CI: use the shared git-sources check

nix.yml ran its own copy of the git-sources job; it now calls
craft-common-actions git-sources.yml.

.github/workflows/nix.yml

@@ -23,39 +23,5 @@ jobs:
     uses: storytold/craft-common-actions/.github/workflows/nix.yml@main
 
   git-sources:
-    name: Git dependencies come from storytold
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - name: Git dependencies come from storytold
-        run: |
-          set -euo pipefail
-          test -f Cargo.lock || { echo "Cargo.lock is missing"; exit 1; }
-          # Source replacement, patches and path overrides in cargo config never show up
-          # in Cargo.lock. Parsed rather than grepped: TOML has many spellings of one key.
-          # Cargo still reads the legacy .cargo/config.
-          python3 - <<'PY'
-          import os, sys, tomllib
-          for path in (".cargo/config", ".cargo/config.toml"):
-              if not os.path.exists(path):
-                  continue
-              config = tomllib.load(open(path, "rb"))
-              replaced = [name for name, source in config.get("source", {}).items()
-                          if isinstance(source, dict) and "replace-with" in source]
-              if replaced or "patch" in config or "paths" in config:
-                  print(f"{path} replaces, patches or overrides a source")
-                  sys.exit(1)
-          PY
-          # Fails when Cargo.lock is out of date with the manifests.
-          cargo metadata --locked --format-version 1 > /dev/null
-          python3 - <<'PY'
-          import sys, tomllib
-          lock = tomllib.load(open("Cargo.lock", "rb"))
-          bad = sorted({p["source"] for p in lock.get("package", [])
-                        if p.get("source", "").startswith("git+")
-                        and not p["source"].startswith("git+https://github.com/storytold/")})
-          if bad:
-              print("Git dependencies outside github.com/storytold:", *bad, sep="\n")
-              sys.exit(1)
-          PY
+    # Tracks @main so suite-wide CI fixes reach every app without a PR in each repository.
+    uses: storytold/craft-common-actions/.github/workflows/git-sources.yml@main

.github/workflows/packaging-lint.yml

@@ -27,6 +27,10 @@ jobs:
     name: Windows installation policy (no app build)
     runs-on: windows-latest
     steps:
+      - name: Harden runner
+        uses: step-security/harden-runner@1d88384fd173af6ecb012dfd0264a306b711241a # v2.22.4
+        with:
+          egress-policy: audit
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false

Cargo.lock

@@ -1064,17 +1064,17 @@ dependencies = [
 [[package]]
 name = "craft-docpath"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 
 [[package]]
 name = "craft-fonts-build"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 
 [[package]]
 name = "craft-i18n"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 dependencies = [
  "fixed_decimal",
  "icu_decimal",
@@ -1097,7 +1097,7 @@ dependencies = [
 [[package]]
 name = "craft-media"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 dependencies = [
  "thiserror 2.0.21",
 ]
@@ -1105,7 +1105,7 @@ dependencies = [
 [[package]]
 name = "craft-ui"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 dependencies = [
  "craft-fonts-build",
  "craft-i18n",
@@ -1126,7 +1126,7 @@ dependencies = [
 [[package]]
 name = "craft-update"
 version = "0.1.0"
-source = "git+https://github.com/storytold/craft-libs?rev=1b34eba41e62138fc2438d2734523b302840b45d#1b34eba41e62138fc2438d2734523b302840b45d"
+source = "git+https://github.com/storytold/craft-libs?rev=6e03f65bf45181db77ba6229716e6624db9eb25b#6e03f65bf45181db77ba6229716e6624db9eb25b"
 dependencies = [
  "chrono",
  "dunce",
@@ -1136,6 +1136,7 @@ dependencies = [
  "image",
  "log",
  "plist",
+ "rustix 1.1.5",
  "semver",
  "serde",
  "serde_json",
@@ -4449,6 +4450,7 @@ dependencies = [
  "soundcraft-video",
  "soundcraft-vst3-host",
  "thiserror 2.0.21",
+ "winsafe",
  "zip",
 ]
 

Cargo.toml

@@ -50,15 +50,15 @@ zip = { version = "9", default-features = false }
 cpal = "0.18"
 
 # Which file paths stored in a session may be opened.
-craft-docpath = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "1b34eba41e62138fc2438d2734523b302840b45d" }
+craft-docpath = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "6e03f65bf45181db77ba6229716e6624db9eb25b" }
 
 # Video containers and bitstreams, shared with the other craft apps.
-craft-media = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "1b34eba41e62138fc2438d2734523b302840b45d" }
+craft-media = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "6e03f65bf45181db77ba6229716e6624db9eb25b" }
 # craft-update: app-specific pretend versions apply to startup and manual checks.
-craft-update = { version = "=0.1.0", git = "https://github.com/storytold/craft-libs", rev = "1b34eba41e62138fc2438d2734523b302840b45d", features = ["egui"] }
+craft-update = { version = "=0.1.0", git = "https://github.com/storytold/craft-libs", rev = "6e03f65bf45181db77ba6229716e6624db9eb25b", features = ["egui"] }
 
 # ui
-craft-ui = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "1b34eba41e62138fc2438d2734523b302840b45d", features = ["serde"] }
+craft-ui = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "6e03f65bf45181db77ba6229716e6624db9eb25b", features = ["serde"] }
 egui = { version = "0.37" }
 # Resizable table columns (About ▸ Contributors / Models); no image loaders.
 egui_extras = { version = "0.37", default-features = false }

crates/audio-io/src/mp4.rs

@@ -4,6 +4,12 @@
 use crate::pcm::{be_u32, be_u64};
 use crate::{AudioError, Result};
 
+/// The most `stts` entries a sound track may have. Symphonia finds each packet's timestamp by
+/// scanning the table from its start, so a table of one-sample runs makes decoding quadratic in
+/// the packet count. Audio encoders write one run per packet length (a handful of entries);
+/// this bound keeps the worst case at a few hundred million steps.
+const MAX_AUDIO_STTS_ENTRIES: u32 = 1 << 14;
+
 #[derive(Clone, Copy)]
 enum Level {
     Top,
@@ -11,7 +17,11 @@ enum Level {
     Trak,
     Mdia,
     Minf,
-    Stbl,
+    /// `audio`: the sample entry is an audio format, so symphonia will decode its packets (whatever the
+    /// handler says: it builds codec parameters from `stsd` alone).
+    Stbl {
+        audio: bool,
+    },
     Udta,
     Meta,
     Ilst,
@@ -55,13 +65,20 @@ fn atoms(b: &[u8], mut pos: usize, end: usize, level: Level) -> Result<bool> {
             (Level::Moov, b"udta") => atoms(b, body, inner, Level::Udta)?,
             (Level::Trak, b"mdia") => atoms(b, body, inner, Level::Mdia)?,
             (Level::Mdia, b"minf") => atoms(b, body, inner, Level::Minf)?,
-            (Level::Minf, b"stbl") => atoms(b, body, inner, Level::Stbl)?,
+            (Level::Minf, b"stbl") => atoms(b, body, inner, Level::Stbl { audio: entry_is_audio(b, body, inner) })?,
             (Level::Meta, b"ilst") => atoms(b, body, inner, Level::Ilst)?,
             (Level::Ilst, _) => atoms(b, body, inner, Level::Tag)?,
-            (Level::Stbl, b"stts" | b"co64") => table(b, body + 4, 8, inner)?,
-            (Level::Stbl, b"stsc") => table(b, body + 4, 12, inner)?,
-            (Level::Stbl, b"stco") => table(b, body + 4, 4, inner)?,
-            (Level::Stbl, b"stsz") => sample_sizes(b, body, inner)?,
+            (Level::Stbl { audio }, b"stts") => {
+                let fits = table(b, body + 4, 8, inner)?;
+                if audio && be_u32(b, body + 4).is_some_and(|n| n > MAX_AUDIO_STTS_ENTRIES) {
+                    return Err(AudioError::Malformed("MP4 audio timing table has more runs than packets could need".into()));
+                }
+                fits
+            }
+            (Level::Stbl { .. }, b"co64") => table(b, body + 4, 8, inner)?,
+            (Level::Stbl { .. }, b"stsc") => table(b, body + 4, 12, inner)?,
+            (Level::Stbl { .. }, b"stco") => table(b, body + 4, 4, inner)?,
+            (Level::Stbl { .. }, b"stsz") => sample_sizes(b, body, inner)?,
             (Level::Mdia, b"hdlr") | (Level::Tag, b"data" | b"name" | b"mean") if len > (b.len() - pos) as u64 => {
                 return Err(malformed(&format!("`{}` atom", String::from_utf8_lossy(kind))));
             }
@@ -75,6 +92,38 @@ fn atoms(b: &[u8], mut pos: usize, end: usize, level: Level) -> Result<bool> {
     Ok(true)
 }
 
+/// The sample entry formats symphonia reads as audio (the list `stsd` is matched against in
+/// symphonia-format-isomp4 0.6); every other format, video and subtitles included, has no audio packets.
+const AUDIO_FORMATS: [&[u8; 4]; 18] = [
+    b"mp4a", b"alac", b"ac-3", b"ec-3", b"fLaC", b"Opus", b".mp3", b"lpcm", b"wave", b"alaw", b"ulaw", b"raw ", b"sowt", b"twos", b"in24", b"in32",
+    b"fl32", b"fl64",
+];
+
+/// Whether the `stbl` atom whose children lie in `pos..end` describes audio: its `stsd` may come before
+/// or after the timing tables, so the children are walked once more for it. Symphonia keeps the last
+/// `stsd` it reads, so the last one decides.
+fn entry_is_audio(b: &[u8], mut pos: usize, end: usize) -> bool {
+    let mut audio = false;
+    while pos < end {
+        let (Some(size), Some(kind)) = (be_u32(b, pos), b.get(pos + 4..pos + 8)) else { return audio };
+        let head = if size == 1 { 16 } else { 8 };
+        if kind == b"stsd" {
+            // Version and flags, the entry count, then the first entry's size and format.
+            audio = b.get(pos + head + 12..pos + head + 16).is_some_and(|f| AUDIO_FORMATS.iter().any(|a| a.as_slice() == f));
+        }
+        let len = match size {
+            0 => return audio,
+            1 => be_u64(b, pos + 8).unwrap_or(0),
+            n => u64::from(n),
+        };
+        match usize::try_from(len).ok().filter(|&n| n >= head).and_then(|n| pos.checked_add(n)) {
+            Some(next) => pos = next,
+            None => return audio,
+        }
+    }
+    audio
+}
+
 /// A sample table's entries, counted at `count`, must fit in the file: symphonia reserves room for
 /// all of them first. False if they run past the table's atom (`end`), where symphonia stops.
 fn table(b: &[u8], count: usize, entry: u64, end: usize) -> Result<bool> {

crates/audio-io/src/symph.rs

@@ -22,6 +22,11 @@ use crate::{AudioBuffer, AudioError, AudioInfo, FileFormat, Result, SampleFormat
 /// takes its frame length from the file (encoders use 4096).
 const MAX_PACKET_FRAMES: u64 = 1 << 20;
 
+/// The most samples (frames × channels) a packet may declare: the PCM decoder allocates that
+/// many for its output up front, so a CAF with thousands of channels and a long packet could
+/// otherwise claim gigabytes before a sample is decoded (64 MiB of f32).
+const MAX_PACKET_SAMPLES: u64 = 1 << 24;
+
 /// How far [`first_marker`] looks for the first format marker: the same 1 MiB a default symphonia
 /// probe scans.
 const MAX_PREFIX_SCAN: usize = 1 << 20;
@@ -508,7 +513,9 @@ fn run(bytes: &[u8], detected: FileFormat, count_only: bool) -> Result<(AudioInf
     }
     let params = audio_params(track).cloned().ok_or_else(|| AudioError::Malformed("track vanished".into()))?;
     let alac = params.extra_data.as_deref().filter(|_| params.codec == CODEC_ID_ALAC).and_then(|d| be_u32(d, 0));
-    if params.max_frames_per_packet.into_iter().chain(alac.map(u64::from)).any(|n| n > MAX_PACKET_FRAMES) {
+    let ch = u64::from(info.channels);
+    if params.max_frames_per_packet.into_iter().chain(alac.map(u64::from)).any(|n| n > MAX_PACKET_FRAMES || n.saturating_mul(ch) > MAX_PACKET_SAMPLES)
+    {
         return Err(AudioError::Malformed("the file declares packets far longer than any codec uses".into()));
     }
     let mut decoder = symphonia::default::get_codecs().make_audio_decoder(&params, &decoder_options()).map_err(map_err)?;
@@ -531,6 +538,13 @@ fn run(bytes: &[u8], detected: FileFormat, count_only: bool) -> Result<(AudioInf
         if packet.track_id != track_id {
             continue;
         }
+        // The declared frames per packet are not the packet's size: a container supplies that on its
+        // own, and the PCM decoder sizes its output by the bytes it is given.
+        if let Some(bytes_per_sample) = params.bits_per_coded_sample.map(|b| u64::from(b / 8)).filter(|&n| n > 0)
+            && packet.data.len() as u64 / bytes_per_sample > MAX_PACKET_SAMPLES
+        {
+            return Err(AudioError::Malformed("a packet holds far more samples than any codec uses".into()));
+        }
         let decoded = match decoder.decode(&packet) {
             Ok(d) => d,
             Err(SymError::DecodeError(m)) => {

crates/audio-io/tests/it/malformed.rs

@@ -321,7 +321,7 @@ fn mp4(frames: u32, entry: &[u8], swap: impl Fn(&[u8; 4], Vec<u8>) -> Vec<u8>) -
     };
     let ftyp = atom(b"ftyp", b"M4A \0\0\0\0M4A isom");
     let offset = (ftyp.len() + moov(0).len() + 8) as u32;
-    let pcm: Vec<u8> = (0..frames as i16).flat_map(|i| (i * 40).to_le_bytes()).collect();
+    let pcm: Vec<u8> = (0..frames as i16).flat_map(|i| i.wrapping_mul(40).to_le_bytes()).collect();
     [ftyp, moov(offset), atom(b"mdat", &pcm)].concat()
 }
 
@@ -373,6 +373,63 @@ fn packets_longer_than_any_codec_uses_are_refused() {
     for entry in [lpcm(1 << 21), alac(1 << 21)] {
         assert!(matches!(decode(&mp4(480, &entry, |_, a| a), None), Err(AudioError::Malformed(m)) if m.contains("declares packets")));
     }
+    // Frames and channels multiply into the decoder's packet buffer; an ordinary stereo stream
+    // with long packets stays well inside the bound.
+    let wide = |channels: u32, frames: u32| {
+        let fields = [&be(&[72])[..], &48_000f64.to_be_bytes(), &be(&[channels, 0x7f00_0000, 16, 4, 2 * channels, frames])].concat();
+        sample_entry(b"lpcm", 2, &fields, &[])
+    };
+    assert!(decode(&mp4(480, &wide(2, 1 << 13), |_, a| a), None).is_ok());
+}
+
+#[test]
+fn an_audio_timing_table_with_a_run_per_sample_is_bounded() {
+    let pcm = sample_entry(b"sowt", 0, &[], &[]);
+    // One stts run per sample: symphonia scans the runs from the start for every packet.
+    let runs = |n: u32| atom(b"stts", &[&[0; 4][..], &n.to_be_bytes(), &[1u32, 1].map(u32::to_be_bytes).concat().repeat(n as usize)[..]].concat());
+    let frames = 1 << 14;
+    let (_, buf) = decode(&mp4(frames, &pcm, |k, a| if k == b"stts" { runs(frames) } else { a }), None).unwrap();
+    assert_eq!(buf.frames(), frames as usize, "a table at the bound still decodes");
+    let f = mp4(frames + 1, &pcm, |k, a| if k == b"stts" { runs(frames + 1) } else { a });
+    assert!(matches!(decode(&f, None), Err(AudioError::Malformed(m)) if m.contains("timing table")), "one run past the bound is refused");
+}
+
+#[test]
+fn the_audio_timing_bound_follows_the_sample_entry_not_the_handler() {
+    let pcm = sample_entry(b"sowt", 0, &[], &[]);
+    let runs = |n: u32| atom(b"stts", &[&[0; 4][..], &n.to_be_bytes(), &[1u32, 1].map(u32::to_be_bytes).concat().repeat(n as usize)[..]].concat());
+    // an audio sample entry under a video handler is still decoded as audio by symphonia
+    let video_handler = atom(b"hdlr", &[0u32, 0, u32::from_be_bytes(*b"vide"), 0, 0, 0, 0].map(u32::to_be_bytes).concat());
+    let frames = (1 << 14) + 1;
+    let f = mp4(frames, &pcm, |k, a| match k {
+        b"stts" => runs(frames),
+        b"hdlr" => video_handler.clone(),
+        _ => a,
+    });
+    assert!(matches!(decode(&f, None), Err(AudioError::Malformed(m)) if m.contains("timing table")), "the handler does not exempt an audio entry");
+}
+
+#[test]
+fn the_last_sample_entry_decides_whether_the_timing_bound_applies() {
+    let pcm = sample_entry(b"sowt", 0, &[], &[]);
+    let video = sample_entry(b"avc1", 0, &[], &[]);
+    let runs = |n: u32| atom(b"stts", &[&[0; 4][..], &n.to_be_bytes(), &[1u32, 1].map(u32::to_be_bytes).concat().repeat(n as usize)[..]].concat());
+    let audio_stsd = atom(b"stsd", &[&[0, 0, 0, 0, 0, 0, 0, 1][..], &pcm].concat());
+    let frames = (1 << 14) + 1;
+    // A video `stsd` first and an audio one after it: symphonia keeps the last, so it decodes audio.
+    let f = mp4(frames, &video, |k, a| if k == b"stts" { [audio_stsd.clone(), runs(frames)].concat() } else { a });
+    assert!(matches!(decode(&f, None), Err(AudioError::Malformed(m)) if m.contains("timing table")), "the later audio entry counts");
+}
+
+#[test]
+fn a_pcm_packet_longer_than_its_declared_frames_is_refused_before_decoding() {
+    let pcm = sample_entry(b"sowt", 0, &[], &[]);
+    // one `stsz` sample of 2 * 2^24 + 2 bytes (just over the packet bound) in a file that holds it
+    let big = 2 * (1usize << 24) + 2;
+    let stsz = atom(b"stsz", &[0u32, big as u32, 1].map(u32::to_be_bytes).concat());
+    let mut f = mp4(1, &pcm, |k, a| if k == b"stsz" { stsz.clone() } else { a });
+    f.resize(f.len() + big, 0);
+    assert!(matches!(decode(&f, None), Err(AudioError::Malformed(m)) if m.contains("packet holds far more samples")));
 }
 
 /// FLAC metadata blocks with field lengths exceeding their block boundary are refused as malformed.

crates/automation/tests/it/automation_roots.rs

@@ -310,6 +310,36 @@ fn links_out_of_the_roots_are_refused() {
     ok(&mut via_alias, "file.import_audio", json!({"path": s(f.read.join("tone.wav"))}));
 }
 
+#[cfg(any(unix, windows))]
+#[test]
+fn exports_refuse_hard_links_without_changing_either_name() {
+    let f = fixture("hard-links");
+    let midi = f.write.join("linked.mid");
+    let preset = f.write.join("linked.json");
+    std::fs::hard_link(f.outside.join("secret.mid"), &midi).unwrap();
+    std::fs::hard_link(f.outside.join("secret.json"), &preset).unwrap();
+    let mut srv = demo_server(Some(&f.read), Some(&f.write));
+    let before = listing(&f.write);
+
+    // Refusal is the safe alternative allowed by #1359: neither the outside inode nor its
+    // in-root alias may be truncated, and no replacement or temporary file may be left behind.
+    refused(&mut srv, "file.export_midi", json!({"path": s(&midi)}), "hard-linked");
+    refused(&mut srv, "track.save_preset", json!({"path": s(&preset), "tracks": ["Kick"]}), "hard-linked");
+    for path in [&midi, &preset, &f.outside.join("secret.mid"), &f.outside.join("secret.json")] {
+        assert_eq!(std::fs::read(path).unwrap(), SECRET.as_bytes());
+    }
+    assert_eq!(listing(&f.write), before);
+
+    // The error offers a new export path; both commands must still work at ordinary paths.
+    let fresh_midi = f.write.join("fresh.mid");
+    ok(&mut srv, "file.export_midi", json!({"path": s(&fresh_midi)}));
+    assert!(std::fs::read(fresh_midi).unwrap().starts_with(b"MThd"));
+    let fresh_preset = f.write.join("fresh.json");
+    ok(&mut srv, "track.save_preset", json!({"path": s(&fresh_preset), "tracks": ["Kick"]}));
+    let preset_json: Value = serde_json::from_slice(&std::fs::read(fresh_preset).unwrap()).unwrap();
+    assert_eq!(preset_json["name"], "Kick");
+}
+
 /// A session file is hostile input too: media it names outside the read root is not loaded,
 /// and the refusal is listed with the other missing media.
 #[test]

crates/clap-host/src/plugin.rs

@@ -10,6 +10,10 @@ use std::sync::atomic::Ordering;
 const MAX_BLOCK: usize = 1 << 16;
 /// Most channels a host strip may ask for.
 const MAX_CHANNELS: usize = 64;
+/// Queue slots that only releases from `note_off` may take: one per key, so a queue that
+/// parameter changes, note-ons or other MIDI filled still has room to release every held key on
+/// a reset (#1464).
+const RELEASE_RESERVE: usize = 128;
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 enum NoteMode {
@@ -79,14 +83,104 @@ impl ClapPlugin {
         self.queue.retain(|e| !matches!(e, Event::Param { .. }));
     }
 
-    /// Inserts keeping the queue time-sorted; drops the event when the queue is full (never
-    /// allocates on the audio thread).
+    /// Queues an event other than a note release; see [`push_event`].
     fn push(&mut self, e: Event) {
-        if self.queue.len() >= self.queue.capacity() {
-            return;
+        push_event(&mut self.queue, e, false);
+    }
+}
+
+/// Inserts keeping the queue time-sorted; drops the event when the queue is full (never
+/// allocates on the audio thread). Only a `release` may take the last [`RELEASE_RESERVE`] slots.
+/// Returns whether the event was queued.
+fn push_event(queue: &mut Vec<Event>, e: Event, release: bool) -> bool {
+    let room = if release { queue.capacity() } else { queue.capacity().saturating_sub(RELEASE_RESERVE) };
+    if queue.len() >= room {
+        return false;
+    }
+    let pos = queue.iter().rposition(|q| q.time() <= e.time()).map_or(0, |i| i + 1);
+    queue.insert(pos, e);
+    true
+}
+
+/// Queues the release of `key` at `time`. The key stays held when the queue has no room, so a
+/// later reset still releases it (#1464).
+fn queue_release(queue: &mut Vec<Event>, held: &mut [bool; 128], notes: NoteMode, time: u32, key: u8) {
+    if let Some(e) = release_event(notes, time, key)
+        && push_event(queue, e, true)
+        && let Some(h) = held.get_mut(usize::from(key))
+    {
+        *h = false;
+    }
+}
+
+/// The release of `key` in the note port's dialect (`None` without a note port).
+fn release_event(notes: NoteMode, time: u32, key: u8) -> Option<Event> {
+    match notes {
+        NoteMode::Clap => Some(Event::NoteOff { time, key }),
+        NoteMode::Midi => Some(Event::Midi { time, data: [0x80, key, 0] }),
+        NoteMode::None => None,
+    }
+}
+
+/// The queue after a reset: [`keep_releases`], then a release at the start of the next block for
+/// every key still `held` that has none yet, so each key is released once. Clears `held`.
+///
+/// It never runs out of room: events other than `note_off` releases fill at most
+/// `capacity - RELEASE_RESERVE` slots, and the releases left are one per key.
+fn release_on_reset(queue: &mut Vec<Event>, held: &mut [bool; 128], notes: NoteMode) {
+    keep_releases(queue);
+    for e in queue.iter() {
+        let key = match *e {
+            Event::NoteOff { key, .. } => Some(key),
+            // Channel 1, where `note_off` sends them.
+            Event::Midi { data: [status, key, velocity], .. } if status & 0x0F == 0 && is_midi_note_off(status, velocity) => Some(key),
+            _ => None,
+        };
+        if let Some(h) = key.and_then(|k| held.get_mut(usize::from(k))) {
+            *h = false;
         }
-        let pos = self.queue.iter().rposition(|q| q.time() <= e.time()).map_or(0, |i| i + 1);
-        self.queue.insert(pos, e);
+    }
+    for key in 0..128u8 {
+        if held.get(usize::from(key)).copied().unwrap_or(false)
+            && let Some(e) = release_event(notes, 0, key)
+        {
+            let _ = push_event(queue, e, true);
+        }
+    }
+    *held = [false; 128];
+}
+
+/// What a reset keeps of the pending events: parameter changes, and the releases (CLAP note-offs
+/// and MIDI note-offs, one per channel and key), all moved to the start of the next block. Note-ons
+/// and other MIDI belong to the position being left. One release per key leaves room in the queue
+/// for `all_notes_off`.
+fn keep_releases(queue: &mut Vec<Event>) {
+    let mut clap_off = [false; 128];
+    let mut midi_off = [[false; 128]; 16];
+    queue.retain(|e| match *e {
+        Event::Param { .. } => true,
+        Event::NoteOff { key, .. } => first_release(clap_off.get_mut(usize::from(key))),
+        Event::Midi { data: [status, key, velocity], .. } if is_midi_note_off(status, velocity) => {
+            first_release(midi_off.get_mut(usize::from(status & 0x0F)).and_then(|c| c.get_mut(usize::from(key))))
+        }
+        _ => false,
+    });
+    for e in queue.iter_mut() {
+        e.set_time(0);
+    }
+}
+
+/// Marks a key's release as seen; true only the first time (false for a key out of range).
+fn first_release(seen: Option<&mut bool>) -> bool {
+    seen.is_some_and(|s| !std::mem::replace(s, true))
+}
+
+/// A MIDI 1.0 note-off: status 0x8n, or a note-on (0x9n) with velocity 0.
+fn is_midi_note_off(status: u8, velocity: u8) -> bool {
+    match status & 0xF0 {
+        0x80 => true,
+        0x90 => velocity == 0,
+        _ => false,
     }
 }
 
@@ -185,8 +279,10 @@ impl Plugin for ClapPlugin {
 
     fn reset(&mut self) {
         self.inst.reset();
-        self.queue.retain(|e| matches!(e, Event::Param { .. }));
-        self.held = [false; 128];
+        // Keep pending releases and release whatever is still held: CLAP asks `reset` to kill
+        // voices, but some plugins' doesn't (Surge XT's), and they would sound on with nothing
+        // left to release them (#1464).
+        release_on_reset(&mut self.queue, &mut self.held, self.notes);
     }
 
     fn set_param(&mut self, id: &str, value: f32) -> bool {
@@ -287,14 +383,7 @@ impl Plugin for ClapPlugin {
             return;
         }
         let time = u32::try_from(offset).unwrap_or(u32::MAX);
-        match self.notes {
-            NoteMode::Clap => self.push(Event::NoteOff { time, key: note }),
-            NoteMode::Midi => self.push(Event::Midi { time, data: [0x80, note, 0] }),
-            NoteMode::None => return,
-        }
-        if let Some(h) = self.held.get_mut(note as usize) {
-            *h = false;
-        }
+        queue_release(&mut self.queue, &mut self.held, self.notes, time, note);
     }
 
     fn midi(&mut self, offset: usize, msg: [u8; 3]) {
@@ -383,3 +472,107 @@ impl PluginEditor for ClapEditor {
         self.link.host().dirty.swap(false, Ordering::Relaxed)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// A reset keeps parameter changes and one release per key, at the start of the next block,
+    /// and drops note-ons and other MIDI.
+    #[test]
+    fn reset_keeps_params_and_one_release_per_key() {
+        let mut q = vec![
+            Event::Param { time: 0, id: 4, value: 0.5 },
+            Event::NoteOn { time: 3, key: 60, velocity: 1.0 },
+            Event::NoteOff { time: 5, key: 60 },
+            Event::NoteOff { time: 9, key: 60 },
+            Event::NoteOff { time: 12, key: 64 },
+            Event::Midi { time: 20, data: [0x90, 62, 90] },
+            Event::Midi { time: 21, data: [0xB0, 64, 127] },
+            Event::Midi { time: 22, data: [0x80, 62, 0] },
+            Event::Midi { time: 23, data: [0x80, 62, 40] },
+            Event::Midi { time: 24, data: [0x83, 62, 0] },
+            Event::Midi { time: 25, data: [0x91, 67, 0] },
+            Event::Midi { time: 26, data: [0x80, 200, 0] },
+        ];
+        keep_releases(&mut q);
+        assert_eq!(
+            q,
+            vec![
+                Event::Param { time: 0, id: 4, value: 0.5 },
+                Event::NoteOff { time: 0, key: 60 },
+                Event::NoteOff { time: 0, key: 64 },
+                Event::Midi { time: 0, data: [0x80, 62, 0] },
+                Event::Midi { time: 0, data: [0x83, 62, 0] },
+                Event::Midi { time: 0, data: [0x91, 67, 0] },
+            ]
+        );
+    }
+
+    /// A queue that parameter changes filled still releases every held key on a reset, once
+    /// each, and keeps the parameter changes.
+    #[test]
+    fn a_full_queue_still_releases_every_held_key_on_reset() {
+        for notes in [NoteMode::Clap, NoteMode::Midi] {
+            let mut q = Vec::with_capacity(EVENT_CAP);
+            for id in 0..EVENT_CAP as u32 {
+                let _ = push_event(&mut q, Event::Param { time: 0, id, value: 0.0 }, false);
+            }
+            assert_eq!(q.len(), EVENT_CAP - RELEASE_RESERVE, "parameter changes leave the reserve free");
+            // Keys 0..4 already have a release queued, and are held again after it.
+            for key in 0..4u8 {
+                let _ = push_event(&mut q, release_event(notes, 7, key).unwrap(), true);
+            }
+            let mut held = [true; 128];
+            release_on_reset(&mut q, &mut held, notes);
+            assert_eq!(held, [false; 128]);
+            assert_eq!(q.iter().filter(|e| matches!(e, Event::Param { .. })).count(), EVENT_CAP - RELEASE_RESERVE, "{notes:?}");
+            for key in 0..128u8 {
+                let want = release_event(notes, 0, key).unwrap();
+                assert_eq!(q.iter().filter(|e| **e == want).count(), 1, "{notes:?}: key {key} is released once");
+            }
+            assert_eq!(q.len(), EVENT_CAP);
+        }
+    }
+
+    /// A release that finds the queue full (parameter changes plus duplicate releases) leaves its
+    /// key held, so the reset that follows still releases it, as the mix's `all_notes_off`
+    /// then `reset` does on Stop.
+    #[test]
+    fn a_release_the_full_queue_drops_is_sent_by_the_next_reset() {
+        for notes in [NoteMode::Clap, NoteMode::Midi] {
+            let mut q = Vec::with_capacity(EVENT_CAP);
+            let mut held = [false; 128];
+            for id in 0..EVENT_CAP as u32 {
+                let _ = push_event(&mut q, Event::Param { time: 0, id, value: 0.0 }, false);
+            }
+            // Key 0 pressed and released over and over fills the reserve with its releases.
+            for t in 0..RELEASE_RESERVE as u32 {
+                held[0] = true;
+                queue_release(&mut q, &mut held, notes, t, 0);
+            }
+            assert_eq!(q.len(), EVENT_CAP, "{notes:?}: the queue is full");
+            held[5] = true;
+            queue_release(&mut q, &mut held, notes, 0, 5);
+            assert!(held[5], "{notes:?}: a release that was not queued leaves its key held");
+            release_on_reset(&mut q, &mut held, notes);
+            for key in [0u8, 5] {
+                let want = release_event(notes, 0, key).unwrap();
+                assert_eq!(q.iter().filter(|e| **e == want).count(), 1, "{notes:?}: key {key} is released once");
+            }
+            assert_eq!(held, [false; 128]);
+        }
+    }
+
+    /// A queue full of releases still has room to release every held key after a reset.
+    #[test]
+    fn reset_keeps_room_to_release_every_held_key() {
+        let mut q = Vec::with_capacity(EVENT_CAP);
+        for i in 0..EVENT_CAP {
+            q.push(Event::NoteOff { time: i as u32, key: (i % 4) as u8 });
+        }
+        keep_releases(&mut q);
+        let want: Vec<Event> = (0..4u8).map(|key| Event::NoteOff { time: 0, key }).collect();
+        assert_eq!(q, want, "one release per key remains");
+    }
+}

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

@@ -4,7 +4,7 @@
 //!   (stepped enum A/B/C), hidden param 9, latency 3 samples.
 //! - `org.soundcraft.test.synth`: instrument, stereo out, CLAP note port; outputs a constant equal
 //!   to the velocity of the held note (0 when none), switching at the event's sample offset. A
-//!   MIDI CC 7 (volume) sets the constant to its value / 127.
+//!   MIDI CC 7 (volume) sets the constant to its value / 127. `reset` leaves the note sounding.
 //!
 //! - `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).
@@ -166,9 +166,9 @@ unsafe extern "C" fn stop_processing(p: *const clap_plugin) {
     unsafe { fx(p) }.processing = false;
 }
 
-unsafe extern "C" fn reset(p: *const clap_plugin) {
-    unsafe { fx(p) }.level = 0.0;
-}
+/// Leaves the synth's note sounding. CLAP asks `reset` to kill voices, but some synths' doesn't
+/// (Surge XT's), so the host must send the releases itself.
+unsafe extern "C" fn reset(_p: *const clap_plugin) {}
 
 fn apply(f: &mut Fx, h: &clap_event_header) {
     if h.space_id != CLAP_CORE_EVENT_SPACE_ID {

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

@@ -109,6 +109,48 @@ fn synth_plays_notes_at_their_offsets() {
     assert!(io[0][19].abs() < 1e-6 && (io[0][20] - 64.0 / 127.0).abs() < 1e-6, "controllers arrive as MIDI at their offset");
 }
 
+/// Renders one 64-frame stereo block of `p` and returns its left channel.
+fn render_block(p: &mut dyn soundcraft_dsp::Plugin) -> Vec<f32> {
+    let mut io = vec![vec![0.0f32; 64], vec![0.0f32; 64]];
+    p.process(&mut io, 64);
+    io.swap_remove(0)
+}
+
+/// Stop, Play and Locate run `all_notes_off` then `reset`: the releases reach a synth whose own
+/// reset leaves its voices sounding, and a later block is silent (#1464).
+#[test]
+fn reset_delivers_the_releases_of_held_notes() {
+    fixture_dir();
+    let mut p = soundcraft_clap_host::create(SYNTH).unwrap();
+    p.prepare(48_000.0, 64, 2);
+    let silent = |b: &[f32]| b.iter().all(|x| x.abs() < 1e-6);
+
+    // As the mix engine does on Stop: release the held note, then reset.
+    p.note_on(0, 60, 127);
+    assert!(render_block(p.as_mut()).iter().all(|&x| (x - 1.0).abs() < 1e-6), "the note sounds");
+    p.all_notes_off();
+    p.reset();
+    assert!(silent(&render_block(p.as_mut())), "all_notes_off's release was dropped by reset");
+
+    // A reset alone releases what is still held.
+    p.note_on(0, 61, 127);
+    render_block(p.as_mut());
+    p.reset();
+    assert!(silent(&render_block(p.as_mut())), "reset did not release the held note");
+
+    // A release queued for a block that never ran is still delivered.
+    p.note_on(0, 62, 127);
+    render_block(p.as_mut());
+    p.note_off(30, 62);
+    p.reset();
+    assert!(silent(&render_block(p.as_mut())), "the pending release was dropped by reset");
+
+    // A note-on queued for the position being left is dropped, not played after the reset.
+    p.note_on(10, 63, 127);
+    p.reset();
+    assert!(silent(&render_block(p.as_mut())), "a note-on from before the reset sounded");
+}
+
 #[test]
 fn layouts_beyond_the_host_limits_are_rejected_not_truncated() {
     fixture_dir();

crates/engine/Cargo.toml

@@ -25,6 +25,9 @@ log.workspace = true
 zip.workspace = true
 craft-docpath.workspace = true
 
+[target.'cfg(windows)'.dependencies]
+winsafe = { version = "0.0.29", features = ["kernel"] }
+
 [dev-dependencies]
 proptest.workspace = true
 

crates/engine/src/autosave.rs

@@ -454,6 +454,32 @@ pub fn create_folder(dir: &Path) -> std::io::Result<()> {
     builder.create(dir)
 }
 
+/// A new folder directly in `parent`, named `{prefix}-` and 32 random hex digits. It is made
+/// exclusively (it is created by this call or the call fails), so a folder or link another account
+/// put there first is never used, and the name cannot be guessed ahead. On Unix it is owner-only
+/// (`0o700`); on other systems it has the mode `parent` gives it.
+pub fn create_unique_folder(parent: &Path, prefix: &str) -> std::io::Result<PathBuf> {
+    use std::hash::{BuildHasher, Hasher};
+    // One plain name: a prefix like `../x` would make a sibling of `parent`, not a child.
+    let mut parts = Path::new(prefix).components();
+    if !matches!((parts.next(), parts.next()), (Some(std::path::Component::Normal(_)), None)) || prefix.contains(['/', '\\']) {
+        return Err(std::io::Error::new(std::io::ErrorKind::InvalidInput, "the folder prefix must be a single name"));
+    }
+    for _ in 0..16 {
+        let random = |_| std::collections::hash_map::RandomState::new().build_hasher().finish();
+        let dir = parent.join(format!("{prefix}-{:016x}{:016x}", random(0), random(1)));
+        let mut builder = std::fs::DirBuilder::new();
+        #[cfg(unix)]
+        std::os::unix::fs::DirBuilderExt::mode(&mut builder, 0o700);
+        match builder.create(&dir) {
+            Ok(()) => return Ok(dir),
+            Err(err) if err.kind() == std::io::ErrorKind::AlreadyExists => {}
+            Err(err) => return Err(err),
+        }
+    }
+    Err(std::io::Error::new(std::io::ErrorKind::AlreadyExists, "no unused folder name"))
+}
+
 fn write_synced(path: &Path, bytes: &[u8]) -> std::io::Result<()> {
     let mut f = std::fs::File::create(path)?;
     f.write_all(bytes)?;
@@ -476,6 +502,25 @@ fn io_error(path: &Path, err: std::io::Error) -> EngineError {
 mod tests {
     use super::*;
     use crate::io::open_session;
+
+    #[test]
+    fn unique_folders_are_new_and_owner_only() {
+        let parent = std::env::temp_dir().join(format!("soundcraft-unique-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&parent);
+        std::fs::create_dir_all(&parent).unwrap();
+        let (a, b) = (create_unique_folder(&parent, "T").unwrap(), create_unique_folder(&parent, "T").unwrap());
+        assert_ne!(a, b);
+        assert!(a.is_dir() && a.parent() == Some(parent.as_path()));
+        assert_eq!(a.file_name().unwrap().len(), "T-".len() + 32);
+        #[cfg(unix)]
+        assert_eq!(std::os::unix::fs::PermissionsExt::mode(&std::fs::metadata(&a).unwrap().permissions()) & 0o777, 0o700);
+        assert!(create_unique_folder(&parent.join("missing"), "T").is_err(), "no parents are made");
+        for bad in ["../outside", "a/b", "a\\b", "..", ".", "", "/abs"] {
+            assert!(create_unique_folder(&parent, bad).is_err(), "{bad:?} is not a single name");
+        }
+        let _ = std::fs::remove_dir_all(&parent);
+    }
+
     use serde_json::json;
     use soundcraft_audio_io::AudioBuffer;
     use soundcraft_model::{ChannelFormat, Clip, TrackKind};

crates/engine/src/clip_group_file.rs

@@ -87,23 +87,30 @@ fn decode_group_audio(
     cmd_id: &str,
 ) -> Result<(Vec<(String, soundcraft_audio_io::AudioBuffer)>, BTreeMap<u64, usize>)> {
     let (mut decoded, mut index, mut file_of) = (Vec::new(), BTreeMap::new(), BTreeMap::new());
+    // The folder as the file system knows it, so a link among the group's files can't lead out.
+    let dir = if dir.as_os_str().is_empty() { Path::new(".") } else { dir };
+    let root = crate::io::canonical_path(dir)?;
     for (old, rel) in audio_entries {
         let full = dir.join(rel);
+        let escapes = |rel: &str| EngineError::BadParams(cmd_id.into(), format!("audio path escapes the group folder: {rel}"));
         if !full.starts_with(dir)
             || Path::new(rel)
                 .components()
                 .any(|c| matches!(c, std::path::Component::ParentDir | std::path::Component::RootDir | std::path::Component::Prefix(_)))
         {
-            return Err(EngineError::BadParams(cmd_id.into(), format!("audio path escapes the group folder: {rel}")));
+            return Err(escapes(rel));
+        }
+        let key = crate::io::canonical_path(&full)?;
+        if !key.starts_with(&root) {
+            return Err(escapes(rel));
         }
-        let key = crate::io::file_key(&full);
         let n = match index.get(&key) {
             Some(n) => *n,
             None => {
-                let bytes = crate::io::read_file(&full)?;
+                let bytes = crate::io::read_file_inside(&full, &root)?;
                 let (_, buf) = soundcraft_audio_io::decode(&bytes, Some("wav")).map_err(|err| EngineError::Io(format!("{rel}: {err}")))?;
                 let buf = crate::io::at_rate(buf, rate, crate::io::MAX_IMPORT_SAMPLES)
-                    .ok_or_else(|| EngineError::Io(format!("{rel}: too large to import")))?;
+                    .map_err(|r| EngineError::Io(format!("{rel}: {}", r.message("too large to import"))))?;
                 decoded.push((rel.clone(), buf));
                 index.insert(key, decoded.len() - 1);
                 decoded.len() - 1
@@ -268,9 +275,59 @@ mod tests {
         std::fs::write(&path, file.to_string()).unwrap();
         let r = e.execute("file.import_clip_groups", &json!({"path": path, "at": 1000, "track": "Bass"}));
         assert!(matches!(r, Err(crate::EngineError::BadParams(..))), "absolute paths are refused: {r:?}");
+        // A link inside the folder that leads out of it is refused once resolved.
+        #[cfg(unix)]
+        {
+            let outside = std::env::temp_dir().join(format!("sc-grp-outside-{}.wav", std::process::id()));
+            std::fs::copy(dir.join("Wait... what_0.wav"), &outside).unwrap();
+            std::os::unix::fs::symlink(&outside, dir.join("link.wav")).unwrap();
+            for rel in file["audio"].as_object_mut().unwrap().values_mut() {
+                *rel = json!("link.wav");
+            }
+            std::fs::write(&path, file.to_string()).unwrap();
+            let r = e.execute("file.import_clip_groups", &json!({"path": path, "at": 1000, "track": "Bass"}));
+            assert!(matches!(r, Err(crate::EngineError::BadParams(..))), "links out of the folder are refused: {r:?}");
+            let _ = std::fs::remove_file(&outside);
+        }
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    /// Under a read root, a link in the group folder to a folder outside the root is refused the same way
+    /// whether or not the file asked for exists there, so the group cannot be used to probe for names.
+    #[cfg(unix)]
+    #[test]
+    fn links_out_of_the_read_root_are_refused_alike_for_existing_and_missing_files() {
+        let base = std::env::temp_dir().join(format!("sc-grp-root-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&base);
+        let (dir, outside) = (base.join("group"), base.join("outside"));
+        std::fs::create_dir_all(&dir).unwrap();
+        std::fs::create_dir_all(&outside).unwrap();
+        let path = dir.join("drums.scgrp").to_string_lossy().to_string();
+        let mut e = crate::demo::demo_engine();
+        let kick = e.session().tracks.iter().find(|t| t.name == "Kick").map(|t| t.id).unwrap();
+        let ids: Vec<_> = e.session().track(kick).unwrap().clips().iter().take(1).map(|c| c.id.0).collect();
+        e.execute("file.export_clip_groups", &json!({"path": path, "clips": ids})).unwrap();
+        let mut file: serde_json::Value = serde_json::from_str(&std::fs::read_to_string(&path).unwrap()).unwrap();
+        let exported = file["audio"].as_object().unwrap().values().next().unwrap().as_str().unwrap().to_string();
+        std::fs::copy(dir.join(&exported), outside.join("real.wav")).unwrap();
+        std::os::unix::fs::symlink(&outside, dir.join("out")).unwrap();
+        let roots = crate::file_access::AutomationRoots::new(&[&dir], &[]).unwrap().unwrap();
+        let mut refusals = Vec::new();
+        for target in ["out/real.wav", "out/missing.wav"] {
+            for rel in file["audio"].as_object_mut().unwrap().values_mut() {
+                *rel = json!(target);
+            }
+            std::fs::write(&path, file.to_string()).unwrap();
+            let r = crate::file_access::confine(Some(&roots), || {
+                e.execute("file.import_clip_groups", &json!({"path": path, "at": 1000, "track": "Bass"}))
+            });
+            refusals.push(r.unwrap_err().to_string());
+        }
+        assert!(refusals[0].contains("outside the read root"), "{}", refusals[0]);
+        assert_eq!(refusals[0].replace("real.wav", "X"), refusals[1].replace("missing.wav", "X"), "existing and missing names are refused alike");
+        let _ = std::fs::remove_dir_all(&base);
+    }
+
     #[test]
     fn imported_clips_carry_no_auto_rename_scheme() {
         let dir = std::env::temp_dir().join(format!("sc-grp-names-{}", std::process::id()));

crates/engine/src/cmd/event.rs

@@ -154,6 +154,7 @@ fn insert_time(e: &mut Engine, p: &Value) -> Result<Value> {
     let s = e.session_mut();
     let ids: Vec<_> = s.tracks.iter().map(|t| t.id).collect();
     for t in ids {
+        crate::edit::separate_all_at(s, t, r.start);
         crate::edit::insert_silence(s, t, r);
         if let Some(tr) = s.track_mut(t) {
             for l in &mut tr.automation {
@@ -185,6 +186,8 @@ fn cut_time(e: &mut Engine, p: &Value) -> Result<Value> {
     let s = e.session_mut();
     let ids: Vec<_> = s.tracks.iter().map(|t| t.id).collect();
     for t in ids {
+        crate::edit::separate_all_at(s, t, r.start);
+        crate::edit::separate_all_at(s, t, r.end);
         crate::edit::clear_range(s, t, r, false);
         crate::edit::shift_from(s, t, r.end, -r.len());
         if let Some(tr) = s.track_mut(t) {

crates/engine/src/cmd/file.rs

@@ -94,9 +94,14 @@ pub fn specs() -> Vec<CommandSpec> {
             let dir = str_param(p, "dir").ok_or_else(|| bad("file.bounce_stems", "`dir` required"))?.to_string();
             let r = range_param(e, "file.bounce_stems", p)?;
             let r = if r.is_empty() { soundcraft_time::Range::new(0, e.session().content_end().max(1)) } else { r };
-            let format = str_param(p, "format")
-                .and_then(soundcraft_audio_io::FileFormat::from_write_extension)
-                .unwrap_or(soundcraft_audio_io::FileFormat::Wav);
+            let format_name = match p.get("format") {
+                None => "wav",
+                Some(value) => value.as_str().ok_or_else(|| bad("file.bounce_stems", "`format` must be a string"))?,
+            };
+            let format = soundcraft_audio_io::FileFormat::from_write_extension(format_name).ok_or_else(|| {
+                let supported = soundcraft_audio_io::FileFormat::writable_extensions().join(", ");
+                bad("file.bounce_stems", format!("cannot write `{format_name}` files (supported: {supported})"))
+            })?;
             let bit_depth = match p.get("bit_depth").map(|b| b.to_string().trim_matches('"').to_string()).as_deref() {
                 Some("16") => soundcraft_audio_io::BitDepth::Int16,
                 Some("32") | Some("32f") => soundcraft_audio_io::BitDepth::Float32,

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

@@ -118,6 +118,71 @@ fn import_audio_honours_new_tracks() {
     let _ = std::fs::remove_dir_all(dir);
 }
 
+#[test]
+fn bounce_stems_rejects_unsupported_formats_before_writing() {
+    let dir = std::env::temp_dir().join(format!("sc-stems-unsupported-format-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir(&dir).unwrap();
+    let stems = dir.join("stems");
+    let mut e = Engine::default();
+    e.execute("track.new", &json!({"count": 1, "name": "Tone", "format": "mono"})).unwrap();
+    let result = e.execute("file.bounce_stems", &json!({"dir": stems, "format": "not-a-format", "start": 0, "end": 1}));
+    let created_output = stems.exists();
+    // Own this directory exclusively; remove any baseline output before the assertion can fail.
+    std::fs::remove_dir_all(&dir).unwrap();
+    let err = result.map(|_| ()).unwrap_err();
+    assert!(err.to_string().contains("cannot write `not-a-format`"), "{err}");
+    assert!(err.to_string().contains("supported: wav"), "{err}");
+    assert!(!created_output, "an unsupported format must not create the output directory");
+}
+
+#[test]
+fn bounce_stems_rejects_non_string_formats_before_writing() {
+    let dir = std::env::temp_dir().join(format!("sc-stems-format-type-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir(&dir).unwrap();
+    let mut e = Engine::default();
+    e.execute("track.new", &json!({"count": 1, "name": "Tone", "format": "mono"})).unwrap();
+    let results: Vec<_> = [json!(null), json!(123), json!(false), json!([]), json!({})]
+        .into_iter()
+        .enumerate()
+        .map(|(index, format)| {
+            let stems = dir.join(index.to_string());
+            let result = e.execute("file.bounce_stems", &json!({"dir": stems, "format": format, "start": 0, "end": 1}));
+            (result, stems.exists())
+        })
+        .collect();
+    std::fs::remove_dir_all(&dir).unwrap();
+    for (result, created_output) in results {
+        let err = result.map(|_| ()).unwrap_err();
+        assert!(err.to_string().contains("`format` must be a string"), "{err}");
+        assert!(!created_output, "a non-string format must not create the output directory");
+    }
+}
+
+#[test]
+fn bounce_stems_accepts_explicit_wav_format() {
+    let dir = std::env::temp_dir().join(format!("sc-stems-explicit-wav-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir(&dir).unwrap();
+    let mut e = Engine::default();
+    let wav = tone_wav(&dir, "tone.wav");
+    e.execute("file.import_audio", &json!({"path": wav})).unwrap();
+    let stems = dir.join("stems");
+    let result = e.execute("file.bounce_stems", &json!({"dir": stems, "format": "wav", "start": 0, "end": 32, "dither": false})).unwrap();
+    let files = result["files"].as_array().unwrap();
+    assert_eq!(files.len(), 1);
+    let path = std::path::Path::new(files[0].as_str().unwrap());
+    assert_eq!(path.parent(), Some(stems.as_path()));
+    assert_eq!(path.extension().and_then(|extension| extension.to_str()), Some("wav"));
+    let (info, audio) = soundcraft_audio_io::decode(&std::fs::read(path).unwrap(), None).unwrap();
+    assert_eq!(info.format, soundcraft_audio_io::FileFormat::Wav);
+    assert_eq!(audio.frames(), 32);
+    assert_eq!(audio.num_channels(), e.session().main_format().channels());
+    assert!(audio.channels.iter().flatten().any(|sample| sample.abs() > 0.01));
+    std::fs::remove_dir_all(&dir).unwrap();
+}
+
 #[test]
 fn bounce_refuses_formats_it_cannot_write() {
     let mut e = Engine::default();

crates/engine/src/cmd/sampler.rs

@@ -75,7 +75,7 @@ pub(crate) fn attach(e: &mut Engine, t: TrackId, name: &str, bytes: &[u8], path:
         return Err(EngineError::Io(format!("{name}: no audio")));
     }
     let buf = crate::io::at_rate(buf, e.session().sample_rate.hz(), MAX_SAMPLE_VALUES)
-        .ok_or_else(|| EngineError::Io(format!("{name}: too long for a sample (ten minutes of 192 kHz stereo at most)")))?;
+        .map_err(|r| EngineError::Io(format!("{name}: {}", r.message("too long for a sample (ten minutes of 192 kHz stereo at most)"))))?;
     let channels = buf.num_channels();
     let s = e.session_mut();
     let src = crate::io::add_source(s, name, buf, path, format.format);

crates/engine/src/edit.rs

@@ -78,9 +78,9 @@ fn rebase_midi_start(clip: &mut Clip, old_start: Samples, t: TimeCtx<'_>) {
     }
 }
 
-/// Split every clip on a track's active playlist that spans `at`. The piece before `at` keeps the
-/// clip's name. The piece after it is a new clip, and takes the next name of the clip's Auto Rename
-/// scheme when it has one.
+/// Split every clip on a track's active playlist that spans `at`, except time- or edit-locked ones.
+/// The piece before `at` keeps the clip's name. The piece after it is a new clip, and takes the next
+/// name of the clip's Auto Rename scheme when it has one.
 pub fn separate_at(s: &mut Session, track: TrackId, at: Samples) -> usize {
     separate_at_if(s, track, at, |_| true)
 }
@@ -88,11 +88,21 @@ pub fn separate_at(s: &mut Session, track: TrackId, at: Samples) -> usize {
 /// [`separate_at`], giving the piece after `at` the next Auto Rename name only when `auto_name`
 /// returns true for it. Any other piece keeps the clip's name, and its scheme does not count up.
 pub fn separate_at_if(s: &mut Session, track: TrackId, at: Samples, auto_name: impl Fn(&Clip) -> bool) -> usize {
+    split_at(s, track, at, auto_name, true)
+}
+
+/// [`separate_at`], splitting time- and edit-locked clips too. For the Event time operations, which
+/// move the whole timeline, locked clips included.
+pub fn separate_all_at(s: &mut Session, track: TrackId, at: Samples) -> usize {
+    split_at(s, track, at, |_| true, false)
+}
+
+fn split_at(s: &mut Session, track: TrackId, at: Samples, auto_name: impl Fn(&Clip) -> bool, skip_locked: bool) -> usize {
     let tc_tempo = s.tempo.clone();
     let sr = s.sample_rate;
     let t = TimeCtx { tempo: &tc_tempo, sr };
     let mut ids = Vec::new();
-    let n_split = s.track(track).map_or(0, |tr| tr.clips().iter().filter(|c| at > c.start && at < c.end()).count());
+    let n_split = s.track(track).map_or(0, |tr| tr.clips().iter().filter(|c| at > c.start && at < c.end() && !(skip_locked && locked(c))).count());
     for _ in 0..n_split {
         ids.push(s.new_clip_id());
     }
@@ -106,6 +116,7 @@ pub fn separate_at_if(s: &mut Session, track: TrackId, at: Samples, auto_name: i
     for c in pl.clips.drain(..) {
         if at > c.start
             && at < c.end()
+            && !(skip_locked && locked(&c))
             && let Some(id) = ids.pop()
             && let Some((l, mut r)) = split_clip(&c, at, id, t)
         {
@@ -125,6 +136,45 @@ pub fn separate_at_if(s: &mut Session, track: TrackId, at: Samples, auto_name: i
     count
 }
 
+/// Split every clip on a track's active playlist at each of `points`, in one pass over the
+/// playlist: [`separate_at_if`] once per point with `|_| false` (no piece takes an Auto Rename
+/// name here), without rebuilding the playlist per point. Returns the number of splits.
+/// `points` are sorted and deduplicated first, so the source offsets of stretched audio can differ
+/// from per-point calls given in another order (each trim rounds its own adjustment).
+pub fn separate_at_points(s: &mut Session, track: TrackId, points: &[Samples]) -> usize {
+    let mut pts = points.to_vec();
+    pts.sort_unstable();
+    pts.dedup();
+    let tc_tempo = s.tempo.clone();
+    let t = TimeCtx { tempo: &tc_tempo, sr: s.sample_rate };
+    // The points strictly inside a clip.
+    let within = |c: &Clip| {
+        let (lo, hi) = (pts.partition_point(|p| *p <= c.start), pts.partition_point(|p| *p < c.end()));
+        lo..hi.max(lo)
+    };
+    let n_split: usize = s.track(track).map_or(0, |tr| tr.clips().iter().map(|c| within(c).len()).sum());
+    let mut ids: Vec<ClipId> = (0..n_split).map(|_| s.new_clip_id()).collect();
+    let Some(pl) = s.track_mut(track).and_then(|t| t.playlist_mut()) else { return 0 };
+    let mut out = Vec::with_capacity(pl.clips.len() + n_split);
+    for c in pl.clips.drain(..) {
+        let mut rest = c;
+        for p in &pts[within(&rest)] {
+            let Some(id) = ids.pop() else { break };
+            match split_clip(&rest, *p, id, t) {
+                Some((l, r)) => {
+                    out.push(l);
+                    rest = r;
+                }
+                None => break,
+            }
+        }
+        out.push(rest);
+    }
+    pl.clips = out;
+    pl.sort();
+    n_split
+}
+
 /// Gives `c` the next name of its Auto Rename scheme, when it has one, and counts the scheme up.
 fn take_auto_name(schemes: &mut std::collections::BTreeMap<u64, soundcraft_model::AutoName>, c: &mut Clip) {
     if let Some(scheme) = c.auto_name.and_then(|k| schemes.get_mut(&k)) {
@@ -427,6 +477,10 @@ pub fn trim_to(s: &mut Session, track: TrackId, range: Range) -> usize {
     let Some(pl) = s.track_mut(track).and_then(|t| t.playlist_mut()) else { return 0 };
     let mut n = 0;
     for c in &mut pl.clips {
+        // Locked clips keep their extent, like they don't move for nudge.
+        if locked(c) {
+            continue;
+        }
         if let Some(i) = c.range().intersect(&range)
             && i != c.range()
         {
@@ -448,6 +502,9 @@ pub fn trim_start_to(s: &mut Session, track: TrackId, at: Samples) -> usize {
     let Some(pl) = s.track_mut(track).and_then(|t| t.playlist_mut()) else { return 0 };
     let mut n = 0;
     for c in &mut pl.clips {
+        if locked(c) {
+            continue;
+        }
         if c.range().contains(at) && at > c.start {
             let old = c.start;
             c.trim_start_to(at);
@@ -458,10 +515,14 @@ pub fn trim_start_to(s: &mut Session, track: TrackId, at: Samples) -> usize {
     n
 }
 
+/// Trim the end of clips after `at` to `at` (Trim End to Insertion).
 pub fn trim_end_to(s: &mut Session, track: TrackId, at: Samples) -> usize {
     let Some(pl) = s.track_mut(track).and_then(|t| t.playlist_mut()) else { return 0 };
     let mut n = 0;
     for c in &mut pl.clips {
+        if locked(c) {
+            continue;
+        }
         if at > c.start && at < c.end() {
             c.trim_end_to(at);
             n += 1;

crates/engine/src/io.rs

@@ -65,6 +65,69 @@ fn read_file_within(path: &Path, session: bool) -> Result<Vec<u8>> {
     Ok(data)
 }
 
+/// `O_NONBLOCK` of the platforms that have a FIFO to wait on (std has no name for it, and this crate has no unsafe
+/// code or libc); 0 elsewhere, where a FIFO open still waits for a writer.
+#[cfg(unix)]
+const O_NONBLOCK: i32 = if cfg!(all(
+    any(target_os = "linux", target_os = "android"),
+    not(any(
+        target_arch = "mips",
+        target_arch = "mips32r6",
+        target_arch = "mips64",
+        target_arch = "mips64r6",
+        target_arch = "sparc",
+        target_arch = "sparc64"
+    ))
+)) {
+    0x800
+} else if cfg!(any(
+    target_os = "macos",
+    target_os = "ios",
+    target_os = "freebsd",
+    target_os = "netbsd",
+    target_os = "openbsd",
+    target_os = "dragonfly"
+)) {
+    0x4
+} else {
+    0
+};
+
+/// [`read_file`] for a file that must lie inside `root` (a canonical folder): the file is opened
+/// once, and the bytes come from that handle only after the handle is shown to be the file the
+/// path resolves to inside `root`. A file swapped in for the path after a check by name is
+/// refused instead of read. Where the handle's identity can't be read (non-Unix targets) the
+/// resolved path is checked against `root` alone.
+pub(crate) fn read_file_inside(path: &Path, root: &Path) -> Result<Vec<u8>> {
+    use std::io::Read;
+    crate::file_access::check_read(path).map_err(EngineError::Io)?;
+    let err = |err: std::io::Error| EngineError::Io(format!("{}: {err}", path.display()));
+    // opened without waiting for a FIFO's writer (the type is checked on the opened handle, below)
+    let mut options = std::fs::OpenOptions::new();
+    options.read(true);
+    #[cfg(unix)]
+    std::os::unix::fs::OpenOptionsExt::custom_flags(&mut options, O_NONBLOCK);
+    let mut file = options.open(path).map_err(err)?;
+    if !file.metadata().map_err(err)?.is_file() {
+        return Err(EngineError::Io(format!("{}: not a regular file", path.display())));
+    }
+    let key = canonical_path(path)?;
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::MetadataExt;
+        let (a, b) = (file.metadata().map_err(err)?, std::fs::metadata(&key).map_err(err)?);
+        if (a.dev(), a.ino()) != (b.dev(), b.ino()) {
+            return Err(EngineError::Io(format!("{}: changed while it was opened", path.display())));
+        }
+    }
+    if !key.starts_with(root) {
+        return Err(EngineError::Io(format!("{}: outside the folder it must stay in", path.display())));
+    }
+    let mut bytes = Vec::new();
+    file.read_to_end(&mut bytes).map_err(err)?;
+    Ok(bytes)
+}
+
 /// [`read_file`] as UTF-8 text.
 pub fn read_text(path: impl AsRef<Path>) -> Result<String> {
     let path = path.as_ref();
@@ -192,6 +255,17 @@ pub(crate) fn make_dir(dir: impl AsRef<Path>) -> Result<()> {
     std::fs::create_dir_all(dir).map_err(|err| EngineError::Io(format!("{}: {err}", dir.display())))
 }
 
+/// `path` with its links followed, inside the automation read root when there is one. The root is
+/// checked on the path as named (links followed, a missing tail resolved by its nearest folder)
+/// before anything is resolved, so a name that leads out of the root is refused the same way
+/// whether or not it exists there.
+pub(crate) fn canonical_path(path: impl AsRef<Path>) -> Result<PathBuf> {
+    let path = path.as_ref();
+    let checked = if path.as_os_str().is_empty() { Path::new(".") } else { path };
+    crate::file_access::check_read(checked).map_err(EngineError::Io)?;
+    std::fs::canonicalize(path).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
+}
+
 /// Write `bytes` to the file at `path`, inside the automation write root when there is one.
 pub(crate) fn write_path(path: impl AsRef<Path>, bytes: impl AsRef<[u8]>) -> Result<()> {
     let path = path.as_ref();
@@ -446,7 +520,7 @@ impl Out {
         if cfg!(target_arch = "wasm32") {
             return Ok(Out::Memory(std::io::Cursor::new(Vec::new())));
         }
-        Ok(Out::File(std::io::BufWriter::with_capacity(1 << 20, std::fs::File::create(part)?)))
+        Ok(Out::File(std::io::BufWriter::with_capacity(1 << 20, create_new(part)?)))
     }
 
     /// Puts the finished file at `path` and returns its size: the part file is synced and renamed
@@ -578,8 +652,28 @@ pub fn export_clips(e: &Engine, ids: &[soundcraft_model::ClipId], dir: &str) ->
         let audio = soundcraft_mix::render_clips(s, t, c.range());
         let buf = AudioBuffer { sample_rate: s.sample_rate.hz(), channels: audio };
         let bytes = soundcraft_audio_io::encode(&buf, &EncodeOptions::default()).map_err(|err| EngineError::Io(err.to_string()))?;
-        let path = clip_file(dir, &sanitize_name(&c.name), &mut names, Path::exists)?;
-        write_file(&path.to_string_lossy(), &bytes)?;
+        let stem = sanitize_name(&c.name);
+        if cfg!(target_arch = "wasm32") {
+            let path = clip_file(dir, &stem, &mut names, Path::exists)?;
+            write_file(&path.to_string_lossy(), &bytes)?;
+            continue;
+        }
+        // The name is taken by creating the file, so whatever entry already has it (a link
+        // to elsewhere included) is left alone rather than written through. An occupied name is
+        // taken whatever it is (a link whose target is outside the write root too): it is only
+        // looked at, never resolved, so the root check does not stop the search for a free name.
+        // The folder itself was checked above.
+        let (mut file, path) = loop {
+            let path = clip_file(dir, &stem, &mut names, |p| std::fs::symlink_metadata(p).is_ok())?;
+            crate::file_access::check_write(&path).map_err(EngineError::Io)?;
+            match std::fs::OpenOptions::new().write(true).create_new(true).open(&path) {
+                Ok(f) => break (f, path),
+                // taken since it was looked at: `names` has it now, so the next name is tried
+                Err(err) if err.kind() == std::io::ErrorKind::AlreadyExists => {}
+                Err(err) => return Err(EngineError::Io(format!("{}: {err}", path.display()))),
+            }
+        };
+        std::io::Write::write_all(&mut file, &bytes).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))?;
     }
     Ok(names.taken.len())
 }
@@ -644,13 +738,13 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
         {
             src.path = f.join(&src.path).to_string_lossy().into_owned();
         }
-        let exists_rel = same_dir && !Path::new(&src.path).is_absolute() && dir.join(&src.path).exists();
+        let exists_rel = same_dir && !Path::new(&src.path).is_absolute() && file_found(dir.join(&src.path));
         let shared = shared_paths.get(i).copied().unwrap_or(false);
         if exists_rel && !src.unsaved && !shared {
             continue;
         }
         let in_folder = Path::new(&src.path).strip_prefix(&audio_dir).ok().and_then(Path::to_str).map(str::to_string);
-        if let Some(f) = in_folder.filter(|_| !src.unsaved && Path::new(&src.path).is_file()) {
+        if let Some(f) = in_folder.filter(|_| !src.unsaved && file_found(&src.path)) {
             src.path = format!("Audio Files/{f}");
             continue;
         }
@@ -672,8 +766,11 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
         let mut stem = sanitize_name(&src.name);
         if overwrite {
             // One file per source id so autosaves never collide or pile up.
+            // (With only an automation write root, `file_found` cannot read an existing file, so each save
+            // writes a new numbered WAV: reuse never reads a file the roots do not allow, which keeps a save
+            // from revealing whether an unreadable file matches the audio.)
             stem = format!("{stem}_{}", src.id.0);
-            if audio_dir.join(format!("{stem}.wav")).exists() {
+            if file_found(audio_dir.join(format!("{stem}.wav"))) {
                 src.path = format!("Audio Files/{stem}.wav");
                 src.unsaved = false;
                 files.insert(Arc::as_ptr(audio), src.path.clone());
@@ -756,11 +853,22 @@ fn sync_dir(dir: &Path) {
 
 fn write_synced(path: &Path, bytes: &[u8]) -> std::io::Result<()> {
     use std::io::Write;
-    let mut f = std::fs::File::create(path)?;
+    let mut f = create_new(path)?;
     f.write_all(bytes)?;
     f.sync_all()
 }
 
+/// Creates `path` as a new file. A leftover of that name (a part file from an interrupted write)
+/// is removed first, but an existing entry is never opened: a link planted at a predictable name
+/// in the destination folder can't redirect the write elsewhere.
+fn create_new(path: &Path) -> std::io::Result<std::fs::File> {
+    match std::fs::remove_file(path) {
+        Err(err) if err.kind() != std::io::ErrorKind::NotFound => return Err(err),
+        _ => {}
+    }
+    std::fs::OpenOptions::new().write(true).create_new(true).open(path)
+}
+
 /// Copies `from` to `to`, which must not exist yet; an existing entry, even a link, is never followed.
 fn copy_new(from: &Path, to: &Path) -> std::io::Result<()> {
     let mut src = std::fs::File::open(from)?;
@@ -840,7 +948,8 @@ fn same_path(a: &Path, b: &Path) -> bool {
 
 /// Store `bytes` as the first of `<stem>.wav`, `<stem>_01.wav`, … in `dir` that is free or already
 /// holds exactly these bytes, so saving never replaces audio; returns the name and whether it was
-/// written.
+/// written. Where the automation roots allow writing in `dir` but not reading (only a write root),
+/// an existing file is never compared, so each save writes a new numbered WAV.
 fn store_wav(dir: &Path, stem: &str, bytes: &[u8]) -> Result<(String, bool)> {
     use std::io::Write;
     for k in 0..10_000u32 {
@@ -855,7 +964,12 @@ fn store_wav(dir: &Path, stem: &str, bytes: &[u8]) -> Result<(String, bool)> {
                 return Ok((name, true));
             }
             Err(err) if err.kind() == std::io::ErrorKind::AlreadyExists => {
-                if std::fs::metadata(&path).is_ok_and(|m| m.len() == bytes.len() as u64) && std::fs::read(&path).is_ok_and(|b| b == bytes) {
+                // Reused only when it may be read: whether it equals the audio must not be
+                // learnt about a file the roots allow writing beside but not reading.
+                if crate::file_access::check_read(&path).is_ok()
+                    && std::fs::metadata(&path).is_ok_and(|m| m.len() == bytes.len() as u64)
+                    && std::fs::read(&path).is_ok_and(|b| b == bytes)
+                {
                     return Ok((name, false));
                 }
             }
@@ -891,7 +1005,99 @@ pub fn write_file(path: &str, bytes: &[u8]) -> Result<()> {
         return deliver(name, bytes).map_err(EngineError::Io);
     }
     crate::file_access::check_write(path).map_err(EngineError::Io)?;
-    std::fs::write(path, bytes).map_err(|err| EngineError::Io(format!("{path}: {err}")))
+    // Follow existing symlinks, and refuse dangling links even without automation roots.
+    let named = Path::new(path);
+    let path = match std::fs::symlink_metadata(named) {
+        Ok(m) if m.file_type().is_symlink() => std::fs::canonicalize(named).map_err(|err| EngineError::Io(format!("{path}: {err}")))?,
+        Ok(_) => named.to_path_buf(),
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => named.to_path_buf(),
+        Err(err) => return Err(EngineError::Io(format!("{path}: {err}"))),
+    };
+    crate::file_access::check_write(&path).map_err(EngineError::Io)?;
+    let metadata = match std::fs::metadata(&path) {
+        Ok(m) if m.is_file() => Some(m),
+        Ok(_) => return Err(EngineError::Io(format!("{}: not a regular file", path.display()))),
+        Err(err) if err.kind() == std::io::ErrorKind::NotFound => None,
+        Err(err) => return Err(EngineError::Io(format!("{}: {err}", path.display()))),
+    };
+    let err = |err: std::io::Error| EngineError::Io(format!("{}: {err}", path.display()));
+    if metadata.as_ref().is_some_and(|m| m.permissions().readonly()) {
+        return Err(err(std::io::ErrorKind::PermissionDenied.into()));
+    }
+    write_export_checked(&path, bytes).map_err(err)
+}
+
+/// Keep the original file and its security metadata. Refuse hard links before truncation: a
+/// link inside an automation root can name a file outside it (#1359).
+#[cfg(unix)]
+fn write_export_checked(path: &Path, bytes: &[u8]) -> std::io::Result<()> {
+    use std::io::Write as _;
+    use std::os::unix::fs::{MetadataExt as _, OpenOptionsExt as _};
+    let mut file = std::fs::OpenOptions::new().write(true).create(true).truncate(false).mode(0o600).open(path)?;
+    let opened = file.metadata()?;
+    if !opened.is_file() {
+        return Err(std::io::Error::other("not a regular file"));
+    }
+    if opened.nlink() > 1 {
+        return Err(hard_link_export_error());
+    }
+    file.set_len(0)?;
+    file.write_all(bytes)?;
+    file.sync_all()
+}
+
+#[cfg(any(unix, windows))]
+fn hard_link_export_error() -> std::io::Error {
+    std::io::Error::other("refusing to overwrite a hard-linked file; choose a new export path")
+}
+
+#[cfg(not(any(unix, windows)))]
+fn write_export_checked(_path: &Path, _bytes: &[u8]) -> std::io::Result<()> {
+    Err(std::io::ErrorKind::Unsupported.into())
+}
+
+/// Windows' stable std metadata API does not expose the link count. Use a safe kernel wrapper
+/// and the same handle for the check and write; no replacement means the destination DACL stays.
+#[cfg(windows)]
+fn write_export_checked(path: &Path, mut bytes: &[u8]) -> std::io::Result<()> {
+    use winsafe::{HFILE, co};
+    // Let std retain its Windows filename normalization and create missing destinations without
+    // truncation. Canonicalization then supplies a verbatim path, including long and UNC paths,
+    // to the raw Win32 wrapper. The handle below is checked before any existing bytes change.
+    let _opened = std::fs::OpenOptions::new().write(true).create(true).truncate(false).open(path)?;
+    let absolute = std::fs::canonicalize(path)?;
+    let path = absolute.to_str().filter(|p| !p.contains('\0')).ok_or(std::io::ErrorKind::InvalidInput)?;
+    let io_error = |err: winsafe::co::ERROR| std::io::Error::other(err.to_string());
+    let (file, _) = HFILE::CreateFile(
+        path,
+        co::GENERIC::WRITE,
+        Some(co::FILE_SHARE::READ | co::FILE_SHARE::WRITE | co::FILE_SHARE::DELETE),
+        None,
+        co::DISPOSITION::OPEN_EXISTING,
+        co::FILE_ATTRIBUTE::NORMAL,
+        Some(co::FILE_FLAG::WRITE_THROUGH),
+        None,
+        None,
+    )
+    .map_err(io_error)?;
+    if file.GetFileType().map_err(io_error)? != co::FILE_TYPE::DISK {
+        return Err(std::io::Error::other("not a regular file"));
+    }
+    match file.GetFileInformationByHandle().map_err(io_error)?.nNumberOfLinks {
+        1 => {}
+        0 => return Err(std::io::ErrorKind::Unsupported.into()),
+        _ => return Err(hard_link_export_error()),
+    }
+    file.SetEndOfFile().map_err(io_error)?;
+    while !bytes.is_empty() {
+        // Win32 takes a DWORD length. Small bounded writes also handle short writes correctly.
+        let count = file.WriteFile(&bytes[..bytes.len().min(64 * 1024)]).map_err(io_error)? as usize;
+        if count == 0 {
+            return Err(std::io::ErrorKind::WriteZero.into());
+        }
+        bytes = &bytes[count..];
+    }
+    Ok(())
 }
 
 /// Unpack a bundle: the one `.scraft` at its top level and the files beside it, by relative path.
@@ -962,6 +1168,89 @@ pub fn plan_takes(e: &Engine, unsaved_dir: &Path, input_channels: usize) -> Vec<
         .collect()
 }
 
+#[cfg(test)]
+mod exclusive_tests {
+    use super::*;
+
+    fn scratch(name: &str) -> PathBuf {
+        let dir = std::env::temp_dir().join(format!("soundcraft-io-{name}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn a_planted_link_at_the_part_name_is_not_written_through() {
+        let dir = scratch("part-link");
+        let (target, part) = (dir.join("elsewhere"), dir.join("session.scraft.tmp"));
+        std::os::unix::fs::symlink(&target, &part).unwrap();
+        write_synced(&part, b"new").unwrap();
+        assert!(!target.exists(), "the link's target was created");
+        assert_eq!(std::fs::read(&part).unwrap(), b"new", "the link itself was replaced by the file");
+        // A leftover regular part file is still replaced.
+        write_synced(&part, b"newer").unwrap();
+        assert_eq!(std::fs::read(&part).unwrap(), b"newer");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn a_file_read_within_a_root_must_resolve_inside_it() {
+        let dir = scratch("within");
+        let (inside, outside) = (dir.join("group"), dir.join("elsewhere"));
+        std::fs::create_dir_all(&inside).unwrap();
+        std::fs::create_dir_all(&outside).unwrap();
+        std::fs::write(inside.join("a.wav"), b"a").unwrap();
+        std::fs::write(outside.join("b.wav"), b"b").unwrap();
+        std::os::unix::fs::symlink(outside.join("b.wav"), inside.join("link.wav")).unwrap();
+        let root = canonical_path(&inside).unwrap();
+        assert_eq!(read_file_inside(&inside.join("a.wav"), &root).unwrap(), b"a");
+        assert!(read_file_inside(&inside.join("link.wav"), &root).is_err());
+        // a FIFO with no writer is refused, not waited on (Linux: the coreutils tool makes it)
+        #[cfg(target_os = "linux")]
+        if std::process::Command::new("mkfifo").arg(inside.join("pipe.wav")).status().is_ok_and(|s| s.success()) {
+            let err = read_file_inside(&inside.join("pipe.wav"), &root).unwrap_err().to_string();
+            assert!(err.contains("not a regular file"), "{err}");
+        }
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn export_skips_a_name_held_by_a_dangling_link() {
+        let dir = scratch("export-link");
+        let e = crate::demo::demo_engine();
+        let (t, c) = e.session().tracks.iter().find_map(|t| t.clips().iter().find(|c| c.is_audio()).map(|c| (t.id, c.clone()))).unwrap();
+        let _ = t;
+        let target = dir.join("elsewhere.wav");
+        std::os::unix::fs::symlink(&target, dir.join(format!("{}.wav", sanitize_name(&c.name)))).unwrap();
+        assert_eq!(export_clips(&e, &[c.id], &dir.to_string_lossy()).unwrap(), 1);
+        assert!(!target.exists(), "the export followed the link");
+        assert!(dir.join(format!("{}-2.wav", sanitize_name(&c.name))).is_file(), "the next free name was used");
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    /// With a write root, a link out of it that holds the name is still just an occupied name.
+    #[cfg(unix)]
+    #[test]
+    fn export_skips_a_link_out_of_the_write_root_too() {
+        let dir = scratch("export-root-link");
+        let e = crate::demo::demo_engine();
+        let c = e.session().tracks.iter().find_map(|t| t.clips().iter().find(|c| c.is_audio()).cloned()).unwrap();
+        let elsewhere = scratch("export-root-elsewhere");
+        let target = elsewhere.join("target.wav");
+        std::os::unix::fs::symlink(&target, dir.join(format!("{}.wav", sanitize_name(&c.name)))).unwrap();
+        let roots = crate::file_access::AutomationRoots::new(&[], &[&dir]).unwrap().unwrap();
+        let n = crate::file_access::confine(Some(&roots), || export_clips(&e, &[c.id], &dir.to_string_lossy())).unwrap();
+        assert_eq!(n, 1);
+        assert!(!target.exists(), "the export followed the link out of the root");
+        assert!(dir.join(format!("{}-2.wav", sanitize_name(&c.name))).is_file(), "the next free name was used");
+        let _ = std::fs::remove_dir_all(&dir);
+        let _ = std::fs::remove_dir_all(&elsewhere);
+    }
+}
+
 #[cfg(test)]
 mod stem_tests {
     #[test]
@@ -1019,6 +1308,164 @@ mod stem_tests {
         let _ = std::fs::remove_dir_all(&root);
     }
 }
+#[cfg(test)]
+mod export_replacement_tests {
+    use super::*;
+    #[cfg(unix)]
+    use std::os::unix::fs::{PermissionsExt, symlink};
+    fn scratch(name: &str) -> PathBuf {
+        let dir = std::env::temp_dir().join(format!("soundcraft-export-{name}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+    #[test]
+    fn export_refuses_hard_links_before_truncating_and_refuses_nonfiles() {
+        let dir = scratch("hard-links");
+        let original = dir.join("original.mid");
+        let write_root = dir.join("write");
+        std::fs::create_dir(&write_root).unwrap();
+        let destination = write_root.join("export.mid");
+        std::fs::write(&original, b"old").unwrap();
+        std::fs::hard_link(&original, &destination).unwrap();
+        for confined in [false, true] {
+            let roots = if confined { crate::file_access::AutomationRoots::new(&[], &[&write_root]).unwrap() } else { None };
+            let result = crate::file_access::confine(roots.as_ref(), || write_file(destination.to_str().unwrap(), b"new"));
+            assert!(result.unwrap_err().to_string().contains("hard-linked"));
+        }
+        assert_eq!(std::fs::read(&original).unwrap(), b"old");
+        assert_eq!(std::fs::read(&destination).unwrap(), b"old");
+        let folder = dir.join("folder");
+        std::fs::create_dir(&folder).unwrap();
+        assert!(write_file(folder.to_str().unwrap(), b"new").is_err());
+        assert!(folder.is_dir());
+        assert!(!std::fs::read_dir(&dir).unwrap().any(|e| e.unwrap().file_name().to_string_lossy().starts_with(".soundcraft-")));
+        let _ = std::fs::remove_dir_all(dir);
+    }
+    #[cfg(windows)]
+    #[test]
+    fn export_supports_paths_longer_than_max_path() {
+        let root = scratch("long-path");
+        let mut dir = root.clone();
+        while dir.as_os_str().len() < 280 {
+            dir.push("long-folder-component");
+        }
+        std::fs::create_dir_all(&dir).unwrap();
+        let path = dir.join("export.mid");
+        write_file(path.to_str().unwrap(), b"new").unwrap();
+        assert_eq!(std::fs::read(&path).unwrap(), b"new");
+        write_file(path.to_str().unwrap(), b"replacement").unwrap();
+        assert_eq!(std::fs::read(&path).unwrap(), b"replacement");
+        std::fs::remove_dir_all(root).unwrap();
+    }
+    #[test]
+    fn export_writes_all_chunks_and_truncates_an_existing_file() {
+        let dir = scratch("chunks");
+        let path = dir.join("export.mid");
+        let bytes = vec![0x5a; 128 * 1024 + 17];
+        write_file(path.to_str().unwrap(), &bytes).unwrap();
+        assert_eq!(std::fs::read(&path).unwrap(), bytes);
+        write_file(path.to_str().unwrap(), b"").unwrap();
+        assert_eq!(std::fs::metadata(&path).unwrap().len(), 0);
+        std::fs::remove_dir_all(dir).unwrap();
+    }
+    #[test]
+    fn export_refuses_readonly_files_without_changing_their_bytes() {
+        let dir = scratch("readonly");
+        let path = dir.join("readonly.mid");
+        std::fs::write(&path, b"old contents").unwrap();
+        let original = std::fs::metadata(&path).unwrap().permissions();
+        let mut readonly = original.clone();
+        readonly.set_readonly(true);
+        std::fs::set_permissions(&path, readonly).unwrap();
+        let result = write_file(path.to_str().unwrap(), b"new");
+        let bytes = std::fs::read(&path).unwrap();
+        std::fs::set_permissions(&path, original).unwrap();
+        assert!(result.is_err());
+        assert_eq!(bytes, b"old contents");
+        std::fs::remove_dir_all(dir).unwrap();
+    }
+    #[cfg(any(unix, windows))]
+    #[test]
+    fn export_preserves_the_existing_file_identity_and_security_metadata() {
+        let dir = scratch("identity");
+        let path = dir.join("existing.mid");
+        std::fs::write(&path, b"long old contents").unwrap();
+        #[cfg(unix)]
+        let identity = |p: &Path| {
+            use std::os::unix::fs::MetadataExt as _;
+            let m = std::fs::metadata(p).unwrap();
+            (m.dev(), m.ino(), m.uid(), m.gid())
+        };
+        #[cfg(windows)]
+        let identity = |p: &Path| {
+            use winsafe::{HFILE, co};
+            let (file, _) = HFILE::CreateFile(
+                p.to_str().unwrap(),
+                co::GENERIC::READ,
+                None,
+                None,
+                co::DISPOSITION::OPEN_EXISTING,
+                co::FILE_ATTRIBUTE::NORMAL,
+                None,
+                None,
+                None,
+            )
+            .unwrap();
+            let i = file.GetFileInformationByHandle().unwrap();
+            (i.dwVolumeSerialNumber, i.nFileIndex())
+        };
+        let before = identity(&path);
+        write_file(path.to_str().unwrap(), b"new").unwrap();
+        assert_eq!(std::fs::read(&path).unwrap(), b"new");
+        // No inode/file-record replacement: owner, group and access-control lists stay attached
+        // to the same file rather than being inherited anew from the parent directory.
+        assert_eq!(identity(&path), before);
+        std::fs::remove_dir_all(dir).unwrap();
+    }
+    #[cfg(unix)]
+    #[test]
+    fn export_replacement_preserves_existing_permissions_and_new_files_are_private() {
+        let dir = scratch("permissions");
+        for mode in [0o600, 0o640] {
+            let path = dir.join(format!("{mode:o}.mid"));
+            std::fs::write(&path, b"old").unwrap();
+            std::fs::set_permissions(&path, std::fs::Permissions::from_mode(mode)).unwrap();
+            write_file(path.to_str().unwrap(), b"new").unwrap();
+            assert_eq!(std::fs::read(&path).unwrap(), b"new");
+            assert_eq!(std::fs::metadata(&path).unwrap().permissions().mode() & 0o777, mode);
+        }
+        let path = dir.join("new.mid");
+        write_file(path.to_str().unwrap(), b"new").unwrap();
+        assert_eq!(std::fs::metadata(&path).unwrap().permissions().mode() & 0o077, 0);
+        let _ = std::fs::remove_dir_all(dir);
+    }
+    #[cfg(unix)]
+    #[test]
+    fn export_replacement_preserves_a_symlink_and_refuses_a_dangling_one() {
+        let dir = scratch("symlinks");
+        let target = dir.join("target.mid");
+        let link = dir.join("link.mid");
+        std::fs::write(&target, b"old").unwrap();
+        std::fs::set_permissions(&target, std::fs::Permissions::from_mode(0o600)).unwrap();
+        symlink("target.mid", &link).unwrap();
+        for confined in [false, true] {
+            let roots = if confined { crate::file_access::AutomationRoots::new(&[], &[&dir]).unwrap() } else { None };
+            crate::file_access::confine(roots.as_ref(), || write_file(link.to_str().unwrap(), b"new")).unwrap();
+            assert!(std::fs::symlink_metadata(&link).unwrap().file_type().is_symlink());
+            assert_eq!(std::fs::read(&target).unwrap(), b"new");
+            assert_eq!(std::fs::metadata(&target).unwrap().permissions().mode() & 0o777, 0o600);
+        }
+        let missing = dir.join("missing.mid");
+        let dangling = dir.join("dangling.mid");
+        symlink(&missing, &dangling).unwrap();
+        assert!(write_file(dangling.to_str().unwrap(), b"new").is_err());
+        assert!(std::fs::symlink_metadata(&dangling).unwrap().file_type().is_symlink());
+        assert!(!missing.exists());
+        assert!(!std::fs::read_dir(&dir).unwrap().any(|e| e.unwrap().file_name().to_string_lossy().starts_with(".soundcraft-")));
+        let _ = std::fs::remove_dir_all(dir);
+    }
+}
 
 #[cfg(test)]
 mod clip_tests {

crates/engine/src/io/import.rs

@@ -7,18 +7,48 @@ use super::{
 /// Largest import we accept (samples per channel × channels), ~4 GiB of f32.
 pub(crate) const MAX_IMPORT_SAMPLES: usize = 1 << 30;
 
-/// `buf` converted to `rate`, unless it would then hold more than `limit` samples: a file with a
-/// tiny sample rate grows by orders of magnitude.
-pub(crate) fn at_rate(mut buf: AudioBuffer, rate: u32, limit: usize) -> Option<AudioBuffer> {
+/// The most a file's audio may grow when converted to the session rate. Sessions run at 8 kHz to
+/// 768 kHz (96×); past this a file is lying about its rate, and converting a few kilobytes would
+/// otherwise allocate and filter hundreds of megabytes.
+const MAX_RATE_EXPANSION: u32 = 128;
+
+/// Why [`at_rate`] refused a conversion.
+#[derive(Debug, PartialEq, Eq)]
+pub(crate) enum RateError {
+    /// The converted audio would hold more samples than the limit.
+    TooLarge,
+    /// The file's rate is so far below the session's that converting would grow it past [`MAX_RATE_EXPANSION`].
+    Ratio { from: u32, to: u32 },
+}
+
+impl RateError {
+    /// The refusal as a sentence: `size` says what a size refusal means to the caller.
+    pub(crate) fn message(&self, size: &str) -> String {
+        match self {
+            RateError::TooLarge => size.to_string(),
+            RateError::Ratio { from, to } => {
+                format!("its {from} Hz sample rate is too low to convert to the session's {to} Hz (at most {MAX_RATE_EXPANSION}-fold)")
+            }
+        }
+    }
+}
+
+/// `buf` converted to `rate`, unless it would then hold more than `limit` samples, or grow more
+/// than [`MAX_RATE_EXPANSION`]-fold: a file with a tiny sample rate grows by orders of magnitude.
+pub(crate) fn at_rate(mut buf: AudioBuffer, rate: u32, limit: usize) -> std::result::Result<AudioBuffer, RateError> {
     let from = buf.sample_rate.max(1);
+    // widened integers: dividing first would truncate 128.86-fold down to 128
+    if u64::from(rate) > u64::from(from) * u64::from(MAX_RATE_EXPANSION) {
+        return Err(RateError::Ratio { from, to: rate });
+    }
     if buf.frames() as f64 * buf.num_channels() as f64 * f64::from(rate) / f64::from(from) > limit as f64 {
-        return None;
+        return Err(RateError::TooLarge);
     }
     if from != rate {
         buf.channels = soundcraft_dsp::offline::resample(&buf.channels, from, rate);
         buf.sample_rate = rate;
     }
-    Some(buf)
+    Ok(buf)
 }
 
 /// A relative `Audio Files/` path no other source in `s` already uses.
@@ -115,7 +145,7 @@ pub fn decode_import(path: &str, rate: u32) -> Result<DecodedImport> {
 fn decode_import_bytes(name: &str, bytes: &[u8], rate: u32) -> Result<(soundcraft_audio_io::AudioInfo, Arc<SourceAudio>)> {
     let ext = Path::new(name).extension().and_then(OsStr::to_str).map(str::to_ascii_lowercase);
     let (info, buf) = soundcraft_audio_io::decode(bytes, ext.as_deref()).map_err(|err| EngineError::Io(format!("{name}: {err}")))?;
-    let buf = at_rate(buf, rate, MAX_IMPORT_SAMPLES).ok_or_else(|| EngineError::Io(format!("{name}: file is too large to import")))?;
+    let buf = at_rate(buf, rate, MAX_IMPORT_SAMPLES).map_err(|e| EngineError::Io(format!("{name}: {}", e.message("file is too large to import"))))?;
     if buf.frames() == 0 {
         return Err(EngineError::Io(format!("{name}: no audio")));
     }
@@ -215,8 +245,22 @@ mod rate_tests {
     #[test]
     fn a_tiny_sample_rate_is_refused_before_it_is_converted() {
         let buf = |rate| AudioBuffer { sample_rate: rate, channels: vec![vec![0.5; 100]; 2] };
-        assert!(at_rate(buf(1), 48_000, 1_000_000).is_none());
+        assert!(at_rate(buf(1), 48_000, 1_000_000).is_err());
         let ok = at_rate(buf(8_000), 48_000, 1_000_000).unwrap();
         assert_eq!((ok.sample_rate, ok.frames()), (48_000, 600));
     }
+
+    #[test]
+    fn an_extreme_rate_expansion_is_refused_whatever_the_sample_budget() {
+        let buf = |rate| AudioBuffer { sample_rate: rate, channels: vec![vec![0.5; 100]; 2] };
+        // 100 frames at 300 Hz would fit the budget as 128 000 samples, but grow 640-fold.
+        assert_eq!(at_rate(buf(300), 192_000, usize::MAX).unwrap_err(), RateError::Ratio { from: 300, to: 192_000 });
+        assert!(at_rate(buf(1_500), 192_000, usize::MAX).is_ok(), "128-fold is the supported extreme");
+        assert!(at_rate(buf(8_000), 768_000, usize::MAX).is_ok(), "the slowest file at the fastest session");
+        // 128.86-fold: integer division would truncate it to 128 and let it through
+        assert_eq!(at_rate(buf(1_490), 192_000, usize::MAX).unwrap_err(), RateError::Ratio { from: 1_490, to: 192_000 });
+        // a short file that is only over the sample budget is a size refusal, not a rate one
+        assert_eq!(at_rate(buf(48_000), 48_000, 10).unwrap_err(), RateError::TooLarge);
+        assert!(RateError::Ratio { from: 300, to: 192_000 }.message("big").contains("300 Hz"));
+    }
 }

crates/engine/src/io/session.rs

@@ -72,7 +72,7 @@ pub(crate) fn open_session_linked(e: &mut Engine, path: &Path, links: &Path) ->
 /// Decode one source's audio file at the session rate.
 pub(super) fn decode_source(bytes: &[u8], ext: Option<&str>, rate: u32) -> std::result::Result<Arc<SourceAudio>, String> {
     let (_, buf) = soundcraft_audio_io::decode(bytes, ext).map_err(|err| err.to_string())?;
-    let buf = at_rate(buf, rate, MAX_IMPORT_SAMPLES).ok_or("too large to load")?;
+    let buf = at_rate(buf, rate, MAX_IMPORT_SAMPLES).map_err(|e| e.message("too large to load"))?;
     Ok(Arc::new(SourceAudio::new(buf)))
 }
 

crates/engine/src/io/strip.rs

@@ -117,9 +117,7 @@ pub fn strip_silence(
     }
     cut_points.push(r.end);
     let old: std::collections::HashSet<_> = s.track(t).map(|x| x.clips().iter().map(|c| c.id).collect()).unwrap_or_default();
-    for p in &cut_points {
-        crate::edit::separate_at_if(s, t, *p, |_| false);
-    }
+    crate::edit::separate_at_points(s, t, &cut_points);
     let kept = strip_pieces(s, t, r, &keep, mode);
     crate::edit::auto_name_new_clips(s, t, &old, |c| !(named && c.is_audio() && c.start >= r.start && c.end() <= r.end));
     Ok(kept)
@@ -144,10 +142,24 @@ fn strip_pieces(s: &mut Session, t: TrackId, r: Range, keep: &[(Samples, Samples
     let audio: Vec<Range> = keep.iter().map(|(a, b)| Range::new(*a, *b)).collect();
     let remove = if mode == StripMode::Extract { &audio } else { &gaps };
     let inside = |c: &Clip, g: &Range| c.start >= g.start && c.end() <= g.end;
+    // The range of `rs` holding `c`: by binary search when `rs` is ascending and disjoint (the
+    // usual case, checked once by the caller), by scan otherwise.
+    let holder = |rs: &[Range], sorted: bool, c: &Clip| {
+        if sorted {
+            let i = rs.partition_point(|g| g.end < c.end());
+            rs.get(i).filter(|g| inside(c, g)).map(|_| i)
+        } else {
+            rs.iter().position(|g| inside(c, g))
+        }
+    };
+    let ordered = |rs: &[Range]| rs.windows(2).all(|w| w[0].end <= w[1].start);
     let Some(pl) = s.track_mut(t).and_then(|x| x.playlist_mut()) else { return if mode == StripMode::Extract { 0 } else { keep.len() } };
-    pl.clips.retain(|c| !remove.iter().any(|g| inside(c, g)));
+    let sorted = ordered(remove);
+    pl.clips.retain(|c| holder(remove, sorted, c).is_none());
     if mode == StripMode::Extract {
-        return gaps.iter().filter(|g| pl.clips.iter().any(|c| inside(c, g))).count();
+        let sorted = ordered(&gaps);
+        let held: std::collections::HashSet<usize> = pl.clips.iter().filter_map(|c| holder(&gaps, sorted, c)).collect();
+        return held.len();
     }
     keep.len()
 }
@@ -294,6 +306,57 @@ mod strip_tests {
         (r, e.session().track(t).unwrap().clips().iter().map(|c| (c.start, c.end())).collect())
     }
 
+    #[test]
+    fn cutting_at_many_points_in_one_pass_equals_cutting_at_each() {
+        let spans = |e: &Engine, t: TrackId| {
+            let mut v: Vec<_> = e.session().track(t).unwrap().clips().iter().map(|c| (c.start, c.end())).collect();
+            v.sort_unstable();
+            v
+        };
+        let points = [30_000, 10, 5_000, 30_000, 120_000, 0, 20_000, 1_000_000];
+        let (mut one, t) = tones(&[0, 20_000, 100_000], 40_000);
+        let (mut each, _) = tones(&[0, 20_000, 100_000], 40_000);
+        crate::edit::separate_at_points(one.session_mut(), t, &points);
+        for p in points {
+            crate::edit::separate_at_if(each.session_mut(), t, p, |_| false);
+        }
+        assert_eq!(spans(&one, t), spans(&each, t));
+        assert!(spans(&one, t).len() > 3);
+        let ids: std::collections::HashSet<_> = one.session().track(t).unwrap().clips().iter().map(|c| c.id).collect();
+        assert_eq!(ids.len(), spans(&one, t).len(), "new pieces have distinct ids");
+    }
+
+    #[test]
+    fn cutting_stretched_audio_at_ascending_points_matches_cutting_at_each() {
+        let pieces = |e: &Engine, t: TrackId| {
+            let mut v: Vec<_> = e
+                .session()
+                .track(t)
+                .unwrap()
+                .clips()
+                .iter()
+                .map(|c| (c.start, c.end(), if let soundcraft_model::ClipContent::Audio { offset, .. } = c.content { offset } else { -1 }))
+                .collect();
+            v.sort_unstable();
+            v
+        };
+        let stretched = || {
+            let (mut e, t) = tones(&[0], 40_000);
+            for c in &mut e.session_mut().track_mut(t).unwrap().playlist_mut().unwrap().clips {
+                c.stretch = 2.0;
+            }
+            (e, t)
+        };
+        let points = [1, 2, 3_001, 12_345];
+        let ((mut one, t), (mut each, _)) = (stretched(), stretched());
+        crate::edit::separate_at_points(one.session_mut(), t, &points);
+        for p in points {
+            crate::edit::separate_at_if(each.session_mut(), t, p, |_| false);
+        }
+        assert_eq!(pieces(&one, t), pieces(&each, t));
+        assert_eq!(pieces(&one, t).len(), points.len() + 1);
+    }
+
     #[test]
     fn strip_keeps_the_audio_and_removes_the_silence() {
         let (r, clips) = strip_mode("strip");

crates/engine/tests/it/edit_modes.rs

@@ -579,3 +579,48 @@ fn moving_a_group_left_past_zero_keeps_its_spacing() {
     run(&mut e, "edit.move_clips", json!({"clips": [ids[0].0, ids[1].0], "by": -1000}));
     assert_eq!(clips(&e, t), [(0, 100), (1500, 100)]);
 }
+
+#[test]
+fn separate_and_range_edits_leave_locked_clips_whole() {
+    let edits = [
+        ("edit.separate", json!({"at": 24_000})),
+        ("edit.separate", json!({"start": 12_000, "end": 36_000})),
+        ("edit.separate_on_grid", json!({"start": 12_000, "end": 36_000})),
+        ("edit.clear", json!({"start": 12_000, "end": 36_000})),
+        ("edit.insert_silence", json!({"start": 24_000, "end": 25_000})),
+    ];
+    for lock in [None, Some("clip.edit_lock"), Some("clip.time_lock")] {
+        for (cmd, p) in &edits {
+            let (mut e, t, ids) = long("slip", &[(0, 48_000, 0)]);
+            if let Some(lock) = lock {
+                run(&mut e, lock, json!({"clips": [ids[0].0]}));
+            }
+            let mut p = p.clone();
+            p["tracks"] = json!([t.0]);
+            run(&mut e, cmd, p);
+            if lock.is_some() {
+                assert_eq!(clips(&e, t), vec![(0, 48_000)], "{lock:?} {cmd}");
+            } else {
+                assert_ne!(clips(&e, t), vec![(0, 48_000)], "unlocked control {cmd}");
+            }
+        }
+    }
+}
+
+/// Event time edits move the entire timeline, including clips protected from ordinary edits.
+#[test]
+fn event_time_edits_split_and_move_locked_clips() {
+    for lock in ["clip.edit_lock", "clip.time_lock"] {
+        for (command, expected) in [
+            ("event.insert_time", vec![(0, 12_000, 0), (36_000, 36_000, 12_000)]),
+            ("event.cut_time", vec![(0, 12_000, 0), (12_000, 12_000, 36_000)]),
+        ] {
+            let (mut e, t, ids) = long("slip", &[(0, 48_000, 0)]);
+            run(&mut e, lock, json!({"clips": [ids[0].0]}));
+            run(&mut e, command, json!({"start": 12_000, "end": 36_000}));
+            let actual: Vec<_> = e.session().track(t).unwrap().clips().iter().map(|c| (c.start, c.length, c.source_offset())).collect();
+            assert_eq!(actual, expected, "{lock} {command}");
+            assert!(e.session().track(t).unwrap().clips().iter().all(soundcraft_engine::edit::locked));
+        }
+    }
+}

crates/engine/tests/it/trim_to_selection.rs

@@ -18,3 +18,68 @@ fn trim_to_selection_keeps_clips_sorted() {
     let clips = engine.session().track(track).unwrap().clips();
     assert_eq!(clips.iter().map(|c| (c.id, c.start, c.length)).collect::<Vec<_>>(), vec![(long, 0, 30), (short, 5, 5)]);
 }
+
+fn three_clip_session() -> (Session, soundcraft_model::TrackId, [soundcraft_model::ClipId; 3]) {
+    let mut session = Session::default();
+    let track = session.add_track(TrackKind::Audio, ChannelFormat::Mono, None);
+    let ids = [session.new_clip_id(), session.new_clip_id(), session.new_clip_id()];
+    session.track_mut(track).unwrap().playlist_mut().unwrap().clips = vec![
+        Clip::audio(ids[0], "free", SourceId(1), 0, 0, 100),
+        Clip::audio(ids[1], "edit-locked", SourceId(1), 0, 100, 100),
+        Clip::audio(ids[2], "time-locked", SourceId(1), 0, 200, 100),
+    ];
+    let pl = session.track_mut(track).unwrap().playlist_mut().unwrap();
+    pl.clips[1].edit_locked = true;
+    pl.clips[2].time_locked = true;
+    (session, track, ids)
+}
+
+#[test]
+fn trim_to_selection_leaves_locked_clips_whole() {
+    let (session, track, ids) = three_clip_session();
+    let mut engine = Engine::new(session);
+    let result = engine.execute("edit.trim_to_selection", &json!({"tracks": [track.0], "start": 50, "end": 250})).unwrap();
+    let clips = engine.session().track(track).unwrap().clips();
+    assert_eq!(clips.iter().map(|c| (c.id, c.start, c.length)).collect::<Vec<_>>(), vec![(ids[0], 50, 50), (ids[1], 100, 100), (ids[2], 200, 100)]);
+    assert_eq!(result["trimmed"], json!(1));
+    engine.undo();
+    assert_eq!(engine.session().track(track).unwrap().clips()[0].length, 100);
+}
+
+#[test]
+fn edit_trim_skips_locked_clips() {
+    let (session, track, ids) = three_clip_session();
+    let mut engine = Engine::new(session);
+    engine.execute("edit.trim_start_to_insertion", &json!({"tracks": [track.0], "at": 150})).unwrap();
+    engine.execute("edit.trim_end_to_insertion", &json!({"tracks": [track.0], "at": 250})).unwrap();
+    let clips = engine.session().track(track).unwrap().clips();
+    assert_eq!(
+        clips.iter().map(|c| (c.id, c.start, c.length)).collect::<Vec<_>>(),
+        vec![(ids[0], 0, 100), (ids[1], 100, 100), (ids[2], 200, 100)],
+        "only unlocked clips trim; the edit-locked and time-locked ones keep their extent"
+    );
+}
+
+/// A lock on one clip must not suppress eligible unlocked clips on the same track.
+#[test]
+fn insertion_trims_still_trim_unlocked_clips_beside_both_lock_kinds() {
+    for (command, expected_start) in [("edit.trim_start_to_insertion", 50), ("edit.trim_end_to_insertion", 0)] {
+        let (mut session, track, ids) = three_clip_session();
+        for clip in &mut session.track_mut(track).unwrap().playlist_mut().unwrap().clips {
+            clip.start = 0;
+        }
+        let before = session.clone();
+        let mut engine = Engine::new(session);
+        let result = engine.execute(command, &json!({"tracks": [track.0], "at": 50})).unwrap();
+        assert_eq!(result["trimmed"], json!(1), "{command}");
+        let clips = engine.session().track(track).unwrap().clips();
+        let free = clips.iter().find(|c| c.id == ids[0]).unwrap();
+        assert_eq!((free.start, free.length), (expected_start, 50), "{command}");
+        for id in &ids[1..] {
+            let locked = clips.iter().find(|c| c.id == *id).unwrap();
+            assert_eq!((locked.start, locked.length), (0, 100), "{command}");
+        }
+        assert!(engine.undo());
+        assert_eq!(engine.session(), &before, "{command} undo");
+    }
+}

crates/mix/src/automation.rs

@@ -1,4 +1,6 @@
 use super::{AutoParam, Samples, Session, TICKS_PER_QUARTER, Track, Transport, db_to_gain};
+use soundcraft_dsp::MIN_DB;
+use soundcraft_model::AutomationLane;
 
 pub(crate) fn transport_at(s: &Session, pos: Samples, playing: bool, recording: bool) -> Transport {
     let sr = s.sample_rate;
@@ -21,15 +23,146 @@ pub(crate) fn transport_at(s: &Session, pos: Samples, playing: bool, recording:
     }
 }
 
-pub(crate) fn volume_db_at(t: &Track, pos: Samples) -> f32 {
+/// One term of a fader's level in dB: a fixed value, or an automation lane (with its default).
+#[derive(Clone, Copy)]
+pub(crate) enum Level<'a> {
+    Fixed(f32),
+    Lane(&'a AutomationLane, f32),
+}
+
+impl Level<'_> {
+    fn at(&self, pos: Samples) -> f32 {
+        match self {
+            Level::Fixed(v) => *v,
+            Level::Lane(l, default) => l.value_at(pos, *default),
+        }
+    }
+
+    /// The lane's first breakpoint after `pos`. Up to it, the level is linear in time.
+    fn next_point(&self, pos: Samples) -> Option<Samples> {
+        match self {
+            Level::Fixed(_) => None,
+            Level::Lane(l, _) => l.points.get(l.points.partition_point(|p| p.at <= pos)).map(|p| p.at),
+        }
+    }
+}
+
+/// A track's volume: its automation lane when the mode reads it, else the fader.
+pub(crate) fn volume_level(t: &Track) -> Level<'_> {
     if t.mixer.automation_mode.reads()
         && t.mixer.automation_mode != soundcraft_model::AutomationMode::Write
         && let Some(l) = t.lane(&AutoParam::Volume)
         && !l.points.is_empty()
     {
-        return l.value_at(pos, t.mixer.volume_db);
+        return Level::Lane(l, t.mixer.volume_db);
     }
-    t.mixer.volume_db
+    Level::Fixed(t.mixer.volume_db)
+}
+
+/// Calls `f(i, j, d0, d1)` for each stretch `i..=j` of the block at `pos` over which the sum of
+/// `levels` is linear in dB, with its values at `i` and `j`. Lanes are linear between breakpoints,
+/// so a stretch ends at the next breakpoint or at the block's last frame.
+fn for_each_segment(levels: &[Level<'_>], pos: Samples, frames: usize, mut f: impl FnMut(usize, usize, f32, f32)) {
+    let db = |at: Samples| levels.iter().map(|l| l.at(at)).sum::<f32>();
+    let last = frames.saturating_sub(1);
+    let mut i = 0usize;
+    while i < frames {
+        let at = pos.saturating_add(i as i64);
+        let j = levels
+            .iter()
+            .filter_map(|l| l.next_point(at))
+            .min()
+            .map_or(last, |k| usize::try_from(k.saturating_sub(pos)).map_or(last, |j| j.min(last)));
+        f(i, j, db(at), db(pos.saturating_add(j as i64)));
+        i = j + 1;
+    }
+}
+
+/// Multiplies `x` by a gain that goes from `d0` dB at its first sample to `d1` dB at its last,
+/// linearly in dB, capped at `max_db` and silent at or below [`MIN_DB`] (or NaN), as `db_to_gain`
+/// would give it sample by sample. Linear in dB is geometric in gain, so the ramp steps by one ratio
+/// instead of converting every sample; the ends are converted exactly.
+pub(crate) fn scale(x: &mut [f32], d0: f32, d1: f32, max_db: f32) {
+    let Some(n) = x.len().checked_sub(1) else { return };
+    // Match db_to_gain's ceiling even when the caller requests no fader cap.
+    let max_db = max_db.min(200.0);
+    if d0.is_nan() || d1.is_nan() {
+        x.fill(0.0);
+        return;
+    }
+    if d0 == d1 || n == 0 {
+        let g = gain(d0, max_db);
+        x.iter_mut().for_each(|v| *v *= g);
+        return;
+    }
+    // Extreme finite trim values can underflow or overflow the geometric recurrence.
+    // Convert those rare ramps directly so an inaudible prefix can recover normally.
+    if !(-1000.0..=1000.0).contains(&d0) || !(-1000.0..=1000.0).contains(&d1) {
+        for (i, v) in x.iter_mut().enumerate() {
+            let t = i as f64 / n as f64;
+            let db = if i == 0 {
+                f64::from(d0)
+            } else if i == n {
+                f64::from(d1)
+            } else {
+                f64::from(d0) * (1.0 - t) + f64::from(d1) * t
+            };
+            *v *= gain(db as f32, max_db);
+        }
+        return;
+    }
+    let step = (f64::from(d1) - f64::from(d0)) / n as f64;
+    let ratio = 10f64.powf(step / 20.0);
+    let (floor, cap) = (f64::from(MIN_DB), f64::from(max_db));
+    let gcap = f64::from(db_to_gain(max_db));
+    let (mut d, mut g) = (f64::from(d0), 10f64.powf(f64::from(d0) / 20.0));
+    if let Some((first, rest)) = x.split_first_mut() {
+        *first *= gain(d0, max_db);
+        if let Some((last, mid)) = rest.split_last_mut() {
+            for v in mid {
+                d += step;
+                g *= ratio;
+                let gd = if d.is_nan() || d <= floor {
+                    0.0
+                } else if d >= cap {
+                    gcap
+                } else {
+                    g
+                };
+                *v *= gd as f32;
+            }
+            *last *= gain(d1, max_db);
+        }
+    }
+}
+
+/// The gain of `db`, at most `max_db`.
+fn gain(db: f32, max_db: f32) -> f32 {
+    if db.is_nan() { 0.0 } else { db_to_gain(db.min(max_db)) }
+}
+
+/// Fader gain over the block at `pos`, read at every frame: multiplies `buf`'s channels by the
+/// gain of the sum of `levels` (dB, at most `max_db`).
+pub(crate) fn apply_gain(levels: &[Level<'_>], pos: Samples, frames: usize, max_db: f32, buf: &mut [Vec<f32>]) {
+    for_each_segment(levels, pos, frames, |i, j, d0, d1| {
+        for c in buf.iter_mut() {
+            if let Some(x) = c.get_mut(i..=j) {
+                scale(x, d0, d1, max_db);
+            }
+        }
+    });
+}
+
+/// [`apply_gain`] from `src` into `dst`.
+pub(crate) fn copy_with_gain(levels: &[Level<'_>], pos: Samples, frames: usize, max_db: f32, src: &[Vec<f32>], dst: &mut [Vec<f32>]) {
+    for_each_segment(levels, pos, frames, |i, j, d0, d1| {
+        for (d, s) in dst.iter_mut().zip(src) {
+            if let (Some(d), Some(s)) = (d.get_mut(i..=j), s.get(i..=j)) {
+                d.copy_from_slice(s);
+                scale(d, d0, d1, max_db);
+            }
+        }
+    });
 }
 
 pub(crate) fn pan_at(t: &Track, idx: usize, pos: Samples) -> f32 {
@@ -69,21 +202,3 @@ pub(crate) fn send_level(t: &Track, i: usize, base: f32, pos: Samples) -> f32 {
     }
     base
 }
-
-#[derive(Debug, Clone, Copy)]
-pub(crate) struct GainRamp {
-    g0: f32,
-    g1: f32,
-    n: usize,
-}
-
-impl GainRamp {
-    pub(crate) fn new(db0: f32, db1: f32, n: usize) -> Self {
-        GainRamp { g0: db_to_gain(db0), g1: db_to_gain(db1), n }
-    }
-
-    #[inline]
-    pub(crate) fn at(&self, i: usize) -> f32 {
-        if self.n == 0 { self.g0 } else { self.g0 + (self.g1 - self.g0) * (i as f32 / self.n as f32) }
-    }
-}

crates/mix/src/clips.rs

@@ -105,6 +105,10 @@ impl ClipFx {
             }
         }
     }
+    /// Whether the EQ or compressor is on: only they carry parameters that settle (a gain does not).
+    pub(crate) fn has_smoothed_modules(&self) -> bool {
+        self.eq.is_some() || self.comp.is_some()
+    }
     pub(crate) fn process(&mut self, io: &mut [Vec<f32>], frames: usize) {
         if let Some(eq) = &mut self.eq {
             eq.process(io, frames);

crates/mix/src/lib.rs

@@ -71,7 +71,7 @@ mod routing;
 mod strip;
 mod threads;
 
-use automation::{GainRamp, pan_at, pan_segment, send_level, transport_at, volume_db_at};
+use automation::{copy_with_gain, pan_at, pan_segment, send_level, transport_at, volume_level};
 pub use instances::{INSTRUMENT_SLOT, InstanceSpec, NewInstance, PluginFailures, PreparedInstance, create_instance, instance_specs, is_third_party};
 pub use meter::StripMeter;
 use midi::sync_sample;
@@ -539,21 +539,8 @@ impl MixEngine {
                         }
                     }
                 }
-                // Match track faders: the next block's first sample must not ramp this one.
-                let last = pos.saturating_add(frames.saturating_sub(1) as i64);
-                let v0 = volume_db_at(t, pos);
-                let v1 = volume_db_at(t, last);
-                let ramp = GainRamp::new(v0, v1, frames.saturating_sub(1));
-                for (ch, src) in strip.buf.iter().enumerate().take(self.main.len()) {
-                    if let Some(m) = self.main.get_mut(ch) {
-                        for i in 0..frames {
-                            let g = ramp.at(i);
-                            if let (Some(d), Some(x)) = (m.get_mut(i), src.get(i)) {
-                                *d = x * g;
-                            }
-                        }
-                    }
-                }
+                // Read at every sample, like track faders: a breakpoint acts on its own sample.
+                copy_with_gain(&[volume_level(t)], pos, frames, f32::INFINITY, &strip.buf, &mut self.main);
                 let m = self.meters.entry(t.id).or_default();
                 m.measure(&self.main, frames, 0.0);
                 m.plugin_failures = strip.failures;

crates/mix/src/offline.rs

@@ -132,33 +132,85 @@ pub fn fold_down_stereo(fmt: ChannelFormat, ch: &[Vec<f32>]) -> Vec<Vec<f32>> {
     out
 }
 
+/// Block size for clip effects in [`render_clips`].
+const CLIP_FX_BLOCK: usize = 4096;
+/// Most a clip effect keeps rendering past its clip's end in [`render_clips`], in seconds.
+const MAX_CLIP_FX_TAIL_SECONDS: f64 = 10.0;
+/// Silent lead-in run before a clip with effects so smoothed parameters (EQ) settle, in seconds
+/// (the smoothers settle within ~0.3 s).
+const CLIP_FX_SETTLE_SECONDS: f64 = 1.0;
+/// Frames an effect advances its smoothed parameters by at a time (the EQ's chunk). Processing starts on a
+/// multiple of it from the selection's start, as a render of the whole selection would, so the smoothers
+/// step at the same samples.
+const CLIP_FX_CHUNK: usize = 32;
+/// A tail block whose peak is below this (-180 dBFS) ends a clip effect's tail.
+const CLIP_FX_TAIL_FLOOR: f32 = 1e-9;
+
 /// Render only one track's clips (no mixer processing) — Consolidate.
 pub fn render_clips(s: &Session, track: TrackId, range: Range) -> Vec<Vec<f32>> {
     let Some(t) = s.track(track) else { return Vec::new() };
     let len = usize::try_from(range.len().max(0)).unwrap_or(0).min(MAX_RENDER_SAMPLES / t.channels().max(1));
     let mut out = vec![vec![0.0f32; len]; t.channels().max(1)];
     let mut scratch = Vec::new();
+    // One reusable block for every clip with effects.
+    let mut block: Vec<Vec<f32>> = Vec::new();
+    let max_tail = s.sample_rate.samples(MAX_CLIP_FX_TAIL_SECONDS).max(0);
     for c in t.clips().iter().filter(|c| !c.muted && c.range().overlaps(&range)) {
         match clip_fx_params(s, c.id.0) {
             None => render_clip(s, c, range.start, len, &mut out, &mut scratch),
             Some(params) => {
-                let mut tmp = vec![vec![0.0f32; len]; out.len()];
-                render_clip(s, c, range.start, len, &mut tmp, &mut scratch);
-                let mut fx = ClipFx::new(s.sample_rate.as_f64() as f32, tmp.len());
+                if block.len() != out.len() {
+                    block = vec![vec![0.0f32; CLIP_FX_BLOCK]; out.len()];
+                }
+                let mut fx = ClipFx::new(s.sample_rate.as_f64() as f32, out.len());
                 fx.configure(params);
-                let mut done = 0;
-                while done < len {
-                    let n = (len - done).min(4096);
-                    let mut block: Vec<Vec<f32>> = tmp.iter().map(|ch| ch.get(done..done + n).map(<[f32]>::to_vec).unwrap_or_default()).collect();
+                // The effects start from silence, so nothing comes out before the clip starts:
+                // process from there through the clip and a bounded tail, not the whole selection.
+                let offset = |at: Samples| usize::try_from(at.saturating_sub(range.start).max(0)).unwrap_or(usize::MAX).min(len);
+                let first = offset(c.start);
+                let clip_end = offset(c.end());
+                let tail_end = offset(c.end().saturating_add(max_tail));
+                // Smoothed parameters start at their defaults; settle them on silence, as the
+                // full-span render did, so the clip opens at the configured setting.
+                // (the clip's own samples start inside the first chunk when `first` is not on the grid)
+                let grid = first - first % CLIP_FX_CHUNK;
+                let mut lead = grid.min(usize::try_from(s.sample_rate.samples(CLIP_FX_SETTLE_SECONDS).max(0)).unwrap_or(0));
+                lead -= lead % CLIP_FX_CHUNK;
+                // a gain-only effect has no smoother to settle
+                if !fx.has_smoothed_modules() {
+                    lead = 0;
+                }
+                while lead > 0 {
+                    let n = lead.min(CLIP_FX_BLOCK);
+                    for ch in &mut block {
+                        ch.fill(0.0);
+                    }
                     fx.process(&mut block, n);
+                    lead -= n;
+                }
+                let mut done = grid;
+                while done < len {
+                    let n = (len - done).min(CLIP_FX_BLOCK);
+                    for ch in &mut block {
+                        ch.fill(0.0);
+                    }
+                    if done < clip_end {
+                        render_clip(s, c, range.start.saturating_add(done as i64), n, &mut block, &mut scratch);
+                    }
+                    fx.process(&mut block, n);
+                    let mut peak = 0.0f32;
                     for (o, b) in out.iter_mut().zip(block.iter()) {
                         if let Some(dst) = o.get_mut(done..done + n) {
                             for (x, y) in dst.iter_mut().zip(b.iter()) {
                                 *x += *y;
+                                peak = peak.max(y.abs());
                             }
                         }
                     }
                     done += n;
+                    if done >= clip_end && (done >= tail_end || peak < CLIP_FX_TAIL_FLOOR) {
+                        break;
+                    }
                 }
             }
         }

crates/mix/src/strip.rs

@@ -1,4 +1,4 @@
-use super::automation::{GainRamp, transport_at, volume_db_at};
+use super::automation::{Level, apply_gain, transport_at, volume_level};
 use super::clips::{ClipFx, clip_fx_params, render_clip};
 use super::instances::{INSTRUMENT_SLOT, PluginFailures, PreparedInstance, create_instance_for, is_third_party};
 use super::midi::{chase_controllers, schedule_notes};
@@ -334,7 +334,7 @@ fn render_instrument(s: &Session, t: &Track, strip: &mut Strip, blk: Block, tran
 fn run_inserts(t: &Track, strip: &mut Strip, blk: Block, transport: &Transport) {
     let Block { pos, frames, .. } = blk;
     let mut gr = 0.0f32;
-    let mut latency = 0usize;
+    let mut latency = strip.instrument.as_ref().filter(|i| !i.failed).map_or(0, |i| i.plugin.latency());
     for (i, ins) in t.mixer.inserts.iter().enumerate() {
         let (Some(ins), Some(Some(slot))) = (ins, strip.plugins.get_mut(i)) else { continue };
         if !ins.active || ins.bypass || slot.failed {
@@ -356,41 +356,28 @@ fn run_inserts(t: &Track, strip: &mut Strip, blk: Block, transport: &Transport)
     strip.latency = latency.min(MAX_LATENCY);
 }
 
-/// Fader gain (volume, trim and VCA automation), ramped across the block.
+/// Fader gain (volume, trim and VCA automation), read at every sample of the block.
 fn apply_fader(s: &Session, t: &Track, strip: &mut Strip, blk: Block) {
     let Block { pos, frames, .. } = blk;
-    // Endpoints are the first and last sample of this block. The next block starts on its own
-    // first sample, so a breakpoint there does not ramp the block before it.
-    let last = pos.saturating_add(frames.saturating_sub(1) as i64);
-    let mut v0 = volume_db_at(t, pos);
-    let mut v1 = volume_db_at(t, last);
     // Trim automation (an offset on top of the volume curve).
-    if let Some(l) = t
+    let trim = t
         .automation
         .iter()
         .find(|l| matches!(&l.param, AutoParam::Plugin { slot: u8::MAX, param } if param == "trim"))
         .filter(|l| !l.points.is_empty())
-    {
-        v0 += l.value_at(pos, 0.0);
-        v1 += l.value_at(last, 0.0);
-    }
+        .map_or(Level::Fixed(0.0), |l| Level::Lane(l, 0.0));
     // VCA master: its fader offsets the member's, and its mute mutes the member.
+    let mut vca_level = Level::Fixed(0.0);
     if let Some(vid) = t.mixer.vca
         && let Some(vca) = s.tracks.iter().find(|x| x.id.0 == vid && x.kind == TrackKind::Vca)
     {
-        v0 += volume_db_at(vca, pos);
-        v1 += volume_db_at(vca, last);
+        vca_level = volume_level(vca);
         if vca.mixer.mute {
             strip.muted = true;
         }
     }
-    let (g0, g1) = if strip.muted { (-144.0, -144.0) } else { (v0.min(12.0), v1.min(12.0)) };
-    let ramp = GainRamp::new(g0, g1, frames.saturating_sub(1));
-    for c in strip.buf.iter_mut() {
-        for (i, x) in c.iter_mut().enumerate().take(frames) {
-            *x *= ramp.at(i);
-        }
-    }
+    let levels = if strip.muted { [Level::Fixed(-144.0), Level::Fixed(0.0), Level::Fixed(0.0)] } else { [volume_level(t), trim, vca_level] };
+    apply_gain(&levels, pos, frames, 12.0, &mut strip.buf);
 }
 
 /// Track mute gates the audio and its pre-fader tap without splitting processor blocks.

crates/mix/src/tests.rs

@@ -941,6 +941,84 @@ fn a_plugins_bogus_latency_is_capped() {
     assert_eq!((eng.track_latency, eng.latency), (MAX_LATENCY, 2 * MAX_LATENCY));
 }
 
+#[test]
+fn a_hosted_instruments_latency_is_compensated() {
+    // #1474: a synth that reports latency plays late. Its delay must count toward the mix
+    // latency and align, the way an insert's does.
+    struct LatentSynth {
+        inner: Box<dyn Plugin>,
+        n: usize,
+        t: usize,
+        pending: Option<usize>,
+    }
+    impl Plugin for LatentSynth {
+        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.inner.set_param(id, v)
+        }
+        fn param(&self, id: &str) -> Option<f32> {
+            self.inner.param(id)
+        }
+        fn note_on(&mut self, offset: usize, _: u8, _: u8) {
+            self.pending = Some(self.t + offset + self.n);
+        }
+        fn process(&mut self, io: &mut [Vec<f32>], frames: usize) {
+            for c in io.iter_mut() {
+                for (i, x) in c.iter_mut().take(frames).enumerate() {
+                    *x = if Some(self.t + i) == self.pending { 0.25 } else { 0.0 };
+                }
+            }
+            self.t += frames;
+        }
+        fn latency(&self) -> usize {
+            self.n
+        }
+    }
+    use soundcraft_midi::{Note, Sequence};
+    let n = 500;
+    let mut s = Session::default();
+    s.edit.delay_compensation = true;
+    let audio = s.add_track(TrackKind::Audio, ChannelFormat::Stereo, None);
+    let mut click = vec![0.0f32; 48_000];
+    click[24_000] = 0.25;
+    s.pool.insert(SourceId(1474), Arc::new(SourceAudio::new(AudioBuffer { sample_rate: 48_000, channels: vec![click.clone(), click] })));
+    let cid = s.new_clip_id();
+    s.track_mut(audio).unwrap().playlist_mut().unwrap().clips.push(Clip::audio(cid, "click", SourceId(1474), 0, 0, 48_000));
+    let inst = s.add_track(TrackKind::Instrument, ChannelFormat::Stereo, None);
+    let mut seq = Sequence::default();
+    seq.notes.push(Note { pitch: 60, velocity: 100, release_velocity: 64, channel: 0, start: 960, length: 240 });
+    let mcid = s.new_clip_id();
+    s.track_mut(inst).unwrap().playlist_mut().unwrap().clips.push(Clip::midi(mcid, "note", 0, 48_000, seq));
+    s.track_mut(inst).unwrap().instrument = Some(Insert::new("clap:test.latent"));
+    let mut eng = MixEngine::new(48_000.0, 1024);
+    eng.set_external_instances(true);
+    eng.adopt(vec![PreparedInstance {
+        track: inst,
+        slot: INSTRUMENT_SLOT,
+        id: "clap:test.latent".into(),
+        ch: 2,
+        plugin: Box::new(LatentSynth { inner: soundcraft_dsp::create("gain").unwrap(), n, t: 0, pending: None }),
+    }]);
+    let mut out = vec![vec![0.0; 1024]; 2];
+    let mut rendered = Vec::new();
+    for b in 0..48 {
+        eng.render(&s, b * 1024, 1024, &mut out);
+        rendered.extend_from_slice(&out[0]);
+    }
+    assert_eq!(eng.latency, n, "the hosted instrument's latency is part of the mix latency");
+    let impulses: Vec<_> = rendered.iter().enumerate().filter(|(_, v)| v.abs() > 1e-6).map(|(i, _)| i).collect();
+    assert_eq!(impulses, vec![24_000 + n], "both the audio click and instrument impulse align");
+    assert!((rendered[24_000 + n] - 0.5).abs() < 1e-6, "the aligned impulses add, neither is missing");
+}
+
 #[test]
 fn input_monitoring_replaces_clips() {
     let (mut s, t) = session_with_dc(0.5, 4800);
@@ -1197,14 +1275,238 @@ fn apply_matrix_span_matches_the_plain_per_sample_sum() {
     }
 }
 
+/// A volume lane through `points` (sample, dB).
+fn volume_lane(points: &[(i64, f32)]) -> soundcraft_model::AutomationLane {
+    let mut l = soundcraft_model::AutomationLane::new(AutoParam::Volume);
+    for &(at, db) in points {
+        l.set_point(at, db);
+    }
+    l
+}
+
+/// Volume automation is read at every sample: a breakpoint acts on its own sample, and between
+/// breakpoints the gain follows the lane (linear in dB), whatever size the render blocks are. A
+/// 480-sample crossfade used to be resolved once per block, so it moved by up to a block and left
+/// a hole or not depending on where the block edge fell.
 #[test]
-fn gain_ramp_matches_converting_both_ends_every_sample() {
-    for (db0, db1, n) in [(-6.0f32, 3.0f32, 512usize), (0.0, 0.0, 1), (-144.0, 0.0, 300), (2.5, -60.0, 0), (f32::NAN, -3.0, 64), (-200.0, 12.0, 7)] {
-        let ramp = crate::automation::GainRamp::new(db0, db1, n);
-        let (g0, g1) = (db_to_gain(db0), db_to_gain(db1));
-        for i in 0..=n {
-            let want = if n == 0 { g0 } else { g0 + (g1 - g0) * (i as f32 / n as f32) };
-            assert_eq!(ramp.at(i).to_bits(), want.to_bits(), "{db0} -> {db1} dB, sample {i} of {n}");
+fn volume_automation_follows_its_breakpoints_in_any_block_size() {
+    let (mut s, a) = session_with_dc(0.5, 8192);
+    let b = add_dc_track(&mut s, 0.5, 8192);
+    // A falls from 0 to -144 dB across 2760..3240 while B rises, and back across 5760..6240.
+    let fall = volume_lane(&[(0, 0.0), (2760, 0.0), (3240, -144.0), (5760, -144.0), (6240, 0.0)]);
+    let rise = volume_lane(&[(0, -144.0), (2760, -144.0), (3240, 0.0), (5760, 0.0), (6240, -144.0)]);
+    // One track's level at 0 dB, through the pan law.
+    let per_track = render_range(&s, Range::new(0, 64), 64)[0][0] / 2.0;
+    s.track_mut(a).unwrap().automation.push(fall.clone());
+    s.track_mut(b).unwrap().automation.push(rise.clone());
+    let want = |i: i64| per_track * (db_to_gain(fall.value_at(i, 0.0)) + db_to_gain(rise.value_at(i, 0.0)));
+    for block in [1024, 512, 333, 64] {
+        let out = render_range(&s, Range::new(0, 8192), block);
+        for (i, &x) in out[0].iter().enumerate() {
+            let w = want(i as i64);
+            assert!((x - w).abs() <= 1e-5 * w.max(1e-3), "block {block}, sample {i}: {x} vs {w}");
         }
     }
 }
+
+/// A master fader's breakpoint acts on its own sample too.
+#[test]
+fn master_volume_automation_follows_its_breakpoints_in_any_block_size() {
+    let (mut s, _) = session_with_dc(0.5, 4096);
+    let dry = render_range(&s, Range::new(0, 64), 64)[0][0];
+    let m = s.add_track(TrackKind::Master, ChannelFormat::Stereo, None);
+    let lane = volume_lane(&[(0, 0.0), (1500, 0.0), (1501, -144.0), (2600, -144.0), (2700, -6.0)]);
+    s.track_mut(m).unwrap().automation.push(lane.clone());
+    for block in [1024, 256, 100] {
+        let out = render_range(&s, Range::new(0, 4096), block);
+        for (i, &x) in out[0].iter().enumerate() {
+            let w = dry * db_to_gain(lane.value_at(i as i64, 0.0));
+            assert!((x - w).abs() <= 1e-5 * w.max(1e-3), "block {block}, sample {i}: {x} vs {w}");
+        }
+    }
+}
+
+/// `scale` gives what `db_to_gain` gives sample by sample, from a ramp's first sample to its last:
+/// silence at or below -144 dB, the cap, NaN, extreme values and one- or two-sample ramps.
+#[test]
+fn stepped_fader_ramps_match_converting_every_sample() {
+    let cases: &[(&str, f32, f32, usize, f32)] = &[
+        ("down to silence", 0.0, -144.0, 480, 12.0),
+        ("up from silence", -144.0, 0.0, 480, 12.0),
+        ("across the cap", 6.0, 18.0, 300, 12.0),
+        ("below the floor and back", -200.0, -20.0, 512, 12.0),
+        ("flat", -6.0, -6.0, 1024, 12.0),
+        ("one sample", -6.0, 3.0, 1, 12.0),
+        ("two samples", -6.0, 3.0, 2, 12.0),
+        ("empty", 0.0, -6.0, 0, 12.0),
+        ("NaN start", f32::NAN, -3.0, 64, 12.0),
+        ("long ramp in one block", 0.0, -60.0, 16_384, 12.0),
+        ("recover from deep silence", -10_000.0, 0.0, 1024, 12.0),
+        ("descend from extreme trim", 10_000.0, -100.0, 1024, 12.0),
+        ("no cap", -12.0, 6.0, 1000, f32::INFINITY),
+        ("gain helper ceiling", 300.0, 0.0, 1024, f32::INFINITY),
+        ("extreme exact endpoint", -1e20, -20.0, 64, 12.0),
+        ("negative infinite start", f32::NEG_INFINITY, -20.0, 64, 12.0),
+        ("positive infinite end", -20.0, f32::INFINITY, 64, 12.0),
+        ("opposite infinities", f32::NEG_INFINITY, f32::INFINITY, 64, 12.0),
+    ];
+    for &(name, d0, d1, n, max_db) in cases {
+        let mut x = vec![1.0f32; n];
+        crate::automation::scale(&mut x, d0, d1, max_db);
+        for (k, &got) in x.iter().enumerate() {
+            let at = if k == 0 {
+                d0
+            } else if k + 1 == n {
+                d1
+            } else {
+                let t = k as f64 / (n - 1) as f64;
+                (f64::from(d0) * (1.0 - t) + f64::from(d1) * t) as f32
+            };
+            let want = if d0.is_nan() || d1.is_nan() || at.is_nan() { 0.0 } else { db_to_gain(at.min(max_db)) };
+            assert!((got - want).abs() <= 1e-5 * want.max(1e-6) || (got == 0.0 && want == 0.0), "{name}, sample {k} of {n}: {got} vs {want}");
+        }
+        if d0.is_nan() || d1.is_nan() {
+            assert!(x.iter().all(|&g| g == 0.0), "{name}: a NaN end is silence");
+            continue;
+        }
+        assert_eq!(x.first().copied().unwrap_or(0.0), if n == 0 { 0.0 } else { db_to_gain(d0.min(max_db)) }, "{name}: first sample exact");
+        if n > 1 {
+            assert_eq!(x[n - 1], db_to_gain(d1.min(max_db)), "{name}: last sample exact");
+        }
+    }
+}
+
+/// Volume, trim and VCA lanes with breakpoints at different samples add up at every sample, a
+/// muted track stays silent, and a render that starts inside a ramp or has breakpoints on block
+/// edges reads the same curve.
+#[test]
+fn summed_fader_lanes_are_read_at_every_sample() {
+    let (mut s, a) = session_with_dc(0.5, 12_288);
+    let muted = add_dc_track(&mut s, 0.5, 12_288);
+    let vca = s.add_track(TrackKind::Vca, ChannelFormat::Mono, None);
+    let one_track = render_range(&s, Range::new(0, 64), 64)[0][0] / 2.0;
+    s.track_mut(muted).unwrap().mixer.mute = true;
+    let vol = volume_lane(&[(0, 0.0), (1024, 0.0), (2048, -30.0), (4096, -6.0)]);
+    let mut trim = soundcraft_model::AutomationLane::new(AutoParam::Plugin { slot: u8::MAX, param: "trim".into() });
+    for (at, db) in [(0, 0.0), (1500, 0.0), (3000, 6.0)] {
+        trim.set_point(at, db);
+    }
+    let vca_lane = volume_lane(&[(0, 0.0), (5120, 0.0), (7000, -12.0)]);
+    let tr = s.track_mut(a).unwrap();
+    tr.automation.push(vol.clone());
+    tr.automation.push(trim.clone());
+    tr.mixer.vca = Some(vca.0);
+    s.track_mut(vca).unwrap().automation.push(vca_lane.clone());
+    // dB at `i`, from the breakpoints themselves.
+    let lin = |pts: &[(i64, f32)], i: i64| match pts.iter().position(|p| p.0 > i) {
+        None => pts[pts.len() - 1].1,
+        Some(0) => pts[0].1,
+        Some(k) => pts[k - 1].1 + (pts[k].1 - pts[k - 1].1) * ((i - pts[k - 1].0) as f32 / (pts[k].0 - pts[k - 1].0) as f32),
+    };
+    let want = |i: i64| {
+        let db = lin(&[(0, 0.0), (1024, 0.0), (2048, -30.0), (4096, -6.0)], i)
+            + lin(&[(0, 0.0), (1500, 0.0), (3000, 6.0)], i)
+            + lin(&[(0, 0.0), (5120, 0.0), (7000, -12.0)], i);
+        one_track * db_to_gain(db.min(12.0))
+    };
+    for (start, block) in [(0i64, 1024), (0, 512), (1700, 333), (1024, 1024), (2047, 64)] {
+        let out = render_range(&s, Range::new(start, 12_288), block);
+        for (k, &x) in out[0].iter().enumerate() {
+            let i = start + k as i64;
+            let w = want(i);
+            assert!((x - w).abs() <= 1e-5 * w.max(1e-3), "start {start}, block {block}, sample {i}: {x} vs {w}");
+        }
+    }
+}
+
+/// Consolidate's clip-effect pass, processing every clip's effects across the whole selection
+/// (what `render_clips` did before it limited them to the clip and its tail).
+fn render_clips_full_span(s: &Session, track: TrackId, range: Range) -> Vec<Vec<f32>> {
+    let t = s.track(track).unwrap();
+    let len = range.len() as usize;
+    let mut out = vec![vec![0.0f32; len]; t.channels().max(1)];
+    let mut scratch = Vec::new();
+    for c in t.clips().iter().filter(|c| !c.muted && c.range().overlaps(&range)) {
+        let params = crate::clips::clip_fx_params(s, c.id.0).unwrap();
+        let mut tmp = vec![vec![0.0f32; len]; out.len()];
+        crate::clips::render_clip(s, c, range.start, len, &mut tmp, &mut scratch);
+        let mut fx = crate::clips::ClipFx::new(48_000.0, tmp.len());
+        fx.configure(params);
+        for done in (0..len).step_by(4096) {
+            let n = (len - done).min(4096);
+            let mut block: Vec<Vec<f32>> = tmp.iter().map(|ch| ch[done..done + n].to_vec()).collect();
+            fx.process(&mut block, n);
+            for (o, b) in out.iter_mut().zip(&block) {
+                o[done..done + n].iter_mut().zip(b).for_each(|(x, y)| *x += y);
+            }
+        }
+    }
+    out
+}
+
+#[test]
+fn consolidate_clip_effects_cover_the_clip_and_its_tail() {
+    let fx_sets: [&[(&str, f64)]; 3] =
+        [&[("comp.lookahead", 5.0), ("comp.threshold", -20.0), ("gain", -6.0)], &[("eq.hpf_on", 1.0), ("gain", 3.0)], &[("eq.low_shelf_gain", 12.0)]];
+    for (k, params) in fx_sets.iter().enumerate() {
+        let mut s = Session::default();
+        let t = s.add_track(TrackKind::Audio, ChannelFormat::Mono, None);
+        s.pool.insert(SourceId(900), Arc::new(SourceAudio::new(AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.5; 4800]] })));
+        let cid = s.new_clip_id();
+        s.track_mut(t).unwrap().playlist_mut().unwrap().clips.push(Clip::audio(cid, "dc", SourceId(900), 0, 20_000, 4800));
+        for (param, value) in params.iter() {
+            s.edit.values.insert(format!("clip_fx.{}.{param}", cid.0), *value);
+        }
+        let range = Range::new(5_000, 100_000);
+        let got = render_clips(&s, t, range);
+        let want = render_clips_full_span(&s, t, range);
+        assert_eq!(got.len(), want.len());
+        assert!(want[0].iter().any(|x| x.abs() > 0.05), "the fixture should sound");
+        if k == 0 {
+            // The compressor's lookahead output after the clip's end is kept.
+            assert!(got[0][20_000 + 4800 - 5_000 + 10].abs() > 1e-3);
+        }
+        for (i, (a, b)) in got[0].iter().zip(&want[0]).enumerate() {
+            assert!((a - b).abs() < 1e-5, "set {k}, sample {i}: {a} vs {b}");
+        }
+    }
+}
+
+/// A clip that starts a few frames into the selection, while the EQ's smoothers are still settling: the
+/// effect's 32-frame chunks must line up with the full-span render's.
+#[test]
+fn consolidate_clip_effects_keep_the_reference_chunk_grid() {
+    for offset in [1i64, 31, 32, 33, 1000] {
+        let mut s = Session::default();
+        let t = s.add_track(TrackKind::Audio, ChannelFormat::Mono, None);
+        s.pool.insert(SourceId(900), Arc::new(SourceAudio::new(AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.5; 4800]] })));
+        let cid = s.new_clip_id();
+        s.track_mut(t).unwrap().playlist_mut().unwrap().clips.push(Clip::audio(cid, "dc", SourceId(900), 0, offset, 4800));
+        s.edit.values.insert(format!("clip_fx.{}.eq.low_shelf_gain", cid.0), 12.0);
+        let range = Range::new(0, 20_000);
+        let got = render_clips(&s, t, range);
+        let want = render_clips_full_span(&s, t, range);
+        for (i, (a, b)) in got[0].iter().zip(&want[0]).enumerate() {
+            assert!((a - b).abs() < 1e-5, "clip at {offset}, sample {i}: {a} vs {b}");
+        }
+    }
+}
+
+#[test]
+fn consolidate_many_tiny_effect_clips_stays_fast() {
+    // Thousands of one-sample clips with effects across a long selection: each one is processed
+    // over its own span, not the whole selection.
+    let mut s = Session::default();
+    let t = s.add_track(TrackKind::Audio, ChannelFormat::Mono, None);
+    s.pool.insert(SourceId(900), Arc::new(SourceAudio::new(AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.5; 1]] })));
+    for i in 0..2000i64 {
+        let cid = s.new_clip_id();
+        s.track_mut(t).unwrap().playlist_mut().unwrap().clips.push(Clip::audio(cid, "x", SourceId(900), 0, i * 1000, 1));
+        s.edit.values.insert(format!("clip_fx.{}.gain", cid.0), -6.0);
+    }
+    let start = std::time::Instant::now();
+    let out = render_clips(&s, t, Range::new(0, 4_000_000));
+    assert!(start.elapsed() < std::time::Duration::from_secs(10), "{:?}", start.elapsed());
+    assert!((out[0][1000] - 0.5 * db_to_gain(-6.0)).abs() < 1e-6);
+    assert_eq!(out[0][1001], 0.0);
+}

crates/model/src/automation.rs

@@ -164,7 +164,10 @@ impl AutomationLane {
                 // Widen so far-apart breakpoints cannot overflow i64.
                 let span = i128::from(b.at) - i128::from(a.at);
                 let off = i128::from(at) - i128::from(a.at);
-                a.value + (b.value - a.value) * (off as f64 / span as f64) as f32
+                // Interpolate in f64: the f32 difference overflows for
+                // opposite-sign values near f32::MAX.
+                let (av, bv) = (f64::from(a.value), f64::from(b.value));
+                (av + (bv - av) * (off as f64 / span as f64)) as f32
             }
             (Some(a), _) => a.value,
             _ => default,
@@ -281,6 +284,17 @@ mod tests {
         assert!(w.is_finite() && (-10.0..=0.0).contains(&w));
     }
 
+    #[test]
+    fn value_at_opposite_sign_extremes_stays_finite() {
+        let mut l = AutomationLane::new(AutoParam::Plugin { slot: 0, param: "Cutoff".into() });
+        l.set_point(0, -3.0e38);
+        l.set_point(1000, 3.0e38);
+        let v = l.value_at(500, 0.0);
+        assert!(v.is_finite() && v.abs() < 1.0e32, "mid value {v}");
+        let w = l.value_at(1, 0.0);
+        assert!(w.is_finite() && w < -2.9e38, "early value {w}");
+    }
+
     #[test]
     fn pan_label_max_does_not_overflow() {
         assert_eq!(AutoParam::Pan(255).label(), "pan 256");

crates/ui-egui/src/app.rs

@@ -46,6 +46,7 @@ impl SoundApp {
             services,
             native_menu_bar: false,
             autosave_dir: None,
+            fallback_take_dir: None,
             autosaver: None,
             autosaved_rev: 0,
             leftovers: Vec::new(),

crates/ui-egui/src/app/playback.rs

@@ -155,15 +155,23 @@ impl SoundApp {
     /// autosave folder. Returns the takes it records.
     fn arm_recorder(&mut self) -> Result<Vec<soundcraft_engine::io::Take>, String> {
         let name = soundcraft_engine::io::sanitize_name(&self.engine.session().name);
-        let unsaved_dir = self.autosave_dir.as_ref().map_or_else(std::env::temp_dir, |d| d.join(name));
+        // Without a settings folder the takes go under the temporary folder, in a folder of this
+        // run's own that nobody else could have made first.
+        let unsaved_dir = match &self.autosave_dir {
+            Some(d) => d.join(name),
+            // A saved session records beside its file: `plan_takes` never uses this folder.
+            None if self.engine.path.is_some() => std::path::PathBuf::new(),
+            None => self.fallback_take_dir()?,
+        };
         let Some(r) = &mut self.recorder else { return Err("no audio input device".into()) };
         let plan = soundcraft_engine::io::plan_takes(&self.engine, &unsaved_dir, r.channels);
         if plan.is_empty() {
             return Err("no audio track is record-enabled".into());
         }
-        // The takes are unsaved work: the folder they go into under the autosave root is
-        // owner-only, like the autosaves, before the recorder makes anything in it.
-        if self.engine.path.is_none() && self.autosave_dir.is_some() {
+        // The takes are unsaved work: on Unix the folder they go into is owner-only, like the
+        // autosaves, before the recorder makes anything in it (other systems get the folder's
+        // inherited access: no ACLs are set, so the temporary folder's own per-user access applies).
+        if self.engine.path.is_none() {
             for dir in plan.iter().filter_map(|(_, _, path)| path.parent()) {
                 soundcraft_engine::autosave::create_folder(dir).map_err(|e| format!("{}: {e}", dir.display()))?;
             }
@@ -176,6 +184,19 @@ impl SoundApp {
         Ok(takes)
     }
 
+    /// The folder for the takes of a session never saved when there is no autosave folder, made on
+    /// first use: exclusively and under a name nobody can guess, so another account cannot have
+    /// made it first, with open permissions or as a link.
+    fn fallback_take_dir(&mut self) -> Result<std::path::PathBuf, String> {
+        if let Some(dir) = &self.fallback_take_dir {
+            return Ok(dir.clone());
+        }
+        let dir = soundcraft_engine::autosave::create_unique_folder(&std::env::temp_dir(), "SoundCraft")
+            .map_err(|e| format!("temporary take folder: {e}"))?;
+        self.fallback_take_dir = Some(dir.clone());
+        Ok(dir)
+    }
+
     fn finish_recording(&mut self) {
         self.engine.transport.recording = false;
         if let Some(p) = &self.player {
@@ -453,3 +474,18 @@ impl SoundApp {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn the_fallback_take_folder_is_made_once_under_the_temporary_folder() {
+        let mut app = SoundApp::new(soundcraft_engine::Engine::default(), None, crate::Services::default());
+        let a = app.fallback_take_dir().unwrap();
+        assert_eq!(a.parent(), Some(std::env::temp_dir().as_path()));
+        assert!(a.is_dir());
+        assert_eq!(app.fallback_take_dir().unwrap(), a, "the same folder for the rest of the run");
+        let _ = std::fs::remove_dir_all(&a);
+    }
+}

crates/ui-egui/src/lib.rs

@@ -291,6 +291,8 @@ pub struct SoundApp {
     pub native_menu_bar: bool,
     /// Folder for crash-recovery autosaves (native apps set it).
     pub autosave_dir: Option<std::path::PathBuf>,
+    /// Where the takes of a session never saved go without an autosave folder: made once per run, under the temporary folder.
+    fallback_take_dir: Option<std::path::PathBuf>,
     /// Writes the open session's autosaves in the background, once there is something to write.
     autosaver: Option<soundcraft_engine::autosave::Autosaver>,
     /// The document revision last handed to the autosaver (0 once that autosave is stale).

crates/ui-egui/src/menus.rs

@@ -298,32 +298,34 @@ pub fn menu_bar(app: &mut SoundApp, ui: &mut egui::Ui) {
                 let extra = ui_aliases();
                 for root in tree() {
                     ui.menu_button(&root.label, |ui| {
-                        ui.add_enabled_ui(menu_entries_enabled, |ui| {
-                            for c in &root.children {
-                                menu_node(app, ui, c, &extra);
-                                if c.path == "File > Open" {
-                                    crate::recent::menu(app, ui);
+                        scrolling(ui, |ui| {
+                            ui.add_enabled_ui(menu_entries_enabled, |ui| {
+                                for c in &root.children {
+                                    menu_node(app, ui, c, &extra);
+                                    if c.path == "File > Open" {
+                                        crate::recent::menu(app, ui);
+                                    }
+                                    if c.path == "Track > New..." {
+                                        instrument_menu(app, ui);
+                                    }
                                 }
-                                if c.path == "Track > New..." {
-                                    instrument_menu(app, ui);
+                                if root.path == "AudioSuite" {
+                                    ui.separator();
+                                    ui.label(egui::RichText::new("Processes selected clips offline").small().color(t.text_dim));
                                 }
-                            }
-                            if root.path == "AudioSuite" {
-                                ui.separator();
-                                ui.label(egui::RichText::new("Processes selected clips offline").small().color(t.text_dim));
-                            }
-                            if root.path == "Window" {
-                                ui.separator();
-                                let mut separate = app.ui.mix_separate;
-                                if ui
-                                    .checkbox(&mut separate, "Mix in Separate Window")
-                                    .on_hover_text("Show Edit and Mix at once, e.g. one per monitor")
-                                    .changed()
-                                {
-                                    let _ = run_ui_command(app, "window.mix_separate", &json!({"value": separate}));
-                                    ui.close();
+                                if root.path == "Window" {
+                                    ui.separator();
+                                    let mut separate = app.ui.mix_separate;
+                                    if ui
+                                        .checkbox(&mut separate, "Mix in Separate Window")
+                                        .on_hover_text("Show Edit and Mix at once, e.g. one per monitor")
+                                        .changed()
+                                    {
+                                        let _ = run_ui_command(app, "window.mix_separate", &json!({"value": separate}));
+                                        ui.close();
+                                    }
                                 }
-                            }
+                            })
                         });
                     });
                 }
@@ -341,6 +343,12 @@ pub fn menu_bar(app: &mut SoundApp, ui: &mut egui::Ui) {
     );
 }
 
+/// A menu taller than the window scrolls instead of running off its bottom edge (#1482).
+fn scrolling<R>(ui: &mut egui::Ui, add: impl FnOnce(&mut egui::Ui) -> R) -> R {
+    let max_h = (ui.ctx().content_rect().height() - 40.0).max(120.0);
+    egui::ScrollArea::vertical().max_height(max_h).show(ui, add).inner
+}
+
 /// Track › Instrument: the instrument picker for the selected instrument track (#374).
 fn instrument_menu(app: &mut SoundApp, ui: &mut egui::Ui) {
     match instrument_track(app.engine.session()) {
@@ -361,9 +369,11 @@ fn instrument_track(s: &soundcraft_model::Session) -> Option<soundcraft_model::T
 fn menu_node(app: &mut SoundApp, ui: &mut egui::Ui, n: &MenuNode, extra: &[(&str, &str)]) {
     if !n.children.is_empty() {
         ui.menu_button(&n.label, |ui| {
-            for c in &n.children {
-                menu_node(app, ui, c, extra);
-            }
+            scrolling(ui, |ui| {
+                for c in &n.children {
+                    menu_node(app, ui, c, extra);
+                }
+            });
         });
         return;
     }

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

@@ -25,34 +25,45 @@ pub(crate) fn route_popup(app: &mut SoundApp, resp: &egui::Response, id: TrackId
     egui::Popup::menu(resp).close_behavior(egui::PopupCloseBehavior::CloseOnClickOutside).show(|ui| route_menu(app, ui, id, input));
 }
 
-/// Input or output menu: no route and buses on both, plus the main output (outputs) or inputs 1-8 (inputs).
+/// Input or output menu: no route and buses on both, plus the main output (outputs) or inputs 1-8
+/// (inputs). Its search field takes typing at once and finds any of them, not just the buses.
 fn route_menu(app: &mut SoundApp, ui: &mut Ui, id: TrackId, input: bool) {
     let key = if input { "input" } else { "output" };
     let cmd = if input { "track.input" } else { "track.output" };
-    if ui.button(if input { "no input" } else { "no output" }).clicked() {
-        let _ = app.run(cmd, json!({"track": id.0, key: "none"}));
-        ui.close();
-    }
+    let hint = if input { "Search inputs…" } else { "Search outputs…" };
+    let search = MenuSearch::show(ui, egui::Id::unique(("route-search", id.0, input)), hint);
+    let busses: Vec<String> = app.engine.session().busses.iter().map(|b| b.name.clone()).collect();
     let main_name = app.engine.session().outputs.first().map_or_else(|| "Out 1-2".to_string(), |o| o.name.clone());
-    if !input && ui.button(main_name).clicked() {
-        let _ = app.run(cmd, json!({"track": id.0, key: "main"}));
-        ui.close();
-    }
+    // (label, the route the command is given)
+    let mut fixed = vec![(if input { "no input" } else { "no output" }.to_string(), "none".to_string())];
     if input {
-        for i in 1..=8 {
-            if ui.button(format!("In {i}")).clicked() {
-                let _ = app.run(cmd, json!({"track": id.0, key: format!("In {i}")}));
-                ui.close();
-            }
+        fixed.extend((1..=8).map(|i| (format!("In {i}"), format!("In {i}"))));
+    } else {
+        fixed.push((main_name, "main".to_string()));
+    }
+    if search.typing() {
+        let visible: Vec<(&String, &String)> =
+            fixed.iter().map(|(l, v)| (l, v)).chain(busses.iter().map(|b| (b, b))).filter(|(l, _)| search.matches(l)).collect();
+        let picked = search.rows(ui, visible.len(), 420.0, |ui, i, highlighted| visible.get(i).is_some_and(|(l, _)| menu_row(ui, highlighted, l)));
+        if let Some((_, value)) = picked.and_then(|i| visible.get(i)) {
+            let _ = app.run(cmd, json!({"track": id.0, key: value}));
+            ui.close();
+        }
+        return;
+    }
+    for (label, value) in &fixed {
+        if ui.button(label).clicked() {
+            let _ = app.run(cmd, json!({"track": id.0, key: value}));
+            ui.close();
         }
     }
     ui.separator();
-    let busses: Vec<String> = app.engine.session().busses.iter().map(|b| b.name.clone()).collect();
     ui.strong("Bus");
-    let search = MenuSearch::show(ui, egui::Id::unique(("route-bus-search", id.0, input)), "Search buses…");
-    let visible: Vec<&String> = busses.iter().filter(|b| search.matches(b)).collect();
-    if let Some(i) = search.rows(ui, visible.len(), 420.0, |ui, i, highlighted| menu_row(ui, highlighted, visible[i])) {
-        let _ = app.run(cmd, json!({"track": id.0, key: visible[i]}));
+    if let Some(bus) = search
+        .rows(ui, busses.len(), 420.0, |ui, i, highlighted| busses.get(i).is_some_and(|b| menu_row(ui, highlighted, b)))
+        .and_then(|i| busses.get(i))
+    {
+        let _ = app.run(cmd, json!({"track": id.0, key: bus}));
         ui.close();
     }
     if ui.button("new bus...").clicked() {

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

@@ -265,20 +265,42 @@ fn draw_roll_background(painter: &egui::Painter, g: &Roll<'_>) {
         }
     }
     // Grid.
+    let step = grid_stride(grid_ticks, px_per_tick);
     let mut tick = 0;
     while tick <= len_ticks {
         let bar = tick % (TICKS_PER_QUARTER * 4) == 0;
         let x = g.x_of(tick);
-        if grid_ticks as f32 * px_per_tick > 4.0 || bar {
-            painter.line_segment(
-                [pos2(x, roll.min.y), pos2(x, roll.max.y)],
-                Stroke::new(1.0, if bar { Color32::from_rgb(80, 80, 86) } else { Color32::from_rgb(50, 50, 54) }),
-            );
-        }
-        tick += grid_ticks;
+        painter.line_segment(
+            [pos2(x, roll.min.y), pos2(x, roll.max.y)],
+            Stroke::new(1.0, if bar { Color32::from_rgb(80, 80, 86) } else { Color32::from_rgb(50, 50, 54) }),
+        );
+        tick = tick.saturating_add(step);
     }
 }
 
+/// Closest lines the grid draws, in points.
+const MIN_GRID_PX: f32 = 4.0;
+
+/// Ticks between grid lines: the grid when its lines are more than [`MIN_GRID_PX`] apart, else
+/// as few common multiples of the grid and a bar as keep that spacing (so every line is a snap
+/// position and falls on a bar). The lines drawn are then bounded by the roll's width, however long
+/// the clip, instead of by its length.
+fn grid_stride(grid_ticks: i64, px_per_tick: f32) -> i64 {
+    let bar_ticks = TICKS_PER_QUARTER * 4;
+    if grid_ticks as f32 * px_per_tick > MIN_GRID_PX {
+        return grid_ticks.max(1);
+    }
+    let grid = grid_ticks.max(1);
+    let (mut a, mut b) = (grid, bar_ticks);
+    while b != 0 {
+        (a, b) = (b, a % b);
+    }
+    let common = (grid / a).saturating_mul(bar_ticks);
+    // `as` saturates a huge or NaN quotient; a zero `px_per_tick` gives one common multiple.
+    let n = (MIN_GRID_PX / (common as f32 * px_per_tick)).ceil().max(1.0) as i64;
+    common.saturating_mul(n)
+}
+
 /// The notes, with a drag in progress applied.
 fn draw_notes(app: &SoundApp, painter: &egui::Painter, g: &Roll<'_>, base: Color32) {
     let Roll { sequence, grid_ticks, .. } = *g;
@@ -478,6 +500,24 @@ fn velocity_lane(app: &mut SoundApp, ui: &mut Ui, g: &Roll<'_>, cid: ClipId, bas
 mod tests {
     use super::*;
 
+    #[test]
+    fn grid_lines_are_bounded_by_the_roll_width_not_the_clip_length() {
+        let sixteenth = TICKS_PER_QUARTER / 4;
+        // A 1000 pt roll showing a 4-bar clip: every sixteenth is 16 pt apart and drawn.
+        assert_eq!(grid_stride(sixteenth, 1000.0 / (16.0 * TICKS_PER_QUARTER as f32)), sixteenth);
+        // The same roll over a clip a billion ticks long: at most a line every 4 pt.
+        let (len, px_per_tick) = (1_000_000_000i64, 1000.0 / 1_000_000_000.0f32);
+        let step = grid_stride(sixteenth, px_per_tick);
+        assert_eq!(step % (TICKS_PER_QUARTER * 4), 0, "lines fall on bars");
+        assert!((len / step) <= 251, "{} lines", len / step);
+        // a dotted quarter grid (1440 ticks): every line is also a grid position
+        let dotted = TICKS_PER_QUARTER * 3 / 2;
+        let step = grid_stride(dotted, px_per_tick);
+        assert_eq!((step % dotted, step % (TICKS_PER_QUARTER * 4)), (0, 0), "lines are snap positions on bars: {step}");
+        assert!((len / step) <= 251, "{} lines", len / step);
+        assert!(grid_stride(0, 0.0) >= TICKS_PER_QUARTER * 4, "a zero grid or width still advances");
+    }
+
     #[test]
     fn switching_clip_drops_selection_and_gestures() {
         let mut st = MidiEditorState { selected: vec![0, 2], clip: Some(ClipId(1)), band: Some(pos2(1.0, 2.0)), ..Default::default() };

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

@@ -115,6 +115,22 @@ fn first_movie_aspect(s: &soundcraft_model::Session) -> Option<f32> {
     s.videos.first().map(|v| v.aspect() as f32)
 }
 
+/// Most thumbnails one clip draws in the Video Universe strip: 8 pt each, so more than the
+/// widest strip holds.
+const MAX_UNIVERSE_THUMBS: usize = 1 << 12;
+
+/// Left edges of the thumbnails of a clip starting at `clip_x` (each `tw` wide) that lie in
+/// `shown_min..shown_max`. The index and position are worked out in `f64`: an `f32` this far from
+/// the origin (a clip starting a billion points left) cannot step by a thumbnail's width.
+fn thumb_xs(clip_x: f32, shown_min: f32, shown_max: f32, tw: f32) -> impl Iterator<Item = f32> {
+    let (origin, tw) = (f64::from(clip_x), f64::from(tw));
+    // Nothing of the clip is in view when the shown span is empty (or inverted).
+    let empty = shown_max <= shown_min;
+    let first = ((f64::from(shown_min) - origin) / tw).floor().max(0.0);
+    let count = if empty { 0 } else { ((f64::from(shown_max) - origin) / tw - first).ceil().max(0.0) as usize };
+    (0..count.min(MAX_UNIVERSE_THUMBS)).map(move |i| (origin + (first + i as f64) * tw) as f32)
+}
+
 fn universe(app: &mut SoundApp, ctx: &egui::Context) {
     app.video.poll(ctx);
     let s = app.engine.session_arc();
@@ -145,8 +161,10 @@ fn universe(app: &mut SoundApp, ctx: &egui::Context) {
             }
             let tw = (cr.height() * v.aspect() as f32).max(8.0);
             let hpx = ((cr.height() * ppp / 16.0).ceil() * 16.0).clamp(16.0, 256.0) as u32;
-            let mut x = cr.min.x;
-            while x < cr.max.x {
+            // Only the thumbnails inside the strip, counted rather than stepped: a clip starting
+            // far left of it has an edge so large that adding a thumbnail's width wouldn't move it.
+            let shown = cr.intersect(r);
+            for x in thumb_xs(cr.min.x, shown.min.x, shown.max.x, tw) {
                 let secs = movie_secs(&s, c.start, offset, strip_position(x, r.min.x, r.width(), end, c.start)).max(0.0);
                 if let Some(tex) = app.video.thumb(ctx, key, &v.path, secs, hpx) {
                     let tr = Rect::from_min_size(pos2(x, cr.min.y), vec2(tw, cr.height()));
@@ -154,7 +172,6 @@ fn universe(app: &mut SoundApp, ctx: &egui::Context) {
                     let uv = Rect::from_min_max(pos2(0.0, 0.0), pos2((vis.width() / tw).clamp(0.0, 1.0), 1.0));
                     painter.image(tex.id(), vis, uv, Color32::WHITE);
                 }
-                x += tw;
             }
         }
         // The Edit window's visible range and the playhead.
@@ -182,7 +199,21 @@ fn universe(app: &mut SoundApp, ctx: &egui::Context) {
 
 #[cfg(test)]
 mod tests {
-    use super::strip_position;
+    use super::{strip_position, thumb_xs};
+
+    #[test]
+    fn thumbnails_of_a_clip_far_left_of_the_strip_are_evenly_spaced() {
+        // 2^30 points left of the strip with 8 pt thumbnails: f32 steps of `first + i` here are 16 apart
+        let xs: Vec<f32> = thumb_xs(-1_073_741_824.0, 0.0, 80.0, 8.0).collect();
+        assert_eq!(xs.len(), 10);
+        assert!(xs.windows(2).all(|w| w[1] - w[0] == 8.0), "{xs:?}");
+        assert_eq!(xs[0], 0.0);
+        // a clip inside the strip starts at its own edge
+        assert_eq!(thumb_xs(10.0, 10.0, 34.0, 8.0).collect::<Vec<_>>(), vec![10.0, 18.0, 26.0]);
+        // a clip ending left of the strip (the shown span is empty or inverted) draws none
+        assert_eq!(thumb_xs(-10.0, 0.0, -1.0, 8.0).count(), 0);
+        assert_eq!(thumb_xs(-10.0, 0.0, 0.0, 8.0).count(), 0);
+    }
 
     // A 1024 px strip over 1_024_000 samples: 1000 samples per point, exact in f32.
     const LEFT: f32 = 100.0;

crates/ui-egui/src/video_track.rs

@@ -90,6 +90,13 @@ impl Worker {
 }
 
 fn open_movie(path: &str) -> Result<Movie, String> {
+    // The last check before the file system: the path came from a session file, so the read
+    // roots apply, and only a regular file is opened (a pipe would hold the video worker
+    // forever).
+    soundcraft_engine::file_access::check_read(path)?;
+    if !std::fs::metadata(path).map_err(|e| format!("{path}: {e}"))?.is_file() {
+        return Err(format!("{path}: not a regular file"));
+    }
     #[cfg(not(target_arch = "wasm32"))]
     {
         let f = std::fs::File::open(path).map_err(|e| format!("{path}: {e}"))?;
@@ -491,3 +498,24 @@ pub fn draw_lane(app: &mut SoundApp, painter: &Painter, s: &Session, track: &Tra
         }
     }
 }
+
+#[cfg(all(test, not(target_arch = "wasm32")))]
+mod tests {
+    use super::open_movie;
+
+    #[test]
+    fn only_a_regular_movie_file_is_opened() {
+        let dir = std::env::temp_dir().join(format!("soundcraft-open-movie-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let (folder, missing, junk, movie) = (dir.to_string_lossy().to_string(), dir.join("none.mp4"), dir.join("junk.mp4"), dir.join("a.mp4"));
+        assert!(open_movie(&folder).err().unwrap_or_default().contains("not a regular file"));
+        assert!(open_movie(&missing.to_string_lossy()).is_err());
+        std::fs::write(&junk, b"not a movie").unwrap();
+        let err = open_movie(&junk.to_string_lossy()).err().unwrap_or_default();
+        assert!(!err.is_empty() && !err.contains("not a regular file"), "{err}");
+        std::fs::write(&movie, soundcraft_video::synth::h264_mp4(2, 2).unwrap()).unwrap();
+        assert!(open_movie(&movie.to_string_lossy()).is_ok());
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}

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

@@ -151,19 +151,19 @@ fn the_views_menu_stays_open_until_a_click_elsewhere() {
 }
 
 #[test]
-fn the_io_columns_route_menus_stay_open_while_searching_buses() {
+fn the_io_columns_route_menus_stay_open_while_searching() {
     let (mut h, _, row) = harness("Kick", "medium", "view.edit_io");
     click(&mut h, pos2(row[0] + HEADER_W + 40.0, row[1] + 29.5));
-    let bus = h.get_by_label("Bus").rect();
+    let first = h.get_by_label("no output").rect();
     let search = h
         .query_all_by_role(egui::accesskit::Role::TextInput)
         .map(|node| node.rect())
-        .filter(|r| r.min.y >= bus.max.y)
-        .min_by(|a, b| a.min.y.total_cmp(&b.min.y))
+        .filter(|r| r.max.y <= first.min.y && r.x_range().contains(first.center().x))
+        .max_by(|a, b| a.min.y.total_cmp(&b.min.y))
         .unwrap()
         .center();
     click(&mut h, search);
-    assert!(h.query_by_label("no output").is_some(), "a click in the bus search closed the Output menu");
+    assert!(h.query_by_label("no output").is_some(), "a click in the menu's search closed the Output menu");
 }
 
 #[test]

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

@@ -0,0 +1,64 @@
+//! A main menu taller than the window scrolls, so its last items can be reached (#1482).
+
+use egui::{Event, Modifiers, MouseWheelUnit, PointerButton, vec2};
+use egui_kittest::Harness;
+use egui_kittest::kittest::Queryable;
+use soundcraft_ui_egui::{Services, SoundApp, menus};
+
+const SIZE: egui::Vec2 = vec2(1200.0, 420.0);
+
+fn step(h: &mut Harness<'_, SoundApp>) {
+    let mut raw = std::mem::take(h.input_mut());
+    let ctx = h.ctx.clone();
+    h.state_mut().raw_input_hook(&ctx, &mut raw);
+    *h.input_mut() = raw;
+    h.step();
+}
+
+#[test]
+fn a_long_main_menu_scrolls_to_its_last_item() {
+    let app = SoundApp::new(soundcraft_engine::demo::demo_engine(), None, Services::default());
+    let mut h = Harness::builder().with_size(SIZE).build_ui_state(
+        |ui, app: &mut SoundApp| {
+            let ctx = ui.ctx().clone();
+            app.logic(&ctx);
+            app.ui(ui);
+        },
+        app,
+    );
+    for _ in 0..4 {
+        step(&mut h);
+    }
+    let options = menus::tree().into_iter().find(|r| r.path == "Options").unwrap();
+    // The menu must scroll all the way to its last entry, a leaf like "Low Latency Monitoring".
+    let last = options.children.last().unwrap().label.clone();
+
+    let at = h.get_by_label("Options").rect().center();
+    let s = &mut h.state_mut().synthetic;
+    s.push(Event::PointerMoved(at));
+    s.push(Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: true, modifiers: Modifiers::NONE });
+    s.push(Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE });
+    for _ in 0..6 {
+        step(&mut h);
+    }
+    let bottom = |h: &Harness<'_, SoundApp>| h.get_by_label_contains(&last).rect().bottom();
+    assert!(bottom(&h) > SIZE.y, "the Options menu is taller than the window, so `{last}` starts out of view");
+
+    // Over the top of the open menu, which drops down below its title.
+    h.state_mut().synthetic.push(Event::PointerMoved(at + vec2(80.0, 120.0)));
+    step(&mut h);
+    for _ in 0..40 {
+        h.state_mut().synthetic.push(Event::MouseWheel {
+            unit: MouseWheelUnit::Line,
+            delta: vec2(0.0, -3.0),
+            modifiers: Modifiers::NONE,
+            phase: egui::TouchPhase::Move,
+            source: egui::MouseWheelSource::Wheel,
+        });
+        step(&mut h);
+    }
+    for _ in 0..10 {
+        step(&mut h);
+    }
+    assert!(bottom(&h) <= SIZE.y, "scrolling the menu brings `{last}` into view (bottom at {})", bottom(&h));
+}

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

@@ -22,6 +22,7 @@ mod group_dialog;
 mod hide_floating;
 mod idle;
 mod key_families;
+mod long_menu_scroll;
 mod marker_rename;
 mod menu_search;
 mod midi_double_click;

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

@@ -169,6 +169,28 @@ fn send_and_output_menus_search_buses_as_soon_as_they_open() {
     assert_eq!(h.state().engine.session().tracks[0].mixer.output, Route::Bus(bus(&h, "Verb")));
 }
 
+/// The I/O menus' search finds the hardware inputs, the main output and "no input/output", not just buses.
+#[test]
+fn io_menus_search_every_route_not_just_buses() {
+    let mut h = harness(vox());
+    open(&mut h, "Input for Vox");
+    type_text(&mut h, "in 3");
+    assert!(h.query_by_label("In 4").is_none(), "only the matches are listed");
+    press(&mut h, Key::Enter);
+    assert_eq!(h.state().engine.session().tracks[0].mixer.input, Route::Hardware("In 3".into()));
+
+    open(&mut h, "Output for Vox");
+    type_text(&mut h, "no out");
+    press(&mut h, Key::Enter);
+    assert_eq!(h.state().engine.session().tracks[0].mixer.output, Route::None);
+
+    let main = h.state().engine.session().outputs.first().map_or_else(|| "Out 1-2".to_string(), |o| o.name.clone());
+    open(&mut h, "Output for Vox");
+    type_text(&mut h, &main.to_lowercase());
+    press(&mut h, Key::Enter);
+    assert_eq!(h.state().engine.session().tracks[0].mixer.output, Route::Main);
+}
+
 /// Scripted typing and Enter reach a menu search even when the host window is unfocused.
 #[test]
 fn scripted_keys_reach_the_search_with_the_window_in_the_background() {

crates/video/src/movie.rs

@@ -380,6 +380,11 @@ impl Movie {
             .collect()
     }
 
+    /// Size the sample table declares for `sample` (0 when there is none).
+    fn declared_size(&self, sample: usize) -> usize {
+        self.mp4.tracks.get(self.track).and_then(|t| t.samples.get(sample)).map_or(0, |s| s.size as usize)
+    }
+
     fn read(&self, sample: usize) -> Result<Vec<u8>> {
         let t = self.mp4.tracks.get(self.track).ok_or(VideoError::NoVideoTrack)?;
         let size = t.samples.get(sample).map_or(0, |s| s.size);
@@ -415,6 +420,13 @@ impl Movie {
                 Ok(Frame { width: f.width, height: f.height, rgba, index, time })
             }
             Codec::Jpeg => {
+                // The frame's own size, from its header, before a pixel is decoded: a frame may differ from
+                // the track's size (as before), but not exceed `MAX_PIXELS`.
+                let reader = image::ImageReader::with_format(std::io::Cursor::new(&data), image::ImageFormat::Jpeg);
+                let (w, h) = reader.into_dimensions().map_err(|e| VideoError::Decode(e.to_string()))?;
+                if u64::from(w) * u64::from(h) > MAX_PIXELS {
+                    return Err(VideoError::Decode("picture too large".into()));
+                }
                 let img = image::load_from_memory_with_format(&data, image::ImageFormat::Jpeg).map_err(|e| VideoError::Decode(e.to_string()))?;
                 let rgba = img.to_rgba8();
                 let (width, height) = rgba.dimensions();
@@ -457,6 +469,14 @@ impl Movie {
         Ok(self.h264_to_frame(p, index))
     }
 
+    /// Most sample bytes one frame request feeds the decoder (eight samples at the 256 MiB cap):
+    /// a request decodes from the previous keyframe, and a sample table whose entries all name
+    /// one large payload would otherwise read and parse it once per sample.
+    const MAX_REQUEST_BYTES: usize = 2 << 30;
+    /// Most samples one frame request feeds without a picture coming out: the reorder depth is
+    /// at most 16, so a stream that produces nothing for this long will produce nothing.
+    const MAX_SAMPLES_WITHOUT_PICTURE: usize = 256;
+
     fn decode_h264(&mut self, index: usize) -> Result<Arc<Frame>> {
         let Codec::H264 { avcc } = &self.codec else { return Err(VideoError::Unsupported("not H.264".into())) };
         let target = self.order.get(index).copied().ok_or(VideoError::OutOfRange)?;
@@ -471,6 +491,7 @@ impl Movie {
         }
         let total = self.order.len();
         let mut last_err: Option<String> = None;
+        let (mut fed, mut without_picture) = (0usize, 0usize);
         // Bounded: each iteration feeds one sample, or flushes once at the end.
         for _ in 0..=total.saturating_add(1) {
             let Some(st) = self.h264.as_mut() else { break };
@@ -485,13 +506,29 @@ impl Movie {
                 let s = st.next;
                 st.next += 1;
                 let pts = self.rank.get(s).copied().unwrap_or(0) as i64;
+                // The declared size is checked before the read allocates it. An error leaves no decoder
+                // behind that has stepped past this sample: the next request starts from its keyframe.
+                if fed.saturating_add(self.declared_size(s)) > Self::MAX_REQUEST_BYTES {
+                    self.h264 = None;
+                    return Err(VideoError::Decode(format!("frame {index} needs more than {} MiB of samples", Self::MAX_REQUEST_BYTES >> 20)));
+                }
                 let data = match self.read(s) {
                     Ok(d) => d,
+                    // an unreadable sample is skipped, as before, and counts as a sample without a picture: the
+                    // request's byte and no-picture budgets bound the walk
                     Err(e) => {
                         last_err = Some(e.to_string());
+                        without_picture += 1;
+                        if without_picture > Self::MAX_SAMPLES_WITHOUT_PICTURE {
+                            return Err(VideoError::Decode(format!(
+                                "no picture in {} samples before frame {index}",
+                                Self::MAX_SAMPLES_WITHOUT_PICTURE
+                            )));
+                        }
                         continue;
                     }
                 };
+                fed = fed.saturating_add(data.len());
                 let Some(st) = self.h264.as_mut() else { break };
                 match st.dec.decode(&data, pts) {
                     Ok(p) => p,
@@ -506,6 +543,10 @@ impl Movie {
                 st.dec.flush()
             };
             let Some(st) = self.h264.as_mut() else { break };
+            without_picture = if pics.is_empty() { without_picture + 1 } else { 0 };
+            if without_picture > Self::MAX_SAMPLES_WITHOUT_PICTURE {
+                return Err(VideoError::Decode(format!("no picture in {} samples before frame {index}", Self::MAX_SAMPLES_WITHOUT_PICTURE)));
+            }
             for p in pics {
                 let q = usize::try_from(p.pts).unwrap_or(usize::MAX);
                 st.last_out = Some(q);

crates/video/src/tests.rs

@@ -121,7 +121,7 @@ fn prores_frame_size_is_checked_before_decoding() {
 }
 
 /// In-memory movie bytes, zero-padded up to `len` without storing the padding. Records the
-/// largest read asked of it and refuses reads over 1 MiB (the test movies are much smaller).
+/// largest read asked of it and refuses reads over 32 MiB (the test movies are much smaller).
 struct PaddedSource {
     bytes: Vec<u8>,
     len: u64,
@@ -134,7 +134,7 @@ impl ByteSource for PaddedSource {
     }
     fn read_at(&self, offset: u64, buf: &mut [u8]) -> std::io::Result<()> {
         self.largest.fetch_max(buf.len(), Ordering::Relaxed);
-        if buf.len() > 1 << 20 {
+        if buf.len() > 32 << 20 {
             return Err(std::io::Error::other("read too large for the test source"));
         }
         let start = usize::try_from(offset).unwrap_or(usize::MAX);
@@ -161,6 +161,80 @@ fn h264_sample_reads_are_capped() {
     assert!(largest <= 256 << 20, "a {largest}-byte read reached the source");
 }
 
+#[test]
+fn one_frame_request_reads_a_bounded_amount_of_samples() {
+    // 65 frames whose `stsz` entries each claim 32 MiB: under the per-sample cap, but together
+    // past the 2 GiB one request may feed the decoder.
+    let mut bytes = h264_mp4(65, 65).unwrap();
+    let at = bytes.windows(4).position(|w| w == b"stsz").unwrap();
+    if bytes[at + 8..at + 12] == [0; 4] {
+        // one size per sample
+        for i in 0..65 {
+            let field = at + 16 + 4 * i;
+            bytes[field..field + 4].copy_from_slice(&(32u32 << 20).to_be_bytes());
+        }
+    } else {
+        // the writer stored one size for all the (equally large) samples
+        bytes[at + 8..at + 12].copy_from_slice(&(32u32 << 20).to_be_bytes());
+    }
+    let src = Arc::new(PaddedSource { bytes, len: 3 << 30, largest: AtomicUsize::new(0) });
+    let mut m = Movie::open_source(src).unwrap();
+    let r = m.frame(64);
+    assert!(matches!(&r, Err(VideoError::Decode(e)) if e.contains("needs more than 2048 MiB of samples")), "{r:?}");
+    // the sample that was refused is not skipped: asking again fails the same way instead of decoding past it
+    let again = m.frame(64);
+    assert!(matches!(&again, Err(VideoError::Decode(e)) if e.contains("needs more than 2048 MiB of samples")), "{again:?}");
+}
+
+/// A source that, once `failing` is set, cannot be read at all.
+struct UnreadableSamples {
+    bytes: Vec<u8>,
+    failing: std::sync::atomic::AtomicBool,
+}
+
+impl ByteSource for UnreadableSamples {
+    fn len(&self) -> u64 {
+        self.bytes.len() as u64
+    }
+    fn read_at(&self, offset: u64, buf: &mut [u8]) -> std::io::Result<()> {
+        let start = usize::try_from(offset).unwrap_or(usize::MAX);
+        if self.failing.load(Ordering::Relaxed) || start.saturating_add(buf.len()) > self.bytes.len() {
+            return Err(std::io::Error::other("unreadable"));
+        }
+        buf.copy_from_slice(&self.bytes[start..start + buf.len()]);
+        Ok(())
+    }
+}
+
+#[test]
+fn a_request_over_unreadable_samples_stops_at_the_no_picture_budget() {
+    // 400 frames of one GOP, none of whose samples can be read once the movie is open: the walk gives up after 256 skipped samples
+    let bytes = h264_mp4(400, 400).unwrap();
+    let src = Arc::new(UnreadableSamples { bytes, failing: false.into() });
+    let mut m = Movie::open_source(src.clone()).unwrap();
+    src.failing.store(true, Ordering::Relaxed);
+    let r = m.frame(399);
+    assert!(matches!(&r, Err(VideoError::Decode(e)) if e.contains("no picture in 256 samples")), "{r:?}");
+}
+
+#[test]
+fn mjpeg_frame_size_is_capped_from_its_header_but_may_differ_from_the_track() {
+    // A frame whose header differs from the track's size still decodes (within the dimension cap, as before)...
+    let mut bytes = mjpeg_mov(2).unwrap();
+    let sof = bytes.windows(2).position(|w| w == [0xFF, 0xC0]).unwrap();
+    bytes[sof + 5..sof + 9].copy_from_slice(&[0, 8, 0, 8]);
+    let mut m = Movie::open(bytes).unwrap();
+    assert!(m.frame(0).is_ok());
+    // ...but one claiming 16 000 x 16 000 is refused from the header, not decoded.
+    let mut bytes = mjpeg_mov(2).unwrap();
+    let sof = bytes.windows(2).position(|w| w == [0xFF, 0xC0]).unwrap();
+    bytes[sof + 5..sof + 9].copy_from_slice(&[0x3E, 0x80, 0x3E, 0x80]);
+    let mut m = Movie::open(bytes).unwrap();
+    let r = m.frame(0);
+    assert!(matches!(&r, Err(VideoError::Decode(e)) if e.contains("picture too large")), "{r:?}");
+    assert!(m.frame(1).is_ok(), "the untouched frame still decodes");
+}
+
 #[test]
 fn unsupported_codec_opens_but_does_not_decode() {
     let mut mw = Mp4Writer::new(Cursor::new(Vec::new()), WriterOptions::new(Brand::Mp4)).unwrap();

docs/gaps.md

@@ -1,6 +1,6 @@
 # Where SoundCraft falls short of Pro Tools
 
-> **Last reviewed:** 2026-10-25 · **Last updated:** 2026-10-25 · **Change:** trivial (G-01: `setup.playback_engine` applies the device buffer in the desktop app; G-04: Clip Looping crossfade and loop count) · **Target:** Avid Pro Tools Ultimate 2026.4.1
+> **Last reviewed:** 2026-10-25 · **Last updated:** 2026-11-04 · **Change:** trivial (G-04: volume automation read at every sample, #1354; previously trivial: G-01: `setup.playback_engine` applies the device buffer in the desktop app; G-04: Clip Looping crossfade and loop count) · **Target:** Avid Pro Tools Ultimate 2026.4.1
 
 Every known shortfall, one entry each, ranked by how much it stops a Pro Tools user from doing
 real work in SoundCraft. This is the work list: pick from the top. Rows marked **alpha blocker**
@@ -92,7 +92,9 @@ When you close a gap, delete its entry (or shrink it) in the same PR, and bump t
 **Fixed (2026-10-16):** Aux, folder and master latency calculations now skip inserts already
 render block, matching track faders. A breakpoint at the next block no longer ramps the preceding
 block, and ramps reach their last-sample value. Regression tests cover nonzero render starts,
-one-sample callbacks and several block sizes. Interior automation breakpoints remain block-dependent.
+one-sample callbacks and several block sizes. Since #1354, track and master volume automation is read at
+every sample, so its interior breakpoints no longer depend on the block; send levels and plugin parameters
+are still read once per block.
 
 disabled for producing NaN or infinity. Subsequent blocks compensate only for healthy inserts;
 regression tests verify rendered impulse timing, retained healthy latency and reset/retry at
@@ -230,6 +232,7 @@ missing. Out of scope unless the owner decides otherwise.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-11-04 | trivial | G-04: track and master volume automation read at every sample, so breakpoints act on their own sample in any block size (#1354); estimates unchanged |
 | 2026-10-25 | trivial | G-04: Clip Looping (#1030) lacks the loop crossfade option, and Number of Loops stops at 512 while length and fill make up to 1000 loops |
 | 2026-10-25 | trivial | G-01: `setup.playback_engine` and `setup.hardware` apply the device and buffer in the desktop app; headless returns `applied: false` |
 | 2026-10-24 | trivial | G-08: 27 processors + 3 instruments, as the plugin registry holds; G-20: the sampler shipped (#108), so it is no longer listed as missing |

packaging/linux/flatpak-bundle.sh

@@ -22,7 +22,7 @@ FLATHUB=https://dl.flathub.org/repo/flathub.flatpakrepo
 TEST=1
 OCI=0
 TARBALL=""
-while [ $# -gt 0 ]; do
+while [[ $# -gt 0 ]]; do
   case "$1" in
     --no-test) TEST=0; shift ;;
     --oci) OCI=1; shift ;;
@@ -40,7 +40,7 @@ case "$ARCH" in
 esac
 BASENAME="soundcraft-$VERSION-linux-$ARCH"
 TARBALL="${TARBALL:-$DIST/$BASENAME.tar.gz}"
-[ -f "$TARBALL" ] || { echo "error: $TARBALL not found (run packaging/linux/package.sh --formats tar first)" >&2; exit 1; }
+[[ -f "$TARBALL" ]] || { echo "error: $TARBALL not found (run packaging/linux/package.sh --formats tar first)" >&2; exit 1; }
 for tool in flatpak flatpak-builder; do
   command -v "$tool" >/dev/null || { echo "error: $tool not found (apt install flatpak flatpak-builder librsvg2-common)" >&2; exit 1; }
 done
@@ -51,7 +51,7 @@ WORK="$CARGO_TARGET_DIR/flatpak-bundle"
 rm -rf "$WORK"
 mkdir -p "$WORK/stage"
 tar -xzf "$TARBALL" -C "$WORK/stage" --strip-components=1
-[ -x "$WORK/stage/bin/soundcraft" ] || { echo "error: $TARBALL has no bin/soundcraft" >&2; exit 1; }
+[[ -x "$WORK/stage/bin/soundcraft" ]] || { echo "error: $TARBALL has no bin/soundcraft" >&2; exit 1; }
 cp "$HERE/flatpak/$APP_ID.bundle.yml" "$WORK/$APP_ID.yml"
 
 flatpak remote-add --user --if-not-exists flathub "$FLATHUB"
@@ -70,7 +70,7 @@ if [[ "$OCI" = 1 ]]; then
   echo "wrote OCI layout to $OUT_OCI"
 fi
 
-if [ "$TEST" = 1 ]; then
+if [[ "$TEST" = 1 ]]; then
   flatpak install --user -y --noninteractive --reinstall "$OUT"
   flatpak info --user "$APP_ID"
   flatpak run --command=soundcraft-cli "$APP_ID" --version