 1;
+                    fresh.push((name.clone(), Arc::clone(audio)));
                     name
                 }
             };
             src.path = audio_dir.join(&name).to_string_lossy().into_owned();
             src.unsaved = true;
+            written.insert(Arc::as_ptr(audio), name.clone());
             copies.insert(src.id, (Arc::downgrade(audio), name));
         }
         let text = s.to_json().map_err(|err| EngineError::Io(err.to_string()))?;
+        // An autosave too large to recover is not written, nor its new copies: the last autosave
+        // stays as it was, and the failure is reported (#892).
+        crate::io::session_size("the autosave", text.len() as u64, true)?;
+        self.next = next;
+        for (name, audio) in &fresh {
+            let opts = EncodeOptions { format: FileFormat::Wav, bit_depth: BitDepth::Float32, dither: false, bwf: None };
+            let bytes = soundcraft_audio_io::encode(&audio.buffer, &opts).map_err(|err| EngineError::Io(err.to_string()))?;
+            create_folder(&audio_dir).and_then(|()| write_synced(&audio_dir.join(name), &bytes)).map_err(|err| io_error(&audio_dir, err))?;
+        }
         write_atomically(&self.dir.join(ORIGIN), origin.unwrap_or_default().as_bytes())?;
         write_atomically(&self.dir.join(SESSION), text.as_bytes())?;
         for (_, name) in std::mem::replace(&mut self.copies, copies).into_values() {
-            let _ = std::fs::remove_file(audio_dir.join(name));
+            if !self.copies.values().any(|(_, kept)| *kept == name) {
+                let _ = std::fs::remove_file(audio_dir.join(name));
+            }
         }
         if let Some(r) = recording {
             let plan = serde_json::to_string(r).map_err(|err| EngineError::Io(err.to_string()))?;
@@ -290,9 +306,7 @@ pub fn leftovers(root: &Path) -> Vec<Leftover> {
         drop(lock);
         match saved {
             Ok(saved) if recording || origin_saved.is_none_or(|o| saved > o) => {
-                let text = std::fs::read_to_string(dir.join(SESSION)).unwrap_or_default();
-                let named = serde_json::from_str::<serde_json::Value>(&text).ok().and_then(|v| v.get("name")?.as_str().map(str::to_string));
-                let name = named.unwrap_or_else(|| dir.file_name().unwrap_or_default().to_string_lossy().into_owned());
+                let name = saved_name(&dir.join(SESSION)).unwrap_or_else(|| dir.file_name().unwrap_or_default().to_string_lossy().into_owned());
                 out.push(Leftover { dir, name, origin, saved, recording });
             }
             _ => {
@@ -304,6 +318,21 @@ pub fn leftovers(root: &Path) -> Vec<Leftover> {
     out
 }
 
+/// The name of the session saved in `file`, read without keeping the rest of it; `None` when the
+/// file is missing, not a session, or too large to open (#892).
+fn saved_name(file: &Path) -> Option<String> {
+    use std::io::Read as _;
+    #[derive(serde::Deserialize)]
+    struct Named {
+        name: String,
+    }
+    if std::fs::metadata(file).ok()?.len() > crate::io::session_limit() {
+        return None;
+    }
+    let read = std::fs::File::open(file).ok()?.take(crate::io::session_limit());
+    serde_json::from_reader::<_, Named>(std::io::BufReader::new(read)).ok().map(|n| n.name)
+}
+
 /// Open `left` as an unsaved version of the session it came from, so Save writes it back there,
 /// with the takes of a recording that never finished placed as Stop would have. Returns the
 /// media that couldn't be loaded.
@@ -507,6 +536,25 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    #[test]
+    fn sources_sharing_one_buffer_share_one_copy() {
+        let dir = folder("autosave-aliases");
+        let mut e = Engine::default();
+        record(&mut e, 0.5);
+        // Nine more source ids over the same decoded audio, as a session file may declare.
+        let s = e.session_mut();
+        let (src, audio) = (s.sources[0].clone(), s.pool.get(s.sources[0].id).cloned().unwrap());
+        for _ in 0..9 {
+            let id = SourceId(s.alloc());
+            s.sources.push(soundcraft_model::Source { id, ..src.clone() });
+            s.pool.insert(id, audio.clone());
+        }
+        let mut a = Autosave::create(&dir.join("Autosave"), "Song").unwrap();
+        a.write(e.session(), None, None).unwrap();
+        assert_eq!(std::fs::read_dir(a.dir.join("Audio Files")).unwrap().count(), 1, "one file for the ten ids");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     fn a_take_recorded_after_undo_gets_its_own_copy() {
         let dir = folder("autosave-undo");
@@ -673,6 +721,70 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    /// A test folder, removed when the test ends, passed or not.
+    struct Gone(PathBuf);
+
+    impl Drop for Gone {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_dir_all(&self.0);
+        }
+    }
+
+    #[test]
+    fn an_autosave_too_large_to_open_writes_nothing_and_keeps_the_last() {
+        // #892, with the limit lowered for this test: a refused autosave makes no audio copies
+        // and keeps the last autosave and its copies as they were.
+        let dir = Gone(folder("autosave-too-large"));
+        let mut e = Engine::default();
+        record(&mut e, 0.5);
+        let mut a = Autosave::create(&dir.0.join("Autosave"), "Song").unwrap();
+        a.write(e.session(), None, None).unwrap();
+        let state = |a: &Autosave| {
+            let mut files: Vec<String> =
+                std::fs::read_dir(a.dir.join("Audio Files")).unwrap().map(|f| f.unwrap().file_name().to_string_lossy().into_owned()).collect();
+            files.sort();
+            let copies: Vec<(SourceId, String)> = a.copies.iter().map(|(id, (_, name))| (*id, name.clone())).collect();
+            (files, copies, a.next, std::fs::read_to_string(a.dir.join(SESSION)).unwrap())
+        };
+        let before = state(&a);
+        record(&mut e, 0.25);
+        {
+            let _limit = crate::io::SessionLimit::set(before.3.len() as u64);
+            for _ in 0..2 {
+                let err = a.write(e.session(), None, None).unwrap_err().to_string();
+                assert!(err.starts_with("the autosave is too large to save"), "{err}");
+                assert!(state(&a) == before);
+            }
+            // The writer thread reports it as it reports any failed autosave.
+            let failure = Arc::new(Mutex::new(None));
+            let pending = Some((e.session_arc(), None, None));
+            let mut w = Writer { root: dir.0.join("Writer"), failure: Arc::clone(&failure), folder: None, pending, last: None, written: Ok(()) };
+            w.write_pending();
+            let reported = failure.lock().unwrap().take().unwrap_or_default();
+            assert!(reported.starts_with("the autosave is too large to save"), "{reported}");
+        }
+        a.write(e.session(), None, None).unwrap();
+        let after = state(&a);
+        assert_eq!((after.0.len(), after.1.len()), (2, 2));
+        assert!(after.0.contains(&before.0[0]));
+    }
+
+    #[test]
+    fn a_leftover_is_named_from_its_session_without_reading_a_huge_one() {
+        // #892: the name is read on its own, and an autosave too large to open is not read.
+        let dir = Gone(folder("autosave-names"));
+        std::fs::create_dir_all(&dir.0).unwrap();
+        let file = dir.0.join(SESSION);
+        let s = Session { name: "Song".into(), ..Session::default() };
+        std::fs::write(&file, s.to_json().unwrap()).unwrap();
+        assert_eq!(saved_name(&file).as_deref(), Some("Song"));
+        std::fs::write(&file, r#"{"name": 5}"#).unwrap();
+        assert_eq!(saved_name(&file), None);
+        std::fs::File::create(&file).unwrap().set_len(crate::io::MAX_SESSION_BYTES + 1).unwrap();
+        assert_eq!(saved_name(&file), None);
+        assert_eq!(saved_name(&dir.0.join("none")), None);
+    }
+
     #[test]
     fn sessions_started_together_get_folders_of_their_own() {
         // #579: the folder name has millisecond resolution, so two sessions created back to back

crates/engine/src/cmd.rs

@@ -347,7 +347,10 @@ pub fn clip_id(p: &Value, cmd: &str) -> Result<ClipId> {
 
 pub fn clip_ids_param(e: &Engine, p: &Value) -> Vec<ClipId> {
     if let Some(arr) = p.get("clips").and_then(Value::as_array) {
-        return arr.iter().filter_map(Value::as_u64).map(ClipId).collect();
+        // Each clip once, in the order given: a repeated id would otherwise be processed (and,
+        // for a render, re-rendered into another source) once per repeat.
+        let mut seen = std::collections::HashSet::new();
+        return arr.iter().filter_map(Value::as_u64).map(ClipId).filter(|id| seen.insert(*id)).collect();
     }
     if let Some(n) = p.get("clip").and_then(Value::as_u64) {
         return vec![ClipId(n)];

crates/engine/src/cmd/audiosuite.rs

@@ -14,7 +14,7 @@ pub fn specs() -> Vec<CommandSpec> {
         "AudioSuite Process",
         [],
         None,
-        "{process: <plugin id> | normalize | reverse | invert | gain | duplicate | time_stretch | pitch_shift | varispeed | speed_ramp | signal_generator, params?: {..}, clips?, tracks?, start?, end?} — signal_generator fills start..end (default: the selection) with a new clip on each audio track in `tracks` (default: the selected tracks); speed_ramp takes change (0 slow down, 1 speed up), selection (0 fit to, 1 extend) and fades (1 on, 0 off)",
+        "{process: <built-in plugin id (engine.plugins)> | normalize | reverse | invert | gain | duplicate | time_stretch | pitch_shift | varispeed | speed_ramp | signal_generator, params?: {..}, clips?, tracks?, start?, end?} — signal_generator fills start..end (default: the selection) with a new clip on each audio track in `tracks` (default: the selected tracks); speed_ramp takes change (0 slow down, 1 speed up), selection (0 fit to, 1 extend) and fades (1 on, 0 off)",
         has_selection,
         process
     )]
@@ -55,6 +55,9 @@ fn process(e: &mut Engine, p: &Value) -> Result<Value> {
                 | "speed_ramp"
                 | "dc_offset_removal"
         );
+    if !known && soundcraft_mix::is_third_party(&name) {
+        return Err(bad("audiosuite.process", format!("`{name}` is a hosted plugin; AudioSuite runs built-in plugins only (engine.plugins)")));
+    }
     if !known {
         return Err(bad("audiosuite.process", format!("unknown process `{name}`")));
     }
@@ -228,6 +231,17 @@ mod tests {
         (crate::Engine::new(s), id)
     }
 
+    #[test]
+    fn hosted_plugin_ids_are_refused_with_the_reason() {
+        let (mut e, id) = gained_clip();
+        for plugin in ["clap:com.example.reverb", "vst3:00112233445566778899AABBCCDDEEFF", "au:aufx:dely:appl"] {
+            let err = e.execute("audiosuite.process", &json!({"process": plugin, "clips": [id.0]})).unwrap_err().to_string();
+            assert!(err.contains("built-in"), "{plugin}: {err}");
+        }
+        let spec = specs().into_iter().find(|s| s.id == "audiosuite.process").unwrap();
+        assert!(spec.params.contains("<built-in plugin id"), "the help says which ids it takes: {}", spec.params);
+    }
+
     #[test]
     fn invert_and_duplicate_keep_clip_gain() {
         let (mut e, id) = gained_clip();

crates/engine/src/cmd/clip.rs

@@ -425,7 +425,7 @@ fn quantize_to_grid(e: &mut Engine, p: &Value) -> Result<Value> {
     let ids = clip_ids_param(e, p);
     let s = e.session();
     let moves: Vec<(soundcraft_model::ClipId, i64)> =
-        ids.iter().filter_map(|id| s.find_clip(*id).map(|(_, c)| (*id, crate::edit::grid_delta(s, c, 0, false)))).collect();
+        ids.iter().filter_map(|id| s.find_clip(*id).map(|(_, c)| (*id, crate::edit::grid_delta(s, c, 0, false, &ids)))).collect();
     let s = e.session_mut();
     for (id, d) in &moves {
         crate::edit::move_clips(s, &[*id], *d, &[]);

crates/engine/src/cmd/edit.rs

@@ -301,6 +301,7 @@ fn cut_copy(e: &mut Engine, p: &Value, cut: bool, id: &str) -> Result<Value> {
             cut_track(s, *t, range, sh, follow);
         }
         s.edit.selection = soundcraft_time::Range::point(range.start);
+        cb.cut_from = Some(range.start);
     }
     let n: usize = cb.tracks.iter().map(Vec::len).sum();
     e.clipboard = cb;
@@ -328,6 +329,7 @@ pub(super) fn clipboard_for_paste(e: &mut Engine) -> Clipboard {
     cb
 }
 
+/// Pastes the clipboard at an explicit position or at the current edit insertion point.
 fn paste(e: &mut Engine, p: &Value) -> Result<Value> {
     let tracks = tracks_required(e, "edit.paste", p)?;
     let given = position_param(e, "edit.paste", p, "at")?;
@@ -335,9 +337,10 @@ fn paste(e: &mut Engine, p: &Value) -> Result<Value> {
     let s = e.session();
     let at = match given {
         Some(at) => at,
-        None if s.edit.edit_mode == EditMode::GridRelative => {
-            s.edit.grid.line_at_or_before(s.edit.selection.start, s.sample_rate, &s.tempo, s.frame_rate).saturating_add(cb.grid_offset)
+        None if s.edit.edit_mode == EditMode::GridRelative && s.edit.selection.is_empty() && cb.cut_from == Some(s.edit.selection.start) => {
+            s.edit.selection.start
         }
+        None if s.edit.edit_mode == EditMode::GridRelative => s.grid_line_at_or_before(s.edit.selection.start).saturating_add(cb.grid_offset),
         None => s.edit.selection.start,
     };
     let sh = shuffle(s) && !cb.automation_only;
@@ -668,11 +671,16 @@ fn separate(e: &mut Engine, p: &Value) -> Result<Value> {
     Ok(json!({"separated": n}))
 }
 
+/// Separates selected clips at every active Grid boundary in the requested range.
 fn separate_on_grid(e: &mut Engine, p: &Value) -> Result<Value> {
     let tracks = tracks_required(e, "edit.separate_on_grid", p)?;
     let r = range_param(e, "edit.separate_on_grid", p)?;
     let s = e.session_mut();
-    let lines = s.edit.grid.lines(r.start, r.end, s.sample_rate, &s.tempo, s.frame_rate, 10_000);
+    let max = if s.edit.grid_clips_markers { usize::MAX } else { 10_001 };
+    let lines = s.grid_lines(r.start, r.end, max);
+    if lines.len() > 10_000 {
+        return Err(bad("edit.separate_on_grid", "the range contains more than 10,000 grid boundaries"));
+    }
     let mut n = 0;
     for t in &tracks {
         for at in &lines {
@@ -956,6 +964,7 @@ fn nudge(e: &mut Engine, p: &Value) -> Result<Value> {
     Ok(json!({"moved": n, "by": step}))
 }
 
+/// Same-track placement at the existing start is a no-op; quantization is a separate command.
 fn move_clips(e: &mut Engine, p: &Value) -> Result<Value> {
     let ids = clip_ids_param(e, p);
     if ids.is_empty() {
@@ -978,17 +987,21 @@ fn move_clips(e: &mut Engine, p: &Value) -> Result<Value> {
     };
     let mode = s.edit.edit_mode;
     let delta = match first {
-        Some(c) if mode.is_grid() && p.get("to").is_some() => ops::grid_delta(s, c, delta, mode == EditMode::GridRelative),
+        Some(_) if mode.is_grid() && p.get("to").is_some() && delta == 0 && dest.iter().all(|(from, to)| from == to) => 0,
+        Some(c) if mode.is_grid() && p.get("to").is_some() => ops::grid_delta(s, c, delta, mode == EditMode::GridRelative, &ids),
         _ => delta,
     };
+    let effective_delta = first.map_or(delta, |clip| delta.max(clip.start.saturating_neg()));
     let s = e.session_mut();
     let n = if mode == EditMode::Shuffle {
         ops::shuffle_clips(s, &ids, delta, &dest).map_err(|why| bad("edit.move_clips", why))?
+    } else if effective_delta == 0 && dest.iter().all(|(from, to)| from == to) {
+        0
     } else {
-        ops::move_clips(s, &ids, delta, &dest)
+        ops::move_clips(s, &ids, effective_delta, &dest)
     };
     s.edit.selected_clips = ids;
-    Ok(json!({"moved": n, "by": delta}))
+    Ok(json!({"moved": n, "by": if mode == EditMode::Shuffle { delta } else { effective_delta }}))
 }
 
 fn trim_clip(e: &mut Engine, p: &Value) -> Result<Value> {

crates/engine/src/cmd/file.rs

@@ -45,6 +45,8 @@ pub fn specs() -> Vec<CommandSpec> {
             s.sources.clear();
             s.videos.clear();
             let text = s.to_json().map_err(|err| EngineError::Io(err.to_string()))?;
+            // A template too large to open is not saved (#892).
+            crate::io::session_size(file.display(), text.len() as u64, true)?;
             if cfg!(target_arch = "wasm32") {
                 crate::io::write_file(&file.to_string_lossy(), text.as_bytes())?;
             } else {

crates/engine/src/cmd/mix.rs

@@ -598,6 +598,7 @@ fn write_current(e: &mut Engine, p: &Value, all: bool) -> Result<Value> {
 }
 
 /// Clip-gain envelope value in dB. An empty envelope contributes nothing, and the last point holds.
+#[cfg(test)]
 fn env_db(env: &[(i64, f32)], at: i64) -> f32 {
     let mut prev: Option<(i64, f32)> = None;
     for &(t, v) in env {
@@ -612,6 +613,38 @@ fn env_db(env: &[(i64, f32)], at: i64) -> f32 {
     prev.map_or(0.0, |(_, v)| v)
 }
 
+/// Repeated lookups in one clip-gain envelope, each O(log n) instead of a walk from its start.
+/// Gives exactly what walking the points in stored order gives, sorted or not: the first point
+/// at or after `at` is the first whose running maximum position reaches `at`.
+struct EnvLookup<'a> {
+    env: &'a [(i64, f32)],
+    /// Largest position among `env[..=i]`.
+    reach: Vec<i64>,
+}
+
+impl<'a> EnvLookup<'a> {
+    fn new(env: &'a [(i64, f32)]) -> Self {
+        let reach = env
+            .iter()
+            .scan(i64::MIN, |m, &(t, _)| {
+                *m = (*m).max(t);
+                Some(*m)
+            })
+            .collect();
+        EnvLookup { env, reach }
+    }
+
+    /// Value in dB at `at` (see `env_db`).
+    fn db(&self, at: i64) -> f32 {
+        let i = self.reach.partition_point(|&m| m < at);
+        let Some(&(t, v)) = self.env.get(i) else { return self.env.last().map_or(0.0, |&(_, v)| v) };
+        match i.checked_sub(1).and_then(|p| self.env.get(p)) {
+            Some(&(pt, pv)) if t > pt => pv + (v - pv) * ((at - pt) as f32 / (t - pt) as f32),
+            _ => v,
+        }
+    }
+}
+
 /// Fold the volume `lane` into the gain envelope of clip `c` over the selection `r`.
 fn bake_volume_into_clip(c: &mut soundcraft_model::Clip, lane: &soundcraft_model::AutomationLane, base: f32, r: soundcraft_time::Range) {
     let delta = |at: i64| lane.value_at(at, base) - base;
@@ -621,39 +654,41 @@ fn bake_volume_into_clip(c: &mut soundcraft_model::Clip, lane: &soundcraft_model
         return;
     }
     let rel = |at: i64| at - c.start;
+    let old_env = std::mem::take(&mut c.gain_env);
+    let env = EnvLookup::new(&old_env);
+    let env_db = |at: i64| env.db(at);
     let rel0 = rel(sel0);
     let rel1 = rel(sel1);
     // Later writes win, so the selection anchors replace any point they land on.
-    let mut pts: Vec<(i64, f32)> =
-        c.gain_env.iter().copied().filter(|&(at, _)| at < rel0.saturating_sub(1) || (sel1 < c.end() && at > rel1)).collect();
+    let mut pts: Vec<(i64, f32)> = old_env.iter().copied().filter(|&(at, _)| at < rel0.saturating_sub(1) || (sel1 < c.end() && at > rel1)).collect();
     if rel0 > 0 {
-        pts.push((rel0 - 1, env_db(&c.gain_env, rel0 - 1)));
+        pts.push((rel0 - 1, env_db(rel0 - 1)));
     }
-    pts.push((rel0, env_db(&c.gain_env, rel0) + delta(sel0)));
+    pts.push((rel0, env_db(rel0) + delta(sel0)));
     for pt in lane.points.iter().filter(|pt| pt.at > sel0 && pt.at < sel1) {
         let at = rel(pt.at);
-        pts.push((at, env_db(&c.gain_env, at) + delta(pt.at)));
+        pts.push((at, env_db(at) + delta(pt.at)));
     }
     // The clip's own gain points inside the selection keep their shape, offset by the lane.
-    for &(at, _) in c.gain_env.iter().filter(|&&(at, _)| at > rel0 && at < rel1) {
-        pts.push((at, env_db(&c.gain_env, at) + delta(c.start.saturating_add(at))));
+    for &(at, _) in old_env.iter().filter(|&&(at, _)| at > rel0 && at < rel1) {
+        pts.push((at, env_db(at) + delta(c.start.saturating_add(at))));
     }
     if sel1 - 1 > sel0 {
         let at = rel(sel1 - 1);
-        pts.push((at, env_db(&c.gain_env, at) + delta(sel1 - 1)));
+        pts.push((at, env_db(at) + delta(sel1 - 1)));
     }
     if sel1 < c.end() {
-        pts.push((rel1, env_db(&c.gain_env, rel1)));
+        pts.push((rel1, env_db(rel1)));
     }
     pts.sort_by_key(|p| p.0);
-    let mut env = Vec::new();
+    let mut baked = Vec::new();
     for p in pts {
-        if env.last().is_some_and(|q: &(i64, f32)| q.0 == p.0) {
-            env.pop();
+        if baked.last().is_some_and(|q: &(i64, f32)| q.0 == p.0) {
+            baked.pop();
         }
-        env.push(p);
+        baked.push(p);
     }
-    c.gain_env = env;
+    c.gain_env = baked;
 }
 
 /// Clear the volume lane over `r` when the clips all sit inside it, else hold the fader there.
@@ -726,8 +761,9 @@ fn clip_gain_to_vol(e: &mut Engine, p: &Value) -> Result<Value> {
                 if let Some(l) = &old {
                     ats.extend(l.points.iter().map(|pt| pt.at).filter(|&at| at > c.start && at < c.end() - 1));
                 }
+                let env = EnvLookup::new(&c.gain_env);
                 for at in ats {
-                    pts.push((at, level(at) + c.gain_db + env_db(&c.gain_env, at - c.start)));
+                    pts.push((at, level(at) + c.gain_db + env.db(at - c.start)));
                 }
                 c.gain_db = 0.0;
                 c.gain_env.clear();

crates/engine/src/cmd/mix/tests.rs

@@ -345,3 +345,36 @@ fn insert_and_send_reject_invalid_slot() {
     let r = e.execute("mix.send", &json!({"track": "Gtr", "bus": "Verb"})).unwrap();
     assert_eq!(r["slot"], 0);
 }
+
+#[test]
+fn indexed_envelope_lookup_matches_the_walk() {
+    let envs: [Vec<(i64, f32)>; 5] = [
+        Vec::new(),
+        vec![(100, -3.0)],
+        vec![(0, 0.0), (100, -6.0), (100, 3.0), (250, -12.0), (900, 1.0)],
+        // Out of order, as a hand-edited session file may hold.
+        vec![(500, -1.0), (100, -6.0), (700, 4.0), (300, 2.0), (700, -9.0), (50, 0.5)],
+        (0..200).map(|i| ((i * 37) % 1000, (i as f32 * 0.7).sin() * 12.0)).collect(),
+    ];
+    for env in &envs {
+        let lookup = EnvLookup::new(env);
+        for at in -20..1100 {
+            assert_eq!(lookup.db(at).to_bits(), env_db(env, at).to_bits(), "{env:?} at {at}");
+        }
+    }
+}
+
+#[test]
+fn clip_gain_to_volume_with_a_large_envelope_stays_fast() {
+    let (mut e, t) = tone_session(&[]);
+    let clip = e.session().track(t).unwrap().clips()[0].id;
+    let n = 200_000i64;
+    let c = e.session_mut().find_clip_mut(clip).unwrap();
+    c.length = n * 5 + 10;
+    c.gain_env = (0..n).map(|i| (i * 5, if i % 2 == 0 { -6.0 } else { 0.0 })).collect();
+    let start = std::time::Instant::now();
+    e.execute("automation.clip_gain_to_volume", &json!({"track": t.0, "start": 0, "end": n * 5 + 10})).unwrap();
+    assert!(start.elapsed() < std::time::Duration::from_secs(10), "{:?}", start.elapsed());
+    let lane = e.session().track(t).unwrap().lane(&AutoParam::Volume).unwrap();
+    assert!(lane.points.len() as i64 >= n);
+}

crates/engine/src/cmd/setup_more.rs

@@ -472,7 +472,7 @@ fn midi_inputs(e: &mut Engine, p: &Value) -> Result<Value> {
 fn import_session_data(e: &mut Engine, p: &Value) -> Result<Value> {
     let id = "file.import_session_data";
     let path = str_param(p, "path").filter(|x| !x.trim().is_empty()).ok_or_else(|| bad(id, "`path` required"))?.to_string();
-    let text_v = crate::io::read_text(&path)?;
+    let text_v = crate::io::read_session_text(&path)?;
     let other = Session::from_json(&text_v).map_err(|err| EngineError::Io(format!("{path}: {err}")))?;
     let names: Option<Vec<String>> =
         p.get("tracks").and_then(Value::as_array).map(|a| a.iter().filter_map(Value::as_str).map(str::to_string).collect());

crates/engine/src/cmd/view.rs

@@ -3,9 +3,9 @@ use super::{CommandSpec, always, bad, bool_or, f32_or, f64_or, i64_or, position_
 
 use crate::{Engine, Result, cmd};
 use serde_json::{Value, json};
-use soundcraft_time::TimeFormat;
-use soundcraft_time::{GridValue, MAX_POSITION, NoteValue};
+use soundcraft_time::{FeetFramesValue, GridScale, GridValue, MAX_POSITION, NoteValue, TimeFormat, TimecodeValue};
 
+/// Returns commands that control saved view, counter, Grid, and Nudge state.
 pub fn specs() -> Vec<CommandSpec> {
     vec![
         cmd!(view "view.zoom_in", "Zoom In", [], Some("Cmd+]"), "{}", always, |e, _| zoom(e, 0.5, None)),
@@ -65,7 +65,18 @@ pub fn specs() -> Vec<CommandSpec> {
         cmd!(noundo "view.ruler", "Rulers", ["View", "Rulers"], None, "{ruler: bars_beats|min_secs|timecode|feet_frames|samples|tempo|meter|markers|key|chords, visible?: bool}", always, ruler),
         cmd!(noundo "view.main_counter", "Main Counter", ["View", "Main Counter"], None, "{format: bars_beats|min_secs|timecode|feet_frames|samples}", always, |e, p| {
             let f = str_param(p, "format").and_then(TimeFormat::from_id).ok_or_else(|| bad("view.main_counter", "unknown format"))?;
-            e.session_mut().edit.main_counter = f;
+            let edit = &mut e.session_mut().edit;
+            edit.main_counter = f;
+            let scale = grid_scale(f);
+            if edit.grid_follow_main && edit.grid.scale() != scale {
+                edit.grid = GridValue::for_scale(scale);
+            }
+            if edit.grid_follow_main {
+                edit.grid_clips_markers = false;
+            }
+            if edit.nudge_follow_main && edit.nudge.scale() != scale {
+                edit.nudge = GridValue::for_scale(scale);
+            }
             Ok(json!({"format": f}))
         }),
         cmd!(noundo "view.sub_counter", "Sub Counter", [], None, "{format?: … | null}", always, |e, p| {
@@ -73,37 +84,80 @@ pub fn specs() -> Vec<CommandSpec> {
             e.session_mut().edit.sub_counter = f;
             Ok(json!({"format": f}))
         }),
-        cmd!(noundo "view.grid", "Grid Value", [], Some("Shift+=/-"), "{value: '1/16' | '1 bar' | '1/8t' | '1/4.' | {seconds} | {frames} | {samples}, or step: ±n values larger or smaller; lines?: bool}", always, |e, p| {
-            let g = value_or_step(p, e.session().edit.grid).ok_or_else(|| bad("view.grid", "unknown grid value"))?;
+        cmd!(noundo "view.grid", "Grid Value", [], Some("Shift+=/-"), "{value?, step?, format?: bars_beats|min_secs|timecode|feet_frames|samples|clips_markers, follow_main?: bool, lines?: bool}", always, |e, p| {
+            let current = e.session().edit.grid;
+            let requested_scale = str_param(p, "format").and_then(GridScale::from_id);
+            let mut g = requested_grid_value(p, current).ok_or_else(|| bad("view.grid", "unknown grid value or format"))?;
             let lines = p.get("lines").and_then(Value::as_bool);
+            let follow = p.get("follow_main").and_then(Value::as_bool);
+            if follow == Some(true) {
+                let scale = grid_scale(e.session().edit.main_counter);
+                if g.scale() != scale {
+                    g = GridValue::for_scale(scale);
+                }
+            }
             let s = e.session_mut();
             s.edit.grid = g;
+            if p.get("value").is_some() || p.get("step").is_some() {
+                s.edit.grid_clips_markers = false;
+            }
+            if let Some(scale) = requested_scale {
+                s.edit.grid_clips_markers = scale == GridScale::ClipsMarkers;
+            }
+            if follow == Some(true) {
+                s.edit.grid_clips_markers = false;
+            }
+            s.edit.grid_follow_main = follow.unwrap_or(
+                s.edit.grid_follow_main && !s.edit.grid_clips_markers && g.scale() == grid_scale(s.edit.main_counter),
+            );
             if let Some(l) = lines { s.edit.grid_lines = l }
-            Ok(json!({"grid": g.label()}))
+            let format = if s.edit.grid_clips_markers { GridScale::ClipsMarkers } else { g.scale() };
+            Ok(json!({"grid": g.label(), "format": format.id(), "follow_main": s.edit.grid_follow_main}))
         }),
         cmd!(noundo "view.grid_lines", "Show Grid Lines", [], None, "{value?: bool}", always, |e, p| {
             let s = e.session_mut();
             s.edit.grid_lines = p.get("value").and_then(Value::as_bool).unwrap_or(!s.edit.grid_lines);
             Ok(json!({"value": s.edit.grid_lines}))
         }),
-        cmd!(noundo "view.nudge", "Nudge Value", [], Some("Alt+Shift+=/-"), "{value or step: like grid}", always, |e, p| {
-            let g = value_or_step(p, e.session().edit.nudge).ok_or_else(|| bad("view.nudge", "unknown nudge value"))?;
-            e.session_mut().edit.nudge = g;
-            Ok(json!({"nudge": g.label()}))
+        cmd!(noundo "view.nudge", "Nudge Value", [], Some("Alt+Shift+=/-"), "{value?, step?, format?: bars_beats|min_secs|timecode|feet_frames|samples, follow_main?: bool}", always, |e, p| {
+            let current = e.session().edit.nudge;
+            if str_param(p, "format").and_then(GridScale::from_id) == Some(GridScale::ClipsMarkers) {
+                return Err(bad("view.nudge", "Clips/Markers is available only for Grid"));
+            }
+            let mut g = requested_grid_value(p, current).ok_or_else(|| bad("view.nudge", "unknown nudge value or format"))?;
+            let follow = p.get("follow_main").and_then(Value::as_bool);
+            if follow == Some(true) {
+                let scale = grid_scale(e.session().edit.main_counter);
+                if g.scale() != scale {
+                    g = GridValue::for_scale(scale);
+                }
+            }
+            let edit = &mut e.session_mut().edit;
+            edit.nudge = g;
+            edit.nudge_follow_main = follow.unwrap_or(edit.nudge_follow_main && g.scale() == grid_scale(edit.main_counter));
+            Ok(json!({"nudge": g.label(), "format": g.scale().id(), "follow_main": edit.nudge_follow_main}))
         }),
     ]
 }
 
 const MIN_SPP: f64 = 0.25;
 const MAX_SPP: f64 = 1_000_000.0;
+/// Pixel column an off-screen edit cursor is brought to when zooming (the engine does not know the viewport width).
+const OFFSCREEN_CURSOR_PX: f64 = 500.0;
 
 fn zoom(e: &mut Engine, f: f64, x: Option<f64>) -> Result<Value> {
     let insertion = e.session().edit.selection.start as f64;
     let z = e.zoom_mut();
     let (old, scroll) = (z.samples_per_px, z.scroll as f64);
     let new = (old * f).clamp(MIN_SPP, MAX_SPP);
-    if let Some(x) = x.or_else(|| Some((insertion - scroll) / old).filter(|x| (0.0..4000.0).contains(x))) {
+    // Without a pointer, the edit cursor is the reference: held in place when visible, centred when off-screen.
+    let cursor_x = (insertion - scroll) / old;
+    if let Some(x) = x {
         z.scroll = soundcraft_time::to_samples(scroll + x * (old - new)).clamp(0, MAX_POSITION);
+    } else if (0.0..4000.0).contains(&cursor_x) {
+        z.scroll = soundcraft_time::to_samples(scroll + cursor_x * (old - new)).clamp(0, MAX_POSITION);
+    } else {
+        z.scroll = soundcraft_time::to_samples(insertion - OFFSCREEN_CURSOR_PX * new).clamp(0, MAX_POSITION);
     }
     z.samples_per_px = new;
     Ok(json!({"samples_per_px": new, "scroll": z.scroll}))
@@ -129,7 +183,33 @@ fn value_or_step(p: &Value, current: GridValue) -> Option<GridValue> {
     Some((0..step.unsigned_abs().min(16)).fold(current, |g, _| g.stepped(step > 0)))
 }
 
-/// Parse grid/nudge values.
+/// Maps a counter format to the corresponding Grid/Nudge scale.
+fn grid_scale(format: TimeFormat) -> GridScale {
+    match format {
+        TimeFormat::BarsBeats => GridScale::BarsBeats,
+        TimeFormat::MinSecs => GridScale::MinSecs,
+        TimeFormat::Timecode => GridScale::Timecode,
+        TimeFormat::FeetFrames => GridScale::FeetFrames,
+        TimeFormat::Samples => GridScale::Samples,
+    }
+}
+
+/// Resolves an explicit value, a step, or a scale change while preserving the current increment.
+fn requested_grid_value(p: &Value, current: GridValue) -> Option<GridValue> {
+    if p.get("value").is_some() || p.get("step").is_some() {
+        return value_or_step(p, current);
+    }
+    let scale = str_param(p, "format").and_then(GridScale::from_id);
+    match scale {
+        Some(GridScale::ClipsMarkers) => Some(current),
+        Some(scale) if current.scale() == scale => Some(current),
+        Some(scale) => Some(GridValue::for_scale(scale)),
+        None if p.get("follow_main").is_some() || p.get("lines").is_some() => Some(current),
+        None => None,
+    }
+}
+
+/// Parse grid/nudge values; legacy `1` and `1/1` mean a bar, while `whole` means four quarter notes.
 pub fn grid_param(p: &Value, key: &str) -> Option<GridValue> {
     let v = p.get(key)?;
     if let Some(sec) = v.get("seconds").and_then(Value::as_f64) {
@@ -138,15 +218,23 @@ pub fn grid_param(p: &Value, key: &str) -> Option<GridValue> {
     if let Some(f) = v.get("frames").and_then(Value::as_i64) {
         return Some(GridValue::Frames(f.clamp(1, 100_000)));
     }
+    if let Some(value) = v.get("timecode").and_then(Value::as_str).and_then(TimecodeValue::from_id) {
+        return Some(GridValue::Timecode(value));
+    }
+    if let Some(value) = v.get("feet_frames").and_then(Value::as_str).and_then(FeetFramesValue::from_id) {
+        return Some(GridValue::FeetFrames(value));
+    }
     if let Some(n) = v.get("samples").and_then(Value::as_i64) {
         return Some(GridValue::Samples(n.clamp(1, i64::from(u32::MAX))));
     }
     let s = v.as_str()?.trim().to_ascii_lowercase();
     let triplet = s.ends_with('t') || s.contains("triplet");
     let dotted = s.ends_with('.') || s.contains("dotted");
-    let core: String = s.chars().take_while(|c| c.is_ascii_digit() || *c == '/' || *c == ' ' || c.is_ascii_alphabetic() && *c != 't').collect();
+    let core = s.replace("triplet", "").replace("dotted", "");
+    let core = core.trim().trim_end_matches(['t', '.']);
     let value = match core.trim() {
-        "1 bar" | "bar" | "1/1" | "1" => NoteValue::Bar,
+        "1" | "1/1" | "1 bar" | "bar" => NoteValue::Bar,
+        "whole" | "whole note" => NoteValue::Whole,
         "1/2" => NoteValue::Half,
         "1/4" => NoteValue::Quarter,
         "1/8" => NoteValue::Eighth,
@@ -162,15 +250,59 @@ pub fn grid_param(p: &Value, key: &str) -> Option<GridValue> {
 mod tests {
     use super::*;
     use soundcraft_time::Samples;
+    /// Grid values accept compact and word-form musical modifiers plus every absolute scale.
     #[test]
     fn grid_values_parse() {
         assert_eq!(grid_param(&json!({"v": "1/16"}), "v"), Some(GridValue::Note { value: NoteValue::Sixteenth, dotted: false, triplet: false }));
         assert_eq!(grid_param(&json!({"v": "1/8t"}), "v"), Some(GridValue::Note { value: NoteValue::Eighth, dotted: false, triplet: true }));
+        assert_eq!(grid_param(&json!({"v": "1/8 triplet"}), "v"), Some(GridValue::Note { value: NoteValue::Eighth, dotted: false, triplet: true }));
         assert_eq!(grid_param(&json!({"v": "1/4."}), "v"), Some(GridValue::Note { value: NoteValue::Quarter, dotted: true, triplet: false }));
+        for alias in ["1", "1/1"] {
+            assert_eq!(grid_param(&json!({"v": alias}), "v"), Some(GridValue::Note { value: NoteValue::Bar, dotted: false, triplet: false }));
+        }
+        assert_eq!(grid_param(&json!({"v": "whole"}), "v"), Some(GridValue::Note { value: NoteValue::Whole, dotted: false, triplet: false }));
+        assert_eq!(grid_param(&json!({"v": "whole note"}), "v"), Some(GridValue::Note { value: NoteValue::Whole, dotted: false, triplet: false }));
         assert_eq!(grid_param(&json!({"v": {"seconds": 0.5}}), "v"), Some(GridValue::Seconds(0.5)));
+        assert_eq!(grid_param(&json!({"v": {"timecode": "quarter_frame"}}), "v"), Some(GridValue::Timecode(TimecodeValue::QuarterFrame)));
+        assert_eq!(grid_param(&json!({"v": {"feet_frames": "foot"}}), "v"), Some(GridValue::FeetFrames(FeetFramesValue::Foot)));
         assert_eq!(grid_param(&json!({"v": "nonsense"}), "v"), None);
     }
 
+    /// Explicit values and formats retain Follow Main only when the selected scale still matches.
+    #[test]
+    fn explicit_grid_and_nudge_scales_keep_follow_state_consistent() {
+        for command in ["view.grid", "view.nudge"] {
+            let mut e = Engine::default();
+            e.execute("view.main_counter", &json!({"format": "min_secs"})).unwrap();
+            e.execute(command, &json!({"follow_main": true})).unwrap();
+            let result = e.execute(command, &json!({"value": {"seconds": 0.1}})).unwrap();
+            assert_eq!(result["follow_main"], true);
+            let result = e.execute(command, &json!({"value": {"feet_frames": "foot"}})).unwrap();
+            assert_eq!(result["follow_main"], false);
+            e.execute(command, &json!({"follow_main": true})).unwrap();
+            let result = e.execute(command, &json!({"format": "bars_beats"})).unwrap();
+            assert_eq!(result["follow_main"], false);
+        }
+        let mut e = Engine::default();
+        e.execute("view.grid", &json!({"format": "clips_markers"})).unwrap();
+        assert!(!e.session().edit.grid_follow_main);
+        e.execute("view.grid", &json!({"value": {"samples": 100}})).unwrap();
+        assert!(!e.session().edit.grid_clips_markers);
+        assert_eq!(e.session().edit.grid, GridValue::Samples(100));
+    }
+
+    /// Historical bar aliases retain meter-dependent duration; the explicit whole note remains distinct.
+    #[test]
+    fn legacy_bar_aliases_and_whole_notes_remain_distinct_in_odd_meter() {
+        let mut e = Engine::default();
+        e.session_mut().tempo = soundcraft_time::TempoMap::new(120.0, 3, 4).unwrap();
+        for (value, expected) in [("1", 72_000), ("1/1", 72_000), ("whole", 96_000)] {
+            e.execute("view.grid", &json!({"value": value, "follow_main": false})).unwrap();
+            let s = e.session();
+            assert_eq!(s.edit.grid.step_samples(0, s.sample_rate, &s.tempo, s.frame_rate), expected);
+        }
+    }
+
     fn view(e: &Engine) -> (f64, Samples) {
         (e.session().edit.zoom.samples_per_px, e.session().edit.zoom.scroll)
     }
@@ -186,6 +318,17 @@ mod tests {
         assert_eq!(view(&e), (100.0, 48_000));
     }
 
+    #[test]
+    fn zoom_in_brings_an_offscreen_edit_cursor_into_view() {
+        let mut e = Engine::default();
+        e.execute("view.zoom_set", &json!({"samples_per_px": 100.0})).unwrap();
+        e.execute("edit.select", &json!({"start": 1_000_000, "end": 1_000_000})).unwrap();
+        e.execute("view.zoom_in", &json!({})).unwrap();
+        let (spp, scroll) = view(&e);
+        let x = (1_000_000.0 - scroll as f64) / spp;
+        assert!((x - OFFSCREEN_CURSOR_PX).abs() < 1.0, "cursor at {x}px");
+    }
+
     #[test]
     fn zoom_and_scroll_stay_in_range() {
         let mut e = Engine::default();
@@ -222,6 +365,7 @@ mod tests {
         assert_eq!(state(&e), before);
     }
 
+    /// Grid and Nudge steps drive edit movement while preserving their selected increments.
     #[test]
     fn grid_and_nudge_values_step_and_nudges_can_use_the_next_value() {
         let mut e = Engine::default();
@@ -243,4 +387,32 @@ mod tests {
         assert_eq!(e.session().edit.selection.start, 6_000);
         assert_eq!(e.session().edit.nudge.label(), "1/16 note");
     }
+
+    /// Grid and Nudge expose independent scale-following state, while Clips/Markers remains Grid-only.
+    #[test]
+    fn grid_and_nudge_choose_scales_follow_the_main_counter_and_keep_clips_markers_grid_only() {
+        let mut e = Engine::default();
+        e.execute("view.grid", &json!({"format": "timecode", "follow_main": false})).unwrap();
+        assert_eq!(e.session().edit.grid, GridValue::Timecode(TimecodeValue::Frame));
+        e.execute("view.grid", &json!({"value": {"timecode": "quarter_frame"}})).unwrap();
+        e.execute("view.grid", &json!({"format": "clips_markers", "follow_main": false})).unwrap();
+        assert_eq!(e.session().edit.grid, GridValue::Timecode(TimecodeValue::QuarterFrame));
+        assert!(e.session().edit.grid_clips_markers);
+        assert!(e.execute("view.nudge", &json!({"format": "clips_markers"})).is_err());
+
+        e.execute("view.grid", &json!({"follow_main": true})).unwrap();
+        e.execute("view.nudge", &json!({"follow_main": true})).unwrap();
+        assert_eq!((e.session().edit.grid, e.session().edit.nudge), (GridValue::Seconds(1.0), GridValue::Seconds(1.0)));
+        assert!(!e.session().edit.grid_clips_markers);
+        e.execute("view.main_counter", &json!({"format": "samples"})).unwrap();
+        assert_eq!((e.session().edit.grid, e.session().edit.nudge), (GridValue::Samples(100), GridValue::Samples(100)));
+        assert!(e.session().edit.grid_follow_main && e.session().edit.nudge_follow_main);
+
+        e.execute("view.grid", &json!({"format": "bars_beats", "follow_main": false})).unwrap();
+        assert_eq!(e.session().edit.grid, GridValue::default());
+        assert!(!e.session().edit.grid_follow_main);
+        e.execute("view.main_counter", &json!({"format": "timecode"})).unwrap();
+        assert_eq!(e.session().edit.grid, GridValue::default());
+        assert_eq!(e.session().edit.nudge, GridValue::Timecode(TimecodeValue::Frame));
+    }
 }

crates/engine/src/dirty.rs

@@ -52,6 +52,9 @@ fn edit_values<'a>(edit: &'a EditState, navigation: &'a EditState) -> impl Parti
         grid,
         nudge,
         grid_lines,
+        grid_follow_main,
+        nudge_follow_main,
+        grid_clips_markers,
         main_counter,
         sub_counter,
         zoom: _,
@@ -130,7 +133,17 @@ fn edit_values<'a>(edit: &'a EditState, navigation: &'a EditState) -> impl Parti
             scrolling,
             solo_mode,
         ),
-        (pre_fader_metering, delay_compensation, keyboard_focus, &navigation.timeline_selection, flags, values),
+        (
+            grid_follow_main,
+            nudge_follow_main,
+            grid_clips_markers,
+            pre_fader_metering,
+            delay_compensation,
+            keyboard_focus,
+            &navigation.timeline_selection,
+            flags,
+            values,
+        ),
     )
 }
 
@@ -186,6 +199,9 @@ mod tests {
             ("grid", |e| e.grid = soundcraft_time::GridValue::Seconds(2.0)),
             ("nudge", |e| e.nudge = soundcraft_time::GridValue::Seconds(2.0)),
             ("grid_lines", |e| e.grid_lines = !e.grid_lines),
+            ("grid_follow_main", |e| e.grid_follow_main = !e.grid_follow_main),
+            ("nudge_follow_main", |e| e.nudge_follow_main = !e.nudge_follow_main),
+            ("grid_clips_markers", |e| e.grid_clips_markers = !e.grid_clips_markers),
             ("main_counter", |e| e.main_counter = TimeFormat::Samples),
             ("sub_counter", |e| e.sub_counter = None),
             ("zoom_toggle", |e| e.zoom_toggle = Some(ZoomToggle { samples_per_px: 64.0, scroll: 0, heights: Vec::new() })),

crates/engine/src/edit.rs

@@ -528,9 +528,15 @@ fn join_gain_env(l: &mut Clip, r: &Clip) {
 }
 
 /// Move clips by `delta`, overwriting what they land on; `dest` sends whole tracks of them
-/// elsewhere (see [`destinations`]).
+/// elsewhere (see [`destinations`]). Same-track moves clamped to zero leave all material intact.
 pub fn move_clips(s: &mut Session, ids: &[ClipId], delta: Samples, dest: &[(TrackId, TrackId)]) -> usize {
     let ids: HashSet<ClipId> = ids.iter().copied().collect();
+    // Limit the shift before removing any clips, so a stationary edit cannot overwrite overlaps.
+    let limit = s.tracks.iter().flat_map(|t| t.clips()).filter(|c| ids.contains(&c.id) && !locked(c)).map(|c| c.start.saturating_neg()).max();
+    let delta = delta.max(limit.unwrap_or(0));
+    if delta == 0 && dest.iter().all(|(from, to)| from == to) {
+        return 0;
+    }
     let mut moving: Vec<(TrackId, Clip)> = Vec::new();
     for t in &mut s.tracks {
         let tid = t.id;
@@ -546,8 +552,6 @@ pub fn move_clips(s: &mut Session, ids: &[ClipId], delta: Samples, dest: &[(Trac
         }
     }
     let n = moving.len();
-    // Limit the shift once, so the group stops at zero together and keeps its spacing.
-    let delta = delta.max(moving.iter().map(|(_, c)| c.start.saturating_neg()).max().unwrap_or(0));
     let placed = moving.into_iter().map(|(tid, mut c)| {
         c.start = c.start.saturating_add(delta);
         (lands(dest, tid), c)
@@ -572,20 +576,7 @@ fn put_clips(s: &mut Session, placed: Vec<(TrackId, Clip)>) {
 
 /// Whether the Edit window shows track `t`: not hidden, and not inside a closed folder at any level.
 pub fn shown(s: &Session, t: &Track) -> bool {
-    !t.hidden && !folder_collapsed(s, t)
-}
-
-/// Hidden because a folder at any level above this track is closed.
-fn folder_collapsed(s: &Session, track: &Track) -> bool {
-    let mut current = track.folder;
-    for _ in 0..64 {
-        let Some(folder) = current.and_then(|folder| s.track(folder)) else { return false };
-        if !folder.folder_open {
-            return true;
-        }
-        current = folder.folder;
-    }
-    false
+    s.track_shown(t)
 }
 
 /// Where the tracks of clips `ids` go when track `from` goes to `to`: each keeps its distance
@@ -790,12 +781,11 @@ pub fn shuffle_clips(s: &mut Session, ids: &[ClipId], delta: Samples, dest: &[(T
 /// How far a Grabber drag by `raw` moves `clip` in Grid mode: Absolute puts its sync point (its
 /// start when it has none inside the clip) on the nearest grid line; Relative moves it by whole
 /// grid steps, keeping its offset from the grid.
-pub fn grid_delta(s: &Session, clip: &Clip, raw: Samples, relative: bool) -> Samples {
-    let (g, sr, map, rate) = (&s.edit.grid, s.sample_rate, &s.tempo, s.frame_rate);
+pub fn grid_delta(s: &Session, clip: &Clip, raw: Samples, relative: bool, moving: &[ClipId]) -> Samples {
     let sync = if (0..clip.length).contains(&clip.sync_point) { clip.sync_point } else { 0 };
     let anchor = clip.start.saturating_add(sync);
-    let from = if relative { g.line_at_or_before(anchor, sr, map, rate) } else { anchor };
-    g.snap(from.saturating_add(raw), sr, map, rate).saturating_sub(from)
+    let from = if relative { s.grid_line_at_or_before_excluding(anchor, moving) } else { anchor };
+    s.snap_to_grid_excluding(from.saturating_add(raw), moving).saturating_sub(from)
 }
 
 /// Trim a clip's edges to `start` and/or `end` like the Trim tool, never past its file. In

crates/engine/src/edit/tests.rs

@@ -330,9 +330,9 @@ fn grid_moves_snap_the_clip_start_or_keep_its_offset() {
     let (s, t) = session_with_clip();
     let step = s.edit.grid.step_samples(0, s.sample_rate, &s.tempo, s.frame_rate);
     let c = s.track(t).unwrap().clips()[0].clone();
-    assert_eq!(c.start + grid_delta(&s, &c, step + 200, false), step);
-    assert_eq!(c.start + grid_delta(&s, &c, step + 200, true), step + 1000);
-    assert_eq!(grid_delta(&s, &c, step / 3, true), 0);
+    assert_eq!(c.start + grid_delta(&s, &c, step + 200, false, &[c.id]), step);
+    assert_eq!(c.start + grid_delta(&s, &c, step + 200, true, &[c.id]), step + 1000);
+    assert_eq!(grid_delta(&s, &c, step / 3, true, &[c.id]), 0);
 }
 
 #[test]

crates/engine/src/io.rs

@@ -42,19 +42,122 @@ pub use strip::{StripMode, StripNames, StripScan, bounded_to_track, name_strippe
 /// one. Only a regular file qualifies: a device or a pipe named by a session or a command would
 /// never end or never answer. Errors name the file.
 pub fn read_file(path: impl AsRef<Path>) -> Result<Vec<u8>> {
-    let path = path.as_ref();
+    read_file_within(path.as_ref(), false)
+}
+
+/// [`read_file`]; a `session` file is refused ([`session_size`]) past [`session_limit`].
+fn read_file_within(path: &Path, session: bool) -> Result<Vec<u8>> {
+    use std::io::Read as _;
     crate::file_access::check_read(path).map_err(EngineError::Io)?;
     let err = |err: std::io::Error| EngineError::Io(format!("{}: {err}", path.display()));
-    if !std::fs::metadata(path).map_err(err)?.is_file() {
+    let meta = std::fs::metadata(path).map_err(err)?;
+    if !meta.is_file() {
         return Err(EngineError::Io(format!("{}: not a regular file", path.display())));
     }
-    std::fs::read(path).map_err(err)
+    if !session {
+        return std::fs::read(path).map_err(err);
+    }
+    session_size(path.display(), meta.len(), false)?;
+    // The file may have grown since: never read more than one byte past the limit.
+    let mut data = Vec::new();
+    std::fs::File::open(path).map_err(err)?.take(session_limit().saturating_add(1)).read_to_end(&mut data).map_err(err)?;
+    session_size(path.display(), data.len() as u64, false)?;
+    Ok(data)
 }
 
 /// [`read_file`] as UTF-8 text.
 pub fn read_text(path: impl AsRef<Path>) -> Result<String> {
     let path = path.as_ref();
-    String::from_utf8(read_file(path)?).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
+    utf8(path, read_file(path)?)
+}
+
+fn utf8(path: &Path, bytes: Vec<u8>) -> Result<String> {
+    String::from_utf8(bytes).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
+}
+
+/// The largest session (`.scraft`) SoundCraft opens or saves. A session is read whole and parsed
+/// in one go, so a larger one is refused by its size before it is read, and never written (it
+/// could not be opened again); real sessions are far smaller.
+pub const MAX_SESSION_BYTES: u64 = 256 << 20;
+
+#[cfg(test)]
+thread_local! {
+    /// A smaller limit than [`MAX_SESSION_BYTES`] for the tests on this thread ([`SessionLimit`]).
+    static TEST_SESSION_LIMIT: std::cell::Cell<Option<u64>> = const { std::cell::Cell::new(None) };
+}
+
+/// [`MAX_SESSION_BYTES`] (in tests, the limit a [`SessionLimit`] set on this thread).
+pub(crate) fn session_limit() -> u64 {
+    #[cfg(test)]
+    if let Some(limit) = TEST_SESSION_LIMIT.with(std::cell::Cell::get) {
+        return limit;
+    }
+    MAX_SESSION_BYTES
+}
+
+/// While it lives, sessions on this thread are opened and saved up to the limit given to
+/// [`SessionLimit::set`] instead of [`MAX_SESSION_BYTES`], so tests reach it with small sessions.
+#[cfg(test)]
+pub(crate) struct SessionLimit;
+
+#[cfg(test)]
+impl SessionLimit {
+    pub(crate) fn set(limit: u64) -> SessionLimit {
+        TEST_SESSION_LIMIT.with(|l| l.set(Some(limit)));
+        SessionLimit
+    }
+}
+
+#[cfg(test)]
+impl Drop for SessionLimit {
+    fn drop(&mut self) {
+        TEST_SESSION_LIMIT.with(|l| l.set(None));
+    }
+}
+
+/// Refuses the session `name` of `len` bytes when it is larger than [`session_limit`]: too large
+/// to open, or, when `saving`, to save.
+pub(crate) fn session_size(name: impl std::fmt::Display, len: u64, saving: bool) -> Result<()> {
+    let limit = session_limit();
+    if len <= limit {
+        return Ok(());
+    }
+    let most = if limit >= 1 << 20 { format!("{} MiB", limit >> 20) } else { format!("{limit} bytes") };
+    Err(EngineError::Io(if saving {
+        format!("{name} is too large to save: over {most}, more than SoundCraft opens")
+    } else {
+        format!("{name} is too large to open (over {most})")
+    }))
+}
+
+/// [`read_text`] for a session file: refused, unread, past [`session_limit`].
+pub(crate) fn read_session_text(path: impl AsRef<Path>) -> Result<String> {
+    let path = path.as_ref();
+    utf8(path, read_file_within(path, true)?)
+}
+
+/// A bare `.scraft` handed over as bytes (the browser) as text: refused, uncopied, past
+/// [`session_limit`].
+pub(crate) fn session_bytes_text(name: &str, bytes: &[u8]) -> Result<String> {
+    session_size(name, bytes.len() as u64, false)?;
+    String::from_utf8(bytes.to_vec()).map_err(|_| EngineError::Io(format!("{name}: not a SoundCraft session")))
+}
+
+/// How many bytes [`Session::to_json`] makes of `s`, counted without keeping them.
+fn json_len(s: &Session) -> u64 {
+    struct Count(u64);
+    impl std::io::Write for Count {
+        fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+            self.0 = self.0.saturating_add(buf.len() as u64);
+            Ok(buf.len())
+        }
+        fn flush(&mut self) -> std::io::Result<()> {
+            Ok(())
+        }
+    }
+    let mut n = Count(0);
+    // A session that cannot be written counts as nothing here: `to_json` reports that error.
+    serde_json::to_writer_pretty(&mut n, s).map_or(0, |()| n.0)
 }
 
 /// Is there a file at `path` the automation read root lets us see? A path outside the root is
@@ -178,6 +281,13 @@ pub struct Bounce {
     enc: Option<soundcraft_audio_io::FileEncoder<Out>>,
 }
 
+/// The Broadcast Wave stamp of timeline position `at`: the session's timecode start plus `at`, in
+/// samples since midnight (`bext` TimeReference; 0 before midnight).
+fn time_stamp(s: &Session, at: Samples) -> soundcraft_audio_io::BwfInfo {
+    let time_reference = u64::try_from(s.timecode_start.saturating_add(at)).unwrap_or(0);
+    soundcraft_audio_io::BwfInfo { time_reference, ..Default::default() }
+}
+
 /// A finished bounce: the size of its file and its levels.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct Bounced {
@@ -208,6 +318,9 @@ impl Bounce {
         let part = path.with_file_name(format!("{name}.part"));
         crate::file_access::check_write(path).map_err(EngineError::Io)?;
         crate::file_access::check_write(&part).map_err(EngineError::Io)?;
+        // A WAV bounce says where it starts on the session's timecode, as other DAWs' bounces do,
+        // so post and broadcast tools can place it (only WAV has a `bext` chunk to say it in).
+        let opts = &EncodeOptions { bwf: opts.bwf.clone().or_else(|| Some(time_stamp(&s, r.start))), ..opts.clone() };
         let enc = (|| -> std::result::Result<_, soundcraft_audio_io::AudioError> {
             let enc = soundcraft_audio_io::FileEncoder::new(Out::create(&part)?, opts, channels, s.sample_rate.hz(), Some(fmt.channel_mask()))?;
             enc.check_room(u64::try_from(r.len()).unwrap_or(0))?;
@@ -487,7 +600,6 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
     let mut s = session.clone();
     let from = s.folder.clone();
     let same_dir = from.as_deref().is_some_and(|f| same_path(f, &dir));
-    let mut written = 0;
     // A file can stay put for all the sources that name it, unless their audio differs.
     let shared_paths: Vec<bool> = {
         let mut audio_by_path: HashMap<&str, HashSet<Option<*const SourceAudio>>> = HashMap::new();
@@ -496,8 +608,11 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
         }
         s.sources.iter().map(|src| audio_by_path.get(src.path.as_str()).is_some_and(|a| a.len() > 1)).collect()
     };
-    // Files written for audio during this save: sources playing the same audio share one.
+    // Files for audio in this save: sources playing the same audio share one. The files still to
+    // write (their stem, audio and the sources naming them) are written once the size is checked.
     let mut files: HashMap<*const SourceAudio, String> = HashMap::new();
+    let mut queued: HashMap<*const SourceAudio, usize> = HashMap::new();
+    let mut pending: Vec<(String, Arc<SourceAudio>, Vec<usize>)> = Vec::new();
     for (i, src) in s.sources.iter_mut().enumerate() {
         if !same_dir
             && s.pool.get(src.id).is_none()
@@ -523,7 +638,14 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
             src.format = FileFormat::Wav;
             continue;
         }
-        make_dir(&audio_dir)?;
+        if let Some((stem, _, sources)) = queued.get(&Arc::as_ptr(audio)).and_then(|&k| pending.get_mut(k)) {
+            // As long as any name the file can get, so the size checked is an upper bound.
+            src.path = format!("Audio Files/{stem}_9999.wav");
+            src.unsaved = false;
+            src.format = FileFormat::Wav;
+            sources.push(i);
+            continue;
+        }
         let mut stem = sanitize_name(&src.name);
         if overwrite {
             // One file per source id so autosaves never collide or pile up.
@@ -535,23 +657,46 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
                 continue;
             }
         }
-        let opts = EncodeOptions { format: FileFormat::Wav, bit_depth: soundcraft_audio_io::BitDepth::Float32, dither: false, bwf: None };
-        let bytes = soundcraft_audio_io::encode(&audio.buffer, &opts).map_err(|err| EngineError::Io(err.to_string()))?;
-        let (name, new) = store_wav(&audio_dir, &stem, &bytes)?;
-        src.path = format!("Audio Files/{name}");
+        src.path = format!("Audio Files/{stem}_9999.wav");
         src.unsaved = false;
         src.format = FileFormat::Wav;
-        files.insert(Arc::as_ptr(audio), src.path.clone());
-        written += usize::from(new);
-    }
-    if written > 0 {
-        sync_dir(&audio_dir);
+        queued.insert(Arc::as_ptr(audio), pending.len());
+        pending.push((stem, Arc::clone(audio), vec![i]));
     }
     s.folder = Some(dir.clone());
     if !overwrite && let Some(stem) = p.file_stem().and_then(OsStr::to_str) {
         s.name = stem.to_string();
     }
-    let text = s.to_json().map_err(|err| EngineError::Io(err.to_string()))?;
+    // Before any audio is written: a session too large to open again is not saved (#892). With no
+    // audio to write, the text checked is the text saved.
+    let checked = if pending.is_empty() {
+        let text = s.to_json().map_err(|err| EngineError::Io(err.to_string()))?;
+        session_size(p.display(), text.len() as u64, true)?;
+        Some(text)
+    } else {
+        session_size(p.display(), json_len(&s), true)?;
+        None
+    };
+    let mut written = 0;
+    for (stem, audio, sources) in &pending {
+        make_dir(&audio_dir)?;
+        let opts = EncodeOptions { format: FileFormat::Wav, bit_depth: soundcraft_audio_io::BitDepth::Float32, dither: false, bwf: None };
+        let bytes = soundcraft_audio_io::encode(&audio.buffer, &opts).map_err(|err| EngineError::Io(err.to_string()))?;
+        let (name, new) = store_wav(&audio_dir, stem, &bytes)?;
+        for &i in sources {
+            if let Some(src) = s.sources.get_mut(i) {
+                src.path = format!("Audio Files/{name}");
+            }
+        }
+        written += usize::from(new);
+    }
+    if written > 0 {
+        sync_dir(&audio_dir);
+    }
+    let text = match checked {
+        Some(text) => text,
+        None => s.to_json().map_err(|err| EngineError::Io(err.to_string()))?,
+    };
     make_dir(&dir)?;
     // Atomic-ish write: temp file then rename.
     let tmp = p.with_extension("scraft.tmp");
@@ -734,6 +879,12 @@ fn read_bundle(bytes: &[u8], limits: BundleLimits) -> Result<(String, std::colle
     if z.len() > limits.entries {
         return Err(EngineError::Io("bundle: too many files".into()));
     }
+    // Entries are stored, so the files we keep can only outgrow the bundle when several entries
+    // point at the same bytes: a small bundle naming one payload thousands of times would be
+    // copied out once per name.
+    if z.has_overlapping_files().map_err(zerr)? {
+        return Err(EngineError::Io("bundle: files share data".into()));
+    }
     let (mut text, mut files, mut total) = (None, std::collections::HashMap::new(), 0u64);
     for i in 0..z.len() {
         let mut f = z.by_index(i).map_err(zerr)?;
@@ -746,10 +897,13 @@ fn read_bundle(bytes: &[u8], limits: BundleLimits) -> Result<(String, std::colle
         if total > limits.bytes {
             return Err(EngineError::Io("bundle: too large".into()));
         }
+        let is_session = !rel.contains('/') && Path::new(&rel).extension().and_then(OsStr::to_str) == Some(soundcraft_model::SESSION_EXTENSION);
+        if is_session && text.is_none() {
+            session_size(format_args!("bundle: {rel}"), size, false)?;
+        }
         let mut data = Vec::new();
         // The declared size is hostile too: never read past it.
         f.by_ref().take(size).read_to_end(&mut data).map_err(|err| EngineError::Io(format!("bundle: {rel}: {err}")))?;
-        let is_session = !rel.contains('/') && Path::new(&rel).extension().and_then(OsStr::to_str) == Some(soundcraft_model::SESSION_EXTENSION);
         if is_session && text.is_none() {
             text = Some(String::from_utf8(data).map_err(|_| EngineError::Io(format!("bundle: {rel} is not text")))?);
         } else {

crates/engine/src/io/bundle.rs

@@ -69,6 +69,8 @@ fn session_bundle_within(session: &Session, limits: BundleLimits) -> Result<(Vec
         src.format = FileFormat::Wav;
     }
     let text = s.to_json().map_err(|err| EngineError::Io(err.to_string()))?;
+    // Its session too: one the reader would refuse is not saved (#892).
+    super::session_size("the session", text.len() as u64, true)?;
     fits(text.len())?;
     w.start_file(format!("{}.{}", sanitize_name(&s.name), soundcraft_model::SESSION_EXTENSION), opts).map_err(zerr)?;
     w.write_all(text.as_bytes()).map_err(ioerr)?;
@@ -100,10 +102,7 @@ pub fn open_session_bytes(e: &mut Engine, name: &str, bytes: &[u8]) -> Result<Ve
     let (text, mut files) = if bytes.starts_with(b"PK\x03\x04") {
         read_bundle(bytes, BUNDLE_LIMITS)?
     } else {
-        (
-            String::from_utf8(bytes.to_vec()).map_err(|_| EngineError::Io(format!("{name}: not a SoundCraft session")))?,
-            std::collections::HashMap::new(),
-        )
+        (super::session_bytes_text(name, bytes)?, std::collections::HashMap::new())
     };
     let mut s = Session::from_json(&text).map_err(|err| EngineError::Io(format!("{name}: {err}")))?;
     let mut missing = Vec::new();
@@ -149,6 +148,38 @@ pub fn open_session_bytes(e: &mut Engine, name: &str, bytes: &[u8]) -> Result<Ve
 mod bundle_tests {
     use super::*;
 
+    #[test]
+    fn a_session_too_large_to_parse_is_refused_from_bytes() {
+        // #892: a session the browser hands over as bytes has the cap a session file has. The
+        // bytes are zeroed on allocation and never read, so they take no memory.
+        let huge = vec![0u8; usize::try_from(super::super::MAX_SESSION_BYTES).unwrap() + 1];
+        let err = open_session_bytes(&mut Engine::default(), "Huge.scraft", &huge).unwrap_err().to_string();
+        assert_eq!(err, "Huge.scraft is too large to open (over 256 MiB)");
+    }
+
+    #[test]
+    fn bundles_and_bare_sessions_keep_to_the_session_limit_both_ways() {
+        // #892, with the limit lowered for this test: a bundle is saved only if its session can
+        // be opened again (#433), and its reader and the bare-bytes reader refuse one past it.
+        let e = crate::demo::demo_engine();
+        let (bundle, fresh) = session_bundle(e.session()).unwrap();
+        let inside = fresh.to_json().unwrap().len() as u64;
+        let bare = e.session().to_json().unwrap();
+        {
+            let _limit = super::super::SessionLimit::set(inside.max(bare.len() as u64));
+            assert!(session_bundle(e.session()).is_ok());
+            assert!(open_session_bytes(&mut Engine::default(), "Song.scraftz", &bundle).is_ok());
+            assert!(open_session_bytes(&mut Engine::default(), "Song.scraft", bare.as_bytes()).is_ok());
+        }
+        let _limit = super::super::SessionLimit::set(inside.min(bare.len() as u64) - 1);
+        let err = session_bundle(e.session()).unwrap_err().to_string();
+        assert!(err.starts_with("the session is too large to save"), "{err}");
+        let err = open_session_bytes(&mut Engine::default(), "Song.scraftz", &bundle).unwrap_err().to_string();
+        assert!(err.starts_with("bundle: ") && err.contains(".scraft is too large to open"), "{err}");
+        let err = open_session_bytes(&mut Engine::default(), "Song.scraft", bare.as_bytes()).unwrap_err().to_string();
+        assert!(err.starts_with("Song.scraft is too large to open"), "{err}");
+    }
+
     #[test]
     fn bundle_round_trips_session_and_audio() {
         let mut e = crate::demo::demo_engine();
@@ -194,6 +225,23 @@ mod bundle_tests {
         }
     }
 
+    #[test]
+    fn entries_sharing_one_payload_are_refused() {
+        use std::io::Write as _;
+        let mut w = zip::ZipWriter::new(std::io::Cursor::new(Vec::new()));
+        let opts = zip::write::SimpleFileOptions::default().compression_method(zip::CompressionMethod::Stored);
+        w.start_file("Song.scraft", opts).unwrap();
+        w.write_all(Session::default().to_json().unwrap().as_bytes()).unwrap();
+        w.start_file("Audio Files/a.wav", opts).unwrap();
+        w.write_all(&[7u8; 4096]).unwrap();
+        for i in 0..100 {
+            w.shallow_copy_file("Audio Files/a.wav", &format!("Audio Files/copy{i}.wav")).unwrap();
+        }
+        let bundle = w.finish().unwrap().into_inner();
+        let err = read_bundle(&bundle, BUNDLE_LIMITS).unwrap_err();
+        assert!(err.to_string().contains("share data"), "{err}");
+    }
+
     #[test]
     fn a_bundle_is_saved_only_if_it_opens_again() {
         // #433: the writer keeps to the reader's limits.

crates/engine/src/io/session.rs

@@ -3,7 +3,7 @@ use super::bundle::save_session_bundle;
 use super::import::add_source;
 use super::import::{MAX_IMPORT_SAMPLES, at_rate, relink_videos};
 use super::{
-    Arc, Engine, EngineError, OsStr, Path, PathBuf, Result, Session, SourceAudio, file_key, read_file, read_text, stored_path, write_session,
+    Arc, Engine, EngineError, OsStr, Path, PathBuf, Result, Session, SourceAudio, file_key, read_file, read_session_text, stored_path, write_session,
 };
 
 /// Save the session to `path` (a `.scraft` file). Audio that only exists in memory is written
@@ -44,7 +44,7 @@ pub fn open_session(e: &mut Engine, path: impl AsRef<Path>) -> Result<Vec<String
 /// [`open_session`], following the media paths in it as if they were stored in the session file
 /// `links` (crash recovery: the session written beside the autosave, its paths from the original).
 pub(crate) fn open_session_linked(e: &mut Engine, path: &Path, links: &Path) -> Result<Vec<String>> {
-    let text = read_text(path)?;
+    let text = read_session_text(path)?;
     let mut s = Session::from_json(&text).map_err(|err| EngineError::Io(err.to_string()))?;
     let dir = path.parent().map(Path::to_path_buf).unwrap_or_default();
     let mut missing = Vec::new();
@@ -98,6 +98,96 @@ mod save_tests {
     use super::*;
     use serde_json::json;
 
+    /// A new, empty scratch folder, removed again when the test ends, passed or not.
+    struct Scratch(std::path::PathBuf);
+
+    impl Scratch {
+        fn new(tag: &str) -> Scratch {
+            let dir = std::env::temp_dir().join(format!("soundcraft-{tag}-{}", std::process::id()));
+            let _ = std::fs::remove_dir_all(&dir);
+            std::fs::create_dir_all(&dir).unwrap();
+            Scratch(dir)
+        }
+    }
+
+    impl Drop for Scratch {
+        fn drop(&mut self) {
+            let _ = std::fs::remove_dir_all(&self.0);
+        }
+    }
+
+    #[test]
+    fn a_session_file_too_large_to_parse_is_refused_unread() {
+        // #892: a session file is read whole and parsed; past the cap it is refused by its size.
+        // The file's length is set, not written, so it takes no time or space to make.
+        let dir = Scratch::new("huge-session");
+        let path = dir.0.join("Huge.scraft");
+        std::fs::File::create(&path).unwrap().set_len(crate::io::MAX_SESSION_BYTES + 1).unwrap();
+        let mut e = crate::demo::demo_engine();
+        let err = open_session(&mut e, &path).unwrap_err().to_string();
+        assert_eq!(err, format!("{} is too large to open (over 256 MiB)", path.display()));
+        assert_eq!(e.session().tracks.len(), crate::demo::demo_engine().session().tracks.len());
+        let err = e.execute("file.import_session_data", &json!({"path": path.to_string_lossy()})).unwrap_err().to_string();
+        assert!(err.contains("too large to open"), "{err}");
+    }
+
+    #[test]
+    fn a_session_too_large_to_open_is_not_saved_and_leaves_nothing_behind() {
+        // #892: what SoundCraft saves, it opens again. A refused save writes no audio and no
+        // session; the limit is lowered for this test so a small session reaches it.
+        let dir = Scratch::new("refused-save");
+        let path = |p: &str| dir.0.join(p).to_string_lossy().into_owned();
+        save_session(&mut with_take(0.5), &path("A/Song.scraft")).unwrap();
+        let saved = std::fs::metadata(path("A/Song.scraft")).unwrap().len();
+        let untouched = |sub: &str| assert!(!dir.0.join(sub).exists(), "{sub} was written");
+        {
+            let _limit = crate::io::SessionLimit::set(saved - 1);
+            let mut e = with_take(0.5);
+            let err = save_session(&mut e, &path("B/Song.scraft")).unwrap_err().to_string();
+            assert_eq!(err, format!("{} is too large to save: over {} bytes, more than SoundCraft opens", path("B/Song.scraft"), saved - 1));
+            assert!(e.is_dirty() && e.path.is_none());
+            let err = e.execute("session.save_copy", &json!({"path": path("C/Song.scraft")})).unwrap_err().to_string();
+            assert!(err.contains("too large to save"), "{err}");
+            for sub in ["B", "C"] {
+                untouched(sub);
+            }
+            // An open refuses the session saved before, now over the limit.
+            let err = open_session(&mut Engine::default(), path("A/Song.scraft")).unwrap_err().to_string();
+            assert!(err.contains("too large to open"), "{err}");
+        }
+        {
+            // A template holds no audio or clips: a smaller limit refuses it.
+            let _limit = crate::io::SessionLimit::set(100);
+            std::fs::create_dir_all(dir.0.join("D")).unwrap();
+            let err = with_take(0.5).execute("session.save_template", &json!({"path": path("D/Song.scraft")})).unwrap_err().to_string();
+            assert!(err.contains("too large to save"), "{err}");
+            untouched("D/Song.scraft");
+        }
+        // Checked before the audio file is named, against the longest name it can get: a
+        // session at the limit plus that margin is saved, and is the same size as before.
+        let _limit = crate::io::SessionLimit::set(saved + 5);
+        save_session(&mut with_take(0.5), &path("B/Song.scraft")).unwrap();
+        assert_eq!(std::fs::metadata(path("B/Song.scraft")).unwrap().len(), saved);
+        assert_eq!(reopen(&path("B/Song.scraft")).session().sources.len(), 1);
+    }
+
+    #[test]
+    fn a_saved_session_parses_as_it_did_through_a_tree() {
+        // #892: parsing the text directly gives the document the `Value` round trip gave.
+        let mut e = crate::demo::demo_engine();
+        e.execute("mix.volume", &json!({"track": "Kick", "db": -7.0})).unwrap();
+        let text = e.session().to_json().unwrap();
+        let mut old: Session = serde_json::from_value(serde_json::from_str(&text).unwrap()).unwrap();
+        old.sanitize();
+        assert_eq!(Session::from_json(&text).unwrap(), old);
+        let mut r = Engine::default();
+        let dir = Scratch::new("reparse");
+        let path = dir.0.join("Song.scraft").to_string_lossy().into_owned();
+        save_session(&mut e, &path).unwrap();
+        assert_eq!(open_session(&mut r, &path).unwrap(), Vec::<String>::new());
+        assert_eq!(r.session().tracks, e.session().tracks);
+    }
+
     #[test]
     fn autosave_copy_leaves_document_untouched_and_reuses_audio() {
         let mut e = crate::demo::demo_engine();

crates/engine/src/lib.rs

@@ -119,6 +119,8 @@ pub struct Clipboard {
     pub markers: Vec<soundcraft_model::MemoryLocation>,
     /// How far the copied range started after a grid line; Relative Grid pastes keep it.
     pub grid_offset: Samples,
+    /// Original insertion point when the clipboard was populated by Cut.
+    pub cut_from: Option<Samples>,
     /// Copy Special › Automation: pasting it leaves the clips alone, in Shuffle mode too.
     pub automation_only: bool,
     /// The Auto Rename schemes of the copied clips, keyed as in their `auto_name`.
@@ -128,7 +130,7 @@ pub struct Clipboard {
 impl Clipboard {
     /// An empty clipboard for material copied from `range`.
     pub fn of_range(s: &Session, range: soundcraft_time::Range) -> Clipboard {
-        let line = s.edit.grid.line_at_or_before(range.start, s.sample_rate, &s.tempo, s.frame_rate);
+        let line = s.grid_line_at_or_before(range.start);
         Clipboard { length: range.len(), grid_offset: range.start.saturating_sub(line), ..Clipboard::default() }
     }
 

crates/engine/src/score.rs

@@ -418,7 +418,9 @@ fn svg_budgeted(parts: &[Part], setup: &ScoreSetup, budget: usize) -> Result<Str
     const STAFF_GAP: f64 = 70.0;
     const SYSTEM_GAP: f64 = 40.0;
     let n_measures = parts.iter().map(|p| p.measures.len()).max().unwrap_or(0);
-    let per = setup.bars_per_system.max(1) as usize;
+    // The layout range the setup offers (1 to 16): a caller's own value can't multiply the
+    // barlines drawn per system beyond it.
+    let per = setup.bars_per_system.clamp(1, 16) as usize;
     let systems = n_measures.div_ceil(per).max(1);
     let label_w = if setup.show_track_names { 70.0 } else { 0.0 };
     let staff_x0 = MARGIN + label_w + 34.0;
@@ -782,6 +784,14 @@ mod tests {
         assert!(m.items.iter().any(|i| i.pitches.is_empty()), "the discarded suffix became rests");
     }
 
+    #[test]
+    fn bars_per_system_is_held_to_the_supported_range() {
+        let setup = ScoreSetup { title: "t".into(), composer: String::new(), bars_per_system: u32::MAX, show_track_names: false };
+        let part = Part { name: "p".into(), bass: false, measures: vec![Measure { numerator: 4, denominator: 4, items: Vec::new() }] };
+        let out = svg_budgeted(std::slice::from_ref(&part), &setup, 1 << 20).unwrap();
+        assert_eq!(out.matches("stroke-width=\"1\"").count(), 16, "sixteen barlines, not billions");
+    }
+
     #[test]
     fn oversized_title_is_refused_by_the_header_check() {
         // An oversized part name/title must be caught by the header check even with no measures:

crates/engine/tests/it/bounce.rs

@@ -123,6 +123,38 @@ fn a_bounce_too_big_for_its_format_fails_and_keeps_the_old_file() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// A WAV bounce is a Broadcast Wave stamped with where it starts on the session's timecode (`bext`
+/// TimeReference, samples since midnight), as other DAWs write it, so post tools can place it.
+#[test]
+fn wav_bounces_carry_their_timecode_position_as_a_bwf_time_reference() {
+    let mut e = soundcraft_engine::demo::demo_engine();
+    let sr = u64::from(e.session().sample_rate.hz());
+    // The session starts at 01:00:00:00; the bounce at 2 s into it.
+    e.session_mut().timecode_start = (3600 * sr) as i64;
+    let (start, end) = (2 * sr, 3 * sr);
+    let dir = scratch("bounce-bext");
+    let stamp = |path: &std::path::Path| {
+        let ext = path.extension().and_then(|x| x.to_str());
+        soundcraft_audio_io::probe(&std::fs::read(path).unwrap(), ext).unwrap().bwf.map(|b| b.time_reference)
+    };
+    let mix = dir.join("Mix.wav");
+    e.execute("file.bounce_mix", &serde_json::json!({"path": mix, "start": start, "end": end})).unwrap();
+    assert_eq!(stamp(&mix), Some(3600 * sr + start), "mix");
+    let stems = dir.join("stems");
+    let files = e.execute("file.bounce_stems", &serde_json::json!({"dir": stems, "start": start, "end": end})).unwrap();
+    let files = files["files"].as_array().unwrap();
+    assert!(!files.is_empty());
+    for f in files {
+        let f = std::path::PathBuf::from(f.as_str().unwrap());
+        assert_eq!(stamp(&f), Some(3600 * sr + start), "{}", f.display());
+    }
+    // A session that starts at zero still says where the bounce starts.
+    e.session_mut().timecode_start = 0;
+    e.execute("file.bounce_mix", &serde_json::json!({"path": mix, "start": start, "end": end})).unwrap();
+    assert_eq!(stamp(&mix), Some(start));
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
 #[test]
 fn dropping_an_unfinished_bounce_cancels_it_and_keeps_the_old_file() {
     let e = soundcraft_engine::demo::demo_engine();

crates/engine/tests/it/edit_modes.rs

@@ -220,6 +220,129 @@ fn relative_grid_pastes_keep_the_offset_from_the_grid() {
     assert_eq!(clips(&e, t).last(), Some(&(5 * step, 1000)));
 }
 
+/// A relative paste restores the insertion point even when Cut creates a new boundary there.
+#[test]
+fn relative_grid_cut_pastes_back_at_its_insertion_boundary() {
+    let (mut e, t, _) = long("relative_grid", &[(1_000, 2_000, 0)]);
+    run(&mut e, "view.grid", json!({"format": "clips_markers", "follow_main": false}));
+    run(&mut e, "edit.cut", json!({"tracks": [t.0], "start": 1_500, "end": 2_000}));
+    run(&mut e, "edit.paste", json!({"tracks": [t.0]}));
+    assert_eq!(e.session().edit.selection.start, 1_500);
+    assert!(clips(&e, t).contains(&(1_500, 500)), "{:?}", clips(&e, t));
+}
+
+/// Moving a group excludes all its clips from Clips/Markers snap candidates.
+#[test]
+fn clips_markers_grid_ignores_every_clip_being_moved() {
+    let (mut e, _, ids) = long("grid", &[(1_000, 1_000, 0), (4_000, 500, 2_000)]);
+    e.session_mut().add_marker("Target", soundcraft_model::MarkerKind::Marker, 2_500, 2_500);
+    run(&mut e, "view.grid", json!({"format": "clips_markers", "follow_main": false}));
+    run(&mut e, "edit.move_clips", json!({"clips": [ids[0].0, ids[1].0], "to": 1_000}));
+    assert_eq!([start(&e, ids[0]), start(&e, ids[1])], [1_000, 4_000]);
+    run(&mut e, "edit.move_clips", json!({"clips": [ids[0].0, ids[1].0], "to": 2_200}));
+    assert_eq!(start(&e, ids[0]), 2_500);
+    assert_eq!(start(&e, ids[1]), 5_500);
+}
+
+/// Zero and clamped moves preserve overlaps while off-grid quantization still changes position.
+#[test]
+fn zero_distance_move_keeps_overlapping_material_and_quantize_still_moves() {
+    let (mut e, t, ids) = long("slip", &[(1_000, 1_000, 0), (1_500, 1_000, 2_000)]);
+    let before = material(&e, t);
+    run(&mut e, "edit.move_clips", json!({"clips": [ids[0].0], "by": 0}));
+    assert_eq!(material(&e, t), before);
+
+    run(&mut e, "edit.select", json!({"clips": [ids[0].0]}));
+    run(&mut e, "clip.quantize_to_grid", json!({}));
+    assert_eq!(start(&e, ids[0]), 0);
+
+    let (mut e, t, ids) = long("slip", &[(0, 1_000, 0), (500, 1_000, 2_000)]);
+    let before = material(&e, t);
+    run(&mut e, "edit.move_clips", json!({"clips": [ids[0].0], "by": -1_000}));
+    assert_eq!(material(&e, t), before);
+}
+
+/// A vertical move remains a real edit and snaps its off-grid start on the destination track.
+#[test]
+fn zero_horizontal_grid_move_to_another_track_still_snaps() {
+    let (mut e, _, [_, clip]) = engine("grid");
+    let destination = new_track(&mut e);
+    run(&mut e, "edit.move_clips", json!({"clips": [clip.0], "to": 2_000, "track": destination.0}));
+    let (track, moved) = e.session().find_clip(clip).unwrap();
+    assert_eq!(track, destination);
+    assert_eq!(moved.start, 0);
+}
+
+/// Nudge and quantization must preserve overlapping material when the clip cannot move.
+#[test]
+fn stationary_nudges_and_quantization_preserve_overlaps() {
+    for (command, params) in [("edit.nudge", json!({"direction": -1})), ("clip.quantize_to_grid", json!({}))] {
+        let (mut e, t, ids) = long("slip", &[(0, 1_000, 0), (500, 1_000, 2_000)]);
+        run(&mut e, "edit.select", json!({"clips": [ids[0].0]}));
+        let before = e.session().track(t).unwrap().clips().to_vec();
+        let result = e.execute(command, &params).unwrap();
+        assert_eq!(e.session().track(t).unwrap().clips(), before, "{command}");
+        if command == "edit.nudge" {
+            assert_eq!(result["moved"], 0);
+        }
+    }
+}
+
+/// Every Nudge scale shifts clips and insertion across a tempo change and drop-frame rates.
+#[test]
+fn every_nudge_scale_moves_by_its_selected_increment() {
+    use soundcraft_time::{FrameRate, SampleRate, TICKS_PER_QUARTER};
+    for rate in [FrameRate::Fps30, FrameRate::Fps29_97Drop, FrameRate::Fps59_94Drop] {
+        for at in [48_000, 144_000] {
+            let cases = [
+                (json!("1/4"), if at < 96_000 { 24_000 } else { 32_000 }),
+                (json!({"seconds": 0.5}), 24_000),
+                (json!({"timecode": "5_frames"}), rate.samples_at_frame(5, SampleRate::HZ_48000)),
+                (json!({"feet_frames": "foot"}), rate.samples_at_frame(16, SampleRate::HZ_48000)),
+                (json!({"samples": 100}), 100),
+            ];
+            for (value, expected) in cases {
+                let (mut e, track, ids) = long("slip", &[(at, 1_000, 0)]);
+                e.session_mut().frame_rate = rate;
+                e.session_mut().tempo.set_tempo(TICKS_PER_QUARTER * 4, 90.0).unwrap();
+                run(&mut e, "edit.select", json!({"tracks": [track.0], "clips": [ids[0].0], "start": at, "end": at}));
+                run(&mut e, "view.nudge", json!({"value": value, "follow_main": false}));
+                let result = e.execute("edit.nudge", &json!({"direction": 1})).unwrap();
+                assert_eq!(result["by"], expected, "{rate:?} at {at}");
+                assert_eq!(result["moved"], 1);
+                assert_eq!(start(&e, ids[0]), at + expected);
+                assert_eq!(e.session().edit.selection.start, at + expected);
+            }
+        }
+    }
+}
+
+/// Separation refuses oversized numeric grids before splitting any material.
+#[test]
+fn separate_on_grid_refuses_a_truncated_boundary_set() {
+    let (mut e, t, _) = long("grid", &[(0, 20_000, 0)]);
+    run(&mut e, "view.grid", json!({"value": {"samples": 1}, "follow_main": false}));
+    assert!(e.execute("edit.separate_on_grid", &json!({"tracks": [t.0], "start": 0, "end": 10_002})).is_err());
+    assert_eq!(clips(&e, t), [(0, 20_000)]);
+}
+
+/// Display thinning must never hide an oversized Clips/Markers separation request.
+#[test]
+fn separate_on_grid_refuses_dense_markers_before_changing_clips() {
+    let (mut e, track, _) = long("grid", &[(0, 100_000, 0)]);
+    let s = e.session_mut();
+    for at in 1..=10_001 {
+        s.add_marker("Boundary", soundcraft_model::MarkerKind::Marker, at, at);
+    }
+    run(&mut e, "view.grid", json!({"format": "clips_markers", "follow_main": false}));
+    let before = e.session().clone();
+    let undo_len = e.undo_history().len();
+    let error = e.execute("edit.separate_on_grid", &json!({"tracks": [track.0], "start": 0, "end": 100_000})).unwrap_err();
+    assert!(error.to_string().contains("10,000"), "{error}");
+    assert_eq!(e.session(), &before);
+    assert_eq!(e.undo_history().len(), undo_len);
+}
+
 #[test]
 fn shuffle_moves_keep_crossfade_partners_whole() {
     let (mut e, t, ids) = long("slip", &[(0, 1000, 10_000), (1000, 1000, 20_000), (2000, 1000, 30_000)]);

crates/mix/src/instances.rs

@@ -68,7 +68,23 @@ pub struct NewInstance {
 /// Creates a plugin (built-in or hosted), restores `state` (if any) and prepares it. Expensive
 /// for third-party plugins: in realtime use, call it on the control thread.
 pub fn create_instance(id: &str, state: Option<&[u8]>, sample_rate: f32, max_block: usize, ch: usize) -> Option<NewInstance> {
+    create_instance_for(id, state, sample_rate, max_block, ch, false)
+}
+
+/// [`create_instance`] for an engine that renders offline (`offline`) or in realtime: the plugin
+/// is told which before it is prepared ([`Plugin::set_offline`]).
+pub(crate) fn create_instance_for(
+    id: &str,
+    state: Option<&[u8]>,
+    sample_rate: f32,
+    max_block: usize,
+    ch: usize,
+    offline: bool,
+) -> Option<NewInstance> {
     let mut plugin = create_plugin(id)?;
+    if offline {
+        plugin.set_offline(true);
+    }
     let refused_state = state.is_some_and(|st| !plugin.load_state(st));
     if refused_state {
         log::warn!("{id}: the plugin did not accept its stored state");

crates/mix/src/lib.rs

@@ -144,6 +144,8 @@ pub struct MixEngine {
     pub metronome: bool,
     /// Third-party instances come from [`MixEngine::adopt`] instead of being created in `sync`.
     external: bool,
+    /// An offline render: the plugins `sync` creates are told so ([`Plugin::set_offline`]).
+    offline: bool,
     /// Instances handed over by the host, waiting for `sync` to place them.
     adopt: HashMap<(TrackId, usize), PreparedInstance>,
     /// Instances `sync` took out of service, for the host to drop (see [`MixEngine::take_retired`]).
@@ -177,6 +179,7 @@ impl MixEngine {
             recording: false,
             metronome: false,
             external: false,
+            offline: false,
             adopt: HashMap::new(),
             retired: Vec::new(),
             work: Vec::new(),
@@ -189,6 +192,11 @@ impl MixEngine {
         self.external = on;
     }
 
+    /// Offline render (a bounce): plugins created from now on are told they render offline.
+    pub fn set_offline(&mut self, on: bool) {
+        self.offline = on;
+    }
+
     /// Takes instances created off the audio thread; the next render's `sync` places them.
     /// An earlier instance waiting for the same slot is retired.
     pub fn adopt(&mut self, instances: Vec<PreparedInstance>) {
@@ -271,7 +279,8 @@ impl MixEngine {
         if self.main.len() != main_ch {
             self.main = vec![vec![0.0; mb]; main_ch];
         }
-        let mut cx = SlotCtx { sr: self.sample_rate, mb, external: self.external, adopt: &mut self.adopt, retired: &mut self.retired };
+        let mut cx =
+            SlotCtx { sr: self.sample_rate, mb, external: self.external, offline: self.offline, adopt: &mut self.adopt, retired: &mut self.retired };
         let gone: Vec<TrackId> = self.strips.keys().filter(|id| s.track(**id).is_none()).copied().collect();
         for id in gone {
             self.meters.remove(&id);

crates/mix/src/midi.rs

@@ -46,12 +46,20 @@ pub(crate) fn schedule_notes(s: &Session, t: &Track, pos: Samples, frames: usize
                 rtp("delay", 0.0).clamp(-1e7, 1e7) as i64,
             )
         };
+        // The block in clip ticks, one tick wider on each side so rounding never drops an event.
+        let near = s.tempo.samples_to_ticks(pos, sr).saturating_sub(base).saturating_sub(1)
+            ..=s.tempo.samples_to_ticks(end, sr).saturating_sub(base).saturating_add(1);
         for n0 in &sequence.notes {
             let mut n = *n0;
             n.velocity = (i64::from(n.velocity) + dv).clamp(1, 127) as u8;
             n.pitch = (i64::from(n.pitch) + dp).clamp(0, 127) as u8;
             n.length = ((n.length as f64 * dur) as i64).max(1);
             n.start = n.start.saturating_add(delay).max(0);
+            // A note whose on and off both fall outside the block sends nothing: skip it before
+            // converting its positions, so a long sequence costs a comparison per note per block.
+            if n.start > *near.end() || n.start.saturating_add(n.length) < *near.start() {
+                continue;
+            }
             let on = s.tempo.tick_to_samples(base.saturating_add(n.start), sr);
             let off = s.tempo.tick_to_samples(base.saturating_add(n.start).saturating_add(n.length), sr).min(clip.end());
             if on >= clip.end() {
@@ -68,8 +76,6 @@ pub(crate) fn schedule_notes(s: &Session, t: &Track, pos: Samples, frames: usize
                 held.retain(|p| *p != n.pitch);
             }
         }
-        let near = s.tempo.samples_to_ticks(pos, sr).saturating_sub(base).saturating_sub(1)
-            ..=s.tempo.samples_to_ticks(end, sr).saturating_sub(base).saturating_add(1);
         // Events before tick 0 are what a start trim hid: they don't play.
         for c in sequence.ctrls.iter().filter(|c| c.tick >= 0) {
             let tick = c.tick.saturating_add(delay).max(0);

crates/mix/src/offline.rs

@@ -57,7 +57,8 @@ impl RangeRender {
     /// Renders the main mix over `range`, or `bus` when one is named.
     pub fn new(s: &Session, bus: Option<BusId>, range: Range, block: usize) -> Self {
         let nch = source_channels(s, bus);
-        let eng = MixEngine::new(s.sample_rate.as_f64() as f32, block);
+        let mut eng = MixEngine::new(s.sample_rate.as_f64() as f32, block);
+        eng.set_offline(true);
         let tmp = vec![vec![0.0f32; eng.max_block()]; nch];
         let len = if nch == 0 { 0 } else { usize::try_from(range.len().max(0)).unwrap_or(0) };
         RangeRender { eng, bus, tmp, start: range.start, done: 0, total: len, latency: 0 }

crates/mix/src/routing.rs

@@ -46,7 +46,8 @@ pub(crate) fn processing_order(s: &Session) -> Vec<usize> {
     } else {
         // A cycle keeps the existing bounded ordering for the entire graph, including any
         // independent acyclic branches. Feedback does not have a finite longest-path depth.
-        auxes.sort_by_key(|&i| bounded_aux_depth(s, i));
+        let depths = bounded_aux_depths(s);
+        auxes.sort_by_key(|&i| depths.get(i).copied().unwrap_or(0));
     }
     order.extend(auxes);
     order
@@ -115,32 +116,38 @@ fn aux_output_busses(t: &Track) -> impl Iterator<Item = BusId> + '_ {
         .filter_map(|route| if let Route::Bus(bus) = route { Some(*bus) } else { None })
 }
 
-/// The previous bounded depth calculation, retained unchanged for any cyclic graph.
-fn bounded_aux_depth(s: &Session, i: usize) -> usize {
-    let mut d = 0;
-    let mut cur = vec![i];
-    for _ in 0..8 {
-        let inputs: Vec<&Route> = cur.iter().filter_map(|&k| s.tracks.get(k)).map(|t| &t.mixer.input).collect();
-        let feeders: Vec<usize> = auxes_feeding(s, &inputs);
-        if feeders.is_empty() {
+/// Hop cap for the bounded depth used when the aux graph has a cycle.
+const MAX_BOUNDED_DEPTH: usize = 8;
+
+/// For each track, the bounded depth used for a cyclic graph: the length of the longest chain of
+/// Aux/Folder feeders into it (through a bus its input reads and the feeder's output or a send
+/// writes), capped at [`MAX_BOUNDED_DEPTH`] hops. One pass per hop over the tracks and their bus
+/// writes, so the cost is linear in the routing, not a fresh feeder search per track per
+/// sort comparison.
+fn bounded_aux_depths(s: &Session) -> Vec<usize> {
+    let is_aux = |t: &Track| matches!(t.kind, TrackKind::Aux | TrackKind::Folder);
+    // Tracks with a feeder chain of the current length ending at them (length 0: every aux).
+    let mut reached: Vec<bool> = s.tracks.iter().map(is_aux).collect();
+    let mut depths = vec![0usize; s.tracks.len()];
+    let mut fed = std::collections::HashSet::<BusId>::new();
+    for hop in 1..=MAX_BOUNDED_DEPTH {
+        fed.clear();
+        for (t, _) in s.tracks.iter().zip(&reached).filter(|(t, r)| **r && is_aux(t)) {
+            fed.extend(aux_output_busses(t));
+        }
+        let mut any = false;
+        for ((t, r), d) in s.tracks.iter().zip(reached.iter_mut()).zip(depths.iter_mut()) {
+            *r = matches!(&t.mixer.input, Route::Bus(b) if fed.contains(b));
+            if *r {
+                *d = hop;
+                any = true;
+            }
+        }
+        if !any {
             break;
         }
-        d += 1;
-        cur = feeders;
     }
-    d
-}
-
-fn auxes_feeding(s: &Session, inputs: &[&Route]) -> Vec<usize> {
-    s.tracks
-        .iter()
-        .enumerate()
-        .filter(|(_, t)| matches!(t.kind, TrackKind::Aux | TrackKind::Folder))
-        .filter(|(_, t)| {
-            inputs.iter().any(|r| matches!(r, Route::Bus(_)) && (&&t.mixer.output == r || t.mixer.sends.iter().flatten().any(|sn| &&sn.target == r)))
-        })
-        .map(|(i, _)| i)
-        .collect()
+    depths
 }
 
 /// Implicit solo: an aux is not muted when a soloed track feeds its input bus.
@@ -204,4 +211,81 @@ mod processing_order_tests {
         // Both deepest independent returns tie with the cycle at the legacy eight-hop cap.
         assert_eq!(processing_order(&s), vec![9, 8, 7, 6, 5, 4, 3, 2, 0, 1, 10]);
     }
+
+    /// The per-track feeder search `bounded_aux_depths` replaced, kept as its reference.
+    fn reference_depth(s: &Session, i: usize) -> usize {
+        let mut d = 0;
+        let mut cur = vec![i];
+        for _ in 0..MAX_BOUNDED_DEPTH {
+            let inputs: Vec<&Route> = cur.iter().filter_map(|&k| s.tracks.get(k)).map(|t| &t.mixer.input).collect();
+            let feeders: Vec<usize> = s
+                .tracks
+                .iter()
+                .enumerate()
+                .filter(|(_, t)| matches!(t.kind, TrackKind::Aux | TrackKind::Folder))
+                .filter(|(_, t)| {
+                    inputs
+                        .iter()
+                        .any(|r| matches!(r, Route::Bus(_)) && (&&t.mixer.output == r || t.mixer.sends.iter().flatten().any(|sn| &&sn.target == r)))
+                })
+                .map(|(i, _)| i)
+                .collect();
+            if feeders.is_empty() {
+                break;
+            }
+            d += 1;
+            cur = feeders;
+        }
+        d
+    }
+
+    #[test]
+    fn bounded_depths_match_the_per_track_feeder_search() {
+        // A small pseudo-random graph of auxes, folders and audio tracks with cycles, joins,
+        // sends and unrouted inputs.
+        let mut s = Session::default();
+        let busses: Vec<_> = (0..6).map(|i| s.add_bus(&format!("B{i}"), ChannelFormat::Stereo)).collect();
+        let mut x = 12345u32;
+        let mut next = |m: usize| {
+            x = x.wrapping_mul(1_103_515_245).wrapping_add(12_345);
+            (x >> 16) as usize % m
+        };
+        for i in 0..30 {
+            let kind = [TrackKind::Aux, TrackKind::Folder, TrackKind::Audio][next(3)];
+            let id = s.add_track(kind, ChannelFormat::Stereo, None);
+            let pick = |n: usize| if n < busses.len() { Route::Bus(busses[n]) } else { Route::Main };
+            let (input, output, send) = (pick(next(8)), pick(next(8)), pick(next(8)));
+            let t = s.track_mut(id).unwrap();
+            t.mixer.input = input;
+            t.mixer.output = output;
+            if i % 2 == 0 {
+                t.mixer.sends[0] = Some(SendSlot::new(send));
+            }
+        }
+        let depths = bounded_aux_depths(&s);
+        for (i, (t, depth)) in s.tracks.iter().zip(&depths).enumerate() {
+            if matches!(t.kind, TrackKind::Aux | TrackKind::Folder) {
+                assert_eq!(*depth, reference_depth(&s, i), "track {i}");
+            }
+        }
+        assert!(depths.contains(&MAX_BOUNDED_DEPTH));
+    }
+
+    #[test]
+    fn a_large_cyclic_graph_orders_quickly() {
+        // Thousands of auxes all reading and writing one bus: every aux feeds every other.
+        let mut s = Session::default();
+        let bus = s.add_bus("Loop", ChannelFormat::Stereo);
+        for _ in 0..3000 {
+            let id = s.add_track(TrackKind::Aux, ChannelFormat::Stereo, None);
+            let t = s.track_mut(id).unwrap();
+            t.mixer.input = Route::Bus(bus);
+            t.mixer.output = Route::Bus(bus);
+            t.mixer.sends[0] = Some(SendSlot::new(Route::Bus(bus)));
+        }
+        let start = std::time::Instant::now();
+        let order = processing_order(&s);
+        assert!(start.elapsed() < std::time::Duration::from_secs(5), "{:?}", start.elapsed());
+        assert_eq!(order, (0..3000).collect::<Vec<_>>());
+    }
 }

crates/mix/src/strip.rs

@@ -1,6 +1,6 @@
 use super::automation::{GainRamp, transport_at, volume_db_at};
 use super::clips::{ClipFx, clip_fx_params, render_clip};
-use super::instances::{INSTRUMENT_SLOT, PluginFailures, PreparedInstance, create_instance, is_third_party};
+use super::instances::{INSTRUMENT_SLOT, PluginFailures, PreparedInstance, create_instance_for, is_third_party};
 use super::midi::{chase_controllers, schedule_notes};
 use super::pan::{PanSpec, apply_matrix, build_matrix, identity_matrix};
 use super::routing::receives_solo;
@@ -24,6 +24,9 @@ pub(crate) struct PluginSlot {
     pub(crate) plugin: Box<dyn Plugin>,
     /// Last values pushed to the plugin, in the insert's parameter-map order.
     applied: Vec<f32>,
+    /// Scratch for `apply_params`: indexes of the track's automation lanes for this slot, kept
+    /// so the audio thread reuses its allocation.
+    lanes: Vec<usize>,
     pub(crate) failed: bool,
 }
 
@@ -157,6 +160,8 @@ pub(crate) struct SlotCtx<'a> {
     pub(crate) sr: f32,
     pub(crate) mb: usize,
     pub(crate) external: bool,
+    /// The engine renders offline: plugins it creates are told so.
+    pub(crate) offline: bool,
     pub(crate) adopt: &'a mut HashMap<(TrackId, usize), PreparedInstance>,
     pub(crate) retired: &'a mut Vec<Box<dyn Plugin>>,
 }
@@ -189,9 +194,9 @@ impl SlotCtx<'_> {
             }
         } else {
             let state = if third { ins.state_bytes() } else { None };
-            create_instance(&ins.plugin, state.as_deref(), self.sr, self.mb, ch).map(|n| n.plugin)
+            create_instance_for(&ins.plugin, state.as_deref(), self.sr, self.mb, ch, self.offline).map(|n| n.plugin)
         }?;
-        Some(PluginSlot { id: ins.plugin.clone(), ch, plugin, applied: Vec::new(), failed: false })
+        Some(PluginSlot { id: ins.plugin.clone(), ch, plugin, applied: Vec::new(), lanes: Vec::new(), failed: false })
     }
 }
 
@@ -491,21 +496,40 @@ pub(crate) fn apply_params(slot: &mut PluginSlot, ins: &soundcraft_model::Insert
     let Ok(slot_u8) = u8::try_from(i) else {
         return apply_values(slot, ins, |_, v| v);
     };
-    let automated = t.mixer.automation_mode.reads()
-        && t.automation.iter().any(|l| matches!(&l.param, AutoParam::Plugin { slot, .. } if *slot == slot_u8) && !l.points.is_empty());
+    let lanes = &t.automation;
+    let name = |j: usize| match lanes.get(j).map(|l| &l.param) {
+        Some(AutoParam::Plugin { param, .. }) => param.as_str(),
+        _ => "",
+    };
+    // This slot's lanes, ordered by parameter name (the parameter map's order) and keeping only
+    // the first lane per name (the one a lookup by name finds). Matching them to the parameters
+    // in one merge costs O(lanes log lanes + params) per block, not O(lanes x params).
+    let mut order = std::mem::take(&mut slot.lanes);
+    order.clear();
+    if t.mixer.automation_mode.reads() {
+        order
+            .extend(lanes.iter().enumerate().filter(|(_, l)| matches!(&l.param, AutoParam::Plugin { slot, .. } if *slot == slot_u8)).map(|(j, _)| j));
+        if !order.iter().any(|&j| lanes.get(j).is_some_and(|l| !l.points.is_empty())) {
+            order.clear();
+        }
+        order.sort_unstable_by(|&a, &b| name(a).cmp(name(b)).then(a.cmp(&b)));
+        order.dedup_by(|later, kept| name(*later) == name(*kept));
+    }
+    let mut next = order.iter().copied().peekable();
     apply_values(slot, ins, |k, val| {
-        if automated
-            && let Some(l) = t.automation.iter().find(|l| matches!(&l.param, AutoParam::Plugin { slot, param } if *slot == slot_u8 && param == k))
+        while next.next_if(|&j| name(j) < k).is_some() {}
+        if let Some(l) = next.peek().filter(|&&j| name(j) == k).and_then(|&j| lanes.get(j))
             && !l.points.is_empty()
         {
             return l.value_at(pos, val);
         }
         val
     });
+    slot.lanes = order;
 }
 
 /// Sends each stored param (as mapped by `value`) to the plugin when it changed since last time.
-fn apply_values(slot: &mut PluginSlot, ins: &soundcraft_model::Insert, value: impl Fn(&str, f32) -> f32) {
+fn apply_values(slot: &mut PluginSlot, ins: &soundcraft_model::Insert, mut value: impl FnMut(&str, f32) -> f32) {
     if slot.applied.len() != ins.params.len() {
         slot.applied = vec![f32::NAN; ins.params.len()];
     }
@@ -517,3 +541,99 @@ fn apply_values(slot: &mut PluginSlot, ins: &soundcraft_model::Insert, value: im
         }
     }
 }
+
+#[cfg(test)]
+mod apply_params_tests {
+    use super::*;
+    use soundcraft_model::{AutomationLane, Insert};
+    use std::sync::Mutex;
+
+    /// A built-in gain that logs every parameter set.
+    struct Recorder {
+        inner: Box<dyn Plugin>,
+        sets: Arc<Mutex<Vec<(String, f32)>>>,
+    }
+
+    impl Plugin for Recorder {
+        fn info(&self) -> &'static soundcraft_dsp::PluginInfo {
+            self.inner.info()
+        }
+        fn prepare(&mut self, sr: f32, mb: usize, ch: usize) {
+            self.inner.prepare(sr, mb, ch);
+        }
+        fn reset(&mut self) {
+            self.inner.reset();
+        }
+        fn set_param(&mut self, id: &str, v: f32) -> bool {
+            self.sets.lock().unwrap().push((id.to_string(), v));
+            true
+        }
+        fn param(&self, id: &str) -> Option<f32> {
+            self.inner.param(id)
+        }
+        fn process(&mut self, io: &mut [Vec<f32>], frames: usize) {
+            self.inner.process(io, frames);
+        }
+    }
+
+    fn recorder() -> (PluginSlot, Arc<Mutex<Vec<(String, f32)>>>) {
+        let sets = Arc::new(Mutex::new(Vec::new()));
+        let plugin = Box::new(Recorder { inner: soundcraft_dsp::create("gain").unwrap(), sets: Arc::clone(&sets) });
+        (PluginSlot { id: "gain".into(), ch: 2, plugin, applied: Vec::new(), lanes: Vec::new(), failed: false }, sets)
+    }
+
+    fn lane(slot: u8, param: &str, point: Option<f32>) -> AutomationLane {
+        let mut l = AutomationLane::new(AutoParam::Plugin { slot, param: param.into() });
+        if let Some(v) = point {
+            l.set_point(0, v);
+        }
+        l
+    }
+
+    #[test]
+    fn first_lane_per_param_of_this_slot_drives_it() {
+        let mut s = Session::default();
+        let t = s.add_track(TrackKind::Audio, ChannelFormat::Stereo, None);
+        let tr = s.track_mut(t).unwrap();
+        tr.automation = vec![
+            lane(0, "c", None),
+            lane(1, "a", Some(5.0)),
+            lane(0, "b", Some(9.0)),
+            lane(0, "c", Some(7.0)),
+            lane(0, "zz", Some(1.0)),
+            lane(0, "b", Some(8.0)),
+        ];
+        let mut ins = Insert::new("gain");
+        for (k, v) in [("a", 1.0), ("b", 2.0), ("c", 3.0), ("d", 4.0)] {
+            ins.params.insert(k.into(), v);
+        }
+        let (mut slot, sets) = recorder();
+        apply_params(&mut slot, &ins, tr, 0, 0);
+        let got = sets.lock().unwrap().clone();
+        let want: Vec<(String, f32)> = [("a", 1.0), ("b", 9.0), ("c", 3.0), ("d", 4.0)].iter().map(|(k, v)| (k.to_string(), *v)).collect();
+        assert_eq!(got, want);
+        // Unchanged values are not sent again.
+        apply_params(&mut slot, &ins, tr, 0, 0);
+        assert_eq!(sets.lock().unwrap().len(), 4);
+    }
+
+    #[test]
+    fn many_params_and_lanes_apply_without_a_quadratic_search() {
+        let n = 40_000;
+        let mut s = Session::default();
+        let t = s.add_track(TrackKind::Audio, ChannelFormat::Stereo, None);
+        let tr = s.track_mut(t).unwrap();
+        tr.automation = (0..n).rev().map(|i| lane(0, &format!("p{i:06}"), Some(i as f32))).collect();
+        let mut ins = Insert::new("gain");
+        for i in 0..n {
+            ins.params.insert(format!("p{i:06}"), -1.0);
+        }
+        let (mut slot, sets) = recorder();
+        let start = std::time::Instant::now();
+        apply_params(&mut slot, &ins, tr, 0, 0);
+        assert!(start.elapsed() < std::time::Duration::from_secs(5), "{:?}", start.elapsed());
+        let got = sets.lock().unwrap();
+        assert_eq!(got.len(), n);
+        assert!(got.iter().all(|(k, v)| k == &format!("p{:06}", *v as usize)));
+    }
+}

crates/model/src/session.rs

@@ -5,7 +5,7 @@ use crate::{
     Bus, BusId, ChannelFormat, Clip, ClipId, Group, GroupId, MarkerId, MarkerKind, MemoryLocation, OutputPath, Source, SourceId, SourcePool,
     TRACK_COLORS, Track, TrackId, TrackKind, VideoSource,
 };
-use soundcraft_time::{FrameRate, GridValue, Range, SampleRate, Samples, TempoMap, TimeFormat};
+use soundcraft_time::{FrameRate, GridScale, GridValue, Range, SampleRate, Samples, TempoMap, TimeFormat};
 
 /// Native session file extension.
 pub const SESSION_EXTENSION: &str = "scraft";
@@ -147,6 +147,7 @@ pub struct ZoomState {
 }
 
 impl Default for ZoomState {
+    /// Starts with a practical overview zoom and five reusable preset levels.
     fn default() -> Self {
         ZoomState { samples_per_px: 1024.0, scroll: 0, waveform_zoom: 1.0, presets: [64.0, 256.0, 1024.0, 4096.0, 16384.0] }
     }
@@ -179,6 +180,15 @@ pub struct EditState {
     pub playhead: Samples,
     pub grid: GridValue,
     pub nudge: GridValue,
+    /// Grid/Nudge time scales follow the main counter when enabled.
+    #[serde(default)]
+    pub grid_follow_main: bool,
+    #[serde(default)]
+    pub nudge_follow_main: bool,
+    /// Grid lines and snapping use visible clip boundaries and memory locations while the numeric
+    /// Grid value is retained for when this mode is left.
+    #[serde(default)]
+    pub grid_clips_markers: bool,
     #[serde(default = "yes")]
     pub grid_lines: bool,
     pub main_counter: TimeFormat,
@@ -244,6 +254,7 @@ fn yes() -> bool {
 }
 
 impl Default for EditState {
+    /// Starts the Edit window in Slip mode with independent Grid and Nudge scales.
     fn default() -> Self {
         EditState {
             tool: Tool::Smart,
@@ -255,6 +266,9 @@ impl Default for EditState {
             playhead: 0,
             grid: GridValue::default(),
             nudge: GridValue::Seconds(1.0),
+            grid_follow_main: false,
+            nudge_follow_main: false,
+            grid_clips_markers: false,
             grid_lines: true,
             main_counter: TimeFormat::MinSecs,
             sub_counter: Some(TimeFormat::Samples),
@@ -490,6 +504,138 @@ impl Session {
         soundcraft_time::parse_position(text, fmt, self.sample_rate, &self.tempo, self.frame_rate, self.timecode_start, self.feet_frames_start())
     }
 
+    /// Whether the Edit window shows a track: unhidden, with every parent folder open.
+    pub fn track_shown(&self, track: &Track) -> bool {
+        if track.hidden {
+            return false;
+        }
+        let mut folder = track.folder;
+        for _ in 0..64 {
+            let Some(parent) = folder.and_then(|id| self.track(id)) else { return true };
+            if !parent.folder_open {
+                return false;
+            }
+            folder = parent.folder;
+        }
+        false
+    }
+
+    /// Collects unique visible active-playlist clip boundaries and memory-location boundaries.
+    fn clip_marker_grid_points(&self, keep: impl Fn(Samples) -> bool, excluded: &[ClipId], include_zero: bool) -> Vec<Samples> {
+        let mut points = Vec::new();
+        let excluded: std::collections::HashSet<ClipId> = excluded.iter().copied().collect();
+        if include_zero && keep(0) {
+            points.push(0);
+        }
+        for clip in
+            self.tracks.iter().filter(|track| self.track_shown(track)).flat_map(|track| track.clips()).filter(|clip| !excluded.contains(&clip.id))
+        {
+            points.extend([clip.start, clip.end()].into_iter().filter(|point| keep(*point)));
+        }
+        for marker in &self.markers {
+            if keep(marker.start) {
+                points.push(marker.start);
+            }
+            if marker.end != marker.start && keep(marker.end) {
+                points.push(marker.end);
+            }
+        }
+        points.sort_unstable();
+        points.dedup();
+        points
+    }
+
+    /// Sample-domain Timecode reference; Feet+Frames applies its origin in frames separately.
+    fn grid_origin(&self) -> Samples {
+        match self.edit.grid.scale() {
+            GridScale::Timecode => self.timecode_start,
+            _ => 0,
+        }
+    }
+
+    /// Grid lines for the current Grid value, including clip and marker boundaries.
+    pub fn grid_lines(&self, start: Samples, end: Samples, max: usize) -> Vec<Samples> {
+        if !self.edit.grid_clips_markers {
+            if let GridValue::FeetFrames(value) = self.edit.grid {
+                return value.lines(start, end, self.sample_rate, self.frame_rate, self.feet_frames_start(), max);
+            }
+            let origin = self.grid_origin();
+            return self
+                .edit
+                .grid
+                .lines(start.saturating_add(origin), end.saturating_add(origin), self.sample_rate, &self.tempo, self.frame_rate, max)
+                .into_iter()
+                .map(|point| point.saturating_sub(origin))
+                .collect();
+        }
+        let points = self.clip_marker_grid_points(|point| point >= start && point < end, &[], true);
+        if points.len() <= max {
+            return points;
+        }
+        match max {
+            0 => Vec::new(),
+            1 => points.first().copied().into_iter().collect(),
+            _ => {
+                let span = i128::from(end).saturating_sub(i128::from(start)).max(1);
+                let mut bucket = None;
+                points
+                    .into_iter()
+                    .filter(|point| {
+                        let next = i128::from(*point).saturating_sub(i128::from(start)).saturating_mul(max as i128) / span;
+                        if bucket == Some(next) {
+                            false
+                        } else {
+                            bucket = Some(next);
+                            true
+                        }
+                    })
+                    .collect()
+            }
+        }
+    }
+
+    /// The current Grid line at or before `position`.
+    pub fn grid_line_at_or_before(&self, position: Samples) -> Samples {
+        self.grid_line_at_or_before_excluding(position, &[])
+    }
+
+    /// Find the current Grid line at or before `position` without boundaries of `excluded` clips.
+    pub fn grid_line_at_or_before_excluding(&self, position: Samples, excluded: &[ClipId]) -> Samples {
+        if !self.edit.grid_clips_markers {
+            if let GridValue::FeetFrames(value) = self.edit.grid {
+                return value.line_at_or_before(position, self.sample_rate, self.frame_rate, self.feet_frames_start());
+            }
+            let origin = self.grid_origin();
+            return self
+                .edit
+                .grid
+                .line_at_or_before(position.saturating_add(origin), self.sample_rate, &self.tempo, self.frame_rate)
+                .saturating_sub(origin);
+        }
+        self.clip_marker_grid_points(|_| true, excluded, true).into_iter().take_while(|point| *point <= position).last().unwrap_or(position)
+    }
+
+    /// Snap to the nearest line in the current Grid.
+    pub fn snap_to_grid(&self, position: Samples) -> Samples {
+        self.snap_to_grid_excluding(position, &[])
+    }
+
+    /// Snap to the nearest current Grid line without using boundaries of `excluded` clips.
+    pub fn snap_to_grid_excluding(&self, position: Samples, excluded: &[ClipId]) -> Samples {
+        if !self.edit.grid_clips_markers {
+            if let GridValue::FeetFrames(value) = self.edit.grid {
+                return value.snap(position, self.sample_rate, self.frame_rate, self.feet_frames_start());
+            }
+            let origin = self.grid_origin();
+            return self.edit.grid.snap(position.saturating_add(origin), self.sample_rate, &self.tempo, self.frame_rate).saturating_sub(origin);
+        }
+        let mut points = self.clip_marker_grid_points(|_| true, excluded, false);
+        if !points.is_empty() {
+            points.push(0);
+        }
+        points.into_iter().min_by_key(|point| i128::from(*point).saturating_sub(i128::from(position)).abs()).unwrap_or(position)
+    }
+
     pub fn next_track_color(&self) -> [u8; 3] {
         let n = self.tracks.iter().filter(|t| t.kind != TrackKind::Master).count();
         TRACK_COLORS.get(n % TRACK_COLORS.len()).copied().unwrap_or([128, 128, 128])
@@ -578,13 +724,36 @@ impl Session {
     }
 
     /// Parse a session; decoded audio must be attached separately (`pool`).
+    ///
+    /// The text is parsed straight into the document, never into a `serde_json::Value` tree
+    /// first (which takes many times the file's size). Only the version is read before that.
+    /// A field of the document given twice in one object is refused (`duplicate field`), as no
+    /// writer repeats one. Keys of maps (plugin params, edit values, Auto Rename schemes, MIDI
+    /// originals) and unknown keys keep the last value given, as before.
     pub fn from_json(text: &str) -> Result<Session, SessionError> {
-        let v: serde_json::Value = serde_json::from_str(text).map_err(|e| SessionError::Format(e.to_string()))?;
-        let ver = v.get("format_version").and_then(serde_json::Value::as_u64).ok_or_else(|| SessionError::Format("missing format_version".into()))?;
+        /// The version alone: every other field is skipped, not kept.
+        #[derive(serde::Deserialize)]
+        struct Head {
+            format_version: Option<serde_json::Number>,
+        }
+        // `Head` would also take a JSON array as its fields in order: only an object has a version.
+        let object = text.trim_start_matches([' ', '\t', '\n', '\r']).starts_with('{');
+        let version = match object.then(|| serde_json::from_str::<Head>(text)) {
+            Some(Ok(head)) => head.format_version,
+            // A version given twice is that error, not a missing version.
+            Some(Err(e)) if e.to_string().starts_with("duplicate field") => return Err(SessionError::Format(e.to_string())),
+            // Valid JSON of another shape (not an object, or a version that is not a number)
+            // has no version; anything else is not JSON.
+            _ => {
+                serde_json::from_str::<serde::de::IgnoredAny>(text).map_err(|e| SessionError::Format(e.to_string()))?;
+                None
+            }
+        };
+        let ver = version.and_then(|v| v.as_u64()).ok_or_else(|| SessionError::Format("missing format_version".into()))?;
         if ver > u64::from(Self::FORMAT_VERSION) {
             return Err(SessionError::Version(u32::try_from(ver).unwrap_or(u32::MAX)));
         }
-        let mut s: Session = serde_json::from_value(v).map_err(|e| SessionError::Format(e.to_string()))?;
+        let mut s: Session = serde_json::from_str(text).map_err(|e| SessionError::Format(e.to_string()))?;
         s.sanitize();
         s.validate()?;
         Ok(s)
@@ -762,6 +931,136 @@ mod tests {
         assert_eq!(back, s);
     }
 
+    /// Clips/Markers mode snaps and draws at clip and memory-location boundaries.
+    #[test]
+    fn clips_markers_grid_uses_visible_clip_edges_and_memory_locations() {
+        let mut s = Session::default();
+        let track = s.add_track(TrackKind::Midi, ChannelFormat::Mono, None);
+        let clip = Clip::midi(s.new_clip_id(), "Notes", 1_000, 2_000, soundcraft_midi::Sequence::default());
+        let clip_id = clip.id;
+        s.track_mut(track).and_then(Track::playlist_mut).unwrap().clips.push(clip);
+        let hidden = s.add_track(TrackKind::Midi, ChannelFormat::Mono, None);
+        let hidden_clip = Clip::midi(s.new_clip_id(), "Hidden", 3_200, 100, soundcraft_midi::Sequence::default());
+        if let Some(track) = s.track_mut(hidden) {
+            track.hidden = true;
+            track.playlist_mut().unwrap().clips.push(hidden_clip);
+        }
+        s.add_marker("Cue", MarkerKind::Marker, 2_500, 2_500);
+        s.add_marker("Selection", MarkerKind::Selection, 4_000, 4_500);
+        s.edit.grid_clips_markers = true;
+
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0, 1_000, 2_500, 3_000, 4_000, 4_500]);
+        assert_eq!(s.grid_line_at_or_before(2_800), 2_500);
+        assert_eq!(s.snap_to_grid(2_800), 3_000);
+        assert_eq!(s.snap_to_grid(3_700), 4_000);
+        assert_eq!(s.grid_lines(2_400, 4_100, 2), [2_500, 4_000]);
+        assert_eq!(s.snap_to_grid(3_200), 3_000);
+        assert_eq!(s.snap_to_grid_excluding(2_800, &[clip_id]), 2_500);
+
+        let folder = s.add_track(TrackKind::Folder, ChannelFormat::Stereo, None);
+        s.track_mut(track).unwrap().folder = Some(folder);
+        s.track_mut(folder).unwrap().folder_open = false;
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0, 2_500, 4_000, 4_500]);
+    }
+
+    /// Open hidden folders keep their visible descendants eligible for lines and snapping.
+    #[test]
+    fn clips_markers_grid_keeps_visible_children_of_hidden_open_folders() {
+        let mut s = Session::default();
+        let outer = s.add_track(TrackKind::Folder, ChannelFormat::Stereo, None);
+        let inner = s.add_track(TrackKind::Folder, ChannelFormat::Stereo, None);
+        let child = s.add_track(TrackKind::Midi, ChannelFormat::Mono, None);
+        let clip = Clip::midi(s.new_clip_id(), "Visible", 1_000, 2_000, soundcraft_midi::Sequence::default());
+        s.track_mut(inner).unwrap().folder = Some(outer);
+        s.track_mut(inner).unwrap().hidden = true;
+        s.track_mut(child).unwrap().folder = Some(inner);
+        s.track_mut(child).unwrap().playlist_mut().unwrap().clips.push(clip);
+        s.edit.grid_clips_markers = true;
+
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0, 1_000, 3_000]);
+        assert_eq!(s.snap_to_grid(2_800), 3_000);
+        assert_eq!(s.grid_line_at_or_before(2_800), 1_000);
+
+        s.track_mut(child).unwrap().hidden = true;
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0]);
+        assert_eq!(s.snap_to_grid(2_800), 2_800);
+        s.track_mut(child).unwrap().hidden = false;
+        s.track_mut(inner).unwrap().folder_open = false;
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0]);
+        s.track_mut(inner).unwrap().folder_open = true;
+        s.track_mut(outer).unwrap().folder_open = false;
+        assert_eq!(s.grid_lines(0, 5_000, 20), [0]);
+    }
+
+    /// With no real Clips/Markers boundaries, snapping leaves the position alone while drawing
+    /// retains the session-start line.
+    #[test]
+    fn empty_clips_markers_grid_does_not_snap_everything_to_zero() {
+        let mut s = Session::default();
+        s.edit.grid_clips_markers = true;
+        assert_eq!(s.grid_lines(0, 1_000, 10), [0]);
+        assert_eq!(s.snap_to_grid(678), 678);
+    }
+
+    /// Frame-based grids share the same references as their displayed counters.
+    #[test]
+    fn frame_grids_apply_session_counter_origins() {
+        let mut s = Session { sample_rate: SampleRate::HZ_48000, frame_rate: FrameRate::Fps30, timecode_start: 1_600, ..Session::default() };
+        s.edit.grid = GridValue::Timecode(soundcraft_time::TimecodeValue::Second);
+        assert_eq!(s.grid_line_at_or_before(47_000), 46_400);
+        assert_eq!(s.snap_to_grid(46_400), 46_400);
+
+        s.edit.grid = GridValue::FeetFrames(soundcraft_time::FeetFramesValue::Foot);
+        s.edit.values.insert(FEET_FRAMES_START.into(), 1.0);
+        assert_eq!(s.grid_line_at_or_before(25_000), 24_000);
+        assert_eq!(s.snap_to_grid(24_000), 24_000);
+    }
+
+    /// Every Feet+Frames increment shares the parser's single rounding at fractional frame rates.
+    #[test]
+    fn feet_frames_grid_matches_parsed_positions_with_signed_frame_origins() {
+        use soundcraft_time::FeetFramesValue;
+        for rate in [FrameRate::Fps23_976, FrameRate::Fps29_97, FrameRate::Fps29_97Drop, FrameRate::Fps59_94Drop] {
+            let mut s = Session { sample_rate: SampleRate::HZ_48000, frame_rate: rate, ..Session::default() };
+            for origin in [-17, -1, 1, 17] {
+                s.edit.values.insert(FEET_FRAMES_START.into(), origin as f64);
+                for value in FeetFramesValue::ALL {
+                    s.edit.grid = GridValue::FeetFrames(value);
+                    for feet in [-64, -2, 0, 1, 2, 4, 7, 12, 128] {
+                        let at = s.parse_position(&format!("{feet}+00"), TimeFormat::FeetFrames).unwrap();
+                        assert_eq!(s.grid_line_at_or_before(at), at, "{rate:?} {value:?} origin {origin}, foot {feet}");
+                        assert_eq!(s.snap_to_grid(at), at);
+                        assert_eq!(s.grid_lines(at - 1, at + 2, 4), [at]);
+                    }
+                }
+            }
+        }
+        let mut s = Session { sample_rate: SampleRate::HZ_48000, frame_rate: FrameRate::Fps29_97, ..Session::default() };
+        s.edit.values.insert(FEET_FRAMES_START.into(), 1.0);
+        s.edit.grid = GridValue::FeetFrames(FeetFramesValue::Foot);
+        assert_eq!(s.snap_to_grid(49_649), 49_650);
+        assert_eq!(s.format_position(49_650, TimeFormat::FeetFrames), "2+00");
+    }
+
+    /// Drop-frame minute boundaries keep their counter alignment with signed session origins.
+    #[test]
+    fn drop_frame_grids_apply_session_origins_at_minute_boundaries() {
+        for (rate, minute_frame) in [(FrameRate::Fps29_97Drop, 1_800), (FrameRate::Fps59_94Drop, 3_600)] {
+            for origin_frame in [-1, 1] {
+                let sr = SampleRate::HZ_48000;
+                let origin = rate.samples_at_frame(origin_frame, sr);
+                let mut s = Session { sample_rate: sr, frame_rate: rate, timecode_start: origin, ..Session::default() };
+                s.edit.grid = GridValue::Timecode(soundcraft_time::TimecodeValue::Second);
+                for boundary in [-minute_frame, minute_frame] {
+                    let at = rate.samples_at_frame(boundary, sr) - origin;
+                    assert_eq!(s.grid_line_at_or_before(at), at, "{rate:?}, origin {origin_frame}");
+                    assert_eq!(s.snap_to_grid(at + 1), at, "{rate:?}, origin {origin_frame}");
+                    assert_eq!(s.grid_lines(at - 1, at + 2, 10), [at]);
+                }
+            }
+        }
+    }
+
     #[test]
     fn session_with_legacy_fit_height_loads() {
         let mut s = Session::default();
@@ -864,6 +1163,53 @@ mod tests {
         assert!(matches!(Session::from_json(&v.to_string()), Err(SessionError::Version(999))));
     }
 
+    #[test]
+    fn the_version_is_checked_as_before() {
+        // #892: the version is read without building the whole document as a tree; the errors
+        // stay what they were.
+        let format = |t: &str| match Session::from_json(t) {
+            Err(SessionError::Format(m)) => m,
+            other => panic!("{t}: {other:?}"),
+        };
+        for t in [
+            "{}",
+            "[]",
+            "[5]",
+            " \n[1, {}]",
+            "\"x\"",
+            "5",
+            "null",
+            r#"{"format_version":"1"}"#,
+            r#"{"format_version":-1}"#,
+            r#"{"format_version":1.5}"#,
+            r#"{"format_version":null}"#,
+            r#"{"format_version":[0,0,0]}"#,
+            r#"{"name":"x","other":{"format_version":1}}"#,
+        ] {
+            assert_eq!(format(t), "missing format_version", "{t}");
+        }
+        for t in ["not json", r#"{"format_version":1"#, r#"{"format_version":1} x"#, r#"{"format_version":"1", ]"#] {
+            let want = serde_json::from_str::<serde_json::Value>(t).unwrap_err().to_string();
+            assert_eq!(format(t), want, "{t}");
+        }
+        let mut v = serde_json::to_value(Session::default()).unwrap();
+        for (ver, want) in [(serde_json::json!(2), 2), (serde_json::json!(1u64 << 40), u32::MAX)] {
+            v["format_version"] = ver;
+            assert_eq!(Session::from_json(&v.to_string()), Err(SessionError::Version(want)));
+        }
+        // A field given twice is refused by name, the version too.
+        let twice = |key: &str| format(&format!(r#"{{"format_version":1,"{key}":"a","{key}":"b"}}"#));
+        assert!(twice("name").starts_with("duplicate field `name` at line 1 column "), "{}", twice("name"));
+        assert!(twice("format_version").starts_with("duplicate field `format_version` at line 1 column "), "{}", twice("format_version"));
+        // A newer version is refused even when the rest would not parse.
+        assert_eq!(Session::from_json(r#"{"format_version":7,"tracks":5}"#), Err(SessionError::Version(7)));
+        // An older or the current version loads as it did.
+        for ver in [0, 1] {
+            v["format_version"] = serde_json::json!(ver);
+            assert_eq!(Session::from_json(&v.to_string()).map(|s| s.format_version), Ok(ver));
+        }
+    }
+
     #[test]
     fn duplicate_ids_are_rejected_on_load() {
         let mut s = Session::default();

crates/model/src/track.rs

@@ -83,8 +83,7 @@ impl TrackKind {
 }
 
 /// Track heights (View › Track Height presets).
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default, serde::Serialize, serde::Deserialize)]
-#[serde(from = "TrackHeightRepr")]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default, serde::Serialize)]
 pub enum TrackHeight {
     /// Any height from Micro to Extreme, in points.
     Custom(u16),
@@ -100,49 +99,69 @@ pub enum TrackHeight {
     Fit(u16),
 }
 
-/// What a saved track height may look like: the current form, or the bare `"Fit"` string older sessions used.
-#[derive(serde::Deserialize)]
-#[serde(untagged)]
-enum TrackHeightRepr {
-    Current(TrackHeightCurrent),
-    LegacyFit(LegacyFit),
+/// A saved track height: `"Micro"` … `"Extreme"` (or `{"Micro": null}` …), `{"Custom": points}`,
+/// `{"Fit": points}`, or the bare `"Fit"` older sessions used. Read as it comes, never buffered (as an
+/// untagged enum would), so anything else in a session file is refused at its first token.
+impl<'de> serde::Deserialize<'de> for TrackHeight {
+    fn deserialize<D: serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
+        d.deserialize_any(HeightVisitor)
+    }
 }
 
-#[derive(serde::Deserialize)]
-enum LegacyFit {
-    Fit,
+const HEIGHT_VARIANTS: &[&str] = &["Custom", "Micro", "Mini", "Small", "Medium", "Large", "Jumbo", "Extreme", "Fit"];
+
+struct HeightVisitor;
+
+impl HeightVisitor {
+    /// The height a variant without a size names.
+    fn preset(name: &str) -> Option<TrackHeight> {
+        Some(match name {
+            "Micro" => TrackHeight::Micro,
+            "Mini" => TrackHeight::Mini,
+            "Small" => TrackHeight::Small,
+            "Medium" => TrackHeight::Medium,
+            "Large" => TrackHeight::Large,
+            "Jumbo" => TrackHeight::Jumbo,
+            "Extreme" => TrackHeight::Extreme,
+            _ => return None,
+        })
+    }
 }
 
-/// Mirror of `TrackHeight` that derives the current serialized form.
-#[derive(serde::Deserialize)]
-enum TrackHeightCurrent {
-    Custom(u16),
-    Micro,
-    Mini,
-    Small,
-    Medium,
-    Large,
-    Jumbo,
-    Extreme,
-    Fit(u16),
-}
+impl<'de> serde::de::Visitor<'de> for HeightVisitor {
+    type Value = TrackHeight;
 
-impl From<TrackHeightRepr> for TrackHeight {
-    fn from(repr: TrackHeightRepr) -> Self {
-        match repr {
-            TrackHeightRepr::Current(TrackHeightCurrent::Custom(p)) => TrackHeight::Custom(p),
-            TrackHeightRepr::Current(TrackHeightCurrent::Micro) => TrackHeight::Micro,
-            TrackHeightRepr::Current(TrackHeightCurrent::Mini) => TrackHeight::Mini,
-            TrackHeightRepr::Current(TrackHeightCurrent::Small) => TrackHeight::Small,
-            TrackHeightRepr::Current(TrackHeightCurrent::Medium) => TrackHeight::Medium,
-            TrackHeightRepr::Current(TrackHeightCurrent::Large) => TrackHeight::Large,
-            TrackHeightRepr::Current(TrackHeightCurrent::Jumbo) => TrackHeight::Jumbo,
-            TrackHeightRepr::Current(TrackHeightCurrent::Extreme) => TrackHeight::Extreme,
-            TrackHeightRepr::Current(TrackHeightCurrent::Fit(p)) => TrackHeight::Fit(p),
+    fn expecting(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        f.write_str("a track height")
+    }
+
+    fn visit_str<E: serde::de::Error>(self, v: &str) -> Result<TrackHeight, E> {
+        match v {
             // Older sessions stored Fit with no size, drawn 88 points tall: the default Medium height.
-            TrackHeightRepr::LegacyFit(LegacyFit::Fit) => TrackHeight::Medium,
+            "Fit" => Ok(TrackHeight::Medium),
+            "Custom" => Err(E::invalid_type(serde::de::Unexpected::UnitVariant, &"a height in points")),
+            other => Self::preset(other).ok_or_else(|| E::unknown_variant(other, HEIGHT_VARIANTS)),
         }
     }
+
+    fn visit_map<A: serde::de::MapAccess<'de>>(self, mut map: A) -> Result<TrackHeight, A::Error> {
+        use serde::de::Error as _;
+        let Some(key) = map.next_key::<String>()? else { return Err(A::Error::invalid_length(0, &"one variant")) };
+        let h = match key.as_str() {
+            "Custom" => TrackHeight::Custom(map.next_value()?),
+            // `{"Fit": null}` is the old size-less Fit too, as above.
+            "Fit" => map.next_value::<Option<u16>>()?.map_or(TrackHeight::Medium, TrackHeight::Fit),
+            other => {
+                let h = Self::preset(other).ok_or_else(|| A::Error::unknown_variant(other, HEIGHT_VARIANTS))?;
+                map.next_value::<()>()?;
+                h
+            }
+        };
+        if map.next_key::<serde::de::IgnoredAny>()?.is_some() {
+            return Err(A::Error::invalid_length(2, &"one variant"));
+        }
+        Ok(h)
+    }
 }
 
 impl TrackHeight {
@@ -383,6 +402,36 @@ mod tests {
         assert_eq!(serde_json::from_str::<TrackHeight>("{\"Custom\":50}").unwrap(), TrackHeight::Custom(50));
     }
 
+    #[test]
+    fn every_saved_height_form_loads_and_nothing_else() {
+        for h in TrackHeight::ALL.into_iter().chain([TrackHeight::Custom(50), TrackHeight::Fit(120)]) {
+            assert_eq!(serde_json::from_str::<TrackHeight>(&serde_json::to_string(&h).unwrap()).unwrap(), h);
+            assert_eq!(serde_json::from_value::<TrackHeight>(serde_json::to_value(h).unwrap()).unwrap(), h);
+        }
+        for h in TrackHeight::ALL {
+            let null = format!("{{{}:null}}", serde_json::to_string(&h).unwrap());
+            assert_eq!(serde_json::from_str::<TrackHeight>(&null).unwrap(), h, "{null}");
+        }
+        assert_eq!(serde_json::from_str::<TrackHeight>(r#"{"Fit":null}"#).unwrap(), TrackHeight::Medium);
+        assert!(serde_json::from_str::<TrackHeight>(r#"{"Custom":null}"#).is_err());
+        for bad in
+            [r#""Custom""#, r#""Huge""#, "7", "[]", "null", "{}", r#"{"Fit":"x"}"#, r#"{"Fit":70000}"#, r#"{"Large":1}"#, r#"{"Fit":1,"Fit":2}"#]
+        {
+            assert!(serde_json::from_str::<TrackHeight>(bad).is_err(), "{bad}");
+        }
+    }
+
+    #[test]
+    fn a_huge_height_is_refused_at_its_first_token() {
+        // #892: the height was read through an untagged enum, which buffers the whole value
+        // first; a session could hold a huge array there. It is refused where it starts.
+        for (open, rest) in [("[", "0,".repeat(100_000) + "0]"), (r#"{"Fit":["#, "0,".repeat(100_000) + "0]}")] {
+            let text = format!("{open}{rest}");
+            let err = serde_json::from_str::<TrackHeight>(&text).unwrap_err();
+            assert!(err.is_data() && err.line() == 1 && err.column() <= open.len() + 1, "{open}: {err}");
+        }
+    }
+
     #[test]
     fn new_track_defaults() {
         let t = Track::new(TrackId(1), "Gtr", TrackKind::Audio, ChannelFormat::Stereo, TRACK_COLORS[0]);

crates/time/src/grid.rs

@@ -1,11 +1,12 @@
 //! Grid and Nudge values: musical or absolute step sizes, grid lines and snapping.
 
-use crate::{FrameRate, SampleRate, Samples, TICKS_PER_QUARTER, TempoMap, to_samples};
+use crate::{FrameRate, SampleRate, Samples, TICKS_PER_QUARTER, TempoMap, Timecode, to_samples};
 
 /// Note values for Bars|Beats grids.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
 pub enum NoteValue {
     Bar,
+    Whole,
     Half,
     Quarter,
     Eighth,
@@ -15,8 +16,10 @@ pub enum NoteValue {
 }
 
 impl NoteValue {
-    pub const ALL: [NoteValue; 7] = [
+    /// Every musical increment in menu order, from largest to smallest.
+    pub const ALL: [NoteValue; 8] = [
         NoteValue::Bar,
+        NoteValue::Whole,
         NoteValue::Half,
         NoteValue::Quarter,
         NoteValue::Eighth,
@@ -24,9 +27,11 @@ impl NoteValue {
         NoteValue::ThirtySecond,
         NoteValue::SixtyFourth,
     ];
+    /// Returns the nominal tick length; bars are adjusted for the active meter when used.
     pub fn ticks(self) -> i64 {
         match self {
             NoteValue::Bar => TICKS_PER_QUARTER * 4,
+            NoteValue::Whole => TICKS_PER_QUARTER * 4,
             NoteValue::Half => TICKS_PER_QUARTER * 2,
             NoteValue::Quarter => TICKS_PER_QUARTER,
             NoteValue::Eighth => TICKS_PER_QUARTER / 2,
@@ -35,9 +40,11 @@ impl NoteValue {
             NoteValue::SixtyFourth => TICKS_PER_QUARTER / 16,
         }
     }
+    /// Returns the menu label for this musical increment.
     pub fn label(self) -> &'static str {
         match self {
             NoteValue::Bar => "1 bar",
+            NoteValue::Whole => "Whole note",
             NoteValue::Half => "1/2 note",
             NoteValue::Quarter => "1/4 note",
             NoteValue::Eighth => "1/8 note",
@@ -48,26 +55,257 @@ impl NoteValue {
     }
 }
 
+/// The time scale used by a Grid or Nudge value.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
+pub enum GridScale {
+    BarsBeats,
+    MinSecs,
+    Timecode,
+    FeetFrames,
+    Samples,
+    ClipsMarkers,
+}
+
+impl GridScale {
+    /// Numeric time scales shared by Grid and Nudge.
+    pub const TIME: [GridScale; 5] = [GridScale::BarsBeats, GridScale::MinSecs, GridScale::Timecode, GridScale::FeetFrames, GridScale::Samples];
+
+    /// Returns the user-facing scale label.
+    pub fn label(self) -> &'static str {
+        match self {
+            GridScale::BarsBeats => "Bars|Beats",
+            GridScale::MinSecs => "Min:Secs",
+            GridScale::Timecode => "Timecode",
+            GridScale::FeetFrames => "Feet+Frames",
+            GridScale::Samples => "Samples",
+            GridScale::ClipsMarkers => "Clips/Markers",
+        }
+    }
+
+    /// Returns the stable command and session identifier.
+    pub fn id(self) -> &'static str {
+        match self {
+            GridScale::BarsBeats => "bars_beats",
+            GridScale::MinSecs => "min_secs",
+            GridScale::Timecode => "timecode",
+            GridScale::FeetFrames => "feet_frames",
+            GridScale::Samples => "samples",
+            GridScale::ClipsMarkers => "clips_markers",
+        }
+    }
+
+    /// Parses a stable identifier or user-facing label.
+    pub fn from_id(id: &str) -> Option<GridScale> {
+        Self::TIME.into_iter().chain([GridScale::ClipsMarkers]).find(|scale| scale.id() == id || scale.label().eq_ignore_ascii_case(id))
+    }
+}
+
+/// Timecode Grid/Nudge increments, ordered independently of the session frame rate.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
+pub enum TimecodeValue {
+    Second,
+    /// Five physical frames, independent of skipped drop-frame labels.
+    FiveFrames,
+    Frame,
+    HalfFrame,
+    QuarterFrame,
+    SubFrame,
+}
+
+impl TimecodeValue {
+    /// Every Timecode increment in menu order, from largest to smallest.
+    pub const ALL: [TimecodeValue; 6] = [
+        TimecodeValue::Second,
+        TimecodeValue::FiveFrames,
+        TimecodeValue::Frame,
+        TimecodeValue::HalfFrame,
+        TimecodeValue::QuarterFrame,
+        TimecodeValue::SubFrame,
+    ];
+
+    /// Returns the user-facing increment label.
+    pub fn label(self) -> &'static str {
+        match self {
+            TimecodeValue::Second => "1 second",
+            TimecodeValue::FiveFrames => "5 frames",
+            TimecodeValue::Frame => "1 frame",
+            TimecodeValue::HalfFrame => "1/2 frame",
+            TimecodeValue::QuarterFrame => "1/4 frame",
+            TimecodeValue::SubFrame => "1 subframe",
+        }
+    }
+
+    /// Returns the stable command and session identifier.
+    pub fn id(self) -> &'static str {
+        match self {
+            TimecodeValue::Second => "second",
+            TimecodeValue::FiveFrames => "5_frames",
+            TimecodeValue::Frame => "frame",
+            TimecodeValue::HalfFrame => "half_frame",
+            TimecodeValue::QuarterFrame => "quarter_frame",
+            TimecodeValue::SubFrame => "subframe",
+        }
+    }
+
+    /// Parses a stable identifier or user-facing label.
+    pub fn from_id(id: &str) -> Option<TimecodeValue> {
+        Self::ALL.into_iter().find(|value| value.id() == id || value.label().eq_ignore_ascii_case(id))
+    }
+
+    /// Returns the increment length in frames at the session rate.
+    fn frames(self, rate: FrameRate) -> f64 {
+        match self {
+            TimecodeValue::Second => rate.nominal() as f64,
+            TimecodeValue::FiveFrames => 5.0,
+            TimecodeValue::Frame => 1.0,
+            TimecodeValue::HalfFrame => 0.5,
+            TimecodeValue::QuarterFrame => 0.25,
+            TimecodeValue::SubFrame => 0.01,
+        }
+    }
+}
+
+/// Feet+Frames Grid/Nudge increments in physical frames, independent of drop-frame label skips.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
+pub enum FeetFramesValue {
+    Foot,
+    Frame,
+    QuarterFrame,
+    SubFrame,
+}
+
+impl FeetFramesValue {
+    /// Every Feet+Frames increment in menu order, from largest to smallest.
+    pub const ALL: [FeetFramesValue; 4] = [FeetFramesValue::Foot, FeetFramesValue::Frame, FeetFramesValue::QuarterFrame, FeetFramesValue::SubFrame];
+
+    /// Returns the user-facing increment label.
+    pub fn label(self) -> &'static str {
+        match self {
+            FeetFramesValue::Foot => "1 foot",
+            FeetFramesValue::Frame => "1 frame",
+            FeetFramesValue::QuarterFrame => "1/4 frame",
+            FeetFramesValue::SubFrame => "1 subframe",
+        }
+    }
+
+    /// Returns the stable command and session identifier.
+    pub fn id(self) -> &'static str {
+        match self {
+            FeetFramesValue::Foot => "foot",
+            FeetFramesValue::Frame => "frame",
+            FeetFramesValue::QuarterFrame => "quarter_frame",
+            FeetFramesValue::SubFrame => "subframe",
+        }
+    }
+
+    /// Parses a stable identifier or user-facing label.
+    pub fn from_id(id: &str) -> Option<FeetFramesValue> {
+        Self::ALL.into_iter().find(|value| value.id() == id || value.label().eq_ignore_ascii_case(id))
+    }
+
+    /// Returns the increment length in frames.
+    fn frames(self) -> f64 {
+        let (num, den) = self.frame_ratio();
+        num as f64 / den as f64
+    }
+
+    /// Exact numerator and denominator of the increment in physical frames.
+    fn frame_ratio(self) -> (i128, i128) {
+        match self {
+            Self::Foot => (16, 1),
+            Self::Frame => (1, 1),
+            Self::QuarterFrame => (1, 4),
+            Self::SubFrame => (1, 100),
+        }
+    }
+
+    /// Apply the counter origin in frames before rounding once to the nearest sample.
+    fn sample_line(self, index: i128, sr: SampleRate, rate: FrameRate, origin: i64) -> Samples {
+        let (num, den) = self.frame_ratio();
+        let (rate_num, rate_den) = rate.rational();
+        let frames = index * num - i128::from(origin) * den;
+        let samples = frames * i128::from(sr.hz().max(1)) * i128::from(rate_den);
+        let divisor = den * i128::from(rate_num);
+        let magnitude = (samples.abs() + divisor / 2) / divisor;
+        let rounded = if samples < 0 { -magnitude } else { magnitude };
+        i64::try_from(rounded).unwrap_or(if rounded < 0 { i64::MIN } else { i64::MAX })
+    }
+
+    /// Find a line index using exact frame arithmetic, allowing for whole-sample rounding.
+    fn line_index(self, position: Samples, sr: SampleRate, rate: FrameRate, origin: i64) -> i128 {
+        let (num, den) = self.frame_ratio();
+        let (rate_num, rate_den) = rate.rational();
+        let scale = i128::from(sr.hz().max(1)) * i128::from(rate_den);
+        let frames = i128::from(position) * i128::from(rate_num) + i128::from(origin) * scale;
+        let mut index = (frames * den).div_euclid(scale * num);
+        if self.sample_line(index + 1, sr, rate, origin) <= position {
+            index += 1;
+        }
+        index
+    }
+
+    /// The Feet+Frames line at or before a sample, relative to the counter's frame origin.
+    pub fn line_at_or_before(self, position: Samples, sr: SampleRate, rate: FrameRate, origin: i64) -> Samples {
+        self.sample_line(self.line_index(position, sr, rate, origin), sr, rate, origin)
+    }
+
+    /// The next distinct sample line; subframe increments may share a sample at low sample rates.
+    fn next_line(self, position: Samples, sr: SampleRate, rate: FrameRate, origin: i64) -> Samples {
+        self.sample_line(self.line_index(position, sr, rate, origin) + 1, sr, rate, origin).max(position.saturating_add(1))
+    }
+
+    /// Snap against frame-origin lines, choosing the earlier line when distances are equal.
+    pub fn snap(self, position: Samples, sr: SampleRate, rate: FrameRate, origin: i64) -> Samples {
+        let lo = self.line_at_or_before(position, sr, rate, origin);
+        let hi = self.next_line(lo, sr, rate, origin);
+        if i128::from(position) - i128::from(lo) <= i128::from(hi) - i128::from(position) { lo } else { hi }
+    }
+
+    /// Distinct Feet+Frames sample lines within `[start, end)`, capped at `max`.
+    pub fn lines(self, start: Samples, end: Samples, sr: SampleRate, rate: FrameRate, origin: i64, max: usize) -> Vec<Samples> {
+        let mut out = Vec::new();
+        let mut line = self.line_at_or_before(start, sr, rate, origin);
+        while line < end && out.len() < max {
+            if line >= start {
+                out.push(line);
+            }
+            let next = self.next_line(line, sr, rate, origin);
+            if next <= line {
+                break;
+            }
+            line = next;
+        }
+        out
+    }
+}
+
 /// A grid or nudge step.
 #[derive(Debug, Clone, Copy, PartialEq, serde::Serialize, serde::Deserialize)]
 pub enum GridValue {
     /// Musical: note value, optionally dotted or triplet.
     Note { value: NoteValue, dotted: bool, triplet: bool },
-    /// Absolute seconds (Min:Secs grids: 0.001 … 10 s).
+    /// Absolute seconds (Min:Secs grids: 0.001 … 1 s).
     Seconds(f64),
     /// Frames at the session timecode rate.
+    /// Kept for sessions and commands written before named timecode increments were added.
     Frames(i64),
+    /// A named Timecode increment, including fractional frames and one second.
+    Timecode(TimecodeValue),
+    /// A Feet+Frames increment (one foot is 16 frames).
+    FeetFrames(FeetFramesValue),
     /// Raw samples.
     Samples(i64),
 }
 
 impl Default for GridValue {
+    /// Starts on a straight sixteenth-note Bars|Beats grid.
     fn default() -> Self {
         GridValue::Note { value: NoteValue::Sixteenth, dotted: false, triplet: false }
     }
 }
 
 impl GridValue {
+    /// Returns the user-facing label for this increment.
     pub fn label(&self) -> String {
         match self {
             GridValue::Note { value, dotted, triplet } => {
@@ -80,15 +318,47 @@ impl GridValue {
                 }
                 s
             }
-            GridValue::Seconds(s) => format!("{s:.3} sec"),
+            GridValue::Seconds(s) => {
+                if *s >= 1.0 {
+                    format!("{s} second{}", if *s == 1.0 { "" } else { "s" })
+                } else {
+                    format!("{} ms", (s * 1000.0).round() as i64)
+                }
+            }
             GridValue::Frames(f) => format!("{f} frame{}", if *f == 1 { "" } else { "s" }),
-            GridValue::Samples(n) => format!("{n} samples"),
+            GridValue::Timecode(value) => value.label().to_string(),
+            GridValue::FeetFrames(value) => value.label().to_string(),
+            GridValue::Samples(n) => format!("{n} sample{}", if *n == 1 { "" } else { "s" }),
         }
     }
 
-    /// The next larger or smaller value of the same kind, or `self` at either end. Note values keep their
-    /// dot or triplet; seconds, frames and samples step by tens.
+    /// Returns the time scale to which this increment belongs.
+    pub fn scale(self) -> GridScale {
+        match self {
+            GridValue::Note { .. } => GridScale::BarsBeats,
+            GridValue::Seconds(_) => GridScale::MinSecs,
+            GridValue::Frames(_) | GridValue::Timecode(_) => GridScale::Timecode,
+            GridValue::FeetFrames(_) => GridScale::FeetFrames,
+            GridValue::Samples(_) => GridScale::Samples,
+        }
+    }
+
+    /// Returns the default increment for a newly selected time scale.
+    pub fn for_scale(scale: GridScale) -> GridValue {
+        match scale {
+            GridScale::BarsBeats => GridValue::default(),
+            GridScale::MinSecs => GridValue::Seconds(1.0),
+            GridScale::Timecode => GridValue::Timecode(TimecodeValue::Frame),
+            GridScale::FeetFrames => GridValue::FeetFrames(FeetFramesValue::Frame),
+            GridScale::Samples => GridValue::Samples(100),
+            GridScale::ClipsMarkers => GridValue::default(),
+        }
+    }
+
+    /// The next larger or smaller menu value of the same kind, or `self` at either end. Note values keep
+    /// their dot or triplet modifier.
     pub fn stepped(self, larger: bool) -> GridValue {
+        /// Finds the next value in a numeric increment ladder without wrapping.
         fn next<T: PartialOrd + Copy>(ladder: &[T], v: T, larger: bool) -> Option<T> {
             if larger { ladder.iter().copied().find(|x| *x > v) } else { ladder.iter().rev().copied().find(|x| *x < v) }
         }
@@ -98,9 +368,11 @@ impl GridValue {
                 let j = if larger { i.checked_sub(1) } else { i.checked_add(1) };
                 j.and_then(|j| NoteValue::ALL.get(j)).map_or(self, |&value| GridValue::Note { value, dotted, triplet })
             }
-            GridValue::Seconds(s) => next(&[0.001, 0.01, 0.1, 1.0, 10.0], s, larger).map_or(self, GridValue::Seconds),
+            GridValue::Seconds(s) => next(&[0.001, 0.01, 0.1, 0.5, 1.0], s, larger).map_or(self, GridValue::Seconds),
             GridValue::Frames(f) => next(&[1, 10, 100], f, larger).map_or(self, GridValue::Frames),
-            GridValue::Samples(n) => next(&[1, 10, 100, 1_000, 10_000, 100_000], n, larger).map_or(self, GridValue::Samples),
+            GridValue::Timecode(value) => step_enum(&TimecodeValue::ALL, value, larger).map_or(self, GridValue::Timecode),
+            GridValue::FeetFrames(value) => step_enum(&FeetFramesValue::ALL, value, larger).map_or(self, GridValue::FeetFrames),
+            GridValue::Samples(n) => next(&[1, 2, 10, 100, 1_000, 10_000], n, larger).map_or(self, GridValue::Samples),
         }
     }
 
@@ -126,12 +398,17 @@ impl GridValue {
             }
             GridValue::Seconds(s) => sr.samples(s.clamp(0.000_01, 3600.0)).max(1),
             GridValue::Frames(f) => to_samples(rate.samples_per_frame(sr) * f.clamp(1, 1_000_000) as f64).max(1),
+            GridValue::Timecode(value) => to_samples(rate.samples_per_frame(sr) * value.frames(rate)).max(1),
+            GridValue::FeetFrames(value) => to_samples(rate.samples_per_frame(sr) * value.frames()).max(1),
             GridValue::Samples(n) => n.max(1),
         }
     }
 
     /// Nearest grid line to `pos`.
     pub fn snap(&self, pos: Samples, sr: SampleRate, map: &TempoMap, rate: FrameRate) -> Samples {
+        if let Self::FeetFrames(value) = *self {
+            return value.snap(pos, sr, rate, 0);
+        }
         let lo = self.line_at_or_before(pos, sr, map, rate);
         let hi = self.next_line(lo, sr, map, rate);
         if (pos - lo) <= (hi - pos) { lo } else { hi }
@@ -140,6 +417,7 @@ impl GridValue {
     /// The grid line at or before `pos`.
     pub fn line_at_or_before(&self, pos: Samples, sr: SampleRate, map: &TempoMap, rate: FrameRate) -> Samples {
         match *self {
+            Self::FeetFrames(value) => value.line_at_or_before(pos, sr, rate, 0),
             GridValue::Note { value, dotted, triplet } => {
                 // Float ticks can land a hair either side of a line's own tick.
                 let mut t = map.samples_to_ticks_f(pos, sr).floor() as i64;
@@ -148,12 +426,14 @@ impl GridValue {
                 } else if map.tick_to_samples(t.saturating_add(1), sr) <= pos {
                     t = t.saturating_add(1);
                 }
-                // Grid lines restart at each bar line so odd meters stay aligned.
+                // Sub-bar values restart at each bar so odd meters stay aligned. A whole note is
+                // always four quarter notes and therefore keeps a continuous tick origin.
                 let bb = map.bar_beat_at_tick(t);
                 let bar_tick = map.bar_start_tick(bb.bar);
-                let step = Self::note_ticks(value, dotted, triplet, map, bar_tick);
-                let k = (t - bar_tick).div_euclid(step);
-                map.tick_to_samples(bar_tick + k * step, sr)
+                let origin = if value == NoteValue::Whole { 0 } else { bar_tick };
+                let step = Self::note_ticks(value, dotted, triplet, map, origin);
+                let k = (t - origin).div_euclid(step);
+                map.tick_to_samples(origin + k * step, sr)
             }
             _ => self.abs_line(self.abs_index_at_or_before(pos, sr, rate), sr, rate),
         }
@@ -162,21 +442,60 @@ impl GridValue {
     /// Position of absolute grid line `k` (Seconds, Frames, Samples), at an exact multiple of the step
     /// rounded once, so rounding never accumulates from line to line.
     fn abs_line(&self, k: i64, sr: SampleRate, rate: FrameRate) -> Samples {
+        if let Self::FeetFrames(value) = *self {
+            return value.sample_line(i128::from(k), sr, rate, 0);
+        }
+        if matches!(self, GridValue::Timecode(TimecodeValue::Second)) && rate.is_drop() {
+            return rate.samples_at_frame(Self::drop_second_frame(k, rate), sr);
+        }
+        if let Some(frames) = self.frame_step(rate) {
+            let whole = frames.round();
+            if frames == whole {
+                return rate.samples_at_frame(k.saturating_mul(whole as i64), sr);
+            }
+            let step = (rate.samples_per_frame(sr) * frames).max(1.0);
+            return to_samples(k as f64 * step);
+        }
         match *self {
             GridValue::Seconds(s) => to_samples(k as f64 * Self::seconds_step(s, sr)),
-            GridValue::Frames(f) => rate.samples_at_frame(k.saturating_mul(f.clamp(1, 1_000_000)), sr),
             GridValue::Samples(n) => k.saturating_mul(n.max(1)),
             GridValue::Note { .. } => 0,
+            GridValue::Frames(_) | GridValue::Timecode(_) | GridValue::FeetFrames(_) => 0,
         }
     }
 
     /// Index of the absolute grid line at or before `pos`.
     fn abs_index_at_or_before(&self, pos: Samples, sr: SampleRate, rate: FrameRate) -> i64 {
-        let mut k = match *self {
-            GridValue::Seconds(s) => (pos as f64 / Self::seconds_step(s, sr)).floor() as i64,
-            GridValue::Frames(f) => rate.frames_at(pos, sr).div_euclid(f.clamp(1, 1_000_000)),
-            GridValue::Samples(n) => return pos.div_euclid(n.max(1)),
-            GridValue::Note { .. } => return 0,
+        if matches!(self, GridValue::Timecode(TimecodeValue::Second)) && rate.is_drop() {
+            let tc = Timecode::from_frames(rate.frames_at(pos, sr), rate);
+            let magnitude = tc.hours.saturating_mul(3600).saturating_add(tc.minutes.saturating_mul(60)).saturating_add(tc.seconds);
+            let mut k = if tc.negative { magnitude.saturating_neg() } else { magnitude };
+            while self.abs_line(k, sr, rate) > pos {
+                let previous = k.saturating_sub(1);
+                if previous == k {
+                    break;
+                }
+                k = previous;
+            }
+            while self.abs_line(k.saturating_add(1), sr, rate) <= pos {
+                let next = k.saturating_add(1);
+                if next == k {
+                    break;
+                }
+                k = next;
+            }
+            return k;
+        }
+        let mut k = if let Some(frames) = self.frame_step(rate) {
+            let step = (rate.samples_per_frame(sr) * frames).max(1.0);
+            (pos as f64 / step).floor() as i64
+        } else {
+            match *self {
+                GridValue::Seconds(s) => (pos as f64 / Self::seconds_step(s, sr)).floor() as i64,
+                GridValue::Samples(n) => return pos.div_euclid(n.max(1)),
+                GridValue::Note { .. } => return 0,
+                GridValue::Frames(_) | GridValue::Timecode(_) | GridValue::FeetFrames(_) => return 0,
+            }
         };
         // Lines are rounded to whole samples, so the floored index can be one off either way.
         if self.abs_line(k, sr, rate) > pos {
@@ -192,8 +511,36 @@ impl GridValue {
         (s.clamp(0.000_01, 3600.0) * sr.as_f64()).max(1.0)
     }
 
+    /// Maps a signed whole-second timecode label to its physical frame at a drop-frame rate.
+    fn drop_second_frame(index: i64, rate: FrameRate) -> i64 {
+        let seconds = index.unsigned_abs();
+        let total_minutes = seconds / 60;
+        let frames = if seconds.is_multiple_of(60) && !total_minutes.is_multiple_of(10) { if rate.nominal() >= 60 { 4 } else { 2 } } else { 0 };
+        Timecode {
+            negative: index < 0,
+            hours: i64::try_from(seconds / 3600).unwrap_or(i64::MAX),
+            minutes: i64::try_from((seconds / 60) % 60).unwrap_or(0),
+            seconds: i64::try_from(seconds % 60).unwrap_or(0),
+            frames,
+        }
+        .to_frames(rate)
+    }
+
+    /// A frame-based increment as a possibly fractional number of frames.
+    fn frame_step(&self, rate: FrameRate) -> Option<f64> {
+        match *self {
+            GridValue::Frames(frames) => Some(frames.clamp(1, 1_000_000) as f64),
+            GridValue::Timecode(value) => Some(value.frames(rate)),
+            GridValue::FeetFrames(value) => Some(value.frames()),
+            _ => None,
+        }
+    }
+
     /// The first grid line strictly after `line`.
     pub fn next_line(&self, line: Samples, sr: SampleRate, map: &TempoMap, rate: FrameRate) -> Samples {
+        if let Self::FeetFrames(value) = *self {
+            return value.next_line(line, sr, rate, 0);
+        }
         if !matches!(self, GridValue::Note { .. }) {
             let next = self.abs_line(self.abs_index_at_or_before(line, sr, rate).saturating_add(1), sr, rate);
             return if next > line { next } else { line.saturating_add(1) };
@@ -205,6 +552,9 @@ impl GridValue {
 
     /// All grid lines within `[start, end)`, capped at `max` lines.
     pub fn lines(&self, start: Samples, end: Samples, sr: SampleRate, map: &TempoMap, rate: FrameRate, max: usize) -> Vec<Samples> {
+        if let Self::FeetFrames(value) = *self {
+            return value.lines(start, end, sr, rate, 0, max);
+        }
         let mut out = Vec::new();
         let mut p = self.line_at_or_before(start, sr, map, rate);
         while p < end && out.len() < max {
@@ -221,10 +571,43 @@ impl GridValue {
     }
 }
 
+/// Moves one position through an ordered increment menu without wrapping.
+fn step_enum<T: Copy + PartialEq>(values: &[T], value: T, larger: bool) -> Option<T> {
+    let index = values.iter().position(|candidate| *candidate == value)?;
+    let next = if larger { index.checked_sub(1) } else { index.checked_add(1) }?;
+    values.get(next).copied()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    /// Frame origins are subtracted before rounding whole frames, quarter frames and subframes.
+    #[test]
+    fn feet_frames_origins_round_only_after_applying_the_frame_offset() {
+        let (sr, rate) = (SampleRate::HZ_48000, FrameRate::Fps29_97);
+        for at in [49_650, 100_901, 177_778] {
+            assert_eq!(FeetFramesValue::Foot.line_at_or_before(at, sr, rate, 1), at);
+            assert_eq!(FeetFramesValue::Foot.snap(at - 1, sr, rate, 1), at);
+        }
+        assert_eq!(FeetFramesValue::QuarterFrame.snap(50_049, sr, rate, 1), 50_050);
+        assert_eq!(FeetFramesValue::SubFrame.lines(49_665, 49_667, sr, rate, 1, 4), [49_666]);
+    }
+
+    /// Dense subframes retain distinct sample lines and remain bounded with extreme signed origins.
+    #[test]
+    fn feet_frames_subframes_handle_dense_steps_and_extreme_origins() {
+        let sr = SampleRate::new(8_000).unwrap();
+        let rate = FrameRate::Fps120;
+        for origin in [i64::MIN, -1, 0, 1, i64::MAX] {
+            assert_eq!(FeetFramesValue::SubFrame.lines(-3, 4, sr, rate, origin, 20), [-3, -2, -1, 0, 1, 2, 3]);
+            for at in [i64::MIN, -1, 0, 1, i64::MAX] {
+                assert_eq!(FeetFramesValue::SubFrame.line_at_or_before(at, sr, rate, origin), at);
+                assert_eq!(FeetFramesValue::SubFrame.snap(at, sr, rate, origin), at);
+            }
+        }
+    }
+
     #[test]
     fn grid_lines_are_their_own_line_at_odd_tempos() {
         let (g, sr, rate) = (GridValue::default(), SampleRate::HZ_48000, FrameRate::Fps30);
@@ -238,6 +621,29 @@ mod tests {
         }
     }
 
+    /// Musical boundaries stay exact across a tempo change while absolute scales remain
+    /// independent of the tempo map.
+    #[test]
+    fn grids_stay_aligned_across_a_tempo_change() {
+        let (sr, rate) = (SampleRate::HZ_48000, FrameRate::Fps29_97Drop);
+        let mut map = TempoMap::default();
+        map.set_tempo(TICKS_PER_QUARTER * 4, 90.0).unwrap();
+        let musical = GridValue::Note { value: NoteValue::Quarter, dotted: false, triplet: false };
+        for tick in [0, TICKS_PER_QUARTER * 3, TICKS_PER_QUARTER * 4, TICKS_PER_QUARTER * 5] {
+            let line = map.tick_to_samples(tick, sr);
+            assert_eq!(musical.line_at_or_before(line, sr, &map, rate), line);
+        }
+        for absolute in [
+            GridValue::Seconds(0.5),
+            GridValue::Timecode(TimecodeValue::Second),
+            GridValue::FeetFrames(FeetFramesValue::Foot),
+            GridValue::Samples(1_000),
+        ] {
+            let line = absolute.next_line(absolute.line_at_or_before(100_000, sr, &map, rate), sr, &map, rate);
+            assert_eq!(absolute.line_at_or_before(line, sr, &map, rate), line, "{absolute:?}");
+        }
+    }
+
     #[test]
     fn sixteenth_grid_at_120() {
         let g = GridValue::default();
@@ -248,14 +654,33 @@ mod tests {
         assert_eq!(g.lines(0, 24_000, sr, &map, rate, 100), vec![0, 6000, 12000, 18000]);
     }
 
+    /// Absolute increments report their expected sample lengths at a fixed rate.
     #[test]
     fn absolute_grids() {
         let (sr, map, rate) = (SampleRate::HZ_48000, TempoMap::default(), FrameRate::Fps25);
         assert_eq!(GridValue::Seconds(1.0).snap(70_000, sr, &map, rate), 48_000);
         assert_eq!(GridValue::Frames(1).step_samples(0, sr, &map, rate), 1920);
+        assert_eq!(GridValue::Timecode(TimecodeValue::Second).step_samples(0, sr, &map, rate), 48_000);
+        assert_eq!(GridValue::Timecode(TimecodeValue::FiveFrames).step_samples(0, sr, &map, rate), 9_600);
+        assert_eq!(GridValue::Timecode(TimecodeValue::HalfFrame).step_samples(0, sr, &map, rate), 960);
+        assert_eq!(GridValue::Timecode(TimecodeValue::QuarterFrame).step_samples(0, sr, &map, rate), 480);
+        assert_eq!(GridValue::Timecode(TimecodeValue::SubFrame).step_samples(0, sr, &map, rate), 19);
+        assert_eq!(GridValue::FeetFrames(FeetFramesValue::Foot).step_samples(0, sr, &map, rate), 30_720);
         assert_eq!(GridValue::Samples(0).step_samples(0, sr, &map, rate), 1);
     }
 
+    /// Bar length follows the meter while a whole note always spans four quarter notes.
+    #[test]
+    fn a_bar_and_a_whole_note_differ_in_three_four() {
+        let (sr, map, rate) = (SampleRate::HZ_48000, TempoMap::new(120.0, 3, 4).unwrap(), FrameRate::Fps25);
+        let note = |value| GridValue::Note { value, dotted: false, triplet: false };
+        assert_eq!(note(NoteValue::Bar).step_samples(0, sr, &map, rate), 72_000);
+        assert_eq!(note(NoteValue::Whole).step_samples(0, sr, &map, rate), 96_000);
+        assert_eq!(note(NoteValue::Bar).line_at_or_before(96_000, sr, &map, rate), 72_000);
+        assert_eq!(note(NoteValue::Whole).line_at_or_before(96_000, sr, &map, rate), 96_000);
+        assert_eq!(note(NoteValue::Half).lines(0, 150_000, sr, &map, rate, 10), [0, 48_000, 72_000, 120_000, 144_000]);
+    }
+
     #[test]
     fn seconds_grid_lines_land_on_whole_seconds() {
         let (sr, map, rate) = (SampleRate::HZ_44100, TempoMap::default(), FrameRate::Fps30);
@@ -268,6 +693,7 @@ mod tests {
         }
     }
 
+    /// Legacy frame grids stay aligned to exact frame starts at fractional rates.
     #[test]
     fn frame_grid_lines_land_on_frame_starts() {
         let sr = SampleRate::HZ_48000;
@@ -291,6 +717,55 @@ mod tests {
         }
     }
 
+    /// Named whole- and sub-frame grids retain the exact-multiple calculation used by legacy frame grids.
+    #[test]
+    fn named_frame_grids_land_on_exact_subdivisions() {
+        let sr = SampleRate::HZ_48000;
+        let map = TempoMap::default();
+        let grids = TimecodeValue::ALL.into_iter().map(GridValue::Timecode).chain(FeetFramesValue::ALL.into_iter().map(GridValue::FeetFrames));
+        for rate in [FrameRate::Fps29_97, FrameRate::Fps23_976] {
+            for grid in grids.clone() {
+                for index in 0..200 {
+                    let line = grid.abs_line(index, sr, rate);
+                    assert_eq!(grid.line_at_or_before(line, sr, &map, rate), line, "{grid:?} {rate:?} line {index}");
+                    assert_eq!(grid.next_line(line, sr, &map, rate), grid.abs_line(index + 1, sr, rate), "{grid:?} {rate:?} line {index}");
+                }
+            }
+        }
+    }
+
+    /// Drop-frame second grids follow labelled second boundaries in both timeline directions.
+    #[test]
+    fn drop_frame_second_grids_follow_timecode_labels() {
+        let sr = SampleRate::HZ_48000;
+        let map = TempoMap::default();
+        let grid = GridValue::Timecode(TimecodeValue::Second);
+        for rate in [FrameRate::Fps29_97Drop, FrameRate::Fps59_94Drop] {
+            for seconds in [0, 59, 60, 61, 600, 601, 3600] {
+                let frame = GridValue::drop_second_frame(seconds, rate);
+                let line = rate.samples_at_frame(frame, sr);
+                assert_eq!(grid.line_at_or_before(line, sr, &map, rate), line, "{rate:?} second {seconds}");
+                assert_eq!(grid.line_at_or_before(-line, sr, &map, rate), -line, "{rate:?} second -{seconds}");
+                for offset in -2..=rate.nominal() + 2 {
+                    let position = rate.samples_at_frame(frame.saturating_add(offset), sr);
+                    let before = grid.line_at_or_before(position, sr, &map, rate);
+                    assert!(before <= position, "{rate:?} second {seconds}, frame offset {offset}");
+                    assert!(grid.next_line(before, sr, &map, rate) > position, "{rate:?} second {seconds}, frame offset {offset}");
+                }
+            }
+            let labelled = Timecode { negative: false, hours: 0, minutes: 1, seconds: 1, frames: 0 }.to_samples(rate, sr);
+            assert_eq!(grid.snap(labelled, sr, &map, rate), labelled);
+        }
+
+        for (rate, minute_frame) in [(FrameRate::Fps29_97Drop, 1800), (FrameRate::Fps59_94Drop, 3600)] {
+            let boundary = rate.samples_at_frame(minute_frame, sr);
+            assert_eq!(grid.line_at_or_before(boundary, sr, &map, rate), boundary, "{rate:?} positive minute boundary");
+            assert_eq!(grid.snap(boundary, sr, &map, rate), boundary, "{rate:?} positive minute snap");
+            assert_eq!(grid.line_at_or_before(-boundary, sr, &map, rate), -boundary, "{rate:?} negative minute boundary");
+            assert_eq!(grid.snap(-boundary, sr, &map, rate), -boundary, "{rate:?} negative minute snap");
+        }
+    }
+
     #[test]
     fn lines_are_capped() {
         let (sr, map, rate) = (SampleRate::HZ_48000, TempoMap::default(), FrameRate::Fps25);
@@ -306,6 +781,7 @@ mod tests {
         assert_eq!(d.step_samples(0, sr, &map, rate), 36_000);
     }
 
+    /// Stepping follows each menu ladder and stops at its endpoints.
     #[test]
     fn values_step_to_the_next_larger_or_smaller() {
         let note = |value, triplet| GridValue::Note { value, dotted: false, triplet };
@@ -315,9 +791,12 @@ mod tests {
         assert_eq!(note(NoteValue::SixtyFourth, false).stepped(false), note(NoteValue::SixtyFourth, false));
         assert_eq!(GridValue::Seconds(0.01).stepped(true), GridValue::Seconds(0.1));
         assert_eq!(GridValue::Seconds(0.5).stepped(false), GridValue::Seconds(0.1));
-        assert_eq!(GridValue::Seconds(10.0).stepped(true), GridValue::Seconds(10.0));
+        assert_eq!(GridValue::Seconds(1.0).stepped(true), GridValue::Seconds(1.0));
         assert_eq!(GridValue::Frames(1).stepped(true), GridValue::Frames(10));
+        assert_eq!(GridValue::Timecode(TimecodeValue::Frame).stepped(false), GridValue::Timecode(TimecodeValue::HalfFrame));
+        assert_eq!(GridValue::FeetFrames(FeetFramesValue::Frame).stepped(true), GridValue::FeetFrames(FeetFramesValue::Foot));
         assert_eq!(GridValue::Samples(100).stepped(false), GridValue::Samples(10));
+        assert_eq!(GridValue::Samples(1).stepped(true), GridValue::Samples(2));
         assert_eq!(GridValue::Samples(1).stepped(false), GridValue::Samples(1));
     }
 

crates/time/src/lib.rs

@@ -12,7 +12,7 @@ mod tempo;
 mod timecode;
 
 pub use format::{TimeFormat, format_length, format_position, parse_position};
-pub use grid::{GridValue, NoteValue};
+pub use grid::{FeetFramesValue, GridScale, GridValue, NoteValue, TimecodeValue};
 pub use tempo::{BarBeat, MeterEvent, TICKS_PER_QUARTER, TempoEvent, TempoMap};
 pub use timecode::{FrameRate, Timecode};
 

crates/time/src/tempo.rs

@@ -40,14 +40,34 @@ pub struct BarBeat {
 
 /// Tempo and meter changes for a session. Always has at least one of each, at tick 0.
 #[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
+#[serde(from = "TempoMapData")]
 pub struct TempoMap {
     tempos: Vec<TempoEvent>,
     meters: Vec<MeterEvent>,
+    /// For each tempo event, the elapsed time at its tick in quarter-note minutes (ticks / bpm,
+    /// summed over the earlier segments). Lets tick/sample conversions binary-search the segment
+    /// instead of walking every earlier tempo change, so converting many positions against a large
+    /// tempo map stays O(log n) each. Rebuilt whenever `tempos` changes.
+    #[serde(skip)]
+    elapsed: Vec<f64>,
+}
+
+/// The serialized form of [`TempoMap`], without the derived lookup table.
+#[derive(serde::Deserialize)]
+struct TempoMapData {
+    tempos: Vec<TempoEvent>,
+    meters: Vec<MeterEvent>,
+}
+
+impl From<TempoMapData> for TempoMap {
+    fn from(d: TempoMapData) -> Self {
+        TempoMap::from_parts(d.tempos, d.meters)
+    }
 }
 
 impl Default for TempoMap {
     fn default() -> Self {
-        TempoMap { tempos: vec![TempoEvent { tick: 0, bpm: 120.0 }], meters: vec![MeterEvent { tick: 0, numerator: 4, denominator: 4 }] }
+        TempoMap::from_parts(vec![TempoEvent { tick: 0, bpm: 120.0 }], vec![MeterEvent { tick: 0, numerator: 4, denominator: 4 }])
     }
 }
 
@@ -60,6 +80,43 @@ fn valid_meter(numerator: u32, denominator: u32) -> bool {
 }
 
 impl TempoMap {
+    fn from_parts(tempos: Vec<TempoEvent>, meters: Vec<MeterEvent>) -> Self {
+        let mut m = TempoMap { tempos, meters, elapsed: Vec::new() };
+        m.reindex();
+        m
+    }
+
+    /// Rebuild `elapsed` from `tempos`. The first segment runs from tick 0 at the first tempo.
+    fn reindex(&mut self) {
+        let mut elapsed = Vec::with_capacity(self.tempos.len());
+        let mut acc = 0.0;
+        let mut seg_tick = 0i64;
+        let mut bpm = self.tempos.first().map_or(120.0, |e| e.bpm);
+        for (i, e) in self.tempos.iter().enumerate() {
+            if i > 0 {
+                // Saturating: a file's ticks are indexed before `sanitize` orders them.
+                acc += e.tick.saturating_sub(seg_tick) as f64 / bpm;
+                seg_tick = e.tick;
+                bpm = e.bpm;
+            }
+            elapsed.push(acc);
+        }
+        self.elapsed = elapsed;
+    }
+
+    /// Samples per quarter-note minute (the unit of `elapsed`) at `sr`.
+    fn samples_per_elapsed(sr: SampleRate) -> f64 {
+        sr.as_f64() * 60.0 / TICKS_PER_QUARTER as f64
+    }
+
+    /// The tempo segment `i` (an index into `tempos`, 0 when it is empty): its start tick (0 for
+    /// the first), bpm and elapsed time at its start.
+    fn segment(&self, i: usize) -> (i64, f64, f64) {
+        let bpm = self.tempos.get(i).or(self.tempos.first()).map_or(120.0, |e| e.bpm);
+        let tick = if i == 0 { 0 } else { self.tempos.get(i).map_or(0, |e| e.tick) };
+        (tick, bpm, self.elapsed.get(i).copied().unwrap_or(0.0))
+    }
+
     pub fn new(bpm: f64, numerator: u32, denominator: u32) -> Result<Self, TimeError> {
         let mut m = TempoMap::default();
         m.set_tempo(0, bpm)?;
@@ -91,6 +148,7 @@ impl TempoMap {
             let (numerator, denominator) = self.meters.first().map_or((4, 4), |m| (m.numerator, m.denominator));
             self.meters.insert(0, MeterEvent { tick: 0, numerator, denominator });
         }
+        self.reindex();
     }
 
     /// Insert or replace the tempo at `tick`.
@@ -105,6 +163,7 @@ impl TempoMap {
             }
             Err(i) => self.tempos.insert(i, TempoEvent { tick, bpm }),
         }
+        self.reindex();
         Ok(())
     }
 
@@ -115,6 +174,7 @@ impl TempoMap {
         }
         let before = self.tempos.len();
         self.tempos.retain(|e| e.tick != tick);
+        self.reindex();
         before != self.tempos.len()
     }
 
@@ -153,18 +213,52 @@ impl TempoMap {
         }
     }
 
-    /// Remove the meters after `tick`, returning each with the bar it starts.
+    /// Remove the meters after `tick`, returning each with the bar it starts: the bar
+    /// [`Self::bar_beat_at_tick`] gives its tick, counted in one pass over the map rather than one
+    /// walk per meter, so a session with many meter changes edits in linear time.
     fn take_meters_after(&mut self, tick: i64) -> Vec<(i64, MeterEvent)> {
-        let later: Vec<_> = self.meters.iter().filter(|e| e.tick > tick).map(|e| (self.bar_beat_at_tick(e.tick).bar, *e)).collect();
+        let mut later = Vec::new();
+        let (mut bar, mut seg_tick) = (1i64, 0i64);
+        for (i, m) in self.meters.iter().enumerate() {
+            let tpb = m.ticks_per_bar();
+            if m.tick > tick {
+                later.push((bar.saturating_add(m.tick.saturating_sub(seg_tick) / tpb), *m));
+            }
+            if let Some(n) = self.meters.get(i + 1) {
+                bar = bar.saturating_add(ceil_div(n.tick.saturating_sub(seg_tick), tpb));
+                seg_tick = n.tick;
+            }
+        }
         self.meters.retain(|e| e.tick <= tick);
         later
     }
 
+    /// The bar and tick of the last meter's segment, where [`Self::bar_start_tick`]'s walk ends.
+    fn last_segment(&self) -> (i64, i64) {
+        let (mut cur_bar, mut cur_tick) = (1i64, 0i64);
+        for (i, m) in self.meters.iter().enumerate() {
+            if let Some(n) = self.meters.get(i + 1) {
+                cur_bar = cur_bar.saturating_add(ceil_div(n.tick.saturating_sub(cur_tick), m.ticks_per_bar()));
+                cur_tick = n.tick;
+            }
+        }
+        (cur_bar, cur_tick)
+    }
+
     /// Put meters back at the start of their bars under the current earlier meters, in bar order.
+    /// Each lands at or past the last meter, so the walk to its bar resumes from there; a bar
+    /// before it (meters off their bar lines) takes the full walk.
     fn restore_meters_at_bars(&mut self, later: Vec<(i64, MeterEvent)>) {
+        let (mut cur_bar, mut cur_tick) = self.last_segment();
         for (bar, ev) in later {
-            let tick = self.bar_start_tick(bar);
+            let tick = if bar >= cur_bar {
+                let tpb = self.meters.last().map_or(MeterEvent { tick: 0, numerator: 4, denominator: 4 }, |m| *m).ticks_per_bar();
+                cur_tick.saturating_add(bar.saturating_sub(cur_bar).saturating_mul(tpb))
+            } else {
+                self.bar_start_tick(bar)
+            };
             self.put_meter(MeterEvent { tick, ..ev });
+            (cur_bar, cur_tick) = if bar >= cur_bar { (bar, tick) } else { self.last_segment() };
         }
     }
 
@@ -204,36 +298,20 @@ impl TempoMap {
     }
 
     fn tick_to_samples_f(&self, tick: i64, sr: SampleRate) -> f64 {
-        let mut acc = 0.0;
-        let mut seg_tick = 0i64;
-        let mut bpm = self.tempos.first().map_or(120.0, |e| e.bpm);
-        for e in self.tempos.iter().skip(1) {
-            if e.tick >= tick {
-                break;
-            }
-            acc += (e.tick - seg_tick) as f64 * Self::samples_per_tick(bpm, sr);
-            seg_tick = e.tick;
-            bpm = e.bpm;
-        }
-        acc + (tick - seg_tick) as f64 * Self::samples_per_tick(bpm, sr)
+        // Tempo events after the first that start before `tick` (the segments it has passed).
+        let passed = self.tempos.get(1..).map_or(0, |rest| rest.partition_point(|e| e.tick < tick));
+        let (seg_tick, bpm, elapsed) = self.segment(passed);
+        elapsed * Self::samples_per_elapsed(sr) + (tick - seg_tick) as f64 * Self::samples_per_tick(bpm, sr)
     }
 
     /// Samples → ticks (fractional).
     pub fn samples_to_ticks_f(&self, s: Samples, sr: SampleRate) -> f64 {
         let s = s as f64;
-        let mut acc = 0.0;
-        let mut seg_tick = 0i64;
-        let mut bpm = self.tempos.first().map_or(120.0, |e| e.bpm);
-        for e in self.tempos.iter().skip(1) {
-            let seg = (e.tick - seg_tick) as f64 * Self::samples_per_tick(bpm, sr);
-            if acc + seg > s {
-                break;
-            }
-            acc += seg;
-            seg_tick = e.tick;
-            bpm = e.bpm;
-        }
-        seg_tick as f64 + (s - acc) / Self::samples_per_tick(bpm, sr)
+        let scale = Self::samples_per_elapsed(sr);
+        // Tempo events after the first that start at or before `s`.
+        let passed = self.elapsed.get(1..).map_or(0, |rest| rest.partition_point(|e| e * scale <= s));
+        let (seg_tick, bpm, elapsed) = self.segment(passed);
+        seg_tick as f64 + (s - elapsed * scale) / Self::samples_per_tick(bpm, sr)
     }
 
     pub fn samples_to_ticks(&self, s: Samples, sr: SampleRate) -> i64 {
@@ -319,6 +397,7 @@ impl TempoMap {
             e.bpm = valid_bpm(e.bpm * factor)?;
         }
         self.tempos = out;
+        self.reindex();
         Ok(())
     }
 }
@@ -396,6 +475,36 @@ mod tests {
         assert_eq!(m.bar_beat_at_tick(m.tick_at_bar_beat(bb)), bb);
     }
 
+    #[test]
+    fn editing_an_early_meter_keeps_later_bars_and_scales_linearly() {
+        // 200 000 meter changes, one per bar, built directly: a walk per meter would take
+        // minutes to edit here, and even to build through `set_meter`.
+        let mut m = TempoMap::new(120.0, 4, 4).unwrap();
+        let mut tick = 0;
+        for bar in 1..200_000i64 {
+            let numerator = 3 + (bar % 2) as u32;
+            tick += m.meters.last().map_or(0, MeterEvent::ticks_per_bar);
+            m.meters.push(MeterEvent { tick, numerator, denominator: 4 });
+        }
+        let sample = [1usize, 1_000, 199_998];
+        let bars = |m: &TempoMap| sample.map(|i| m.bar_beat_at_tick(m.meters[i].tick).bar);
+        assert_eq!(bars(&m), [2, 1_001, 199_999]);
+        m.set_meter(0, 7, 8).unwrap();
+        assert_eq!(bars(&m), [2, 1_001, 199_999], "later meters keep their bar numbers");
+        assert_eq!(m.meters.len(), 200_000);
+        assert!(m.meters.windows(2).all(|w| w[0].tick < w[1].tick));
+        assert!(m.remove_meter(m.meters[1].tick));
+        assert_eq!([1usize, 999, 199_997].map(|i| m.bar_beat_at_tick(m.meters[i].tick).bar), [3, 1_001, 199_999]);
+        // Meters off their bar lines (counted as bars 2 and 4) land where they always did: on
+        // bar 2 of the new meter, then two bars of their own later.
+        let mut off = TempoMap::new(120.0, 4, 4).unwrap();
+        off.meters.push(MeterEvent { tick: 100, numerator: 3, denominator: 4 });
+        off.meters.push(MeterEvent { tick: 5_000, numerator: 5, denominator: 4 });
+        off.set_meter(0, 2, 4).unwrap();
+        let placed: Vec<(i64, u32)> = off.meters.iter().map(|e| (e.tick, e.numerator)).collect();
+        assert_eq!(placed, vec![(0, 2), (2 * TICKS_PER_QUARTER, 3), (8 * TICKS_PER_QUARTER, 5)]);
+    }
+
     #[test]
     fn eighth_note_meters() {
         let m = TempoMap::new(120.0, 6, 8).unwrap();
@@ -407,24 +516,24 @@ mod tests {
     fn sanitize_keeps_what_the_setters_accept() {
         let tempo = |tick, bpm| TempoEvent { tick, bpm };
         let meter = |tick, numerator, denominator| MeterEvent { tick, numerator, denominator };
-        let mut m = TempoMap {
-            tempos: vec![tempo(960, 4e9), tempo(3840, 90.0), tempo(-5, 100.0), tempo(1920, 60.0), tempo(1920, 70.0)],
-            meters: vec![meter(0, 0, 4), meter(3840, 3, 4)],
-        };
+        let mut m = TempoMap::from_parts(
+            vec![tempo(960, 4e9), tempo(3840, 90.0), tempo(-5, 100.0), tempo(1920, 60.0), tempo(1920, 70.0)],
+            vec![meter(0, 0, 4), meter(3840, 3, 4)],
+        );
         m.sanitize();
         assert_eq!(m.tempos(), [tempo(0, 60.0), tempo(1920, 60.0), tempo(3840, 90.0)]);
         assert_eq!(m.meters(), [meter(0, 3, 4), meter(3840, 3, 4)]);
-        let mut empty = TempoMap { tempos: Vec::new(), meters: Vec::new() };
+        let mut empty = TempoMap::from_parts(Vec::new(), Vec::new());
         empty.sanitize();
         assert_eq!(empty, TempoMap::default());
     }
 
     #[test]
     fn sanitize_drops_events_beyond_the_position_range() {
-        let mut m = TempoMap {
-            tempos: vec![TempoEvent { tick: 0, bpm: 120.0 }, TempoEvent { tick: i64::MAX, bpm: 90.0 }],
-            meters: vec![MeterEvent { tick: 0, numerator: 4, denominator: 4 }, MeterEvent { tick: i64::MAX, numerator: 3, denominator: 4 }],
-        };
+        let mut m = TempoMap::from_parts(
+            vec![TempoEvent { tick: 0, bpm: 120.0 }, TempoEvent { tick: i64::MAX, bpm: 90.0 }],
+            vec![MeterEvent { tick: 0, numerator: 4, denominator: 4 }, MeterEvent { tick: i64::MAX, numerator: 3, denominator: 4 }],
+        );
         m.sanitize();
         assert_eq!(m, TempoMap::default());
         assert_eq!(m.bar_start_tick(2), TICKS_PER_QUARTER * 4);
@@ -446,4 +555,68 @@ mod tests {
         assert_eq!(m.bar_beat_at_tick(-TICKS_PER_QUARTER * 4), BarBeat { bar: 0, beat: 1, tick: 0 });
         assert_eq!(m.bar_beat_at_tick(-TICKS_PER_QUARTER), BarBeat { bar: 0, beat: 4, tick: 0 });
     }
+
+    /// The segment walk the indexed conversions replaced, kept as the reference they must match.
+    fn linear_tick_to_samples(m: &TempoMap, tick: i64, sr: SampleRate) -> i64 {
+        let mut acc = 0.0;
+        let mut seg_tick = 0i64;
+        let mut bpm = m.tempos[0].bpm;
+        for e in m.tempos.iter().skip(1) {
+            if e.tick >= tick {
+                break;
+            }
+            acc += (e.tick - seg_tick) as f64 * TempoMap::samples_per_tick(bpm, sr);
+            seg_tick = e.tick;
+            bpm = e.bpm;
+        }
+        to_samples(acc + (tick - seg_tick) as f64 * TempoMap::samples_per_tick(bpm, sr))
+    }
+
+    #[test]
+    fn indexed_conversions_match_the_segment_walk() {
+        let sr = SampleRate::HZ_48000;
+        let mut m = TempoMap::default();
+        for i in 1..200i64 {
+            m.set_tempo(i * 487, 40.0 + ((i * 37) % 300) as f64).unwrap();
+        }
+        assert!(m.remove_tempo(487 * 50));
+        for tick in (-1000..200 * 487 + 5000).step_by(113) {
+            let s = m.tick_to_samples(tick, sr);
+            assert_eq!(s, linear_tick_to_samples(&m, tick, sr), "tick {tick}");
+            assert!((m.samples_to_ticks(s, sr) - tick).abs() <= 1, "tick {tick}");
+        }
+        let json = serde_json::to_string(&m).unwrap();
+        assert!(!json.contains("elapsed"));
+        let back: TempoMap = serde_json::from_str(&json).unwrap();
+        assert_eq!(back, m);
+        assert_eq!(back.tick_to_samples(150 * 487 + 3, sr), m.tick_to_samples(150 * 487 + 3, sr));
+    }
+
+    #[test]
+    fn a_file_with_wild_ticks_is_indexed_without_overflow() {
+        let json = r#"{"tempos":[{"tick":0,"bpm":120.0},{"tick":-9223372036854775808,"bpm":100.0},{"tick":9223372036854775807,"bpm":90.0}],"meters":[{"tick":0,"numerator":4,"denominator":4}]}"#;
+        let mut m: TempoMap = serde_json::from_str(json).unwrap();
+        m.sanitize();
+        assert_eq!(m.tempos().first().map(|e| e.tick), Some(0));
+        assert_eq!(m.elapsed.len(), m.tempos().len());
+    }
+
+    #[test]
+    fn conversions_against_a_large_tempo_map_stay_fast() {
+        // 200k tempo changes, then 200k conversions each way: quadratic if every conversion walks
+        // the earlier segments, well under a second when it binary-searches them.
+        let sr = SampleRate::HZ_48000;
+        let n = 200_000i64;
+        let tempos = (0..n).map(|i| TempoEvent { tick: i * 10, bpm: 60.0 + (i % 7) as f64 }).collect();
+        let mut m = TempoMap::from_parts(tempos, vec![MeterEvent { tick: 0, numerator: 4, denominator: 4 }]);
+        m.sanitize();
+        let start = std::time::Instant::now();
+        let mut sum = 0i64;
+        for i in 0..n {
+            let s = m.tick_to_samples(i * 10 + 5, sr);
+            sum = sum.wrapping_add(s).wrapping_add(m.samples_to_ticks(s, sr));
+        }
+        assert!(sum != 0);
+        assert!(start.elapsed() < std::time::Duration::from_secs(5), "{:?}", start.elapsed());
+    }
 }

crates/ui-egui/Cargo.toml

@@ -24,6 +24,7 @@ soundcraft-video.workspace = true
 # 0.37 makes the bundled faces opt-in; the app's own font loader starts from
 # `FontDefinitions::default()`, and kittest never supplies fonts to this root.
 egui = { workspace = true, features = ["default_fonts", "monochrome_emoji_fonts"] }
+egui_extras = { workspace = true }
 web-time.workspace = true
 serde.workspace = true
 serde_json.workspace = true

crates/ui-egui/src/credits.rs

@@ -262,71 +262,213 @@ pub fn contributors_ui(ui: &mut egui::Ui) {
     let list = sorted(CONTRIBUTORS, v.names, v.key, v.ascending);
     ui.label(RichText::new(format!("{} contributors · {} commits", list.len(), group(TOTAL_COMMITS))).small().weak());
     ui.separator();
-    egui::ScrollArea::both().auto_shrink([false, false]).show(ui, |ui| {
-        if list.is_empty() {
-            ui.label("No contributor data was built into this copy.");
-        } else if v.table {
-            table(ui, &list, &mut v);
-        } else {
+    if list.is_empty() {
+        ui.label("No contributor data was built into this copy.");
+    } else if v.table {
+        // The table scrolls vertically itself, under a fixed header; it only scrolls sideways
+        // once its columns are dragged wider than the dialog.
+        egui::ScrollArea::horizontal().auto_shrink([false, false]).show(ui, |ui| table(ui, &list, &mut v));
+    } else {
+        egui::ScrollArea::vertical().auto_shrink([false, false]).show(ui, |ui| {
             contributors_grab_bag(ui, &list, v.names);
-        }
-    });
+        });
+    }
     ui.data_mut(|d| d.insert_temp(id, v));
 }
 
-fn table(ui: &mut egui::Ui, list: &[&Contributor], v: &mut View) {
-    egui::Grid::new("credits_table").striped(true).num_columns(SortKey::ALL.len()).show(ui, |ui| {
-        for k in SortKey::ALL {
-            let arrow = if v.key == k { if v.ascending { " ⏶" } else { " ⏷" } } else { "" };
-            if ui.button(RichText::new(format!("{}{arrow}", k.label().1)).strong()).on_hover_text(k.label().0).clicked() {
-                if v.key == k {
-                    v.ascending = !v.ascending;
-                } else {
-                    v.key = k;
-                    v.ascending = k.default_ascending();
-                }
-            }
-        }
-        ui.end_row();
-        for c in list {
-            ui.hyperlink_to(c.name(v.names), format!("https://github.com/{}", c.login)).on_hover_text(c.summary());
-            ui.label(group(c.prs));
-            ui.label(group(c.commits));
-            ui.label(group(c.lines_added));
-            ui.label(group(c.lines_deleted));
-            ui.label(signed(c.lines_delta()));
-            ui.label(group(c.binary_added));
-            ui.label(group(c.binary_deleted));
-            ui.label(day(c.first_commit));
-            ui.label(day(c.last_commit));
-            ui.end_row();
-        }
-    });
+/// How the contributor table's spare width is shared out: all of it to Name.
+const CONTRIBUTOR_GROW: [f32; 10] = [1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0];
+
+/// How the model table's spare width is shared out: to Company and Model, the text columns.
+const MODEL_GROW: [f32; 6] = [1.0, 2.0, 0.0, 0.0, 0.0, 0.0];
+
+/// The narrowest a column can be dragged.
+const MIN_COLUMN: f32 = 28.0;
+
+/// The width a column needs for its header and its widest cell.
+fn natural(ui: &egui::Ui, header: RichText, cells: impl Iterator<Item = String>) -> f32 {
+    let measure = |text: egui::WidgetText| text.into_galley(ui, Some(egui::TextWrapMode::Extend), f32::INFINITY, egui::TextStyle::Body).size().x;
+    let widest = cells.map(|c| measure(c.into())).fold(measure(header.into()), f32::max);
+    widest + 2.0 * ui.spacing().button_padding.x
 }
 
-/// About › Models: AI models credited in Co-Authored-By trailers.
+/// Opening column widths: each column's natural width, with the spare room shared out by `grow`,
+/// so the columns fill `room` exactly. When there is too little room, only the growing columns
+/// give way, each in proportion to its width above [`MIN_COLUMN`], and none goes below that.
+fn fit_widths(natural: &[f32], grow: &[f32], room: f32) -> Vec<f32> {
+    let spare = room - natural.iter().sum::<f32>();
+    let weight = grow.iter().sum::<f32>();
+    let slack = |w: f32| (w - MIN_COLUMN).max(0.0);
+    let flexible: f32 = natural.iter().zip(grow).filter(|(_, g)| **g > 0.0).map(|(w, _)| slack(*w)).sum();
+    natural
+        .iter()
+        .zip(grow)
+        .map(|(w, g)| {
+            if *g > 0.0 && spare >= 0.0 {
+                w + spare * g / weight
+            } else if *g > 0.0 && flexible > 0.0 {
+                w - (-spare).min(flexible) * slack(*w) / flexible
+            } else {
+                *w
+            }
+        })
+        .collect()
+}
+
+/// A striped table whose columns open at [`fit_widths`], so it fills the width and nothing scrolls
+/// sideways. Every column, the last included, can be dragged wider or narrower at its right edge:
+/// only a table dragged wider than the window scrolls sideways. Text too long for its column is
+/// clipped. When a column's natural width or the window changes, the columns go back to a new fit,
+/// dropping any dragged widths.
+fn fitted_table<'a>(ui: &'a mut egui::Ui, id: &str, natural: &[f32], grow: &[f32]) -> egui_extras::TableBuilder<'a> {
+    // Every cell is followed by the item gap, and the vertical scrollbar keeps its margins.
+    let s = ui.spacing();
+    let gaps = s.item_spacing.x * natural.len() as f32;
+    let bar = s.scroll.bar_width + s.scroll.bar_inner_margin + s.scroll.bar_outer_margin;
+    let widths = fit_widths(natural, grow, (ui.available_width() - gaps - bar).max(0.0));
+    // The table keeps its own column widths, so a change in what they were fitted to has to clear
+    // them. A longer name can leave the fit itself unchanged, and scrolling can nudge the available
+    // width, so this compares the natural widths and the clip rect, which scrolling never moves.
+    let fit = egui::Id::unique(("credits_fit", id));
+    let measured = (natural.to_vec(), ui.clip_rect().width());
+    let refit = ui.data_mut(|d| d.get_temp::<(Vec<f32>, f32)>(fit)).as_ref() != Some(&measured);
+    ui.data_mut(|d| d.insert_temp(fit, measured));
+    let mut t =
+        egui_extras::TableBuilder::new(ui).id_salt(id).striped(true).resizable(true).auto_shrink([false, false]).max_scroll_height(f32::INFINITY);
+    if refit {
+        t.reset();
+    }
+    for w in widths {
+        t = t.column(egui_extras::Column::initial(w).at_least(MIN_COLUMN).clip(true));
+    }
+    t
+}
+
+/// Add a cell's widget right-aligned (counts, dates) or left-aligned (names), vertically centred.
+fn aligned<R>(ui: &mut egui::Ui, right: bool, add: impl FnOnce(&mut egui::Ui) -> R) -> R {
+    let layout = if right { egui::Layout::right_to_left(egui::Align::Center) } else { egui::Layout::left_to_right(egui::Align::Center) };
+    ui.with_layout(layout, add).inner
+}
+
+fn row_height(ui: &egui::Ui) -> f32 {
+    ui.text_style_height(&egui::TextStyle::Body) + 6.0
+}
+
+/// One contributor's table cells after the name, in `SortKey::ALL` order.
+fn cells(c: &Contributor) -> [String; 9] {
+    [
+        group(c.prs),
+        group(c.commits),
+        group(c.lines_added),
+        group(c.lines_deleted),
+        signed(c.lines_delta()),
+        group(c.binary_added),
+        group(c.binary_deleted),
+        day(c.first_commit).to_string(),
+        day(c.last_commit).to_string(),
+    ]
+}
+
+/// A contributor-table header. The sorted column is highlighted; its direction shows on the
+/// toolbar's sort-order button, so no arrow widens the column.
+fn header_text(k: SortKey) -> RichText {
+    RichText::new(k.label().1).strong()
+}
+
+fn table(ui: &mut egui::Ui, list: &[&Contributor], v: &mut View) {
+    let h = row_height(ui);
+    let rows: Vec<[String; 9]> = list.iter().map(|c| cells(c)).collect();
+    let widths: Vec<f32> = SortKey::ALL
+        .iter()
+        .enumerate()
+        .map(|(i, &k)| match i.checked_sub(1) {
+            None => natural(ui, header_text(k), list.iter().map(|c| c.name(v.names))),
+            Some(col) => natural(ui, header_text(k), rows.iter().filter_map(|r| r.get(col).cloned())),
+        })
+        .collect();
+    fitted_table(ui, "credits_table", &widths, &CONTRIBUTOR_GROW)
+        .header(h + 4.0, |mut header| {
+            for k in SortKey::ALL {
+                header.col(|ui| {
+                    let r = aligned(ui, k != SortKey::Name, |ui| ui.selectable_label(v.key == k, header_text(k))).on_hover_text(k.label().0);
+
+                    if r.clicked() {
+                        if v.key == k {
+                            v.ascending = !v.ascending;
+                        } else {
+                            v.key = k;
+                            v.ascending = k.default_ascending();
+                        }
+                    }
+                });
+            }
+        })
+        .body(|mut body| {
+            for (c, cells) in list.iter().zip(rows) {
+                body.row(h, |mut row| {
+                    row.col(|ui| {
+                        aligned(ui, false, |ui| ui.hyperlink_to(c.name(v.names), format!("https://github.com/{}", c.login)))
+                            .on_hover_text(c.summary());
+                    });
+                    for text in cells {
+                        row.col(|ui| {
+                            aligned(ui, true, |ui| ui.label(text));
+                        });
+                    }
+                });
+            }
+        });
+}
+
+/// About ▸ Models: AI models credited in Co-Authored-By trailers.
 pub fn models_ui(ui: &mut egui::Ui) {
     if MODELS.is_empty() {
         ui.label("No model credits were built into this copy.");
         return;
     }
     let assisted: u64 = MODELS.iter().map(|m| m.commits).max().unwrap_or(0).max(1);
-    egui::ScrollArea::both().auto_shrink([false, false]).show(ui, |ui| {
-        egui::Grid::new("credits_models").striped(true).num_columns(6).show(ui, |ui| {
-            for h in ["Company", "Model", "Version", "Commits", "% of all commits", "Lines +/−"] {
-                ui.label(RichText::new(h).strong());
-            }
-            ui.end_row();
-            for m in MODELS {
-                ui.label(m.company);
-                ui.label(m.model);
-                ui.label(m.version);
-                ui.label(group(m.commits));
-                ui.label(format!("{:.0}%", 100.0 * m.commits as f64 / TOTAL_COMMITS.max(assisted) as f64));
-                ui.label(format!("+{} / −{}", group(m.lines_added), group(m.lines_deleted)));
-                ui.end_row();
-            }
-        });
+    let h = row_height(ui);
+    let titles = ["Company", "Model", "Version", "Commits", "% of all commits", "Lines +/−"];
+    // Company, Model and Version read as text; the counts line up on the right.
+    let right = [false, false, false, true, true, true];
+    let rows: Vec<[String; 6]> = MODELS
+        .iter()
+        .map(|m| {
+            [
+                m.company.to_string(),
+                m.model.to_string(),
+                m.version.to_string(),
+                group(m.commits),
+                format!("{:.0}%", 100.0 * m.commits as f64 / TOTAL_COMMITS.max(assisted) as f64),
+                format!("+{} / −{}", group(m.lines_added), group(m.lines_deleted)),
+            ]
+        })
+        .collect();
+    let widths: Vec<f32> = titles
+        .iter()
+        .enumerate()
+        .map(|(i, title)| natural(ui, RichText::new(*title).strong(), rows.iter().filter_map(|r| r.get(i).cloned())))
+        .collect();
+    egui::ScrollArea::horizontal().id_salt("credits_models").auto_shrink([false, false]).show(ui, |ui| {
+        fitted_table(ui, "credits_models", &widths, &MODEL_GROW)
+            .header(h + 4.0, |mut header| {
+                for (title, r) in titles.into_iter().zip(right) {
+                    header.col(|ui| {
+                        aligned(ui, r, |ui| ui.label(RichText::new(title).strong()));
+                    });
+                }
+            })
+            .body(|mut body| {
+                for cells in rows {
+                    body.row(h, |mut row| {
+                        for (text, r) in cells.into_iter().zip(right) {
+                            row.col(|ui| {
+                                aligned(ui, r, |ui| ui.label(text));
+                            });
+                        }
+                    });
+                }
+            });
     });
 }
 
@@ -406,4 +548,131 @@ mod tests {
         assert_eq!(day("2026-10-07T18:45:23Z"), "2026-10-07");
         assert_eq!(day(""), "—");
     }
+
+    #[test]
+    fn columns_fill_the_room_and_spare_width_goes_to_growing_columns() {
+        assert_eq!(fit_widths(&[100.0, 40.0, 60.0], &[1.0, 0.0, 0.0], 300.0), [200.0, 40.0, 60.0]);
+        assert_eq!(fit_widths(&[100.0, 40.0, 60.0], &[1.0, 2.0, 0.0], 230.0), [110.0, 60.0, 60.0]);
+        let w = fit_widths(&[123.0, 45.5, 67.25], &[1.0, 0.0, 2.0], 512.0);
+        assert!((w.iter().sum::<f32>() - 512.0).abs() < 0.01, "a fitted table neither scrolls nor leaves a gap: {w:?}");
+    }
+
+    #[test]
+    fn too_little_room_shrinks_only_growing_columns() {
+        assert_eq!(fit_widths(&[100.0, 40.0, 60.0], &[1.0, 0.0, 0.0], 150.0), [50.0, 40.0, 60.0]);
+        assert_eq!(fit_widths(&[100.0, 40.0, 60.0], &[1.0, 0.0, 0.0], 0.0), [MIN_COLUMN, 40.0, 60.0]);
+        assert_eq!(fit_widths(&[100.0, 40.0], &[0.0, 0.0], 50.0), [100.0, 40.0]);
+    }
+
+    #[test]
+    fn a_column_at_the_minimum_leaves_the_shortfall_to_the_others() {
+        let w = fit_widths(&[100.0, 300.0, 50.0], &[1.0, 1.0, 0.0], 140.0);
+        assert!((w.iter().sum::<f32>() - 140.0).abs() < 0.01, "the columns still fit the room: {w:?}");
+        assert!(w.iter().all(|c| *c >= MIN_COLUMN), "no column goes below the minimum: {w:?}");
+        assert_eq!(fit_widths(&[100.0, 300.0, 50.0], &[1.0, 1.0, 0.0], 0.0), [MIN_COLUMN, MIN_COLUMN, 50.0]);
+    }
+
+    const WINDOW: f32 = 640.5;
+    const NATURAL: [f32; 3] = [120.0, 80.0, 80.0];
+    const GROW: [f32; 3] = [1.0, 0.0, 0.0];
+
+    /// One frame of a table long enough to scroll; the rects of its header cells.
+    fn table_frame(ctx: &egui::Context, width: f32, natural: &[f32], events: Vec<egui::Event>) -> Vec<egui::Rect> {
+        scrolled_frame(ctx, width, natural, 0.0, events)
+    }
+
+    /// [`table_frame`], scrolled `offset` points sideways.
+    fn scrolled_frame(ctx: &egui::Context, width: f32, natural: &[f32], offset: f32, events: Vec<egui::Event>) -> Vec<egui::Rect> {
+        let screen_rect = Some(egui::Rect::from_min_size(egui::Pos2::ZERO, egui::vec2(width, 300.0)));
+        let raw = egui::RawInput { screen_rect, events, ..Default::default() };
+        let mut cells = Vec::new();
+        let out = ctx.run_ui(raw, |ui| {
+            cells.clear();
+            egui::ScrollArea::horizontal().auto_shrink([false, false]).horizontal_scroll_offset(offset).show(ui, |ui| {
+                fitted_table(ui, "test", natural, &GROW)
+                    .header(20.0, |mut header| {
+                        for _ in natural {
+                            header.col(|ui| cells.push(ui.max_rect()));
+                        }
+                    })
+                    .body(|mut body| {
+                        for _ in 0..40 {
+                            body.row(20.0, |mut row| {
+                                for _ in natural {
+                                    row.col(|ui| {
+                                        ui.label("x");
+                                    });
+                                }
+                            });
+                        }
+                    });
+            });
+        });
+        out.drop_without_applying_deltas();
+        cells
+    }
+
+    /// A new context with the table open and settled, and the rects of its header cells.
+    fn opened_table() -> (egui::Context, Vec<egui::Rect>) {
+        let ctx = egui::Context::default();
+        table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+        let cells = table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+        (ctx, cells)
+    }
+
+    /// Drags a column's right edge, which runs midway through the gap after `cell`, then lets go.
+    fn drag_edge(ctx: &egui::Context, cell: egui::Rect, by: f32) {
+        use egui::{Event, Modifiers, PointerButton};
+        let start = egui::pos2(cell.right() + 4.0, cell.center().y);
+        let halfway = start + egui::vec2(by / 2.0, 0.0);
+        let end = start + egui::vec2(by, 0.0);
+        let moved = Event::PointerMoved;
+        let button = |pos, pressed| Event::PointerButton { pos, button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE };
+        for event in [moved(start), button(start, true), moved(halfway), moved(end), button(end, false)] {
+            table_frame(ctx, WINDOW, &NATURAL, vec![event]);
+        }
+    }
+
+    #[test]
+    fn every_column_can_be_dragged_at_its_right_edge_and_stays_there() {
+        let (_, opened) = opened_table();
+        for (dragged, cell) in opened.iter().enumerate() {
+            let (ctx, _) = opened_table();
+            drag_edge(&ctx, *cell, -30.0);
+            table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+            let after = table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+            for (column, (was, now)) in opened.iter().zip(&after).enumerate() {
+                let want = if column == dragged { was.width() - 30.0 } else { was.width() };
+                assert!((now.width() - want).abs() < 1.0, "dragging column {dragged}: column {column} is {now:?}, was {was:?}");
+            }
+        }
+    }
+
+    #[test]
+    fn a_changed_fit_replaces_the_column_widths() {
+        let (ctx, opened) = opened_table();
+        drag_edge(&ctx, opened[0], -30.0);
+        let longer_name = table_frame(&ctx, WINDOW, &[200.0, 80.0, 80.0], Vec::new());
+        assert!((longer_name[0].width() - opened[0].width()).abs() < 1.0, "a longer name drops a dragged width: {longer_name:?}");
+        let wider = table_frame(&ctx, WINDOW, &[120.0, 200.0, 80.0], Vec::new());
+        let widths: Vec<f32> = wider.iter().map(|c| c.width().round()).collect();
+        assert!(widths.ends_with(&[200.0, 80.0]), "a longer cell widens its column: {widths:?}");
+        assert!(wider[2].right() < WINDOW, "the table still fits the window: {wider:?}");
+        let narrower = table_frame(&ctx, 400.0, &NATURAL, Vec::new());
+        assert!(narrower[2].right() < 400.0, "a narrower window refits the table: {narrower:?}");
+    }
+
+    #[test]
+    fn scrolling_sideways_keeps_dragged_widths() {
+        let (ctx, opened) = opened_table();
+        drag_edge(&ctx, opened[0], 100.0);
+        table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+        let dragged = table_frame(&ctx, WINDOW, &NATURAL, Vec::new());
+        assert!((dragged[0].width() - opened[0].width() - 100.0).abs() < 1.0, "the drag took: {dragged:?}");
+        for offset in [13.3, 27.77, 41.1, 0.6] {
+            scrolled_frame(&ctx, WINDOW, &NATURAL, offset, Vec::new());
+            let scrolled = scrolled_frame(&ctx, WINDOW, &NATURAL, offset, Vec::new());
+            assert!((scrolled[0].width() - dragged[0].width()).abs() < 1.0, "scrolled {offset}: {scrolled:?}");
+        }
+    }
 }

crates/ui-egui/src/dialogs.rs

@@ -20,7 +20,7 @@ use audiosuite::SPEED_RAMP_CHOICES;
 use audiosuite::audiosuite_window;
 pub use files::{NotUnicode, ask_to_save, open_path, open_session_bytes, run_or_ask, takes_path, unicode};
 use files::{OPEN_PENDING, default_dir, open_pending_session, path_dialog};
-use strip_silence::{AUTO_NAME_LABELS, STRIP_NAME_LABELS, StripRectangles, auto_rename_action, strip_name_fields, strip_silence_action};
+use strip_silence::{AUTO_NAME_LABELS, STRIP_NAME_LABELS, StripRectangles, StripValues, auto_rename_action, strip_name_fields, strip_silence_action};
 pub use strip_silence::{StripRects, strip_silence_rectangles};
 
 pub mod new_tracks;
@@ -78,6 +78,8 @@ pub struct Dialogs {
     pending_session: Option<(String, Vec<u8>)>,
     /// The naming scheme Strip Silence gives the clips it leaves, kept from one use to the next.
     pub strip_names: StripNames,
+    /// The values Strip Silence last had, which it opens with next time.
+    strip_values: StripValues,
     /// The Strip Silence rectangles the Edit window draws while Strip Silence is open.
     strip_rectangles: StripRectangles,
 }
@@ -211,7 +213,10 @@ impl Dialogs {
                 Dialog::Number { cmd: id.into(), title: "Quantize strength".into(), key: "strength".into(), value: 100.0, suffix: "%".into() }
             }
             "edit.fades_create" => Dialog::Fades { shape: "equal power".into() },
-            "edit.strip_silence" => Dialog::StripSilence { threshold: -48.0, min_ms: 50.0, pre_ms: 5.0, post_ms: 20.0 },
+            "edit.strip_silence" => {
+                let StripValues([threshold, min_ms, pre_ms, post_ms]) = self.strip_values;
+                Dialog::StripSilence { threshold, min_ms, pre_ms, post_ms }
+            }
             "track.group" => {
                 let s = e.session();
                 let members = s.tracks.iter().map(|t| (t.id.0, t.name.clone(), s.edit.selected_tracks.contains(&t.id))).collect();
@@ -712,6 +717,14 @@ pub fn show(app: &mut SoundApp, ctx: &egui::Context) {
                 }
             }
         });
+    // Strip Silence keeps the values it shows, however it closes: Escape, Cancel or one of its actions.
+    match &d {
+        Dialog::StripSilence { threshold, min_ms, pre_ms, post_ms } => {
+            app.dialogs.strip_values = StripValues([*threshold, *min_ms, *pre_ms, *post_ms])
+        }
+        Dialog::StripSilenceRename { strip, .. } => app.dialogs.strip_values = StripValues(*strip),
+        _ => {}
+    }
     if esc || ctx.memory(|m| m.data.get_temp::<bool>(egui::Id::unique("dlg_cancel")).unwrap_or(false)) {
         keep = false;
         action = None;

crates/ui-egui/src/dialogs/strip_silence.rs

@@ -3,6 +3,17 @@ use super::{Arc, ClipId, Dialog, SoundApp, StripNames, Tokens, TrackId, Value, j
 /// What Strip keeps on each track: the Strip Silence rectangles.
 pub type StripRects = Arc<Vec<(TrackId, Vec<soundcraft_time::Range>)>>;
 
+/// The Strip Silence values (threshold dB, min strip duration, clip start and end pads in ms) the
+/// window opens with: the ones it last had, or these defaults before its first use.
+#[derive(Debug, Clone, Copy)]
+pub(super) struct StripValues(pub(super) [f64; 4]);
+
+impl Default for StripValues {
+    fn default() -> Self {
+        Self([-48.0, 50.0, 5.0, 20.0])
+    }
+}
+
 /// The session revision and the Strip Silence values (as bits) that rectangles were found for.
 type StripKey = (u64, [u64; 4]);
 

crates/ui-egui/src/edit_window.rs

@@ -167,14 +167,20 @@ fn main_area_content(app: &mut SoundApp, ui: &mut Ui) {
     }
     app.edit_layout.content_h = content_h;
     let clip_rect = Rect::from_min_max(pos2(full.min.x, tl.min.y), pos2(full.max.x, tl.max.y));
+    let grid = clips::GridLines::new(app.engine.session(), tl);
+    let grid_revision = app.engine.revision;
     for (id, r) in app.edit_layout.rows.clone() {
         let row = rect(r);
         if row.max.y >= clip_rect.min.y && row.min.y <= clip_rect.max.y {
             let mut child = ui.new_child(egui::UiBuilder::new().max_rect(row));
             child.set_clip_rect(clip_rect);
-            track_row(app, &mut child, TrackId(id), row, tl, &cols);
+            track_row(app, &mut child, TrackId(id), row, tl, &cols, &grid);
         }
     }
+    // Keep one consistent grid snapshot during this pass, then refresh after a row edits it.
+    if app.engine.revision != grid_revision {
+        ui.ctx().request_repaint();
+    }
     // Below the tracks a click clears the selection and a double-click opens New Tracks.
     let empty = Rect::from_min_max(pos2(full.min.x, y.max(tl.min.y)), tl.max);
     if empty.height() > 4.0 {

crates/ui-egui/src/edit_window/clips.rs

@@ -25,26 +25,41 @@ pub(super) fn draw_strip_silence(painter: &egui::Painter, s: &Session, tl: Rect,
     }
 }
 
-pub(super) fn grid_lines(painter: &egui::Painter, s: &Session, tl: Rect, lane: Rect) {
-    let t = Tokens::current();
-    let view = Range::new(sample_at(s, tl, tl.min.x).max(0), sample_at(s, tl, tl.max.x));
-    let sr = s.sample_rate;
-    // Bar lines always; grid lines when enabled and dense enough.
-    let bar = GridValue::Note { value: NoteValue::Bar, dotted: false, triplet: false };
-    let bar_px = bar.step_samples(view.start, sr, &s.tempo, s.frame_rate) as f64 / s.edit.zoom.samples_per_px;
-    if bar_px > 6.0 {
-        let col = grid_veil(t.bar_line, t.playlist_bg);
-        for at in bar.lines(view.start, view.end, sr, &s.tempo, s.frame_rate, 600) {
-            let x = x_of(s, tl, at);
-            painter.line_segment([pos2(x, lane.min.y), pos2(x, lane.max.y)], Stroke::new(1.0, col));
+/// Grid positions computed once for the current viewport and shared by all visible lanes.
+#[derive(Default)]
+pub(super) struct GridLines {
+    bars: Vec<f32>,
+    grid: Vec<f32>,
+}
+
+impl GridLines {
+    /// Collect and project visible lines before drawing any lanes in this frame.
+    pub(super) fn new(s: &Session, tl: Rect) -> Self {
+        let mut lines = Self::default();
+        let view = Range::new(sample_at(s, tl, tl.min.x).max(0), sample_at(s, tl, tl.max.x));
+        let sr = s.sample_rate;
+        // Bar lines always; grid lines when enabled and dense enough.
+        let bar = GridValue::Note { value: NoteValue::Bar, dotted: false, triplet: false };
+        let bar_px = bar.step_samples(view.start, sr, &s.tempo, s.frame_rate) as f64 / s.edit.zoom.samples_per_px;
+        if bar_px > 6.0 {
+            lines.bars = bar.lines(view.start, view.end, sr, &s.tempo, s.frame_rate, 600).into_iter().map(|at| x_of(s, tl, at)).collect();
         }
+        if s.edit.grid_lines {
+            let step_px = s.edit.grid.step_samples(view.start, sr, &s.tempo, s.frame_rate) as f64 / s.edit.zoom.samples_per_px;
+            if s.edit.grid_clips_markers || step_px > 7.0 {
+                let visible_columns = tl.width().ceil().clamp(1.0, 16_384.0) as usize;
+                lines.grid = s.grid_lines(view.start, view.end, visible_columns).into_iter().map(|at| x_of(s, tl, at)).collect();
+            }
+        }
+        lines
     }
-    if s.edit.grid_lines {
-        let step_px = s.edit.grid.step_samples(view.start, sr, &s.tempo, s.frame_rate) as f64 / s.edit.zoom.samples_per_px;
-        if step_px > 7.0 {
-            let col = grid_veil(t.grid_line, t.playlist_bg);
-            for at in s.edit.grid.lines(view.start, view.end, sr, &s.tempo, s.frame_rate, 2000) {
-                let x = x_of(s, tl, at);
+
+    /// Draw the prepared lines on one lane, preserving bar and grid colors and stacking order.
+    pub(super) fn draw(&self, painter: &egui::Painter, lane: Rect) {
+        let t = Tokens::current();
+        for (positions, color) in [(&self.bars, t.bar_line), (&self.grid, t.grid_line)] {
+            let col = grid_veil(color, t.playlist_bg);
+            for &x in positions {
                 painter.line_segment([pos2(x, lane.min.y), pos2(x, lane.max.y)], Stroke::new(1.0, col));
             }
         }

crates/ui-egui/src/edit_window/drag.rs

@@ -64,7 +64,8 @@ pub(super) fn drive_drag(app: &mut SoundApp, ctx: &egui::Context) {
             let plan = drag_plan(ctx, &s, app.engine.revision, clips, (*from_track, *tt), *grab_at);
             *delta = move_delta(&plan, &s, *from_track, at - *grab_at, ctx.input(|i| i.modifiers.command));
         }
-        Some(Gesture::TrimStart { to, .. } | Gesture::TrimEnd { to, .. }) => *to = drag_snap(&s, at, ctx.input(|i| i.modifiers.command)),
+        Some(Gesture::TrimStart { clip, to, .. }) => *to = trim_drag_snap(&s, *clip, at, true, ctx.input(|i| i.modifiers.command)),
+        Some(Gesture::TrimEnd { clip, to, .. }) => *to = trim_drag_snap(&s, *clip, at, false, ctx.input(|i| i.modifiers.command)),
         Some(Gesture::MidiClip { to, .. }) => *to = at,
         Some(Gesture::Fade { clip, fade_in, to, .. }) => {
             if let Some(range) = s.find_clip(*clip).and_then(|(_, c)| fade_drag_range(c, *fade_in, at)) {
@@ -206,7 +207,18 @@ fn finish_drag(app: &mut SoundApp, s: &Session, tl: Rect, p: Option<Pos2>) {
 
 /// Grid snapping while dragging; holding Cmd/Ctrl swaps Grid and Slip.
 pub(super) fn drag_snap(s: &Session, at: Samples, flip: bool) -> Samples {
-    if s.edit.edit_mode.is_grid() != flip { s.edit.grid.snap(at, s.sample_rate, &s.tempo, s.frame_rate) } else { at }
+    drag_snap_excluding(s, at, flip, &[])
+}
+
+/// Grid snapping that ignores boundaries belonging to clips changed by the gesture.
+pub(super) fn drag_snap_excluding(s: &Session, at: Samples, flip: bool, excluded: &[ClipId]) -> Samples {
+    if s.edit.edit_mode.is_grid() != flip { s.snap_to_grid_excluding(at, excluded) } else { at }
+}
+
+/// Snap a trim while preserving the clip edge when the pointer returns to its origin.
+pub(super) fn trim_drag_snap(s: &Session, clip: ClipId, at: Samples, start: bool, flip: bool) -> Samples {
+    let origin = s.find_clip(clip).map(|(_, clip)| if start { clip.start } else { clip.end() });
+    if origin == Some(at) { at } else { drag_snap_excluding(s, at, flip, &[clip]) }
 }
 
 /// What a clip drag works out once per target track rather than every frame: where the tracks go
@@ -216,6 +228,7 @@ pub(super) struct DragPlan {
     pub(super) dest: Option<Vec<(TrackId, TrackId)>>,
     pub(super) groups: Vec<(TrackId, Samples, Vec<Samples>)>,
     pub(super) moving: Vec<(TrackId, Samples, Samples)>,
+    moving_ids: Vec<ClipId>,
     grabbed: Option<Clip>,
 }
 
@@ -246,10 +259,11 @@ pub(super) fn drag_plan(
     };
     let ids: HashSet<ClipId> = clips.iter().copied().collect();
     let movable = |c: &&Clip| ids.contains(&c.id) && !ops::locked(c);
-    let moving = s.tracks.iter().flat_map(|t| t.clips().iter().filter(movable).map(|c| (t.id, c.start, c.length))).collect();
+    let moving: Vec<_> = s.tracks.iter().flat_map(|t| t.clips().iter().filter(movable).map(|c| (t.id, c.start, c.length))).collect();
+    let moving_ids: Vec<_> = s.tracks.iter().flat_map(|t| t.clips().iter().filter(movable).map(|c| c.id)).collect();
     let mine: Vec<&Clip> = s.track(from).map(|t| t.clips().iter().filter(movable).collect()).unwrap_or_default();
     let grabbed = mine.iter().rev().find(|c| c.range().contains(grab_at)).or_else(|| mine.iter().min_by_key(|c| c.start)).map(|c| (*c).clone());
-    let plan = Arc::new(DragPlan { dest, groups, moving, grabbed });
+    let plan = Arc::new(DragPlan { dest, groups, moving, moving_ids, grabbed });
     ctx.data_mut(|d| d.insert_temp(id, (key, Arc::clone(&plan))));
     plan
 }
@@ -258,6 +272,10 @@ pub(super) fn drag_plan(
 /// Shuffle lands the earliest clip bound for the target track on a slot there, as
 /// `edit.move_clips` does; Grid snaps the grabbed clip.
 fn move_delta(plan: &DragPlan, s: &Session, from: TrackId, raw: Samples, flip: bool) -> Samples {
+    let track_changed = plan.dest.as_ref().is_some_and(|dest| ops::lands(dest, from) != from);
+    if raw == 0 && !track_changed {
+        return 0;
+    }
     let mode = s.edit.edit_mode;
     if mode == EditMode::Shuffle {
         let to = plan.dest.as_ref().map_or(from, |d| ops::lands(d, from));
@@ -268,7 +286,7 @@ fn move_delta(plan: &DragPlan, s: &Session, from: TrackId, raw: Samples, flip: b
     } else if mode.is_grid() != flip
         && let Some(c) = &plan.grabbed
     {
-        ops::grid_delta(s, c, raw, mode == EditMode::GridRelative)
+        ops::grid_delta(s, c, raw, mode == EditMode::GridRelative, &plan.moving_ids)
     } else {
         raw
     }

crates/ui-egui/src/edit_window/header.rs

@@ -115,8 +115,18 @@ fn name_plate(app: &mut SoundApp, ui: &mut Ui, track: &Track, head: Rect, select
         track.name.clone()
     };
     let name_color = if selected { t.text_dark } else { t.text.lerp_to_gamma(t.text_dim, 0.4) };
-    ui.painter().with_clip_rect(name_r).text(pos2(name_r.min.x + 1.5, name_r.center().y), Align2::LEFT_CENTER, &shown_name, bold(12.5), name_color);
-    let nresp = ui.interact(name_r, ui.scope_id().with(("name", id.0)), Sense::click_and_drag());
+    let font = bold(12.5);
+    let galley = ui.painter().layout_no_wrap(shown_name.clone(), font.clone(), name_color);
+    let overflows = galley.size().x > name_r.width() - 3.0;
+    let (text_pos, align) =
+        if overflows { (pos2(name_r.min.x + 1.5, name_r.center().y), Align2::LEFT_CENTER) } else { (name_r.center(), Align2::CENTER_CENTER) };
+    ui.painter().with_clip_rect(name_r).text(text_pos, align, &shown_name, font, name_color);
+    let mut nresp = ui.interact(name_r, ui.scope_id().with(("name", id.0)), Sense::click_and_drag());
+    if overflows {
+        nresp = nresp.on_hover_ui(|ui| {
+            ui.label(&shown_name);
+        });
+    }
     if nresp.double_clicked() {
         app.dialogs.open_rename_track(id, &track.name);
     } else if nresp.clicked() {
@@ -190,8 +200,9 @@ fn toggle_keys(app: &mut SoundApp, ui: &mut Ui, track: &Track, head: Rect) {
     let h = head.height();
     let at = |x: f32, y: f32, w: f32, h: f32| Rect::from_min_size(pos2(head.min.x + x, head.min.y + y), vec2(w, h));
     let m = &track.mixer;
-    if h >= 37.0 {
-        let (records, mixes) = (track.kind.has_playlist(), track.kind != TrackKind::Master);
+    let is_master = track.kind == TrackKind::Master;
+    if h >= 37.0 && !is_master {
+        let (records, mixes) = (track.kind.has_playlist(), true);
         let implied = !m.solo && app.engine.session().tracks.iter().any(|t| t.mixer.solo);
         let keys = [
             (HeaderKey::Rec, m.record_arm, false, "mix.record_arm", records),
@@ -213,10 +224,13 @@ fn view_selector(app: &mut SoundApp, ui: &mut Ui, track: &Track, head: Rect) {
     let id = track.id;
     let h = head.height();
     let at = |x: f32, y: f32, w: f32, h: f32| Rect::from_min_size(pos2(head.min.x + x, head.min.y + y), vec2(w, h));
-    if h >= 58.0 {
+    let is_master = track.kind == TrackKind::Master;
+    let view_y = if is_master { 20.0 } else { 39.0 };
+    let view_min_h = if is_master { 37.0 } else { 58.0 };
+    if h >= view_min_h {
         let vresp = header_selector(
             ui,
-            at(17.0, 39.0, 105.0, 17.0),
+            at(17.0, view_y, 105.0, 17.0),
             ui.scope_id().with(("view", id.0)),
             &view_label(&track.view),
             t.text,
@@ -225,10 +239,32 @@ fn view_selector(app: &mut SoundApp, ui: &mut Ui, track: &Track, head: Rect) {
         );
         egui::Popup::menu(&vresp).show(|ui| view_menu(app, ui, track));
     }
+    if is_master && h >= 58.0 {
+        let mode = track.mixer.automation_mode;
+        let col = match mode {
+            soundcraft_model::AutomationMode::Read => t.auto_read,
+            soundcraft_model::AutomationMode::Write => t.auto_write,
+            soundcraft_model::AutomationMode::Touch | soundcraft_model::AutomationMode::TouchLatch => t.auto_touch,
+            soundcraft_model::AutomationMode::Latch => t.auto_latch,
+            _ => t.text_dim,
+        };
+        let mode_name = format!("Automation mode for {}", track.name);
+        let aresp = header_selector(ui, at(17.0, 39.0, 105.0, 17.0), ui.scope_id().with(("auto_mode", id.0)), mode.label(), col, true, &mode_name);
+        egui::Popup::menu(&aresp).show(|ui| {
+            for m in soundcraft_model::AutomationMode::ALL {
+                if ui.selectable_label(m == mode, m.label()).clicked() {
+                    let _ = app.run("mix.automation_mode", json!({"track": id.0, "mode": m.label()}));
+                }
+            }
+        });
+    }
 }
 
 /// Freeze, voice and automation mode.
 fn voice_row(app: &mut SoundApp, ui: &mut Ui, track: &Track, head: Rect) {
+    if track.kind == TrackKind::Master {
+        return;
+    }
     let t = Tokens::current();
     let id = track.id;
     let h = head.height();

crates/ui-egui/src/edit_window/input.rs

@@ -9,9 +9,10 @@ use super::{
 
 // ---- interaction -----------------------------------------------------------------------------
 
+/// Apply snapping when the current edit mode or Snap to Grid option enables it.
 pub(super) fn snap(s: &Session, at: Samples) -> Samples {
     let on = s.edit.edit_mode.is_grid() || s.edit.flag(ops::SNAP_TO_GRID);
-    if on { s.edit.grid.snap(at, s.sample_rate, &s.tempo, s.frame_rate) } else { at }
+    if on { s.snap_to_grid(at) } else { at }
 }
 
 pub(super) fn clip_at(track: &Track, at: Samples) -> Option<&Clip> {

crates/ui-egui/src/edit_window/rulers.rs

@@ -222,7 +222,8 @@ pub(super) fn draw_rulers(app: &mut SoundApp, ui: &mut Ui, area: Rect, tl: Rect,
                     } else if resp.clicked()
                         && let Some(m) = hit
                     {
-                        let _ = app.run("markers.recall", json!({"number": m.number}));
+                        let command = if ui.input(|i| i.modifiers.alt) { "markers.delete" } else { "markers.recall" };
+                        let _ = app.run(command, json!({"number": m.number}));
                     }
                 }
             }

crates/ui-egui/src/edit_window/tests.rs

@@ -2,6 +2,25 @@ use super::*;
 use egui::accesskit::Role;
 use egui_kittest::{Harness, kittest::Queryable};
 
+/// A trim cannot snap to the clip's own old boundary in Clips/Markers mode.
+#[test]
+fn clips_markers_trim_ignores_the_trimmed_clip() {
+    let mut s = Session::default();
+    let track = s.add_track(TrackKind::Midi, soundcraft_model::ChannelFormat::Mono, None);
+    let clip = Clip::midi(s.new_clip_id(), "Notes", 1_000, 1_000, soundcraft_midi::Sequence::default());
+    let clip_id = clip.id;
+    s.track_mut(track).and_then(Track::playlist_mut).unwrap().clips.push(clip);
+    s.add_marker("Inside", soundcraft_model::MarkerKind::Marker, 1_500, 1_500);
+    s.add_marker("Target", soundcraft_model::MarkerKind::Marker, 2_500, 2_500);
+    s.edit.edit_mode = soundcraft_model::EditMode::Grid;
+    s.edit.grid_clips_markers = true;
+
+    assert_eq!(super::drag::drag_snap(&s, 2_100, false), 2_000);
+    assert_eq!(super::drag::drag_snap_excluding(&s, 2_100, false, &[clip_id]), 2_500);
+    assert_eq!(super::drag::trim_drag_snap(&s, clip_id, 1_000, true, false), 1_000);
+    assert_eq!(super::drag::trim_drag_snap(&s, clip_id, 2_000, false, false), 2_000);
+}
+
 /// The painted header selectors are interactive controls; their accessible name is the field
 /// they edit, not the short value text ("Read", "Waveform") painted inside them.
 #[test]
@@ -1508,3 +1527,50 @@ fn alt_click_on_a_breakpoint_deletes_it() {
         assert_eq!(h.state().engine.session().track(track).unwrap().clips(), clips.as_slice(), "{tool}");
     }
 }
+
+#[test]
+fn alt_click_on_a_marker_deletes_it() {
+    let mut engine = soundcraft_engine::demo::demo_engine();
+    engine.session_mut().edit.rulers = vec!["markers".into()];
+    engine.execute("markers.add", &json!({"at": 48_000, "name": "Alt-delete me"})).unwrap();
+    let mut h = harness_with(engine);
+    let s = h.state().engine.session_arc();
+    let marker = s.markers.iter().find(|m| m.name == "Alt-delete me").unwrap();
+    let at = pos2(x_of(&s, timeline(&h), marker.start), timeline(&h).min.y - 11.5);
+    let before = s.markers.len();
+
+    click_with(&mut h, at, egui::Modifiers::ALT);
+
+    assert_eq!(h.state().engine.session().markers.len(), before - 1);
+    assert!(!h.state().engine.session().markers.iter().any(|m| m.name == "Alt-delete me"));
+}
+
+#[test]
+fn short_track_name_is_centered_and_long_name_is_left_aligned() {
+    let mut h = harness(2);
+    let s = h.state().engine.session_arc();
+    let first = s.tracks[0].id.0;
+    let second = s.tracks[1].id.0;
+    h.state_mut().run("track.rename", json!({"track": first, "name": "Vocal"})).unwrap();
+    h.state_mut().run("track.rename", json!({"track": second, "name": "A Very Long Track Name That Exceeds Header Width"})).unwrap();
+    h.step();
+
+    let r0 = row(&h, 0);
+    let r1 = row(&h, 1);
+
+    let first_text = h.output().shapes.iter().find_map(|s| match &s.shape {
+        Shape::Text(t) if t.galley.text() == "Vocal" && s.clip_rect.intersects(r0) => Some((t.pos, t.galley.size())),
+        _ => None,
+    });
+    let long_text = h.output().shapes.iter().find_map(|s| match &s.shape {
+        Shape::Text(t) if t.galley.text() == "A Very Long Track Name That Exceeds Header Width" && s.clip_rect.intersects(r1) => Some(t.pos),
+        _ => None,
+    });
+
+    let (first_pos, first_size) = first_text.expect("short track name should be rendered in edit header");
+    let long_pos = long_text.expect("long track name should be rendered in edit header");
+
+    assert_eq!(long_pos.x, r1.min.x + 17.5);
+    let first_center_x = first_pos.x + first_size.x * 0.5;
+    assert!((first_center_x - (r0.min.x + 64.5)).abs() <= 0.1, "short name should be centered (center was at {first_center_x})");
+}

crates/ui-egui/src/edit_window/tracks.rs

@@ -1,5 +1,5 @@
 use super::automation::draw_automation;
-use super::clips::{ClipLane, draw_clip, draw_live_take, draw_strip_silence, grid_lines};
+use super::clips::{ClipLane, GridLines, draw_clip, draw_live_take, draw_strip_silence};
 use super::header::{header_column, track_header};
 use super::input::lane_interaction;
 use super::layout::{Column, HEADER_W, LANE_H, STRIP_W, lane_rect, sample_at, x_of};
@@ -58,7 +58,8 @@ pub(crate) fn click_track(app: &mut SoundApp, id: TrackId, mods: egui::Modifiers
 
 // ---- track rows ------------------------------------------------------------------------------
 
-pub(super) fn track_row(app: &mut SoundApp, ui: &mut Ui, id: TrackId, row: Rect, tl: Rect, cols: &[Column]) {
+/// Draw one track with grid positions shared by all lanes in the current frame.
+pub(super) fn track_row(app: &mut SoundApp, ui: &mut Ui, id: TrackId, row: Rect, tl: Rect, cols: &[Column], grid: &GridLines) {
     let t = Tokens::current();
     let s = app.engine.session_arc();
     let Some(track) = s.track(id) else { return };
@@ -84,7 +85,7 @@ pub(super) fn track_row(app: &mut SoundApp, ui: &mut Ui, id: TrackId, row: Rect,
     let s = app.engine.session_arc();
     // Shown grid lines go over the clips; otherwise the bar lines stay behind them.
     if !s.edit.grid_lines {
-        grid_lines(&painter, &s, tl, lane);
+        grid.draw(&painter, lane);
     }
     let view = Range::new(sample_at(&s, tl, tl.min.x), sample_at(&s, tl, tl.max.x));
     let auto_view = AutoParam::parse(&track.view);
@@ -98,7 +99,7 @@ pub(super) fn track_row(app: &mut SoundApp, ui: &mut Ui, id: TrackId, row: Rect,
     draw_live_take(app, &painter, &s, track, tl, lane);
     crate::video_track::draw_lane(app, &painter, &s, track, tl, lane);
     if s.edit.grid_lines {
-        grid_lines(&painter, &s, tl, lane);
+        grid.draw(&painter, lane);
     }
     if let Some(p) = &auto_view {
         draw_automation(&painter, &s, track, p, tl, lane);

crates/ui-egui/src/icons.rs

@@ -176,6 +176,19 @@ pub fn draw(painter: &Painter, r: Rect, name: &str, c: Color32) {
                 painter.line_segment([p(r, x, 0.5 - h), p(r, x, 0.5 + h)], s);
             }
         }
+        "link_track" => {
+            // A link chain below two track rows, so the track link reads apart from the timeline link's plain chain.
+            painter.line_segment([p(r, 0.12, 0.18), p(r, 0.88, 0.18)], s);
+            painter.line_segment([p(r, 0.12, 0.32), p(r, 0.88, 0.32)], s);
+            painter.circle_stroke(p(r, 0.38, 0.72), r.width() * 0.16, s);
+            painter.circle_stroke(p(r, 0.62, 0.72), r.width() * 0.16, s);
+        }
+        "insertion_follows" => {
+            // The insertion line, a lead, and the playhead arrow it follows.
+            painter.line_segment([p(r, 0.3, 0.14), p(r, 0.3, 0.86)], s);
+            painter.line_segment([p(r, 0.42, 0.5), p(r, 0.62, 0.5)], s);
+            painter.add(Shape::convex_polygon(vec![p(r, 0.84, 0.5), p(r, 0.64, 0.34), p(r, 0.64, 0.66)], c, Stroke::NONE));
+        }
         _ => {
             painter.rect_stroke(r.shrink(r.width() * 0.25), 1.0, s, egui::StrokeKind::Middle);
         }

crates/ui-egui/src/mix_window/routing.rs

@@ -11,7 +11,12 @@ pub(crate) fn route_name(app: &SoundApp, r: &Route) -> String {
 }
 
 pub(crate) fn input_name(app: &SoundApp, track: &Track) -> String {
-    if track.kind.has_playlist() && track.mixer.input == Route::None { "In 1".to_string() } else { route_name(app, &track.mixer.input) }
+    if track.kind.has_playlist() && track.mixer.input == Route::None {
+        let channels = track.format.channels();
+        if channels == 1 { "In 1".to_string() } else { format!("In 1-{channels}") }
+    } else {
+        route_name(app, &track.mixer.input)
+    }
 }
 
 /// The input or output menu under `resp`. It closes only on a click outside, so its bus search
@@ -59,3 +64,19 @@ fn route_menu(app: &mut SoundApp, ui: &mut Ui, id: TrackId, input: bool) {
         ui.close();
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::input_name;
+    use crate::{Services, SoundApp};
+    use serde_json::json;
+
+    #[test]
+    fn stereo_track_defaults_to_a_stereo_input_pair() {
+        let mut app = SoundApp::new(soundcraft_engine::Engine::default(), None, Services::default());
+        app.run("track.new", json!({"format": "stereo"})).unwrap();
+        let track = &app.engine.session().tracks[0];
+
+        assert_eq!(input_name(&app, track), "In 1-2");
+    }
+}

crates/ui-egui/src/mix_window/sends.rs

@@ -388,8 +388,17 @@ fn send_route_menu(app: &mut SoundApp, ui: &Ui, field: &egui::Response, id: Trac
         },
     );
     let Some((picked, footer)) = shown else { return };
-    if let Some(bus) = picked {
-        let _ = app.run("mix.send", json!({"track": id.0, "slot": slot, "bus": bus}));
+    // As in Pro Tools, a new send opens its Send window (moving it from any other send), so its
+    // fader is on screen right away. A send that only changes destination leaves the window alone.
+    let show_new_send = |app: &mut SoundApp| {
+        if !has_send {
+            app.ui.send_window = Some((id, slot));
+        }
+    };
+    if let Some(bus) = picked
+        && app.run("mix.send", json!({"track": id.0, "slot": slot, "bus": bus})).is_ok()
+    {
+        show_new_send(app);
     }
     match footer {
         Some(SendFooter::NewBus) => {
@@ -399,8 +408,10 @@ fn send_route_menu(app: &mut SoundApp, ui: &Ui, field: &egui::Response, id: Trac
             {
                 n += 1;
             }
-            if app.run("mix.new_bus", json!({"name": format!("Bus {n}")})).is_ok() {
-                let _ = app.run("mix.send", json!({"track": id.0, "slot": slot, "bus": format!("Bus {n}")}));
+            if app.run("mix.new_bus", json!({"name": format!("Bus {n}")})).is_ok()
+                && app.run("mix.send", json!({"track": id.0, "slot": slot, "bus": format!("Bus {n}")})).is_ok()
+            {
+                show_new_send(app);
             }
         }
         Some(SendFooter::RemoveSend) => {
@@ -464,4 +475,79 @@ mod tests {
         assert_eq!(field(&h), search, "the search field stays put");
         assert!((footer(&h).top() - full.top()).abs() < 1.0, "cleared, the footer is back under the full list: {:?} vs {full:?}", footer(&h));
     }
+
+    /// Kick's send A slot in a test harness, with buses "Aux" and "Other"; with `existing_send`, the
+    /// slot already sends to "Other".
+    fn kick_send_harness(existing_send: bool) -> (Harness<'static, (SoundApp, TrackId)>, TrackId) {
+        let mut app = SoundApp::new(soundcraft_engine::demo::demo_engine(), None, Services::default());
+        app.run("mix.new_bus", json!({"name": "Aux"})).unwrap();
+        app.run("mix.new_bus", json!({"name": "Other"})).unwrap();
+        let kick = app.engine.session().track_by_name("Kick").unwrap().id;
+        if existing_send {
+            app.run("mix.send", json!({"track": kick.0, "slot": 0, "bus": "Other"})).unwrap();
+        }
+        let mut ready = false;
+        let h = Harness::builder().with_size(vec2(600.0, 800.0)).build_ui_state(
+            move |ui, (app, kick): &mut (SoundApp, TrackId)| {
+                if !ready {
+                    crate::fonts::install(ui.ctx(), true);
+                    crate::theme::apply(ui.ctx(), false);
+                    ready = true;
+                    return;
+                }
+                let track = app.engine.session().track(*kick).cloned().unwrap();
+                let r = Rect::from_min_size(ui.max_rect().min + vec2(20.0, 20.0), vec2(120.0, 24.0));
+                send_slot(app, ui, &track, 0, r);
+            },
+            (app, kick),
+        );
+        (h, kick)
+    }
+
+    /// Creating a send opens its Send window, so the new send's fader is on screen right away (#1269).
+    #[test]
+    fn creating_a_send_opens_its_send_window() {
+        let _palette = crate::theme::lock_test_palette();
+        let (mut h, kick) = kick_send_harness(false);
+        h.run();
+        h.get_by_label("Send A for Kick").click();
+        h.run();
+        h.get_by_label("Aux").click();
+        h.run();
+        let (app, _) = h.state();
+        let send = app.engine.session().track(kick).and_then(|t| t.mixer.sends.first().cloned().flatten());
+        assert!(send.is_some(), "the send was created");
+        assert_eq!(app.ui.send_window, Some((kick, 0)), "the new send's window is open");
+    }
+
+    /// So does a send made with "new bus...".
+    #[test]
+    fn a_send_to_a_new_bus_opens_its_send_window() {
+        let _palette = crate::theme::lock_test_palette();
+        let (mut h, kick) = kick_send_harness(false);
+        h.run();
+        h.get_by_label("Send A for Kick").click();
+        h.run();
+        h.get_by_label("new bus...").click();
+        h.run();
+        let (app, _) = h.state();
+        assert!(app.engine.session().track(kick).and_then(|t| t.mixer.sends.first().cloned().flatten()).is_some(), "the send was created");
+        assert_eq!(app.ui.send_window, Some((kick, 0)), "the new send's window is open");
+    }
+
+    /// Moving an existing send to another bus keeps the Send window as it was.
+    #[test]
+    fn changing_a_sends_destination_leaves_the_send_window_alone() {
+        let _palette = crate::theme::lock_test_palette();
+        let (mut h, kick) = kick_send_harness(true);
+        h.run();
+        h.get_by_label("Send A for Kick").click();
+        h.run();
+        h.get_by_label("Aux").click();
+        h.run();
+        let (app, _) = h.state();
+        let target = app.engine.session().track(kick).and_then(|t| t.mixer.sends.first().cloned().flatten()).map(|s| route_name(app, &s.target));
+        assert_eq!(target.as_deref(), Some("Aux"), "the send moved");
+        assert_eq!(app.ui.send_window, None, "no window opened");
+    }
 }

crates/ui-egui/src/panels/about.rs

@@ -7,7 +7,7 @@ pub(super) fn about(app: &mut SoundApp, ctx: &egui::Context) {
         return;
     }
     let tab_id = egui::Id::unique("about_tab");
-    egui::Window::new("About SoundCraft").open(&mut open).default_size(vec2(640.0, 420.0)).collapsible(false).show(ctx, |ui| {
+    egui::Window::new("About SoundCraft").open(&mut open).default_size(vec2(820.0, 420.0)).collapsible(false).show(ctx, |ui| {
         let mut tab = ui.data_mut(|d| d.get_temp::<u8>(tab_id)).unwrap_or(0);
         ui.horizontal(|ui| {
             for (i, l) in (0u8..).zip(["About", "Contributors", "Models"]) {

crates/ui-egui/src/panels/tracks.rs

@@ -46,9 +46,28 @@ pub fn tracks_and_groups(app: &mut SoundApp, ui: &mut Ui) {
     if crate::widgets::icon_button(&mut ui.new_child(egui::UiBuilder::new().max_rect(plus)), plus.size(), "plus", false, &tip).clicked() {
         let _ = app.dialogs.open_for_command(&app.engine, "track.new");
     }
-    let tracks: Vec<(u64, String, bool, [u8; 3], bool)> = {
+    let tracks: Vec<(u64, String, bool, [u8; 3], bool, usize)> = {
         let s = app.engine.session();
-        s.tracks.iter().map(|x| (x.id.0, x.name.clone(), !x.hidden, x.color, s.edit.selected_tracks.contains(&x.id))).collect()
+        s.tracks
+            .iter()
+            .map(|x| {
+                let mut current = x.folder;
+                let mut depth = 0;
+                let mut seen = Vec::new();
+                while let Some(folder_id) = current {
+                    if seen.contains(&folder_id) {
+                        break;
+                    }
+                    seen.push(folder_id);
+                    let Some(folder) = s.track(folder_id) else {
+                        break;
+                    };
+                    depth += 1;
+                    current = folder.folder;
+                }
+                (x.id.0, x.name.clone(), !x.hidden, x.color, s.edit.selected_tracks.contains(&x.id), depth)
+            })
+            .collect()
     };
     let hidden = egui::scroll_area::ScrollBarVisibility::AlwaysHidden;
     let lists = with_pending_offset(egui::ScrollArea::vertical().id_salt("tracks_scroll"), ui, "tracks_scroll")
@@ -56,7 +75,7 @@ pub fn tracks_and_groups(app: &mut SoundApp, ui: &mut Ui) {
         .auto_shrink([false, false])
         .scroll_bar_visibility(hidden);
     let out = lists.show(ui, |ui| {
-        for (id, name, shown, color, sel) in tracks {
+        for (id, name, shown, color, sel, depth) in tracks {
             let (r, resp) = ui.allocate_exact_size(vec2(ui.available_width(), 17.0), Sense::click_and_drag());
             resp.widget_info(|| egui::WidgetInfo::selected(egui::Role::Button, true, sel, &name));
             if sel {
@@ -70,7 +89,8 @@ pub fn tracks_and_groups(app: &mut SoundApp, ui: &mut Ui) {
             }
             ui.painter().rect_filled(Rect::from_min_size(pos2(r.min.x + 20.0, r.min.y + 3.0), vec2(4.0, 11.0)), 0.0, rgb(color));
             ui.painter().with_clip_rect(r).text(
-                pos2(r.min.x + 30.0, r.center().y),
+                // Indent stops growing at eight levels so a deep name keeps room in the column.
+                pos2(r.min.x + 30.0 + depth.min(8) as f32 * 10.0, r.center().y),
                 Align2::LEFT_CENTER,
                 &name,
                 regular(11.5),

crates/ui-egui/src/toolbar.rs

@@ -3,11 +3,11 @@
 use crate::theme::{Tokens, bold, mono, regular};
 use crate::widgets::{icon_button, key, key_fill};
 use crate::{SoundApp, icons};
-use egui::{Align2, Color32, CornerRadius, Rect, Sense, Stroke, StrokeKind, Ui, pos2, vec2};
+use egui::{Align2, Color32, CornerRadius, Painter, Rect, Sense, Stroke, StrokeKind, Ui, pos2, vec2};
 use serde_json::json;
 use soundcraft_engine::edit::{SHUFFLE_LOCK, SNAP_TO_GRID};
-use soundcraft_model::{EditMode, Tool};
-use soundcraft_time::{TimeFormat, format_length};
+use soundcraft_model::{EditMode, EditState, Session, Tool};
+use soundcraft_time::{FeetFramesValue, GridScale, GridValue, NoteValue, TimeFormat, TimecodeValue, format_length};
 
 pub const HEIGHT: f32 = 78.0;
 
@@ -205,14 +205,7 @@ fn tools(app: &mut SoundApp, ui: &mut Ui) {
             ui.horizontal(|ui| {
                 ui.spacing_mut().item_spacing.x = 2.0;
                 let e = app.engine.session().edit.clone();
-                let toggles: [(&str, &str, bool, &str); 5] = [
-                    ("options.tab_to_transient", "tab_transient", e.tab_to_transient, "Tab to Transient"),
-                    ("options.link_timeline_edit", "link", e.link_timeline_edit, "Link Timeline and Edit Selection"),
-                    ("options.link_track_edit", "link", e.link_track_edit, "Link Track and Edit Selection"),
-                    ("options.mirrored_midi", "note", e.mirrored_midi, "Mirrored MIDI Editing"),
-                    ("options.automation_follows_edit", "wave", e.automation_follows_edit, "Automation Follows Edit"),
-                ];
-                for (id, icon, on, tip) in toggles {
+                for (id, icon, on, tip) in option_toggles(&e) {
                     if icon_button(ui, vec2(36.0, 18.0), icon, on, tip).clicked() {
                         let _ = app.run(id, json!({}));
                     }
@@ -227,6 +220,18 @@ fn tools(app: &mut SoundApp, ui: &mut Ui) {
     });
 }
 
+/// The Edit-window toolbar's option toggles: (command id, icon, on, tooltip).
+fn option_toggles(e: &EditState) -> [(&'static str, &'static str, bool, &'static str); 6] {
+    [
+        ("options.tab_to_transient", "tab_transient", e.tab_to_transient, "Tab to Transient"),
+        ("options.link_timeline_edit", "link", e.link_timeline_edit, "Link Timeline and Edit Selection"),
+        ("options.link_track_edit", "link_track", e.link_track_edit, "Link Track and Edit Selection"),
+        ("options.insertion_follows_playback", "insertion_follows", e.insertion_follows_playback, "Insertion Follows Playback"),
+        ("options.mirrored_midi", "note", e.mirrored_midi, "Mirrored MIDI Editing"),
+        ("options.automation_follows_edit", "wave", e.automation_follows_edit, "Automation Follows Edit"),
+    ]
+}
+
 fn fmt_pos(app: &SoundApp, at: i64, f: TimeFormat) -> String {
     let s = app.engine.session();
     s.format_position(at, f)
@@ -276,12 +281,12 @@ fn counters(app: &mut SoundApp, ui: &mut Ui) {
     ui.painter().text(pos2(r.max.x - 8.0, y), Align2::RIGHT_CENTER, format!("{st} · {dev}"), regular(10.0), t.text_dim);
 }
 
-/// Grid-line toggle, grid value menu and nudge value menu.
+/// Draws the compact Grid and Nudge readouts and their scale menus.
 fn grid_nudge(app: &mut SoundApp, ui: &mut Ui) {
     let t = Tokens::current();
-    let (grid, nudge, lines) = {
+    let (grid, nudge, lines, grid_follow, nudge_follow, clips_markers) = {
         let e = &app.engine.session().edit;
-        (e.grid, e.nudge, e.grid_lines)
+        (e.grid, e.nudge, e.grid_lines, e.grid_follow_main, e.nudge_follow_main, e.grid_clips_markers)
     };
     let (r, _) = ui.allocate_exact_size(vec2(170.0, 64.0), Sense::hover());
     ui.painter().rect(r, CornerRadius::same(4), t.counter_bg, Stroke::new(1.0, t.counter_border), StrokeKind::Inside);
@@ -293,39 +298,243 @@ fn grid_nudge(app: &mut SoundApp, ui: &mut Ui) {
         let _ = app.run("view.grid_lines", json!({}));
     }
     let gr = Rect::from_min_max(pos2(r.min.x + 60.0, r.min.y + 6.0), pos2(r.max.x - 4.0, r.min.y + 26.0));
-    ui.painter().text(pos2(gr.max.x - 14.0, gr.center().y), Align2::RIGHT_CENTER, grid.label(), mono(11.0), t.counter_text);
+    let grid_label = if clips_markers { GridScale::ClipsMarkers.label().to_string() } else { compact_grid_label(app.engine.session(), grid) };
+    if !clips_markers {
+        draw_compact_note_icon(ui.painter(), gr, grid, t.counter_text);
+    }
+    ui.painter().text(pos2(gr.max.x - 14.0, gr.center().y), Align2::RIGHT_CENTER, grid_label, mono(11.0), t.counter_text);
     let gresp = ui.interact(gr, ui.scope_id().with("grid_value"), Sense::click());
-    value_menu(app, &gresp, "view.grid");
+    value_menu(app, &gresp, "view.grid", grid, grid_follow, clips_markers, true);
     ui.painter().text(pos2(r.min.x + 10.0, r.min.y + 44.0), Align2::LEFT_CENTER, "Nudge", regular(11.0), t.counter_label);
     let nr = Rect::from_min_max(pos2(r.min.x + 60.0, r.min.y + 34.0), pos2(r.max.x - 4.0, r.min.y + 54.0));
-    ui.painter().text(pos2(nr.max.x - 14.0, nr.center().y), Align2::RIGHT_CENTER, nudge.label(), mono(11.0), t.counter_text);
+    draw_compact_note_icon(ui.painter(), nr, nudge, t.counter_text);
+    ui.painter().text(
+        pos2(nr.max.x - 14.0, nr.center().y),
+        Align2::RIGHT_CENTER,
+        compact_grid_label(app.engine.session(), nudge),
+        mono(11.0),
+        t.counter_text,
+    );
     let nresp = ui.interact(nr, ui.scope_id().with("nudge_value"), Sense::click());
-    value_menu(app, &nresp, "view.nudge");
+    value_menu(app, &nresp, "view.nudge", nudge, nudge_follow, false, false);
     for rr in [gr, nr] {
         icons::draw(ui.painter(), Rect::from_center_size(pos2(rr.max.x - 6.0, rr.center().y), vec2(10.0, 10.0)), "triangle_down", t.text_dim);
     }
 }
 
-fn value_menu(app: &mut SoundApp, resp: &egui::Response, cmd: &str) {
-    egui::Popup::menu(resp).show(|ui| {
-        for v in ["1 bar", "1/2", "1/4", "1/8", "1/16", "1/32", "1/64", "1/8t", "1/16t", "1/4."] {
-            if ui.button(v).clicked() {
-                let _ = app.run(cmd, json!({"value": v}));
+/// Formats a Grid/Nudge increment in the compact counter style for its time scale.
+fn compact_grid_label(session: &Session, value: GridValue) -> String {
+    match value {
+        GridValue::Note { value, dotted, triplet } => {
+            let at_tick = session.tempo.samples_to_ticks(session.edit.selection.start, session.sample_rate);
+            let meter = session.tempo.meter_at_tick(at_tick);
+            let mut ticks = if value == NoteValue::Bar { meter.ticks_per_bar() } else { value.ticks() };
+            if dotted {
+                ticks = ticks * 3 / 2;
             }
+            if triplet {
+                ticks = ticks * 2 / 3;
+            }
+            let per_bar = meter.ticks_per_bar().max(1);
+            let per_beat = meter.ticks_per_beat().max(1);
+            let bars = ticks / per_bar;
+            let remaining = ticks % per_bar;
+            format!("{bars}|{}|{:03}", remaining / per_beat, remaining % per_beat)
+        }
+        GridValue::Seconds(seconds) => {
+            let samples = session.sample_rate.samples(seconds);
+            format_length(session.edit.selection.start, samples, TimeFormat::MinSecs, session.sample_rate, &session.tempo, session.frame_rate)
+        }
+        GridValue::Frames(frames) => {
+            let samples = session.frame_rate.samples_at_frame(frames, session.sample_rate);
+            format!(
+                "{}.00",
+                format_length(session.edit.selection.start, samples, TimeFormat::Timecode, session.sample_rate, &session.tempo, session.frame_rate)
+            )
+        }
+        GridValue::Timecode(value) => match value {
+            TimecodeValue::Second => "00:00:01:00.00",
+            TimecodeValue::FiveFrames => "00:00:00:05.00",
+            TimecodeValue::Frame => "00:00:00:01.00",
+            TimecodeValue::HalfFrame => "00:00:00:00.50",
+            TimecodeValue::QuarterFrame => "00:00:00:00.25",
+            TimecodeValue::SubFrame => "00:00:00:00.01",
+        }
+        .to_string(),
+        GridValue::FeetFrames(value) => match value {
+            FeetFramesValue::Foot => "1+00",
+            FeetFramesValue::Frame => "0+01",
+            FeetFramesValue::QuarterFrame => "0+00.25",
+            FeetFramesValue::SubFrame => "0+00.01",
+        }
+        .to_string(),
+        GridValue::Samples(samples) => samples.to_string(),
+    }
+}
+
+/// Draws the musical symbol beside a compact Bars|Beats value.
+fn draw_compact_note_icon(painter: &Painter, rect: Rect, value: GridValue, color: Color32) {
+    let GridValue::Note { value, dotted, triplet } = value else { return };
+    draw_note_value_icon(painter, Rect::from_min_size(pos2(rect.min.x + 1.0, rect.min.y + 2.0), vec2(14.0, 16.0)), value, dotted, triplet, color);
+}
+
+/// Draws a musical duration and its optional dotted or triplet modifier.
+fn draw_note_value_icon(painter: &Painter, rect: Rect, value: NoteValue, dotted: bool, triplet: bool, color: Color32) {
+    let stroke = Stroke::new(1.2, color);
+    let head = pos2(rect.min.x + 4.0, rect.max.y - 3.5);
+    if value == NoteValue::Bar {
+        painter.line_segment([pos2(rect.min.x + 2.0, rect.min.y + 2.0), pos2(rect.min.x + 2.0, rect.max.y - 2.0)], stroke);
+        painter.line_segment([pos2(rect.min.x + 5.0, rect.min.y + 2.0), pos2(rect.min.x + 5.0, rect.max.y - 2.0)], stroke);
+        painter.line_segment([pos2(rect.min.x + 2.0, rect.min.y + 3.0), pos2(rect.min.x + 10.0, rect.min.y + 3.0)], stroke);
+    } else {
+        let hollow = matches!(value, NoteValue::Whole | NoteValue::Half);
+        if hollow {
+            painter.circle_stroke(head, 2.2, stroke);
+        } else {
+            painter.circle_filled(head, 2.2, color);
+        }
+        if value != NoteValue::Whole {
+            let stem_x = head.x + 2.0;
+            painter.line_segment([pos2(stem_x, head.y), pos2(stem_x, rect.min.y + 2.0)], stroke);
+            let flags = match value {
+                NoteValue::Eighth => 1,
+                NoteValue::Sixteenth => 2,
+                NoteValue::ThirtySecond => 3,
+                NoteValue::SixtyFourth => 4,
+                _ => 0,
+            };
+            for flag in 0..flags {
+                let y = rect.min.y + 2.0 + flag as f32 * 2.0;
+                painter.line_segment([pos2(stem_x, y), pos2(stem_x + 4.0, y + 2.5)], stroke);
+            }
+        }
+    }
+    if dotted {
+        painter.circle_filled(pos2(rect.max.x - 1.5, head.y), 1.0, color);
+    }
+    if triplet {
+        painter.text(pos2(rect.min.x, rect.min.y), Align2::LEFT_TOP, "3", regular(7.0), color);
+    }
+}
+
+/// Shows the complete Grid or Nudge increment, scale, and follow-mode menu.
+fn value_menu(app: &mut SoundApp, resp: &egui::Response, cmd: &str, current: GridValue, follow_main: bool, clips_markers: bool, allow_clips: bool) {
+    egui::Popup::menu(resp).show(|ui| {
+        ui.set_min_width(210.0);
+        match current.scale() {
+            GridScale::BarsBeats => {
+                let selected = match current {
+                    GridValue::Note { value, .. } => value,
+                    _ => NoteValue::Sixteenth,
+                };
+                let suffix = match current {
+                    GridValue::Note { dotted: true, .. } => ".",
+                    GridValue::Note { triplet: true, .. } => "t",
+                    _ => "",
+                };
+                for value in NoteValue::ALL {
+                    let id = match value {
+                        NoteValue::Bar => "1 bar",
+                        NoteValue::Whole => "whole",
+                        NoteValue::Half => "1/2",
+                        NoteValue::Quarter => "1/4",
+                        NoteValue::Eighth => "1/8",
+                        NoteValue::Sixteenth => "1/16",
+                        NoteValue::ThirtySecond => "1/32",
+                        NoteValue::SixtyFourth => "1/64",
+                    };
+                    menu_note_value(ui, app, cmd, selected == value, value, json!(format!("{id}{suffix}")));
+                }
+                ui.separator();
+                let (value, dotted, triplet) = match current {
+                    GridValue::Note { value, dotted, triplet } => (value, dotted, triplet),
+                    _ => (NoteValue::Sixteenth, false, false),
+                };
+                let base = match value {
+                    NoteValue::Bar => "1 bar",
+                    NoteValue::Whole => "whole",
+                    NoteValue::Half => "1/2",
+                    NoteValue::Quarter => "1/4",
+                    NoteValue::Eighth => "1/8",
+                    NoteValue::Sixteenth => "1/16",
+                    NoteValue::ThirtySecond => "1/32",
+                    NoteValue::SixtyFourth => "1/64",
+                };
+                menu_modifier(ui, app, cmd, dotted, "Dotted", "·", json!(if dotted { base.to_string() } else { format!("{base}.") }));
+                menu_modifier(ui, app, cmd, triplet, "Triplet", "3", json!(if triplet { base.to_string() } else { format!("{base}t") }));
+            }
+            GridScale::MinSecs => {
+                for seconds in [1.0, 0.5, 0.1, 0.01, 0.001] {
+                    let value = GridValue::Seconds(seconds);
+                    menu_value(ui, app, cmd, current == value, &value.label(), json!({"seconds": seconds}));
+                }
+            }
+            GridScale::Timecode => {
+                for value in TimecodeValue::ALL {
+                    let selected = current == GridValue::Timecode(value)
+                        || matches!(
+                            (current, value),
+                            (GridValue::Frames(5), TimecodeValue::FiveFrames) | (GridValue::Frames(1), TimecodeValue::Frame)
+                        );
+                    menu_value(ui, app, cmd, selected, value.label(), json!({"timecode": value.id()}));
+                }
+            }
+            GridScale::FeetFrames => {
+                for value in FeetFramesValue::ALL {
+                    menu_value(ui, app, cmd, current == GridValue::FeetFrames(value), value.label(), json!({"feet_frames": value.id()}));
+                }
+            }
+            GridScale::Samples => {
+                for samples in [10_000, 1_000, 100, 10, 2, 1] {
+                    let value = GridValue::Samples(samples);
+                    menu_value(ui, app, cmd, current == value, &value.label(), json!({"samples": samples}));
+                }
+            }
+            GridScale::ClipsMarkers => {}
         }
         ui.separator();
-        for (label, v) in [
-            ("1 msec", json!({"seconds": 0.001})),
-            ("10 msec", json!({"seconds": 0.01})),
-            ("100 msec", json!({"seconds": 0.1})),
-            ("1 second", json!({"seconds": 1.0})),
-            ("1 frame", json!({"frames": 1})),
-            ("100 samples", json!({"samples": 100})),
-        ] {
-            if ui.button(label).clicked() {
-                let _ = app.run(cmd, json!({"value": v}));
+        for scale in GridScale::TIME {
+            let selected = !clips_markers && current.scale() == scale;
+            if ui.selectable_label(selected, scale.label()).clicked() {
+                let _ = app.run(cmd, json!({"format": scale.id(), "follow_main": false}));
+                ui.close();
             }
         }
+        if allow_clips && ui.selectable_label(clips_markers, GridScale::ClipsMarkers.label()).clicked() {
+            let _ = app.run(cmd, json!({"format": GridScale::ClipsMarkers.id(), "follow_main": false}));
+            ui.close();
+        }
+        ui.separator();
+        if ui.selectable_label(follow_main, "Follow Main Time Scale").clicked() {
+            let _ = app.run(cmd, json!({"follow_main": !follow_main}));
+            ui.close();
+        }
+    });
+}
+
+/// Adds one text menu value and dispatches its command when selected.
+fn menu_value(ui: &mut Ui, app: &mut SoundApp, cmd: &str, selected: bool, label: &str, value: serde_json::Value) {
+    if ui.selectable_label(selected, label).clicked() {
+        let _ = app.run(cmd, json!({"value": value}));
+        ui.close();
+    }
+}
+
+/// Adds one musical value with its duration symbol.
+fn menu_note_value(ui: &mut Ui, app: &mut SoundApp, cmd: &str, selected: bool, note: NoteValue, value: serde_json::Value) {
+    ui.horizontal(|ui| {
+        let (rect, _) = ui.allocate_exact_size(vec2(18.0, 18.0), Sense::hover());
+        draw_note_value_icon(ui.painter(), rect, note, false, false, ui.visuals().text_color());
+        menu_value(ui, app, cmd, selected, note.label(), value);
+    });
+}
+
+/// Adds a dotted or triplet modifier with its compact symbol.
+fn menu_modifier(ui: &mut Ui, app: &mut SoundApp, cmd: &str, selected: bool, label: &str, symbol: &str, value: serde_json::Value) {
+    ui.horizontal(|ui| {
+        let (rect, _) = ui.allocate_exact_size(vec2(18.0, 18.0), Sense::hover());
+        ui.painter().text(rect.center(), Align2::CENTER_CENTER, symbol, regular(11.0), ui.visuals().text_color());
+        menu_value(ui, app, cmd, selected, label, value);
     });
 }
 
@@ -385,8 +594,7 @@ fn transport(app: &mut SoundApp, ui: &mut Ui) {
     });
 }
 
-/// Count-off, meter and tempo readouts; the tempo value is editable in place for the tempo event at or before the
-/// playhead.
+/// Count-off, meter and tempo readouts; the tempo value edits the event at or before the playhead.
 fn tempo_meter(app: &mut SoundApp, ui: &mut Ui) {
     let t = Tokens::current();
     let (bpm, meter, countoff, click, bars) = {
@@ -448,6 +656,7 @@ fn tempo_value(app: &mut SoundApp, ui: &mut Ui, right: f32, y: f32, bpm: f64) {
     resp.on_hover_text("Drag to change the tempo (Shift: fine steps), or click to type it");
 }
 
+/// Draws the compact stereo main-output meter.
 fn output_meter(app: &mut SoundApp, ui: &mut Ui) {
     let (r, _) = ui.allocate_exact_size(vec2(26.0, 64.0), Sense::hover());
     let m = app.main_meter;
@@ -457,3 +666,129 @@ fn output_meter(app: &mut SoundApp, ui: &mut Ui) {
         crate::widgets::meter(ui, rr, m.level[c], m.hold[c], m.clip);
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::Services;
+    use egui_kittest::{Harness, kittest::Queryable};
+
+    /// Builds a compact Grid/Nudge toolbar test harness.
+    fn harness() -> Harness<'static, SoundApp> {
+        let app = SoundApp::new(soundcraft_engine::Engine::default(), None, Services::default());
+        let mut harness = Harness::builder().with_size(vec2(700.0, 700.0)).build_ui_state(
+            |ui, app: &mut SoundApp| {
+                let edit = &app.engine.session().edit;
+                let (grid, grid_follow, clips, nudge, nudge_follow) =
+                    (edit.grid, edit.grid_follow_main, edit.grid_clips_markers, edit.nudge, edit.nudge_follow_main);
+                let grid_anchor = ui.button("Grid menu");
+                value_menu(app, &grid_anchor, "view.grid", grid, grid_follow, clips, true);
+                let nudge_anchor = ui.button("Nudge menu");
+                value_menu(app, &nudge_anchor, "view.nudge", nudge, nudge_follow, false, false);
+            },
+            app,
+        );
+        harness.run_steps(3);
+        harness
+    }
+
+    /// Opens a toolbar value menu and lets the popup settle.
+    fn open(harness: &mut Harness<SoundApp>, label: &str) {
+        harness.get_by_label(label).click();
+        harness.run_steps(3);
+    }
+
+    /// Compact values use their corresponding counter formats and symbols.
+    #[test]
+    fn compact_grid_values_use_their_counter_formats() {
+        let session = Session::default();
+        let note = |value, dotted, triplet| GridValue::Note { value, dotted, triplet };
+        assert_eq!(compact_grid_label(&session, note(NoteValue::Quarter, false, false)), "0|1|000");
+        assert_eq!(compact_grid_label(&session, note(NoteValue::Eighth, false, true)), "0|0|320");
+        assert_eq!(compact_grid_label(&session, GridValue::Seconds(0.001)), "0:00.001");
+        assert_eq!(compact_grid_label(&session, GridValue::Timecode(TimecodeValue::Second)), "00:00:01:00.00");
+        assert_eq!(compact_grid_label(&session, GridValue::Timecode(TimecodeValue::QuarterFrame)), "00:00:00:00.25");
+        assert_eq!(compact_grid_label(&session, GridValue::FeetFrames(FeetFramesValue::Foot)), "1+00");
+        assert_eq!(compact_grid_label(&session, GridValue::Samples(10_000)), "10000");
+    }
+
+    /// The Grid menu exposes every scale and retains its numeric value in Clips/Markers mode.
+    #[test]
+    fn grid_menu_exposes_each_scale_and_keeps_the_increment_in_clips_markers_mode() {
+        let mut harness = harness();
+        open(&mut harness, "Grid menu");
+        for label in ["Bars|Beats", "Min:Secs", "Timecode", "Feet+Frames", "Samples", "Clips/Markers", "Follow Main Time Scale"] {
+            let _ = harness.get_by_label(label);
+        }
+        for label in ["1 bar", "Whole note", "1/2 note", "1/4 note", "1/8 note", "1/16 note", "1/32 note", "1/64 note", "Dotted", "Triplet"] {
+            let _ = harness.get_by_label(label);
+        }
+
+        harness.get_by_label("Timecode").click();
+        harness.run_steps(3);
+        open(&mut harness, "Grid menu");
+        for label in ["1 second", "5 frames", "1 frame", "1/2 frame", "1/4 frame", "1 subframe"] {
+            let _ = harness.get_by_label(label);
+        }
+        harness.get_by_label("1/4 frame").click();
+        harness.run_steps(3);
+        open(&mut harness, "Grid menu");
+        harness.get_by_label("Clips/Markers").click();
+        harness.run_steps(3);
+        let edit = &harness.state().engine.session().edit;
+        assert_eq!(edit.grid, GridValue::Timecode(TimecodeValue::QuarterFrame));
+        assert!(edit.grid_clips_markers);
+        open(&mut harness, "Grid menu");
+        harness.get_by_label("1/2 frame").click();
+        harness.run_steps(3);
+        let edit = &harness.state().engine.session().edit;
+        assert_eq!(edit.grid, GridValue::Timecode(TimecodeValue::HalfFrame));
+        assert!(!edit.grid_clips_markers);
+    }
+
+    /// Selecting another musical increment preserves the active dotted or triplet modifier.
+    #[test]
+    fn note_menu_keeps_the_current_modifier_when_changing_value() {
+        let mut harness = harness();
+        harness.state_mut().run("view.grid", json!({"value": "1/8t"})).unwrap();
+        harness.run_steps(3);
+        open(&mut harness, "Grid menu");
+        harness.get_by_label("1/16 note").click();
+        harness.run_steps(3);
+        assert_eq!(harness.state().engine.session().edit.grid, GridValue::Note { value: NoteValue::Sixteenth, dotted: false, triplet: true });
+        open(&mut harness, "Grid menu");
+        harness.get_by_label("Whole note").click();
+        harness.run_steps(3);
+        assert_eq!(harness.state().engine.session().edit.grid, GridValue::Note { value: NoteValue::Whole, dotted: false, triplet: true });
+    }
+
+    /// The Nudge menu exposes every numeric scale without the Grid-only Clips/Markers mode.
+    #[test]
+    fn nudge_menu_has_every_numeric_scale_but_no_clips_markers_mode() {
+        let mut harness = harness();
+        open(&mut harness, "Nudge menu");
+        for label in ["Bars|Beats", "Min:Secs", "Timecode", "Feet+Frames", "Samples", "Follow Main Time Scale"] {
+            let _ = harness.get_by_label(label);
+        }
+        assert_eq!(harness.query_all_by_label("Clips/Markers").count(), 0);
+        harness.get_by_label("Samples").click();
+        harness.run_steps(3);
+        open(&mut harness, "Nudge menu");
+        for label in ["10000 samples", "1000 samples", "100 samples", "10 samples", "2 samples", "1 sample"] {
+            let _ = harness.get_by_label(label);
+        }
+    }
+
+    /// #1262: the two link toggles differ only by their icon, so each option toggle needs its own.
+    #[test]
+    fn option_toggles_have_distinct_icons() {
+        let toggles = option_toggles(&EditState::default());
+        let timeline = toggles.iter().find(|t| t.0 == "options.link_timeline_edit").unwrap();
+        let track = toggles.iter().find(|t| t.0 == "options.link_track_edit").unwrap();
+        assert_ne!(timeline.1, track.1, "the timeline and track links need different icons");
+        let mut icons: Vec<&str> = toggles.iter().map(|t| t.1).collect();
+        icons.sort_unstable();
+        icons.dedup();
+        assert_eq!(icons.len(), toggles.len(), "every option toggle needs its own icon");
+    }
+}

crates/ui-egui/tests/grid_lines.rs

@@ -1,5 +1,6 @@
 use egui::{Color32, FullOutput, Pos2, RawInput, Rect, Shape, pos2, vec2};
 use serde_json::json;
+use soundcraft_model::{ChannelFormat, Clip, TrackId, TrackKind};
 use soundcraft_ui_egui::theme::Tokens;
 use soundcraft_ui_egui::{Services, SoundApp, edit_window};
 
@@ -22,6 +23,7 @@ fn near(a: [i32; 3], b: Color32) -> bool {
     a.iter().zip([b.r(), b.g(), b.b()]).all(|(x, y)| (x - i32::from(y)).abs() <= 6)
 }
 
+/// Numeric Grid lines retain their stacking order over clips in both themes.
 #[test]
 fn grid_lines_are_drawn_over_clips_while_shown() {
     let mut app = SoundApp::new(soundcraft_engine::demo::demo_engine(), None, Services::default());
@@ -68,3 +70,94 @@ fn grid_lines_are_drawn_over_clips_while_shown() {
         }
     }
 }
+
+/// Clips/Markers grid lines reach the timeline at memory-location boundaries.
+#[test]
+fn clips_markers_grid_draws_a_line_at_a_memory_location() {
+    let mut app = SoundApp::new(soundcraft_engine::demo::demo_engine(), None, Services::default());
+    let ctx = egui::Context::default();
+    let kick = app.engine.session().track_by_name("Kick").unwrap();
+    let clip = &kick.clips()[0];
+    let marker = clip.start + clip.length / 3;
+    app.run("markers.add", json!({"at": marker, "name": "Grid target"})).unwrap();
+    app.run("view.grid", json!({"format": "clips_markers", "lines": true})).unwrap();
+
+    frame(&ctx, &mut app);
+    let out = frame(&ctx, &mut app);
+    let session = app.engine.session();
+    let kick = session.track_by_name("Kick").unwrap();
+    let [x0, y0, x1, y1] = app.edit_layout.timeline;
+    let timeline = Rect::from_min_max(pos2(x0, y0), pos2(x1, y1));
+    let row = app.edit_layout.rows.iter().find(|(id, _)| *id == kick.id.0).unwrap().1;
+    let lane = Rect::from_min_max(pos2(timeline.min.x, row[1]), pos2(timeline.max.x, row[1] + kick.height.points()));
+    let expected_x = edit_window::x_of(session, timeline, marker);
+
+    assert!(out.shapes.iter().any(|shape| {
+        matches!(
+            &shape.shape,
+            Shape::LineSegment { points: [a, b], .. }
+                if a.x == expected_x && b.x == expected_x && a.y == lane.min.y && b.y == lane.max.y
+        )
+    }));
+}
+
+/// Whether a vertical grid line spans the main lane of a visible track at the requested sample.
+fn line_on_track(out: &FullOutput, app: &SoundApp, track: TrackId, at: i64) -> bool {
+    let s = app.engine.session();
+    let [x0, y0, x1, y1] = app.edit_layout.timeline;
+    let timeline = Rect::from_min_max(pos2(x0, y0), pos2(x1, y1));
+    let row = app.edit_layout.rows.iter().find(|(id, _)| *id == track.0).unwrap().1;
+    let bottom = row[1] + s.track(track).unwrap().height.points();
+    let x = edit_window::x_of(s, timeline, at);
+    out.shapes.iter().any(|shape| {
+        matches!(&shape.shape, Shape::LineSegment { points: [a, b], .. }
+            if a.x == x && b.x == x && a.y == row[1] && b.y == bottom)
+    })
+}
+
+/// Shared frame lines reflect visible children, edited boundaries, scrolling and zoom on every lane.
+#[test]
+fn clips_markers_lines_refresh_across_lanes_and_hidden_open_folders() {
+    let mut engine = soundcraft_engine::Engine::default();
+    let s = engine.session_mut();
+    let folder = s.add_track(TrackKind::Folder, ChannelFormat::Stereo, None);
+    let child = s.add_track(TrackKind::Midi, ChannelFormat::Mono, None);
+    let other = s.add_track(TrackKind::Midi, ChannelFormat::Mono, None);
+    s.track_mut(folder).unwrap().hidden = true;
+    s.track_mut(child).unwrap().folder = Some(folder);
+    let clip = Clip::midi(s.new_clip_id(), "Visible", 1_200, 5_000, Default::default());
+    let clip_id = clip.id;
+    s.track_mut(child).unwrap().playlist_mut().unwrap().clips.push(clip);
+    s.add_marker("Boundary", soundcraft_model::MarkerKind::Marker, 9_000, 9_000);
+    s.edit.grid_clips_markers = true;
+    s.edit.grid_lines = true;
+    let mut app = SoundApp::new(engine, None, Services::default());
+    let ctx = egui::Context::default();
+
+    for (start, marker, scroll, zoom) in [(1_200, 9_000, 0, 20.0), (3_000, 11_000, 0, 20.0), (3_000, 11_000, 1_000, 40.0)] {
+        let s = app.engine.session_mut();
+        s.find_clip_mut(clip_id).unwrap().start = start;
+        s.markers[0].start = marker;
+        s.markers[0].end = marker;
+        s.edit.zoom.scroll = scroll;
+        s.edit.zoom.samples_per_px = zoom;
+        frame(&ctx, &mut app);
+        let out = frame(&ctx, &mut app);
+        assert!(!app.edit_layout.rows.iter().any(|(id, _)| *id == folder.0));
+        for track in [child, other] {
+            assert!(line_on_track(&out, &app, track, start));
+            assert!(line_on_track(&out, &app, track, marker));
+            if start != 1_200 {
+                assert!(!line_on_track(&out, &app, track, 1_200));
+                assert!(!line_on_track(&out, &app, track, 9_000));
+            }
+        }
+    }
+
+    app.engine.session_mut().track_mut(folder).unwrap().folder_open = false;
+    frame(&ctx, &mut app);
+    let out = frame(&ctx, &mut app);
+    assert!(!app.edit_layout.rows.iter().any(|(id, _)| *id == child.0));
+    assert!(!line_on_track(&out, &app, other, 3_000));
+    assert!(line_on_track(&out, &app, other, 11_000));
+}

crates/ui-egui/tests/it/send_window.rs

@@ -1,5 +1,6 @@
 //! A send's level opens its Send window, as in Pro Tools: a fader with Alt-click for 0 dB, moved to
-//! another send by clicking that send's level, closed by clicking the same one again.
+//! another send by clicking that send's level, closed by clicking the same one again. Creating a send
+//! opens it too.
 
 use egui::{Event, Modifiers, PointerButton, Pos2, vec2};
 use egui_kittest::Harness;
@@ -75,6 +76,33 @@ fn a_sends_level_opens_its_send_window() {
     assert!(h.query_by_label_contains("Vox · Send").is_none());
 }
 
+/// Creating a send opens its Send window, so the new send's fader is on screen right away (#1269). The
+/// window moves there from the send it was showing, and undoing the new send closes it.
+#[test]
+fn a_new_send_shows_its_fader_at_once() {
+    let (mut h, vox) = harness();
+    h.get_by_label("Send A level for Vox").click();
+    h.run_steps(3);
+    assert!(h.query_by_label_contains("Vox · Send A").is_some());
+
+    h.get_by_label("Send C for Vox").click();
+    h.run_steps(3);
+    // Send A's own "Verb" label is on screen too, so pick the menu's button.
+    h.get_by_role_and_label(egui::accesskit::Role::Button, "Verb").click();
+    h.run_steps(3);
+    assert!(h.state().engine.session().tracks[0].mixer.sends[2].is_some(), "send C was created");
+    assert_eq!(h.state().ui.send_window, Some((vox, 2)));
+    assert!(h.query_by_label_contains("Vox · Send C").is_some(), "the window shows the new send");
+    assert!(h.query_by_label_contains("Vox · Send A").is_none(), "and no longer send A");
+    assert!(h.query_by_label("Send level").is_some(), "the new send's fader is on screen");
+
+    h.state_mut().engine.execute("edit.undo", &json!({})).unwrap();
+    h.run_steps(3);
+    assert!(h.state().engine.session().tracks[0].mixer.sends[2].is_none(), "the send was undone");
+    assert_eq!(h.state().ui.send_window, None, "undoing the send closes its window");
+    assert!(h.query_by_label_contains("Vox · Send").is_none());
+}
+
 /// Escape first closes a send menu or cancels level typing, then a further Escape closes the send window.
 #[test]
 fn escape_closes_the_send_window_after_menus_and_typing() {

crates/ui-egui/tests/it/strip_silence_dialog.rs

@@ -3,6 +3,7 @@ use egui::{Event, Key, Modifiers, vec2};
 use egui_kittest::{Harness, kittest::Queryable};
 use serde_json::json;
 use soundcraft_model::TrackId;
+use soundcraft_ui_egui::dialogs::Dialog;
 use soundcraft_ui_egui::{Services, SoundApp, menus};
 
 /// Selects the whole Kick track and opens Edit > Strip Silence from the menu.
@@ -89,3 +90,58 @@ fn strip_silence_strip_removes_the_silence() {
     assert_eq!(strip, stripped(track));
     assert!(covered(&strip) < covered(&before));
 }
+
+/// Values other than the ones Strip Silence first opens with.
+const CHANGED: [f64; 4] = [-30.0, 120.0, 12.0, 40.0];
+
+/// Sets the open Strip Silence window's values, as dragging its sliders would.
+fn set_values(h: &mut Harness<'_, SoundApp>, values: [f64; 4]) {
+    let Some(Dialog::StripSilence { threshold, min_ms, pre_ms, post_ms }) = &mut h.state_mut().dialogs.open else {
+        panic!("Strip Silence is not open")
+    };
+    [*threshold, *min_ms, *pre_ms, *post_ms] = values;
+    h.run_steps(2);
+}
+
+/// Opens Edit > Strip Silence again from the menu and returns the values it shows.
+fn reopen(h: &mut Harness<'_, SoundApp>) -> [f64; 4] {
+    assert_eq!(h.state().dialogs.open_name(), None, "Strip Silence is closed before it opens again");
+    menus::invoke_menu(h.state_mut(), "edit.strip_silence", "Edit > Strip Silence");
+    h.run_steps(2);
+    let Some(Dialog::StripSilence { threshold, min_ms, pre_ms, post_ms }) = h.state().dialogs.open.clone() else {
+        panic!("Strip Silence did not open again")
+    };
+    [threshold, min_ms, pre_ms, post_ms]
+}
+
+#[test]
+fn strip_silence_opens_with_the_values_escape_closed_it_with() {
+    let (mut h, _, _) = strip_silence_dialog();
+    set_values(&mut h, CHANGED);
+    h.event(Event::Key { key: Key::Escape, physical_key: None, pressed: true, repeat: false, modifiers: Modifiers::NONE });
+    h.run_steps(2);
+    assert_eq!(reopen(&mut h), CHANGED);
+}
+
+#[test]
+fn strip_silence_opens_with_the_values_strip_used() {
+    let (mut h, _, _) = strip_silence_dialog();
+    set_values(&mut h, CHANGED);
+    h.get_by_role_and_label(Role::Button, "Strip").click();
+    h.run_steps(2);
+    assert_eq!(reopen(&mut h), CHANGED);
+}
+
+#[test]
+fn strip_silence_keeps_its_values_through_rename_and_cancel() {
+    let (mut h, _, _) = strip_silence_dialog();
+    set_values(&mut h, CHANGED);
+    h.get_by_role_and_label(Role::Button, "Rename…").click();
+    h.run_steps(3);
+    h.get_by_role_and_label(Role::Button, "Cancel").click();
+    h.run_steps(3);
+    assert_eq!(h.state().dialogs.open_name(), Some("strip_silence"), "Cancel in Rename goes back to Strip Silence");
+    h.get_by_role_and_label(Role::Button, "Cancel").click();
+    h.run_steps(2);
+    assert_eq!(reopen(&mut h), CHANGED);
+}

crates/ui-egui/tests/it/track_list.rs

@@ -50,6 +50,16 @@ impl Rig {
             .expect("row not in the Tracks list")
     }
 
+    fn text_x(&self, name: &str) -> f32 {
+        self.shapes
+            .iter()
+            .find_map(|c| match &c.shape {
+                Shape::Text(t) if t.galley.text() == name && t.pos.x < 150.0 => Some(t.pos.x),
+                _ => None,
+            })
+            .expect("text not in the Tracks list")
+    }
+
     fn press(&mut self, at: Pos2, pressed: bool) {
         self.frame(vec![
             Event::PointerMoved(at),
@@ -90,3 +100,35 @@ fn clicking_a_track_list_row_still_selects_the_track() {
     r.press(at, false);
     assert_eq!(r.app.engine.session().edit.selected_tracks, vec![r.order()[2]]);
 }
+
+#[test]
+fn a_track_inside_a_folder_is_indented_in_the_track_list() {
+    let mut r = Rig::new();
+    let child = r.order()[1];
+    let child_name = r.app.engine.session().track(child).unwrap().name.clone();
+    r.app.run("track.move_to_new_folder", json!({"tracks": [child.0], "name": "Folder"})).unwrap();
+    r.frame(vec![]);
+    let folder = r.app.engine.session().tracks.iter().find(|track| track.is_folder()).unwrap();
+
+    assert!(r.text_x(&child_name) > r.text_x(&folder.name), "child is not indented under the folder");
+}
+
+#[test]
+fn deeply_nested_tracks_keep_indenting_past_six_folders() {
+    let mut r = Rig::new();
+    let child = r.order()[1];
+    let child_name = r.app.engine.session().track(child).unwrap().name.clone();
+    r.app.run("track.move_to_new_folder", json!({"tracks": [child.0], "name": "Folder 1"})).unwrap();
+
+    let mut parent = r.app.engine.session().tracks.iter().find(|track| track.name == "Folder 1").unwrap().id;
+    for depth in 2..=7 {
+        r.app.run("track.move_to_new_folder", json!({"tracks": [parent.0], "name": format!("Folder {depth}")})).unwrap();
+        parent = r.app.engine.session().tracks.iter().find(|track| track.name == format!("Folder {depth}")).unwrap().id;
+    }
+    r.frame(vec![]);
+
+    // "Folder 1" is the child's own folder and the seventh level; "Folder 7" is the outermost.
+    assert_eq!(r.app.engine.session().track(parent).unwrap().name, "Folder 7");
+    assert!(r.text_x(&child_name) > r.text_x("Folder 1"), "deeply nested child is not indented under its own folder");
+    assert!(r.text_x("Folder 1") > r.text_x("Folder 2"), "each level indents further");
+}

crates/video/src/h264/dpb.rs

@@ -72,6 +72,22 @@ impl Dpb {
         self.entries.retain(|e| e.needed_for_output || e.mark != RefMark::Unused);
     }
 
+    /// Make room for a picture: output one (C.4.5.3), or, when none waits for output and
+    /// references alone fill the DPB (marking that keeps more than it holds), drop the reference
+    /// decoded longest ago. False when the DPB is empty.
+    fn make_room(&mut self, out: &mut Vec<Output>) -> bool {
+        if self.bump(out) {
+            return true;
+        }
+        let Some(i) = self.entries.iter().enumerate().filter(|(_, e)| e.mark != RefMark::Unused).min_by_key(|(_, e)| e.frame.id).map(|(i, _)| i)
+        else {
+            return false;
+        };
+        self.entries[i].mark = RefMark::Unused;
+        self.prune();
+        true
+    }
+
     /// Output the picture with the smallest POC (C.4.5.3 "bumping"). Returns false if none waits.
     fn bump(&mut self, out: &mut Vec<Output>) -> bool {
         let Some(i) = self.entries.iter().enumerate().filter(|(_, e)| e.needed_for_output).min_by_key(|(_, e)| e.poc).map(|(i, _)| i) else {
@@ -134,21 +150,29 @@ impl Dpb {
         poc_state: &mut dyn FnMut(u32),
     ) {
         let mut unused = (prev_ref_frame_num + 1) % max_frame_num;
+        // Only the last `max_num_ref_frames` missing frames can still be references when the gap
+        // ends: the sliding window drops the earlier ones first, so building their pictures would
+        // be work (up to 65 535 frame copies from one slice header) thrown straight away. They
+        // advance the POC state only.
+        let gap = (frame_num + max_frame_num - unused) % max_frame_num;
+        let skip = gap.saturating_sub(u32::try_from(max_num_ref_frames.max(1)).unwrap_or(u32::MAX));
         let mut guard = 0;
         while unused != frame_num && guard < max_frame_num {
-            self.sliding_window(unused, max_frame_num, max_num_ref_frames);
-            let (frame, meta) = make_frame(unused);
             poc_state(unused);
-            self.entries.push(DpbEntry {
-                poc: frame.poc,
-                frame,
-                frame_num: unused,
-                long_term_frame_idx: 0,
-                mark: RefMark::Short,
-                needed_for_output: false,
-                non_existing: true,
-                meta,
-            });
+            if guard >= skip {
+                self.sliding_window(unused, max_frame_num, max_num_ref_frames);
+                let (frame, meta) = make_frame(unused);
+                self.entries.push(DpbEntry {
+                    poc: frame.poc,
+                    frame,
+                    frame_num: unused,
+                    long_term_frame_idx: 0,
+                    mark: RefMark::Short,
+                    needed_for_output: false,
+                    non_existing: true,
+                    meta,
+                });
+            }
             unused = (unused + 1) % max_frame_num;
             guard += 1;
         }
@@ -277,6 +301,11 @@ impl Dpb {
                         }
                     }
                 }
+                3 | 6 if self.max_long_term_frame_idx.is_none_or(|max| m.long_term_frame_idx > max) => {
+                    // A long-term index outside what MMCO 4 (or the IDR) allowed (8.2.5.4.3): a
+                    // conforming stream never sends one, and honouring it would let distinct
+                    // indices retain references past the DPB's capacity.
+                }
                 3 => {
                     let pn = i64::from(curr_pic_num) - (i64::from(m.difference_of_pic_nums_minus1) + 1);
                     for e in &mut self.entries {
@@ -384,13 +413,13 @@ impl Dpb {
                     out.push(Output { frame, poc, meta });
                     return;
                 }
-                if !self.bump(out) {
+                if !self.make_room(out) {
                     break;
                 }
             }
         } else {
             while self.entries.len() >= self.capacity {
-                if !self.bump(out) {
+                if !self.make_room(out) {
                     break;
                 }
             }
@@ -429,6 +458,98 @@ mod tests {
         Mmco { op, difference_of_pic_nums_minus1: diff, long_term_pic_num: 0, long_term_frame_idx: 0, max_long_term_frame_idx_plus1: 0 }
     }
 
+    fn frame(id: u32) -> (FrameRef, Arc<OutputMeta>) {
+        let meta = OutputMeta {
+            pts: 0,
+            key: false,
+            crop: (0, 0, 0, 0),
+            full_range: false,
+            colour_primaries: 0,
+            transfer_characteristics: 0,
+            matrix_coefficients: 0,
+            sar: (1, 1),
+            draft: false,
+        };
+        (Arc::new(crate::h264::picture::Frame::new(id, 0, 1, 1)), Arc::new(meta))
+    }
+
+    /// A P slice header of a reference picture, with nothing else set.
+    fn reference_slice() -> SliceHeader {
+        SliceHeader {
+            nal_ref_idc: 1,
+            nal_unit_type: 1,
+            idr: false,
+            first_mb_in_slice: 0,
+            slice_type_raw: 0,
+            slice_type: SliceType::P,
+            pps_id: 0,
+            colour_plane_id: 0,
+            frame_num: 0,
+            field_pic: false,
+            bottom_field: false,
+            idr_pic_id: 0,
+            pic_order_cnt_lsb: 0,
+            delta_pic_order_cnt_bottom: 0,
+            delta_pic_order_cnt: [0; 2],
+            redundant_pic_cnt: 0,
+            direct_spatial_mv_pred: false,
+            num_ref_idx_active: [1, 0],
+            ref_pic_list_mod: [Vec::new(), Vec::new()],
+            pred_weight_table: None,
+            no_output_of_prior_pics: false,
+            long_term_reference: false,
+            adaptive_ref_pic_marking: false,
+            mmcos: Vec::new(),
+            cabac_init_idc: 0,
+            slice_qp_delta: 0,
+            sp_for_switch: false,
+            slice_qs_delta: 0,
+            disable_deblocking_filter_idc: 0,
+            slice_alpha_c0_offset_div2: 0,
+            slice_beta_offset_div2: 0,
+            slice_group_change_cycle: 0,
+            header_bits: 0,
+        }
+    }
+
+    #[test]
+    fn a_frame_num_gap_builds_only_the_frames_that_stay_references() {
+        let mut dpb = Dpb::new();
+        let (mut built, mut poc_updates) = (Vec::new(), 0u32);
+        // frame_num 0 was the last reference; the next slice says 60_000: 59 999 missing frames.
+        dpb.fill_frame_num_gap(0, 60_000, 1 << 16, 4, &mut |n| (built.push(n), frame(n)).1, &mut |_| poc_updates += 1);
+        assert_eq!(poc_updates, 59_999, "every missing frame advances the POC state");
+        assert_eq!(built, vec![59_996, 59_997, 59_998, 59_999], "only the ones the sliding window would keep are built");
+        assert_eq!(dpb.entries.iter().map(|e| e.frame_num).collect::<Vec<_>>(), built);
+        // A gap shorter than the window builds every frame, as before.
+        let mut dpb = Dpb::new();
+        let mut built = Vec::new();
+        dpb.fill_frame_num_gap(7, 10, 16, 4, &mut |n| (built.push(n), frame(n)).1, &mut |_| {});
+        assert_eq!(built, vec![8, 9]);
+    }
+
+    #[test]
+    fn long_term_marking_cannot_grow_the_dpb_past_its_capacity() {
+        let mut dpb = Dpb::new();
+        dpb.capacity = 4;
+        let mut out = Vec::new();
+        let mut sh = SliceHeader { adaptive_ref_pic_marking: true, ..reference_slice() };
+        // Each picture takes a distinct long-term index, after MMCO 4 allowed 1000 of them.
+        for n in 0..40u32 {
+            sh.frame_num = n;
+            sh.mmcos = vec![Mmco { op: 4, max_long_term_frame_idx_plus1: 1000, ..mmco(0, 0) }, Mmco { op: 6, long_term_frame_idx: n, ..mmco(0, 0) }];
+            let (f, meta) = frame(n);
+            dpb.store_picture(&sh, f, n as i32, 1 << 16, 16, meta, &mut out);
+            assert!(dpb.entries.len() <= 4, "{} entries after picture {n}", dpb.entries.len());
+        }
+        // An index past what MMCO 4 allowed is ignored: the picture is a short-term reference.
+        sh.frame_num = 40;
+        sh.mmcos = vec![Mmco { op: 6, long_term_frame_idx: 5000, ..mmco(0, 0) }];
+        let (f, meta) = frame(40);
+        dpb.store_picture(&sh, f, 40, 1 << 16, 16, meta, &mut out);
+        assert_eq!(dpb.entries.iter().find(|e| e.frame_num == 40).map(|e| e.mark), Some(RefMark::Short));
+    }
+
     #[test]
     fn mmco_huge_difference_does_not_panic() {
         for op in [1, 3] {

crates/video/src/h264/params.rs

@@ -397,6 +397,10 @@ impl Sps {
         let pic_height_in_map_units = plus(r.read_ue()?, 1, "picture too large")?;
         ensure!(pic_width_in_mbs <= 1024 && pic_height_in_map_units <= 1024, "picture too large");
         let frame_mbs_only = r.read_flag()?;
+        // Picture state is allocated from these before any macroblock is read: the movie's pixel
+        // budget applies here too, so a 16 384-square SPS can't claim its planes.
+        let coded_mbs = u64::from(pic_width_in_mbs) * u64::from(pic_height_in_map_units) * if frame_mbs_only { 1 } else { 2 };
+        ensure!(coded_mbs * 256 <= crate::movie::MAX_PIXELS, "picture too large");
         let mb_adaptive_frame_field = if !frame_mbs_only { r.read_flag()? } else { false };
         let direct_8x8_inference = r.read_flag()?;
         let frame_crop = if r.read_flag()? { Some((r.read_ue()?, r.read_ue()?, r.read_ue()?, r.read_ue()?)) } else { None };
@@ -699,6 +703,37 @@ mod tests {
         assert_eq!(l, [10; 16]);
     }
 
+    #[test]
+    fn an_sps_past_the_pixel_budget_is_refused_before_allocation() {
+        // As `parse_minimal_baseline_sps`, with `mbs` × `mbs` macroblocks.
+        let sps = |mbs: u32, frame_mbs_only: bool| {
+            let mut w = BitWriter::new();
+            w.write_bits(66, 8);
+            w.write_bits(0xC0, 8);
+            w.write_bits(30, 8);
+            w.write_ue(0);
+            w.write_ue(0);
+            w.write_ue(2);
+            w.write_ue(1);
+            w.write_bit(false);
+            w.write_ue(mbs - 1);
+            w.write_ue(mbs - 1);
+            w.write_bit(frame_mbs_only);
+            if !frame_mbs_only {
+                w.write_bit(false); // mb_adaptive_frame_field
+            }
+            w.write_bit(true);
+            w.write_bit(false);
+            w.write_bit(false);
+            w.rbsp_trailing();
+            Sps::parse(&w.finish())
+        };
+        assert!(sps(512, true).is_ok(), "8192 × 8192 is the budget");
+        assert!(sps(513, true).is_err(), "one macroblock column more is past it");
+        assert!(sps(512, false).is_err(), "field pictures double the map units");
+        assert!(sps(362, false).is_ok());
+    }
+
     #[test]
     fn parse_minimal_baseline_sps() {
         // profile 66, level 30, sps_id 0, log2_max_frame_num_minus4 0, poc type 2, 1 ref, 11x9 MBs.

crates/vst3-host/src/ffi/instance.rs

@@ -75,6 +75,8 @@ pub(crate) struct Instance {
     pub(super) active: bool,
     pub(super) processing: bool,
     pub(super) max_frames: usize,
+    /// `kRealtime` or `kOffline`, for `setupProcessing` and every `process` call.
+    pub(super) process_mode: i32,
     pub(super) in_params: ComWrapper<ParamChanges>,
     pub(super) out_params: ComWrapper<ParamChanges>,
     pub(super) in_events: ComWrapper<EventList>,
@@ -251,6 +253,12 @@ impl Instance {
         self.active
     }
 
+    /// Offline (`kOffline`: no realtime pressure, e.g. a bounce) or realtime processing, from the
+    /// next [`Instance::configure`] on.
+    pub fn set_offline(&mut self, offline: bool) {
+        self.process_mode = if offline { sv::ProcessModes_::kOffline } else { sv::ProcessModes_::kRealtime } as i32;
+    }
+
     fn bus_count(&self, media: sv::MediaTypes, dir: sv::BusDirections) -> i32 {
         // SAFETY: valid component.
         unsafe { self.component.getBusCount(media as sv::MediaType, dir as sv::BusDirection) }.max(0)
@@ -359,12 +367,8 @@ impl Instance {
             return Err(Vst3Error::Process("plugin cannot process 32-bit float".into()));
         }
         let max = i32::try_from(max_frames).unwrap_or(i32::MAX);
-        let mut setup = sv::ProcessSetup {
-            processMode: sv::ProcessModes_::kRealtime as i32,
-            symbolicSampleSize: sample32,
-            maxSamplesPerBlock: max,
-            sampleRate: sample_rate,
-        };
+        let mut setup =
+            sv::ProcessSetup { processMode: self.process_mode, symbolicSampleSize: sample32, maxSamplesPerBlock: max, sampleRate: sample_rate };
         // SAFETY: valid processor, inactive; `setup` is a valid struct for the call.
         if !ok(unsafe { p.setupProcessing(&mut setup) }) {
             return Err(Vst3Error::Process("setupProcessing failed".into()));
@@ -450,7 +454,7 @@ impl Instance {
             None => self.context.projectTimeSamples = project_time,
         }
         let mut data = sv::ProcessData {
-            processMode: sv::ProcessModes_::kRealtime as i32,
+            processMode: self.process_mode,
             symbolicSampleSize: sv::SymbolicSampleSizes_::kSample32 as i32,
             numSamples: i32::try_from(frames).unwrap_or(0),
             numInputs: i32::try_from(inputs.bufs.len()).unwrap_or(0),

crates/vst3-host/src/ffi/module.rs

@@ -137,6 +137,16 @@ mod cf {
     }
 }
 
+/// A libloading error with the system's reason. libloading's own text is only "dlopen failed"
+/// (or "dlsym failed", "LoadLibraryExW failed"); the reason (`dlerror`, the Windows error) is its
+/// source.
+fn with_reason(e: &libloading::Error) -> String {
+    match std::error::Error::source(e) {
+        Some(why) => format!("{e}: {why}"),
+        None => e.to_string(),
+    }
+}
+
 /// Opens the shared library and runs the platform module entry (`bundleEntry` with a
 /// `CFBundleRef` on macOS, `InitDll` on Windows, `ModuleEntry` with the `dlopen` handle on Linux).
 /// Also returns the matching module exit, when the entry ran and the module exports one.
@@ -146,7 +156,7 @@ fn open_library(bundle: &Path, exe: &Path) -> Result<(libloading::Library, Optio
         use libloading::os::unix::{Library as UnixLib, RTLD_LOCAL, RTLD_NOW};
         // SAFETY: loading a shared library runs its static initialisers. That is inherent to
         // hosting plugins; we only load files found in VST3 plugin folders or named explicitly.
-        let lib = unsafe { UnixLib::open(Some(exe), RTLD_NOW | RTLD_LOCAL) }.map_err(|e| e.to_string())?;
+        let lib = unsafe { UnixLib::open(Some(exe), RTLD_NOW | RTLD_LOCAL) }.map_err(|e| with_reason(&e))?;
         type ModuleEntry = unsafe extern "C" fn(*mut c_void) -> bool;
         // SAFETY: `ModuleEntry` is the VST3-mandated Linux entry with this signature.
         let entry = unsafe { lib.get::<ModuleEntry>(b"ModuleEntry\0") }.ok().map(|s| *s);
@@ -170,7 +180,7 @@ fn open_library(bundle: &Path, exe: &Path) -> Result<(libloading::Library, Optio
     {
         // SAFETY: loading a shared library runs its static initialisers. That is inherent to
         // hosting plugins; we only load files found in VST3 plugin folders or named explicitly.
-        let lib = unsafe { libloading::Library::new(exe) }.map_err(|e| e.to_string())?;
+        let lib = unsafe { libloading::Library::new(exe) }.map_err(|e| with_reason(&e))?;
         let mut exit: Option<ModuleExit> = None;
         #[cfg(windows)]
         {
@@ -335,7 +345,7 @@ impl Bundle {
         // SAFETY: `GetPluginFactory` is the VST3-mandated export with this signature.
         let get = match unsafe { lib.get::<GetFactory>(b"GetPluginFactory\0") } {
             Ok(sym) => *sym,
-            Err(e) => return Err(fail(format!("not a VST3 plugin: {e}"))),
+            Err(e) => return Err(fail(format!("not a VST3 plugin (no GetPluginFactory): {}", with_reason(&e)))),
         };
         // SAFETY: the module is loaded and its entry function (if any) has run.
         let raw = unsafe { get() };
@@ -449,6 +459,7 @@ impl Bundle {
             active: false,
             processing: false,
             max_frames: 0,
+            process_mode: sv::ProcessModes_::kRealtime as i32,
             in_params: ComWrapper::new(ParamChanges::new(PARAM_QUEUE_CAP)),
             out_params: ComWrapper::new(ParamChanges::new(PARAM_QUEUE_CAP)),
             in_events: ComWrapper::new(EventList::new(EVENT_CAP)),

crates/vst3-host/src/lib.rs

@@ -307,6 +307,21 @@ mod tests {
         let _ = std::fs::remove_dir_all(&d);
     }
 
+    /// A binary the system refuses to load reports the system's reason (missing library, wrong
+    /// glibc, not an ELF file), not just "dlopen failed".
+    #[test]
+    fn a_binary_that_does_not_load_says_why() {
+        let d = std::env::temp_dir().join(format!("soundcraft-vst3-reason-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&d);
+        std::fs::create_dir_all(&d).unwrap();
+        let f = d.join("garbage.vst3");
+        std::fs::write(&f, b"\x7fELF this is not a plugin \x00\x01\x02").unwrap();
+        let msg = load_bundle(&f).err().map(|e| e.to_string()).unwrap_or_default();
+        let reason = msg.split_once("failed: ").map_or("", |(_, r)| r.trim());
+        assert!(!reason.is_empty(), "no reason in: {msg}");
+        let _ = std::fs::remove_dir_all(&d);
+    }
+
     // Unix only: the test points a ".vst3" at a system library through a symlink.
     #[cfg(unix)]
     #[test]
@@ -326,6 +341,7 @@ mod tests {
         std::os::unix::fs::symlink(&lib, d.join("z.vst3")).unwrap();
         let e = load_bundle(&d.join("z.vst3")).unwrap_err();
         assert!(e.to_string().contains("not a VST3 plugin"), "{e}");
+        assert!(e.to_string().contains("GetPluginFactory"), "the system's reason names the missing export: {e}");
         let _ = std::fs::remove_dir_all(&d);
     }
 }

crates/vst3-host/src/plugin.rs

@@ -259,6 +259,11 @@ impl Plugin for Vst3Plugin {
         }
     }
 
+    fn set_offline(&mut self, offline: bool) {
+        // `processMode`, set up by the next `prepare`.
+        self.inst.set_offline(offline);
+    }
+
     fn reset(&mut self) {
         // Keep pending releases and release whatever is still held, so the processor's voices stop
         // on the next block instead of sounding on while the host forgets them.

crates/vst3-host/tests/fixture/src/lib.rs

@@ -14,8 +14,9 @@
 //! - "Fixture Wide 16x64", "Fixture Wide 32 buses", "Fixture Wide 65 buses", "Fixture Wide 65
 //!   channels" (`Fx`): effects advertising wide layouts (16 buses of 64 channels, 32 and 65 buses
 //!   of 2 channels, one bus of 65 channels per direction), through `getBusInfo` only. `process` writes 1.0 into every channel
-//!   of output bus 0 when the host's buffers match the advertised layout, -1.0 when they do not.
-//!   Report 3 samples of latency.
+//!   of output bus 0 when the host's buffers match the advertised layout (2.0 when the host set it
+//!   up and runs it with `kOffline`), -1.0 when they do not or when `process` gets another
+//!   `processMode` than `setupProcessing` did. Report 3 samples of latency.
 //!
 //! The module checks the host's module lifecycle the way real plugins depend on it (see "module
 //! lifecycle" below) and aborts the process when it is broken.
@@ -25,7 +26,7 @@
 #![allow(non_snake_case, clippy::missing_safety_doc)]
 
 use std::ffi::{c_char, c_int, c_void};
-use std::sync::atomic::{AtomicBool, AtomicI64, AtomicU32, AtomicU64, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, AtomicI64, AtomicU32, AtomicU64, AtomicUsize, Ordering};
 use vst3::Steinberg::Vst::*;
 use vst3::Steinberg::*;
 use vst3::{Class, ComRef, ComWrapper, uid};
@@ -640,6 +641,8 @@ impl IEditControllerTrait for Synth {
 struct Wide {
     buses: i32,
     channels: i32,
+    /// The `processMode` of the last `setupProcessing`.
+    mode: AtomicI32,
     _live: Live,
 }
 
@@ -704,7 +707,8 @@ impl IAudioProcessorTrait for Wide {
     unsafe fn getLatencySamples(&self) -> u32 {
         3
     }
-    unsafe fn setupProcessing(&self, _setup: *mut ProcessSetup) -> tresult {
+    unsafe fn setupProcessing(&self, setup: *mut ProcessSetup) -> tresult {
+        self.mode.store(unsafe { &*setup }.processMode, Ordering::Relaxed);
         kResultOk
     }
     unsafe fn setProcessing(&self, _state: TBool) -> tresult {
@@ -714,10 +718,11 @@ impl IAudioProcessorTrait for Wide {
         let d = unsafe { &*data };
         let fits =
             |bufs: *mut AudioBusBuffers, n: i32| n == self.buses && (0..n as usize).all(|i| unsafe { &*bufs.add(i) }.numChannels == self.channels);
-        let ok = fits(d.inputs, d.numInputs) && fits(d.outputs, d.numOutputs);
+        let ok = fits(d.inputs, d.numInputs) && fits(d.outputs, d.numOutputs) && d.processMode == self.mode.load(Ordering::Relaxed);
+        let fit = if d.processMode == ProcessModes_::kOffline as i32 { 2.0 } else { 1.0 };
         if d.numOutputs > 0 {
             for ch in unsafe { channels(&*d.outputs, d.numSamples.max(0) as usize) } {
-                ch.fill(if ok { 1.0 } else { -1.0 });
+                ch.fill(if ok { fit } else { -1.0 });
             }
         }
         kResultOk
@@ -791,7 +796,7 @@ impl IPluginFactoryTrait for Factory {
             .into_iter()
             .find_map(|(c, layout)| (c == cid).then_some(layout))
         {
-            ComWrapper::new(Wide { buses, channels, _live: Live::new(&OBJECTS) }).to_com_ptr::<FUnknown>()
+            ComWrapper::new(Wide { buses, channels, mode: AtomicI32::new(-1), _live: Live::new(&OBJECTS) }).to_com_ptr::<FUnknown>()
         } else {
             None
         };

crates/vst3-host/tests/it/fixture_e2e.rs

@@ -331,6 +331,18 @@ fn layouts_beyond_the_host_limits_are_rejected_not_truncated() {
     }
 }
 
+#[test]
+fn offline_renders_set_up_and_process_in_offline_mode() {
+    for (offline, want) in [(false, 1.0), (true, 2.0)] {
+        let mut p = soundcraft_vst3_host::create(&id_of("Fixture Wide 16x64")).unwrap();
+        p.set_offline(offline);
+        p.prepare(44_100.0, 64, 2);
+        let mut io = vec![vec![0.5f32; 64]; 2];
+        p.process(&mut io, 64);
+        assert!(io.iter().flatten().all(|&x| x == want), "offline {offline}: {:?}", &io[0][..4]);
+    }
+}
+
 #[test]
 fn many_buses_like_multi_out_instruments_are_activated() {
     // Multi-out instruments declare dozens of buses (SSD Sampler 5: 32); only the main one is

docs/cli.md

@@ -14,7 +14,7 @@ flags, values and defaults. This page does not repeat them.
 | `convert` | Converts an audio file: resample, change the bit depth, normalize |
 | `run` | Runs engine commands on a new, demo or saved session; can bounce, save and inspect |
 | `script` | Runs a file of engine commands, one `ID JSON` per line |
-| `commands` | Lists the engine commands |
+| `commands` | Lists the engine commands; with `--json`, each one's details as `describe` prints them |
 | `describe` | Prints one engine command's details as JSON |
 | `app` | Calls a running app's control channel (see [the control protocol](control-protocol.md)) |
 | `mcp` | Serves MCP on stdin and stdout (see [the MCP guide](mcp.md)) |
@@ -29,16 +29,19 @@ soundcraft-cli convert in.wav out.flac --bit-depth 16 --rate 44100
 soundcraft-cli run --demo --cmd 'mix.volume={"track":"Kick","db":-6}' --bounce mix.wav
 soundcraft-cli script steps.txt --demo --keep-going --save out.scraft
 soundcraft-cli commands bounce
+soundcraft-cli commands --json --compact
 soundcraft-cli describe file.bounce_mix
 ```
 
 ## Output and exit codes
 
 Results go to standard output, as JSON where a program is meant to read them. `info` (on an audio
-file), `describe`, `app` and the `--inspect` output of `run` and `script` pretty-print it; `--compact`
-prints the same JSON on one line. The result lines of `run` and `script` (`ID: JSON`) and the
-`--bounce` and `--save` results are always one line each. `commands`, `plugins`, `parity` and the
-`.scraft` summary of `info` are text. Errors go to standard error as `error: <message>`. `mcp` writes only the protocol
+file), `describe`, `commands --json`, `app` and the `--inspect` output of `run` and `script`
+pretty-print it; `--compact` prints the same JSON on one line. The result lines of `run` and
+`script` (`ID: JSON`) and the `--bounce` and `--save` results are always one line each. `commands`
+(without `--json`), `plugins`, `parity` and the `.scraft` summary of `info` are text. The
+`enabled` and `disabled_reason` fields of `describe` and `commands --json` are worked out against
+an empty session, not a session you have open. Errors go to standard error as `error: <message>`, and so do the warnings and errors SoundCraft and the plugin hosts log (`warning: <message>`, `error: <message>`), such as a plugin that fails to load. `mcp` writes only the protocol
 to standard output.
 
 | Exit code | Meaning |
@@ -138,8 +141,8 @@ output replacing an input without `--in-place`, and the ast-grep rules in `lint/
 
 Rules not followed yet:
 
-- **JSON flag (rule 1.3).** `commands`, `plugins`, `parity` and the `info` summary of a `.scraft`
-  session print text and have no `--json` flag. Whether such listings need one is an open question
+- **JSON flag (rule 1.3).** `plugins`, `parity` and the `info` summary of a `.scraft` session
+  print text and have no `--json` flag (`commands` has one). Whether such listings need one is an open question
   in the RFC itself.
 - **`string-error` rule (section 3).** Its ast-grep rule is on for the CLI code and the shared flags,
   not yet for the rest of the workspace.

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity
 
-> **Last reviewed:** 2026-10-19 · **Last updated:** 2026-10-19 · **Change:** trivial (Float32 file headroom, #791) · **Target:** Avid Pro Tools Ultimate 2026.4.1
+> **Last reviewed:** 2026-10-19 · **Last updated:** 2026-11-02 · **Change:** trivial (bounces carry a BWF time reference, #1296; previously trivial: Float32 file headroom, #791) · **Target:** Avid Pro Tools Ultimate 2026.4.1
 
 Every format Pro Tools reads or writes, and ours. The Pro Tools list comes from the document types
 its bundle declares (`CFBundleDocumentTypes` in Info.plist: names only, nothing else read) and its
@@ -33,7 +33,7 @@ Legend: ✅ supported and tested · 🟡 partial · ❌ missing · — not appli
 
 | Format | Pro Tools | Read | Write | Tests / notes |
 |---|---|---|---|---|
-| WAV / BWF (PCM 16/24/32, float 32), `bext` | native | ✅ | ✅ | Native reader/writer, TPDF dither option; Float32 retains finite headroom (#791); also 8-bit and float 64 read. An empty data chunk followed by metadata reads as no audio; an unfinalised recording's audio is still read (#466). |
+| WAV / BWF (PCM 16/24/32, float 32), `bext` | native | ✅ | ✅ | Native reader/writer, TPDF dither option; Float32 retains finite headroom (#791); also 8-bit and float 64 read. An empty data chunk followed by metadata reads as no audio; an unfinalised recording's audio is still read (#466). WAV bounces (mix and stems) carry a `bext` TimeReference: the session's timecode start plus the bounce start (#1296). |
 | RF64 / BW64 (> 4 GiB) | read/write | ✅ | ✅ | `encode_wav_rf64` |
 | WAV `WAVE_FORMAT_EXTENSIBLE` multichannel with channel mask | read/write | ✅ | ✅ | `encode_with_channel_mask`; default 5.1 import creates a stereo track (#89, PR #128) |
 | AIFF / AIFF-C | native | ✅ | ✅ (`fl32`) | Native; `fl32` retains finite headroom (#791) |
@@ -80,6 +80,7 @@ Legend: ✅ supported and tested · 🟡 partial · ❌ missing · — not appli
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-11-02 | trivial | WAV bounces (mix and stems) write a `bext` TimeReference: session timecode start plus bounce start (#1296) |
 | 2026-10-19 | trivial | WAV and AIFF-C Float32 encoders retain finite headroom (#791); whole-file, streaming and bounce regression tests |
 | 2026-10-13 | trivial | WAV: empty data chunk with trailing metadata (#466) |
 | 2026-10-13 | minor | Fade curvature round-trips in sessions with a zero default for older files. Format version and readiness estimate unchanged |

xtask/src/version.rs

@@ -197,8 +197,11 @@ mod tests {
 
     #[test]
     fn a_failed_update_restores_the_manifest() {
-        let root = std::env::temp_dir().join(format!("xtask-version-restore-{}", std::process::id()));
-        std::fs::create_dir_all(&root).unwrap();
+        // Created exclusively: a folder already there (planted, or left by a failed run) would be
+        // someone else's, and a link inside it could redirect the writes below.
+        let nanos = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.subsec_nanos());
+        let root = std::env::temp_dir().join(format!("xtask-version-restore-{}-{nanos}", std::process::id()));
+        std::fs::create_dir(&root).unwrap();
         let path = root.join("Cargo.toml");
         std::fs::write(&path, MANIFEST).unwrap();
         let err = set(&root, &path, MANIFEST, "2.0.0", || Err("cargo update failed".into())).unwrap_err();