diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 8aa227bc8..434c2b685 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -1385,98 +1385,6 @@ pub fn upgrade_effects(p: &mut Project) {
 mod rq_tests;
 #[cfg(test)]
 mod tests;
-#[cfg(test)]
-mod tests_3d;
-#[cfg(test)]
-mod tests_anim_presets;
-#[cfg(test)]
-mod tests_anim_tools;
-#[cfg(test)]
-mod tests_camera_track;
-#[cfg(test)]
-mod tests_codec_options;
-#[cfg(test)]
-mod tests_color_view;
-#[cfg(test)]
-mod tests_crypto_pick;
-#[cfg(test)]
-mod tests_delete_keys;
-#[cfg(test)]
-mod tests_disk_cache;
-#[cfg(test)]
-mod tests_effects;
-#[cfg(test)]
-mod tests_essential;
-#[cfg(test)]
-mod tests_essential_more;
-#[cfg(test)]
-mod tests_face;
-#[cfg(test)]
-mod tests_fidelity;
-#[cfg(test)]
-mod tests_frame_export;
-#[cfg(test)]
-mod tests_fuzz_open;
-#[cfg(test)]
-mod tests_import_project;
-#[cfg(test)]
-mod tests_key_metadata_order;
-#[cfg(test)]
-mod tests_keylight;
-#[cfg(test)]
-mod tests_limits;
-#[cfg(test)]
-mod tests_lottie;
-#[cfg(test)]
-mod tests_m137;
-#[cfg(test)]
-mod tests_m145;
-#[cfg(test)]
-mod tests_markers;
-#[cfg(test)]
-mod tests_mask_warp;
-#[cfg(test)]
-mod tests_menu_cmds;
-#[cfg(test)]
-mod tests_model3d;
-#[cfg(test)]
-mod tests_motion_blur_depth;
-#[cfg(test)]
-mod tests_project_items;
-#[cfg(test)]
-mod tests_proxy;
-#[cfg(test)]
-mod tests_quick_offset;
-#[cfg(test)]
-mod tests_replace_source;
-#[cfg(test)]
-mod tests_rig3d;
-#[cfg(test)]
-mod tests_sequence;
-#[cfg(test)]
-mod tests_settings;
-#[cfg(test)]
-mod tests_shortcut_cmds;
-#[cfg(test)]
-mod tests_stubs;
-#[cfg(test)]
-mod tests_styles;
-#[cfg(test)]
-mod tests_tail;
-#[cfg(test)]
-mod tests_text;
-#[cfg(test)]
-mod tests_text_edit;
-#[cfg(test)]
-mod tests_timeline;
-#[cfg(test)]
-mod tests_timeline_interchange;
-#[cfg(test)]
-mod tests_track;
-#[cfg(test)]
-mod tests_vector_import;
-#[cfg(test)]
-mod tests_viewer;
 
 /// Font families available to text layers (bundled + scanned system fonts).
 /// Text animation presets: (id, name), for menus.
@@ -1579,16 +1487,4 @@ pub fn font_menu(prefs: &prefs::Prefs) -> Vec<FontRow> {
     out.extend(all.iter().map(|f| row(f, false)));
     out
 }
-#[cfg(test)]
-mod tests_history;
-#[cfg(test)]
-mod tests_models;
-#[cfg(test)]
-mod tests_paint;
-#[cfg(test)]
-mod tests_panels;
-#[cfg(test)]
-mod tests_roto;
 
-#[cfg(test)]
-mod tests_key_time;
diff --git a/crates/engine/src/offload/tests.rs b/crates/engine/src/offload/tests.rs
index 55c349e1d..b448d09c4 100644
--- a/crates/engine/src/offload/tests.rs
+++ b/crates/engine/src/offload/tests.rs
@@ -240,7 +240,7 @@ fn pose(f: u32) -> ([f64; 2], f64, f64) {
 
 #[test]
 fn track_analysis_runs_through_the_offload_as_one_undo_step() {
-    let (mut s, clip, _) = crate::tests_track::setup(crate::tests_track::patch_frames(pose));
+    let (mut s, clip, _) = crate::tests::track::setup(crate::tests::track::patch_frames(pose));
     s.offload = Some(Arc::new(InlineWith(s.footage.clone())));
     s.execute("track.motion", serde_json::json!({})).unwrap();
     s.execute("track.setPoint", serde_json::json!({"point": 1, "center": pose(0).0, "featureSize": [36, 36], "searchSize": [80, 80]})).unwrap();
@@ -254,7 +254,7 @@ fn track_analysis_runs_through_the_offload_as_one_undo_step() {
     let tp = l.trackers().next().unwrap().0.track_points().next().unwrap().clone();
     let fc = tp.get("featureCenter").unwrap();
     assert_eq!(fc.keys.len(), 25);
-    let v = fc.value_at(crate::tests_track::frame_time(12)).as_vec2();
+    let v = fc.value_at(crate::tests::track::frame_time(12)).as_vec2();
     assert!((v[0] - pose(12).0[0]).abs() < 0.3 && (v[1] - pose(12).0[1]).abs() < 0.3, "{v:?}");
     assert_eq!(s.history.undo.len(), undo + 1);
     assert_eq!(s.history.undo.last().unwrap().0, "Analyze Track");
@@ -270,7 +270,7 @@ fn track_analysis_runs_through_the_offload_as_one_undo_step() {
 
 #[test]
 fn cancelling_offloaded_jobs() {
-    let (mut s, _, _) = crate::tests_track::setup(crate::tests_track::patch_frames(pose));
+    let (mut s, _, _) = crate::tests::track::setup(crate::tests::track::patch_frames(pose));
     let off = Arc::new(Hanging::default());
     s.offload = Some(off.clone());
     s.exporter = Some(Arc::new(crate::rq_tests::MockExporter { log: Default::default() }));
diff --git a/crates/engine/src/rq_tests.rs b/crates/engine/src/rq_tests.rs
index 81a187226..4c39cc89e 100644
--- a/crates/engine/src/rq_tests.rs
+++ b/crates/engine/src/rq_tests.rs
@@ -67,11 +67,11 @@ fn add_configure_render() {
     let r = s.execute("renderQueue.setOutputModule", json!({"item": id, "format": "png", "channels": "rgba"})).unwrap();
     assert!(r["outputPath"].as_str().unwrap().ends_with("_[#####].png"), "{r}");
     assert!(s.execute("renderQueue.setOutputModule", json!({"item": id, "format": "jpeg", "channels": "rgba"})).is_err());
-    let r = s.execute("renderQueue.setOutput", json!({"item": id, "path": crate::tests_stubs::tmp_out("rq/out.mov")})).unwrap();
+    let r = s.execute("renderQueue.setOutput", json!({"item": id, "path": crate::tests::stubs::tmp_out("rq/out.mov")})).unwrap();
     assert_eq!(r["output"]["format"], "ProRes", "Output To with .mov switches to ProRes");
-    assert_eq!(std::path::Path::new(r["outputPath"].as_str().unwrap()), std::path::PathBuf::from(crate::tests_stubs::tmp_out("rq/out.mov")));
+    assert_eq!(std::path::Path::new(r["outputPath"].as_str().unwrap()), std::path::PathBuf::from(crate::tests::stubs::tmp_out("rq/out.mov")));
     // A second item that fails, a third that is unqueued.
-    let b = s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests_stubs::tmp_out("rq/fail.gif")})).unwrap();
+    let b = s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests::stubs::tmp_out("rq/fail.gif")})).unwrap();
     let c = s.execute("renderQueue.add", json!({"output": "/tmp/rq/skip.mp4"})).unwrap();
     s.execute("renderQueue.setRender", json!({"item": c["item"], "render": false})).unwrap();
     assert_eq!(s.project.render_queue[2].status.label(), "Unqueued");
@@ -79,12 +79,12 @@ fn add_configure_render() {
     assert_eq!(r["items"].as_array().unwrap().len(), 2);
     assert_eq!(
         ex.log.lock().unwrap().iter().map(std::path::PathBuf::from).collect::<Vec<_>>(),
-        [std::path::PathBuf::from(crate::tests_stubs::tmp_out("rq/out.mov")), std::path::PathBuf::from(crate::tests_stubs::tmp_out("rq/fail.gif"))]
+        [std::path::PathBuf::from(crate::tests::stubs::tmp_out("rq/out.mov")), std::path::PathBuf::from(crate::tests::stubs::tmp_out("rq/fail.gif"))]
     );
     let q = &s.project.render_queue;
     assert_eq!(q[0].status.label(), "Done");
     assert!(q[0].started.is_some() && q[0].render_time.is_some());
-    assert_eq!(std::path::Path::new(q[0].last_output.as_deref().unwrap()), std::path::PathBuf::from(crate::tests_stubs::tmp_out("rq/out.mov")));
+    assert_eq!(std::path::Path::new(q[0].last_output.as_deref().unwrap()), std::path::PathBuf::from(crate::tests::stubs::tmp_out("rq/out.mov")));
     assert_eq!(q[1].status, RenderStatus::Failed("boom".into()));
     assert_eq!(q[2].status.label(), "Unqueued");
     let events = s.drain_events();
@@ -130,8 +130,8 @@ fn failure_toast_names_the_first_reason() {
     }
     let mut s = demo();
     s.exporter = Some(Arc::new(Failing));
-    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests_stubs::tmp_out("rq/first.gif")})).unwrap();
-    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests_stubs::tmp_out("rq/second.gif")})).unwrap();
+    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests::stubs::tmp_out("rq/first.gif")})).unwrap();
+    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests::stubs::tmp_out("rq/second.gif")})).unwrap();
     s.execute("renderQueue.render", json!({})).unwrap();
     let events = s.drain_events();
     let toast = events.iter().find_map(|e| if let Event::Toast { message, error: true } = e { Some(message.as_str()) } else { None });
diff --git a/crates/engine/src/session_settings.rs b/crates/engine/src/session_settings.rs
index a56d1849b..7abdfb53d 100644
--- a/crates/engine/src/session_settings.rs
+++ b/crates/engine/src/session_settings.rs
@@ -120,7 +120,7 @@ impl Session {
         // opens a disk cache (often the platform folder, through a settings store) would take
         // over the store of a roto test running beside it. Serialise them with the roto tests.
         #[cfg(test)]
-        crate::tests_roto::hold_roto_cache_test_lock();
+        crate::tests::roto::hold_roto_cache_test_lock();
         let dc = match &self.disk_cache {
             Some(c) if c.folder() == folder.as_path() => {
                 c.set_max_bytes(max);
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index b3f0602b3..01dd1d5e9 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -1,735 +1,53 @@
-use serde_json::json;
-
-use crate::Session;
-
-fn demo() -> Session {
-    let mut s = Session::default();
-    s.execute("file.openDemoProject", json!({})).unwrap();
-    s
-}
-
-#[test]
-fn demo_opens_and_renders() {
-    let s = demo();
-    let cid = s.active_comp_id().unwrap();
-    let img = s.render(cid, s.time(), effectcraft_render::RenderOpts { scale: 0.25, ..Default::default() });
-    assert_eq!((img.width, img.height), (480, 270));
-    let lit = img.data.iter().filter(|p| p[3] > 0.99).count();
-    assert!(lit > 100_000, "{lit}");
-}
-
-/// The session's layer cache never changes pixels: scrubbing the demo (including back and
-/// forth, and across an edit made through a command) matches cache-less renders exactly.
-#[test]
-fn demo_layer_cache_is_transparent() {
-    let mut s = demo();
-    let cid = s.active_comp_id().unwrap();
-    let opts = effectcraft_render::RenderOpts { scale: 0.25, ..Default::default() };
-    let uncached = |s: &Session, t: f64| {
-        let mut r = effectcraft_render::Renderer::new(&s.project, s.footage.as_ref(), opts);
-        r.expr = s.expr.as_deref();
-        r.comp_frame(cid, effectcraft_time::Tick::from_seconds_f64(t))
-    };
-    let check = |s: &Session, t: f64| {
-        let a = s.render(cid, effectcraft_time::Tick::from_seconds_f64(t), opts);
-        let b = uncached(s, t);
-        assert!(a.data.iter().zip(&b.data).all(|(p, q)| (0..4).all(|c| (p[c] - q[c]).abs() < 1e-6)), "t={t}");
-    };
-    for t in [0.5, 1.0, 3.0, 3.0334, 6.0, 3.0, 0.5] {
-        check(&s, t);
-    }
-    assert!(s.layer_cache.stats().hits > 0);
-    // Edit the title's glow through the command layer, then scrub again.
-    let title = s.project.comp(cid).unwrap().layers.iter().find(|l| l.name == "EFFECTCRAFT").map(|l| l.id.0).unwrap();
-    s.execute("prop.set", json!({"layer": title, "path": "effects/#1/radius", "value": 5.0})).unwrap();
-    for t in [3.0, 0.5] {
-        check(&s, t);
-    }
-}
-
-/// `layer.addItem` puts the layer at `index` (1-based) in the stack and starts it at `time`, as a
-/// drop in the Timeline does (#89).
-#[test]
-fn add_item_at_a_stack_index_and_time() {
-    let mut s = Session::default();
-    let clip = s.execute("comp.new", json!({"name": "Clip", "width": 16, "height": 16, "frameRate": 30, "duration": 1})).unwrap()["comp"].as_u64().unwrap();
-    s.execute("comp.new", json!({"name": "Main", "width": 32, "height": 32, "frameRate": 30, "duration": 4})).unwrap();
-    for name in ["C", "B", "A"] {
-        s.execute("layer.newSolid", json!({"name": name})).unwrap();
-    }
-    let names = |s: &Session| s.active_comp().unwrap().layers.iter().map(|l| l.name.clone()).collect::<Vec<_>>();
-    s.execute("layer.addItem", json!({"item": clip, "index": 2, "time": 1.01})).unwrap();
-    assert_eq!(names(&s), ["A", "Clip", "B", "C"]);
-    let l = &s.active_comp().unwrap().layers[1];
-    assert_eq!(l.in_point, effectcraft_time::Tick::from_seconds_f64(1.0), "on the nearest frame");
-    // Past the bottom: the bottom.
-    s.execute("layer.addItem", json!({"item": clip, "index": 99})).unwrap();
-    assert_eq!(names(&s).last().map(String::as_str), Some("Clip 2"));
-    assert!(s.execute("layer.addItem", json!({"item": clip, "index": 0})).is_err(), "1-based");
-}
-
-/// Files dropped on the Timeline or the Composition viewer (`file.import {addToComp}`) become
-/// layers of the comp that was active, one under the other, where they were dropped (#85, #89).
-#[test]
-fn imported_files_go_into_the_comp_where_they_were_dropped() {
-    use effectcraft_project::{Footage, FootageKind};
-    struct Probe;
-    impl crate::Importer for Probe {
-        fn probe(&self, path: &str) -> Result<Footage, String> {
-            Ok(Footage { path: path.into(), kind: FootageKind::Still, width: 64, height: 32, has_video: true, ..Default::default() })
-        }
-    }
-    let mut s = Session { importer: Some(std::sync::Arc::new(Probe)), ..Default::default() };
-    s.execute("comp.new", json!({"name": "Main", "width": 320, "height": 180, "frameRate": 30, "duration": 4})).unwrap();
-    s.execute("layer.newSolid", json!({"name": "Bg"})).unwrap();
-    let params = json!({"paths": ["/drop/a.png", "/drop/b.png"], "addToComp": true, "position": [40.0, 50.0], "index": 1, "time": 1.0});
-    s.execute("file.import", params).unwrap();
-    let comp = s.active_comp().unwrap();
-    assert_eq!(comp.layers.iter().map(|l| l.name.as_str()).collect::<Vec<_>>(), ["a.png", "b.png", "Bg"]);
-    for l in &comp.layers[..2] {
-        assert_eq!(l.props.prop("transform/position").map(|p| p.value.clone()), Some(effectcraft_keyframe::Value::Vec3([40.0, 50.0, 0.0])));
-        assert_eq!(l.in_point, effectcraft_time::Tick::from_seconds_f64(1.0));
-    }
-    // Without `addToComp` they only import.
-    s.execute("file.import", json!({"paths": ["/drop/c.png"]})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers.len(), 3);
-    assert!(s.execute("layer.addItem", json!({"item": "a.png", "position": [1.0]})).is_err(), "position needs x and y");
-}
-
-/// #270: files dropped or picked in the Import dialog (`file.import {background}`) are probed in
-/// a background job that says which file it is reading and how many are left; then they arrive
-/// in one undo step, all selected, with a count. The same file imported again arrives again.
-#[test]
-fn background_imports_report_progress_and_select_what_arrived() {
-    use effectcraft_project::{Footage, FootageKind, ItemId};
-    use std::sync::Arc;
-    use std::sync::atomic::{AtomicUsize, Ordering};
-    /// Probes file k once `allow` > k (a slow video; 5 s at most, so an import that waits for it
-    /// fails the test instead of hanging it); `.xyz` files fail.
-    struct Gated {
-        started: AtomicUsize,
-        allow: Arc<AtomicUsize>,
-    }
-    impl crate::Importer for Gated {
-        fn probe(&self, path: &str) -> Result<Footage, String> {
-            let k = self.started.fetch_add(1, Ordering::SeqCst);
-            let until = std::time::Instant::now() + std::time::Duration::from_secs(5);
-            while self.allow.load(Ordering::SeqCst) <= k && std::time::Instant::now() < until {
-                std::thread::sleep(std::time::Duration::from_millis(1));
-            }
-            if path.ends_with(".xyz") {
-                return Err("unsupported file".into());
-            }
-            Ok(Footage { path: path.into(), kind: FootageKind::Still, width: 64, height: 32, has_video: true, ..Default::default() })
-        }
-    }
-    let allow = Arc::new(AtomicUsize::new(1));
-    let mut s = Session { importer: Some(Arc::new(Gated { started: AtomicUsize::new(0), allow: allow.clone() })), ..Default::default() };
-    s.execute("comp.new", json!({"name": "Main", "width": 320, "height": 180, "frameRate": 30, "duration": 4})).unwrap();
-    let undo = s.history.undo.len();
-    let r = s.execute("file.import", json!({"paths": ["/drop/a.png", "/drop/b.png", "/drop/a.png"], "background": true})).unwrap();
-    let job = r["job"].as_str().unwrap().to_string();
-    // The first file is through; the second is being read.
-    let running = |s: &mut Session| s.execute("jobs.list", json!({})).unwrap()["running"].as_array().unwrap().clone();
-    let deadline = std::time::Instant::now() + std::time::Duration::from_secs(10);
-    while running(&mut s)[0]["done"] != json!(1) && std::time::Instant::now() < deadline {
-        std::thread::sleep(std::time::Duration::from_millis(2));
-    }
-    let row = running(&mut s)[0].clone();
-    assert_eq!(row["id"], json!(job));
-    assert_eq!(row["label"], json!("Importing 3 files"));
-    assert_eq!(row["message"], json!("b.png (2 of 3)"));
-    assert_eq!((row["done"].as_u64(), row["total"].as_u64()), (Some(1), Some(3)));
-    assert!(s.project.items.values().all(|i| i.name != "a.png"), "nothing is added before the import finishes");
-    allow.store(usize::MAX, Ordering::SeqCst);
-    s.execute("jobs.wait", json!({})).unwrap();
-    let names = |s: &Session, ids: &[ItemId]| ids.iter().map(|i| s.project.item(*i).unwrap().name.clone()).collect::<Vec<_>>();
-    assert_eq!(names(&s, &s.state.project_selection), ["a.png", "b.png", "a.png"], "everything imported is selected, the same file twice too");
-    assert_eq!(s.history.undo.len(), undo + 1, "one undo step");
-    let rec = s.job_log.last().unwrap();
-    assert_eq!((rec.status.as_str(), rec.message.as_str()), ("done", "Imported 3 items"));
-    assert!(s.drain_events().iter().any(|e| matches!(e, crate::Event::Toast { message, .. } if message == "Imported 3 items")));
-    // Dropped on the viewer: they become layers too; a file that can't be read is reported.
-    s.execute("file.import", json!({"paths": ["/drop/c.png", "/drop/d.xyz"], "background": true, "addToComp": true, "position": [10.0, 20.0]})).unwrap();
-    s.execute("jobs.wait", json!({})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers.iter().map(|l| l.name.as_str()).collect::<Vec<_>>(), ["c.png"]);
-    assert_eq!(s.job_log.last().unwrap().message, "Imported 1 item. /drop/d.xyz: unsupported file");
-    // Agents and scripts import at once by default.
-    let r = s.execute("file.import", json!({"paths": ["/drop/e.png"]})).unwrap();
-    assert_eq!(r["items"].as_array().map(Vec::len), Some(1));
-}
-
-/// Audio, Lock and Shy don't change pixels: toggling them keeps the cached layers (#103).
-#[test]
-fn audio_lock_and_shy_keep_cached_layers() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "C", "width": 160, "height": 90, "frameRate": 30, "duration": 1})).unwrap();
-    s.execute("layer.newSolid", json!({"color": "#3080ff", "width": 80, "height": 40})).unwrap();
-    s.execute("effect.apply", json!({"layer": "#1", "effect": "Gaussian Blur"})).unwrap();
-    s.execute("prop.set", json!({"layer": "#1", "path": "effects/#1/blurriness", "value": 12})).unwrap();
-    let cid = s.active_comp_id().unwrap();
-    let t = s.time();
-    s.render(cid, t, Default::default());
-    let before = s.layer_cache.stats();
-    for sw in ["audio", "lock", "shy"] {
-        s.execute("layer.setSwitch", json!({"layers": ["#1"], "switch": sw, "value": sw != "audio"})).unwrap();
-    }
-    s.render(cid, t, Default::default());
-    let after = s.layer_cache.stats();
-    assert_eq!(after.misses, before.misses, "no layer rendered again");
-    assert!(after.hits > before.hits);
-}
-
-#[test]
-fn every_command_has_unique_id_and_runs_or_reports() {
-    let mut ids = std::collections::HashSet::new();
-    for c in crate::command_specs() {
-        assert!(ids.insert(c.id), "duplicate {}", c.id);
-    }
-    assert!(ids.len() >= 90, "{}", ids.len());
-}
-
-#[test]
-fn layer_workflow_with_undo() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "Test", "width": 640, "height": 360, "frameRate": 30, "duration": 4})).unwrap();
-    let r = s.execute("layer.newSolid", json!({"color": "#336699"})).unwrap();
-    let lid = r["layer"].as_u64().unwrap();
-    s.execute("prop.set", json!({"layer": lid, "path": "transform/opacity", "value": 50})).unwrap();
-    let tree = s.execute("layer.tree", json!({"layer": lid})).unwrap();
-    assert!(tree.to_string().contains("\"value\":50.0"));
-    s.execute("prop.toggleAnimation", json!({"layer": lid, "path": "transform/position"})).unwrap();
-    s.execute("time.set", json!({"time": 2.0})).unwrap();
-    s.execute("prop.set", json!({"layer": lid, "path": "transform/position", "value": [100, 100]})).unwrap();
-    let comp = s.active_comp().unwrap();
-    let pos = comp.layers[0].props.prop("transform/position").unwrap();
-    assert_eq!(pos.keys.len(), 2);
-    s.execute("prop.select", json!({"layer": lid, "path": "transform/position"})).unwrap();
-    assert_eq!(s.state.selected_keys.len(), 2);
-    s.execute("keys.easyEase", json!({})).unwrap();
-    s.execute("keys.move", json!({"delta": 0.5})).unwrap();
-    let pos = s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().clone();
-    assert!((pos.keys[0].time.seconds() - 0.5).abs() < 0.02);
-    assert_eq!(pos.keys[0].out_interp, effectcraft_keyframe::Interp::Bezier);
-    // undo back to before the move
-    s.execute("edit.undo", json!({})).unwrap();
-    let pos = s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().clone();
-    assert!(pos.keys[0].time.seconds().abs() < 0.02);
-    s.execute("effect.apply", json!({"layer": lid, "effect": "Gaussian Blur"})).unwrap();
-    s.execute("prop.set", json!({"layer": lid, "path": "effects/#1/blurriness", "value": 12})).unwrap();
-    // Applying selects the new effect (Edit ▸ Duplicate would duplicate it); select the layer.
-    s.execute("layer.select", json!({"layers": [lid]})).unwrap();
-    s.execute("edit.duplicate", json!({})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers.len(), 2);
-    s.execute("layer.precompose", json!({"layers": [1, 2], "name": "Pre"})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers.len(), 1);
-}
-
-#[test]
-fn text_shape_mask_matte_parent() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"width": 800, "height": 450, "duration": 3})).unwrap();
-    let t = s.execute("layer.newText", json!({"text": "Hello", "size": 90})).unwrap()["layer"].as_u64().unwrap();
-    s.execute("layer.addTextAnimator", json!({"layer": t, "properties": ["position", "opacity"]})).unwrap();
-    let sh = s.execute("layer.newShape", json!({"kind": "star", "fill": "#ffcc00"})).unwrap()["layer"].as_u64().unwrap();
-    s.execute("layer.addShapeItem", json!({"layer": sh, "kind": "trim"})).unwrap();
-    s.execute("layer.addMask", json!({"layer": sh, "shape": "ellipse"})).unwrap();
-    s.execute("layer.setMask", json!({"layer": sh, "mask": 1, "mode": "Subtract", "inverted": true})).unwrap();
-    s.execute("layer.setTrackMatte", json!({"layer": sh, "matte": t, "kind": "luma"})).unwrap();
-    s.execute("layer.setParent", json!({"layers": [sh], "parent": t})).unwrap();
-    assert!(s.execute("layer.setParent", json!({"layers": [t], "parent": sh})).is_err());
-    s.execute("layer.setBlendMode", json!({"layers": [sh], "mode": "Screen"})).unwrap();
-    s.execute("layer.setSwitch", json!({"layers": [sh], "switch": "threeD"})).unwrap();
-    let cid = s.active_comp_id().unwrap();
-    let _ = s.render(cid, s.time(), Default::default());
-    let info = s.execute("comp.info", json!({})).unwrap();
-    assert_eq!(info["layers"].as_array().unwrap().len(), 2);
-}
-
-/// The toolbar's Fill / Stroke change a selected shape layer's paint (#205): a shape drawn
-/// without a stroke gets one, later edits change it, and the Contents "Add:" items (#206) include
-/// an empty Path and a Gradient Stroke that render.
-#[test]
-fn toolbar_fill_and_stroke_paint_selected_shape_layers() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
-    let sh = s.execute("layer.newShape", json!({"kind": "rect", "fill": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
-    let paint = |s: &mut Session| s.execute("shape.fillStroke", json!({})).unwrap();
-    assert_eq!(paint(&mut s)["stroke"], serde_json::Value::Null, "drawn without a stroke");
-    s.execute("shape.fillStroke", json!({"stroke": "#00ff00", "strokeWidth": 6})).unwrap();
-    let p = paint(&mut s);
-    assert_eq!((p["stroke"][1].as_f64(), p["strokeWidth"].as_f64()), (Some(1.0), Some(6.0)), "{p}");
-    s.execute("shape.fillStroke", json!({"fill": "#0000ff", "strokeWidth": 3})).unwrap();
-    let p = paint(&mut s);
-    assert_eq!((p["fill"][2].as_f64(), p["strokeWidth"].as_f64()), (Some(1.0), Some(3.0)), "{p}");
-    // One stroke, before the fill (paths, stroke, fill), and each change is one undo step.
-    let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap().clone();
-    let group = l.props.group("contents/group").unwrap();
-    let order: Vec<&str> = group.sub("contents").unwrap().groups().map(|g| g.match_id.as_str()).collect();
-    assert_eq!(order, ["rect", "stroke", "fill"]);
-    s.execute("edit.undo", json!({})).unwrap();
-    assert_eq!(paint(&mut s)["strokeWidth"].as_f64(), Some(6.0));
-    // Only shape layers.
-    s.execute("layer.newSolid", json!({"color": "#808080"})).unwrap();
-    assert!(s.execute("shape.fillStroke", json!({"fill": "#ffffff"})).is_err());
-    for kind in ["path", "gstroke"] {
-        let r = s.execute("layer.addShapeItem", json!({"layer": sh, "kind": kind})).unwrap();
-        assert!(r["path"].as_str().is_some_and(|p| p.starts_with("contents/")), "{r}");
-    }
-    let cid = s.active_comp_id().unwrap();
-    let _ = s.render(cid, s.time(), Default::default());
-}
-
-/// The toolbar's Fill Options / Stroke Options change a selected shape layer's paint kind (#732):
-/// None switches the fill off, a gradient turns the Fill into a Gradient Fill that keeps its
-/// opacity, Solid Color turns it back, and a Stroke kind adds a stroke where there is none.
-#[test]
-fn toolbar_fill_and_stroke_kinds_change_selected_shape_layers() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
-    let sh = s.execute("layer.newShape", json!({"kind": "rect", "fill": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
-    let items = |s: &Session| -> Vec<(String, bool)> {
-        let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap();
-        l.props.group("contents/group/contents").unwrap().groups().map(|g| (g.match_id.clone(), g.enabled)).collect()
-    };
-    let kinds = |s: &mut Session| {
-        let p = s.execute("shape.fillStroke", json!({})).unwrap();
-        (p["fillType"].as_str().unwrap().to_string(), p["strokeType"].as_str().unwrap().to_string())
-    };
-    assert_eq!(kinds(&mut s), ("solid".into(), "none".into()));
-    let cid = s.active_comp_id().unwrap();
-    let centre = |s: &Session| s.render(cid, s.time(), Default::default()).get(200, 150);
-    let red = centre(&s);
-    // None switches the fill off: nothing is drawn, and the item stays.
-    s.execute("shape.fillStroke", json!({"fillType": "none"})).unwrap();
-    assert_eq!(items(&s), [("rect".into(), true), ("fill".into(), false)]);
-    assert_eq!(kinds(&mut s).0, "none");
-    assert_ne!(centre(&s), red, "the fill is off");
-    // A radial gradient: the Fill becomes a Gradient Fill (switched on) that keeps its opacity.
-    s.execute("shape.fillStroke", json!({"fillType": "solid", "fill": "#ff0000"})).unwrap();
-    assert_eq!(centre(&s), red);
-    let opacity = |s: &Session, m: &str| {
-        let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap();
-        l.props.group(&format!("contents/group/contents/{m}")).unwrap().get("opacity").unwrap().value.as_f64()
-    };
-    s.execute("prop.set", json!({"layer": sh, "path": "contents/group/contents/fill/opacity", "value": 40})).unwrap();
-    s.execute("shape.fillStroke", json!({"fillType": "radial"})).unwrap();
-    assert_eq!(items(&s), [("rect".into(), true), ("gfill".into(), true)]);
-    assert_eq!((kinds(&mut s).0.as_str(), opacity(&s, "gfill")), ("radial", 40.0));
-    s.execute("shape.fillStroke", json!({"fillType": "linear"})).unwrap();
-    assert_eq!(kinds(&mut s).0, "linear");
-    s.execute("shape.fillStroke", json!({"fillType": "solid", "fill": "#00ff00"})).unwrap();
-    assert_eq!(items(&s), [("rect".into(), true), ("fill".into(), true)]);
-    assert_eq!(opacity(&s, "fill"), 40.0);
-    // A Stroke kind adds a stroke (before the fill); None switches it off again; undo is per step.
-    s.execute("shape.fillStroke", json!({"strokeType": "linear"})).unwrap();
-    assert_eq!(items(&s), [("rect".into(), true), ("gstroke".into(), true), ("fill".into(), true)]);
-    s.execute("shape.fillStroke", json!({"strokeType": "none"})).unwrap();
-    assert_eq!(kinds(&mut s), ("solid".into(), "none".into()));
-    s.execute("edit.undo", json!({})).unwrap();
-    assert_eq!(kinds(&mut s), ("solid".into(), "linear".into()));
-    assert!(s.execute("shape.fillStroke", json!({"fillType": "plaid"})).is_err());
-}
-
-/// Selecting a mask in the Timeline (its row or its Mask Path) selects all of its points, so the
-/// viewer drags the whole mask (#203); a shape's Path item works the same way.
-#[test]
-fn selecting_a_mask_selects_its_points() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
-    let l = s.execute("layer.newSolid", json!({"color": "#808080"})).unwrap()["layer"].as_u64().unwrap();
-    let m1 = s.execute("layer.addMask", json!({"layer": l, "shape": "rect"})).unwrap()["mask"].as_u64().unwrap();
-    let m2 = s.execute("layer.addMask", json!({"layer": l, "shape": "ellipse"})).unwrap()["mask"].as_u64().unwrap();
-    let points = |s: &Session, m: u64| s.state.selected_vertices.iter().filter(|v| v.mask == m).count();
-    s.execute("prop.select", json!({"layer": l, "prop": m1, "selectKeys": false})).unwrap();
-    assert_eq!((points(&s, m1), s.state.selected_vertices.len()), (4, 4));
-    // Mask Path selects them too; Shift-adding another mask keeps the first.
-    let path = s.active_comp().unwrap().layer(effectcraft_project::LayerId(l)).unwrap().props.find_group(m2).unwrap().get("path").unwrap().uid;
-    s.execute("prop.select", json!({"layer": l, "prop": path, "add": true})).unwrap();
-    assert_eq!((points(&s, m1), points(&s, m2)), (4, 4));
-    // Another mask replaces them; another property deselects them.
-    s.execute("prop.select", json!({"layer": l, "prop": m2})).unwrap();
-    assert_eq!((points(&s, m1), points(&s, m2)), (0, 4));
-    // Delete removes the selected mask (not only its points).
-    s.execute("edit.clear", json!({})).unwrap();
-    let masks = |s: &Session| s.active_comp().unwrap().layer(effectcraft_project::LayerId(l)).unwrap().masks().unwrap().children.len();
-    assert_eq!(masks(&s), 1);
-    s.execute("prop.select", json!({"layer": l, "path": "transform/opacity"})).unwrap();
-    assert!(s.state.selected_vertices.is_empty());
-    let sh = s.execute("layer.newShape", json!({"kind": "star"})).unwrap()["layer"].as_u64().unwrap();
-    let star = s.execute("layer.addShapeItem", json!({"layer": sh, "kind": "path"})).unwrap()["uid"].as_u64().unwrap();
-    s.execute("prop.select", json!({"layer": sh, "prop": star})).unwrap();
-    assert_eq!(s.state.selected_vertices.len(), 0, "an empty Path has no points");
-}
-
-#[test]
-fn save_and_open_roundtrip() {
-    let mut s = demo();
-    let dir = std::env::temp_dir().join(format!("ec-test-{}", std::process::id()));
-    std::fs::create_dir_all(&dir).unwrap();
-    let path = dir.join("demo.ecproj").to_string_lossy().to_string();
-    s.execute("file.saveAs", json!({"path": path})).unwrap();
-    let before = s.project.clone();
-    let mut s2 = Session::default();
-    s2.execute("file.open", json!({"path": path})).unwrap();
-    assert_eq!(*before, *s2.project);
-    let _ = std::fs::remove_dir_all(dir);
-}
-
-#[test]
-fn help_links_emit_urls() {
-    let mut s = Session::default();
-    let r = s.execute("help.discord", json!({})).unwrap();
-    assert_eq!(r["url"], "https://discord.gg/artcraft");
-    assert!(s.drain_events().iter().any(|e| matches!(e, crate::Event::OpenUrl(u) if u.contains("discord"))));
-    assert_eq!(s.execute("help.github", json!({})).unwrap()["url"], "https://github.com/storytold/effectcraft");
-}
-
-#[test]
-fn time_navigation() {
-    let mut s = demo();
-    s.execute("time.start", json!({})).unwrap();
-    let r = s.execute("time.nextKey", json!({})).unwrap();
-    assert!(r["time"].as_f64().unwrap() > 0.0);
-    s.execute("time.set", json!({"frame": 45})).unwrap();
-    assert_eq!(s.execute("time.step", json!({"frames": 5})).unwrap()["frame"], 50);
-}
-
-#[test]
-fn time_navigation_per_property() {
-    let mut s = demo();
-    // An animated property and the comp times of its keys.
-    let comp = s.active_comp().unwrap().clone();
-    let mut found = None;
-    for l in &comp.layers {
-        l.props.walk("", &mut |_, pr| {
-            if found.is_none() && pr.keys.len() >= 2 {
-                found = Some((pr.uid, pr.keys.iter().map(|k| l.comp_time(k.time)).collect::<Vec<_>>()));
-            }
-        });
-    }
-    let (uid, times) = found.expect("demo has an animated property");
-    s.set_time(effectcraft_time::Tick::ZERO);
-    let half = comp.frame_duration().0 / 2;
-    let expect = times.iter().copied().filter(|t| t.0 > half).min().unwrap();
-    s.execute("time.go", json!({"to": "nextKey", "prop": uid})).unwrap();
-    let snap = |t| comp.frame_rate.snap(t);
-    assert_eq!(s.time(), snap(expect));
-    // Going back from past the last key lands on the last key.
-    s.set_time(comp.duration);
-    s.execute("time.go", json!({"to": "prevKey", "prop": uid})).unwrap();
-    assert_eq!(s.time(), snap(*times.iter().max().unwrap()));
-}
-
-#[test]
-fn set_text_paragraph_fill_and_leading() {
-    use effectcraft_keyframe::{Justify, Value as KValue};
-    let mut s = demo();
-    let t = s.execute("layer.newText", json!({"text": "Hi"})).unwrap()["layer"].as_u64().unwrap();
-    let doc = |s: &Session| {
-        let l = s.active_comp().unwrap().layer(crate::project::LayerId(t)).unwrap().clone();
-        match &l.props.prop("text/sourceText").unwrap().value {
-            KValue::Text(d) => (**d).clone(),
-            v => panic!("{v:?}"),
-        }
-    };
-    for (key, j) in [
-        ("justifyLeft", Justify::JustifyLastLeft),
-        ("justifyCenter", Justify::JustifyLastCenter),
-        ("justifyRight", Justify::JustifyLastRight),
-        ("justifyAll", Justify::JustifyAll),
-        ("center", Justify::Center),
-    ] {
-        s.execute("layer.setText", json!({"layer": t, "justify": key})).unwrap();
-        assert_eq!(doc(&s).justify, j, "{key}");
-    }
-    s.execute("layer.setText", json!({"layer": t, "leading": 50, "applyFill": false, "applyStroke": true})).unwrap();
-    let d = doc(&s);
-    assert_eq!((d.leading, d.apply_fill, d.apply_stroke), (Some(50.0), false, true));
-    s.execute("layer.setText", json!({"layer": t, "leading": "auto"})).unwrap();
-    assert_eq!(doc(&s).leading, None);
-    s.execute("layer.setText", json!({"layer": t, "hScale": 120, "vScale": 80, "baselineShift": 4, "smallCaps": true, "strokeOverFill": true})).unwrap();
-    let d = doc(&s);
-    assert_eq!((d.h_scale, d.v_scale, d.baseline_shift, d.small_caps, d.stroke_over_fill), (120.0, 80.0, 4.0, true, true));
-}
-
-#[test]
-fn property_groups_report_actionable_errors() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "T"})).unwrap();
-    let l = s.execute("layer.newText", json!({"text": "Hi"})).unwrap()["layer"].as_u64().unwrap();
-    let uid = s.active_comp().unwrap().layer(crate::project::LayerId(l)).unwrap().props.group("text/pathOptions").unwrap().uid;
-    for selector in [json!({"path": "text"}), json!({"path": "text/pathOptions"}), json!({"path": format!("@{uid}")}), json!({"prop": uid})] {
-        let mut params = selector;
-        params["layer"] = json!(l);
-        for cmd in ["prop.get", "prop.set"] {
-            let err = s.execute(cmd, params.clone()).unwrap_err().to_string();
-            assert!(err.contains("is a property group"), "{cmd}: {err}");
-            assert!(err.contains("get_layer"), "{cmd}: {err}");
-        }
-    }
-    assert!(s.execute("prop.get", json!({"layer": l, "path": "text/sourceText"})).is_ok());
-    let err = s.execute("prop.get", json!({"layer": l, "path": "missing"})).unwrap_err().to_string();
-    assert!(err.contains("no property `missing`"), "{err}");
-}
-
-#[test]
-fn prop_get_and_render_rgba8() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "T", "width": 320, "height": 180, "duration": 2.0, "frameRate": 30})).unwrap();
-    let l = s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
-    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 0.0, "value": [0, 0]})).unwrap();
-    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 1.0, "value": [100, 50]})).unwrap();
-    let v = s.execute("prop.get", json!({"layer": l, "path": "transform/position", "time": 1.0})).unwrap();
-    assert_eq!(v["animated"], true);
-    assert_eq!(v["keys"].as_array().unwrap().len(), 2);
-    assert_eq!(v["value"][0].as_f64().unwrap(), 100.0);
-    let cid = s.resolve_comp(Some(&json!("T"))).unwrap();
-    let (w, h, rgba) = s.render_rgba8(cid, effectcraft_time::Tick::ZERO, 160).unwrap();
-    assert_eq!((w, h), (160, 90));
-    assert_eq!(rgba.len(), (w * h * 4) as usize);
-}
-
-#[test]
-fn params_docs_parse() {
-    use crate::commands::accepted_params;
-    let k = |d: &str| accepted_params(d).unwrap();
-    assert_eq!(k("{layers: [id|name|#n], add?, toggle?}"), ["layers", "add", "toggle"]);
-    assert_eq!(k("{time? (s) | frame? | timecode?}"), ["time", "frame", "timecode"]);
-    assert_eq!(k("{interpolation?|in?|out?: linear|bezier|hold, autoBezier?}"), ["interpolation", "in", "out", "autoBezier"]);
-    assert_eq!(k("{keys: [{layer, prop, time}], add?}"), ["keys", "add"]);
-    assert_eq!(k("{label: Red|Yellow|Aqua|…, layers?}"), ["label", "layers"]);
-    assert_eq!(k("{name?, background? [r,g,b]|#hex, open?}"), ["name", "background", "open"]);
-    assert!(k("{}").is_empty());
-    assert!(accepted_params("free text").is_none());
-    // Every registered command documents its params as a parseable key list.
-    for c in crate::command_specs() {
-        assert!(accepted_params(c.params).is_some(), "{}: {}", c.id, c.params);
-    }
-}
-
-#[test]
-fn execute_checked_rejects_unknown_params() {
-    let mut s = demo();
-    let e = s.execute_checked("layer.select", json!({"index": 2})).unwrap_err().to_string();
-    assert!(e.contains("`index`") && e.contains("layers, add, toggle"), "{e}");
-    s.execute_checked("layer.select", json!({"layers": ["#2"]})).unwrap();
-    assert_eq!(s.state.selected_layers.len(), 1);
-    // Aliases and always-accepted keys.
-    s.execute_checked("layer.select", json!({"layer": "#1", "comp": s.active_comp_id().unwrap().0})).unwrap();
-    s.execute_checked("time.set", json!({"frame": 3})).unwrap();
-    assert!(s.execute_checked("edit.undo", json!({"steps": 2})).is_err());
-    // Non-object params are not validated; the unchecked path stays lenient.
-    s.execute("layer.select", json!({"layers": ["#1"], "index": 2})).unwrap();
-}
-
-#[test]
-fn layer_tree_paths_resolve() {
-    let mut s = demo();
-    s.execute("effect.apply", json!({"layer": 1, "effect": "Gaussian Blur"})).unwrap();
-    let comp = s.execute("comp.info", json!({})).unwrap();
-    let mut checked = 0;
-    for l in comp["layers"].as_array().unwrap() {
-        let tree = s.execute("layer.tree", json!({"layer": l["id"]})).unwrap();
-        let mut stack = vec![tree["properties"].clone()];
-        while let Some(n) = stack.pop() {
-            if let Some(ch) = n["children"].as_array() {
-                stack.extend(ch.iter().cloned());
-                continue;
-            }
-            let path = n["path"].as_str().unwrap();
-            let got = s.execute("prop.get", json!({"layer": l["id"], "path": path})).unwrap();
-            assert_eq!(got["uid"], n["uid"], "path {path} on layer {}", l["name"]);
-            checked += 1;
-        }
-    }
-    assert!(checked > 20, "{checked}");
-}
-
-#[test]
-fn comp_settings_anchor_start_timecode_renderer() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "A", "width": 100, "height": 100, "duration": 2.0})).unwrap();
-    let l = s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
-    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 0.0, "value": [10, 20]})).unwrap();
-    let pos = |s: &Session| {
-        let pr = s.active_comp().unwrap().layer(crate::project::LayerId(l)).unwrap().props.prop("transform/position").unwrap().clone();
-        pr.keys[0].value.components()
-    };
-    // Center anchor: grow by 100x50 → shift by half.
-    s.execute("comp.settings", json!({"width": 200, "height": 150})).unwrap();
-    assert_eq!(pos(&s)[..2], [60.0, 45.0]);
-    // Top-left anchor: no shift. Bottom-right: full shift.
-    s.execute("comp.settings", json!({"width": 300, "anchor": 0})).unwrap();
-    assert_eq!(pos(&s)[..2], [60.0, 45.0]);
-    s.execute("comp.settings", json!({"width": 200, "height": 100, "anchor": 8})).unwrap();
-    assert_eq!(pos(&s)[..2], [-40.0, -5.0]);
-    s.execute("comp.settings", json!({"startTimecode": "0:00:01:00", "renderer": "advanced3D"})).unwrap();
-    let c = s.active_comp().unwrap();
-    assert_eq!(c.display_start, c.frame_rate.tick_of(30));
-    assert_eq!(c.renderer, crate::project::Renderer::Advanced3D);
-}
-
-/// `advanced3D` is a value of `renderer`, not a key: comp.new / comp.settings don't advertise it
-/// in their schemas and reject it as unknown instead of ignoring it (#177).
-#[test]
-fn renderer_values_are_not_parameter_keys() {
-    let mut s = Session::default();
-    for (id, p) in [("comp.new", json!({"name": "A"})), ("comp.settings", json!({}))] {
-        let spec = crate::command_specs().iter().find(|c| c.id == id).unwrap();
-        let keys = crate::commands::accepted_params(spec.params).unwrap();
-        assert!(keys.contains(&"renderer".to_string()) && !keys.contains(&"advanced3D".to_string()), "{id}: {keys:?}");
-        let mut bad = p.clone();
-        bad["advanced3D"] = json!(true);
-        let e = s.execute_checked(id, bad).unwrap_err().to_string();
-        assert!(e.contains("unknown parameter(s) `advanced3D`"), "{id}: {e}");
-        let mut good = p;
-        good["renderer"] = json!("advanced3D");
-        s.execute_checked(id, good).unwrap();
-        assert_eq!(s.active_comp().unwrap().renderer, crate::project::Renderer::Advanced3D, "{id}");
-        s.execute("comp.renderer", json!({"renderer": "classic3d"})).unwrap();
-    }
-}
-
-#[test]
-fn comp_rejects_zero_and_negative_frame_rates() {
-    let mut s = Session::default();
-    for fps in [0.0, -30.0, 0.0001] {
-        assert!(s.execute("comp.new", json!({"frameRate": fps})).is_err(), "{fps}");
-    }
-    s.execute("comp.new", json!({"frameRate": 30, "duration": 1})).unwrap();
-    assert!(s.execute("comp.settings", json!({"frameRate": 0})).is_err());
-    assert_eq!(s.active_comp().unwrap().frame_rate, crate::time::FrameRate::FPS_30);
-}
-
-#[test]
-fn render_queue_add_accepts_documented_settings_when_checked() {
-    let mut s = demo();
-    let r = s.execute_checked(
-        "renderQueue.add",
-        json!({"format": "gif", "output": "/tmp/x.gif", "resolution": "quarter", "timeSpan": "custom", "start": 0.0, "end": 0.5, "quality": "draft", "loop": true}),
-    );
-    // Without an exporter the add itself still succeeds (rendering is what needs one).
-    assert!(r.is_ok(), "{r:?}");
-    assert!(s.execute_checked("renderQueue.add", json!({"bogus": 1})).is_err());
-}
-
-#[test]
-fn new_text_rejects_malformed_positions_without_creating_a_layer() {
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "C", "width": 64, "height": 64, "duration": 1})).unwrap();
-    for position in [json!([]), json!([10]), json!(["x", 20]), json!([null, 20])] {
-        let err = s.execute("layer.newText", json!({"text": "Hello", "position": position})).unwrap_err();
-        assert!(err.to_string().contains("position: [x, y]"), "{err}");
-        assert!(s.active_comp().unwrap().layers.is_empty());
-    }
-    s.execute("layer.newText", json!({"name": "Valid", "text": "Hello", "position": [10, 20]})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().value, effectcraft_keyframe::Value::Vec3([10.0, 20.0, 0.0]));
-    s.execute("layer.newText", json!({"text": "No explicit position"})).unwrap();
-    assert_eq!(s.active_comp().unwrap().layers.len(), 2);
-}
-
-/// The active comp and the open comp tabs are saved with the project and restored on open (#748).
-#[test]
-fn reopening_a_project_restores_its_active_comp() {
-    use effectcraft_project::ItemId;
-    let dir = std::env::temp_dir().join(format!("ec-test-748-{}", std::process::id()));
-    std::fs::create_dir_all(&dir).unwrap();
-    let path = dir.join("view.ecproj").to_string_lossy().to_string();
-    let mut s = Session::default();
-    let a = s.execute("comp.new", json!({"name": "CompA"})).unwrap()["comp"].as_u64().unwrap();
-    let b = s.execute("comp.new", json!({"name": "CompB"})).unwrap()["comp"].as_u64().unwrap();
-    let c = s.execute("comp.new", json!({"name": "CompC"})).unwrap()["comp"].as_u64().unwrap();
-    s.execute("comp.open", json!({"comp": "CompB"})).unwrap();
-    s.state.open_comps.retain(|id| id.0 != c);
-    s.execute("file.saveAs", json!({"path": path})).unwrap();
-    let mut s2 = Session::default();
-    s2.execute("file.open", json!({"path": path})).unwrap();
-    assert_eq!(s2.state.active_comp, Some(ItemId(b)));
-    assert_eq!(s2.state.open_comps, vec![ItemId(a), ItemId(b)]);
-    assert!(!s2.is_dirty());
-
-    // A file from before the view was saved opens on its first comp, as it always did.
-    let text = std::fs::read_to_string(&path).unwrap();
-    let mut old: serde_json::Value = serde_json::from_str(&text).unwrap();
-    let obj = old.as_object_mut().unwrap();
-    obj.remove("activeComp");
-    obj.remove("openComps");
-    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
-    let mut s3 = Session::default();
-    s3.execute("file.open", json!({"path": path})).unwrap();
-    assert_eq!((s3.state.active_comp, s3.state.open_comps.clone()), (Some(ItemId(a)), vec![ItemId(a)]));
-
-    // Ids that no longer name a comp (edited by hand, or written by another tool) fall back.
-    obj_set(&mut old, json!(999), json!([999, b, "x"]));
-    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
-    let mut s4 = Session::default();
-    s4.execute("file.open", json!({"path": path})).unwrap();
-    assert_eq!((s4.state.active_comp, s4.state.open_comps.clone()), (Some(ItemId(b)), vec![ItemId(b)]));
-    obj_set(&mut old, json!(999), json!([]));
-    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
-    let mut s5 = Session::default();
-    s5.execute("file.open", json!({"path": path})).unwrap();
-    assert_eq!((s5.state.active_comp, s5.state.open_comps.clone()), (Some(ItemId(a)), vec![ItemId(a)]));
-
-    // XML copies carry it too.
-    let xml = dir.join("view.ecprojx").to_string_lossy().to_string();
-    s.execute("file.saveAs", json!({"path": xml})).unwrap();
-    let mut s6 = Session::default();
-    s6.execute("file.open", json!({"path": xml})).unwrap();
-    assert_eq!(s6.state.active_comp, Some(ItemId(b)));
-    let _ = std::fs::remove_dir_all(dir);
-
-    fn obj_set(v: &mut serde_json::Value, active: serde_json::Value, open: serde_json::Value) {
-        let o = v.as_object_mut().unwrap();
-        o.insert("activeComp".into(), active);
-        o.insert("openComps".into(), open);
-    }
-}
-
-/// Layer times are saved as exact ticks and read back unchanged, and each comp reopens at the
-/// current time it was saved at, not at 0, where a layer starting later shows nothing (#1714).
-#[test]
-fn reopening_a_project_restores_layer_times_and_current_time() {
-    use effectcraft_project::ItemId;
-    use effectcraft_time::{FrameRate, Tick};
-    let dir = std::env::temp_dir().join(format!("ec-test-1714-{}", std::process::id()));
-    std::fs::create_dir_all(&dir).unwrap();
-    let path = dir.join("times.ecproj").to_string_lossy().to_string();
-    let mut s = Session::default();
-    s.execute("comp.new", json!({"name": "C", "width": 108, "height": 192, "duration": 60})).unwrap();
-    s.execute("layer.newSolid", json!({"name": "crown"})).unwrap();
-    let cid = s.active_comp_id().unwrap();
-    let comp = std::sync::Arc::make_mut(&mut s.project).comp_mut(cid).unwrap();
-    comp.frame_rate = FrameRate::FPS_59_94;
-    // The layer from the issue: 34f, 315f and 3033f at 59.94 fps.
-    let l = comp.layers.first_mut().unwrap();
-    (l.start_time, l.in_point, l.out_point) = (Tick(144_086_342_400), Tick(1_334_917_584_000), Tick(12_853_349_308_800));
-    s.execute("time.set", json!({"time": 6.0})).unwrap();
-    let t = s.time();
-    // A second comp keeps its own time.
-    let b = ItemId(s.execute("comp.new", json!({"name": "B"})).unwrap()["comp"].as_u64().unwrap());
-    s.execute("time.set", json!({"time": 2.0})).unwrap();
-    let tb = s.time();
-    s.execute("comp.open", json!({"comp": "C"})).unwrap();
-    s.execute("file.saveAs", json!({"path": path})).unwrap();
-
-    let mut s2 = Session::default();
-    s2.execute("file.open", json!({"path": path})).unwrap();
-    let l = s2.project.comp(cid).unwrap().layers.first().unwrap();
-    assert_eq!((l.start_time, l.in_point, l.out_point), (Tick(144_086_342_400), Tick(1_334_917_584_000), Tick(12_853_349_308_800)));
-    assert_eq!((s2.time(), s2.state.times.get(&b).copied()), (t, Some(tb)));
-    assert!(l.in_point <= s2.time() && s2.time() < l.out_point, "the layer shows at the reopened time");
-    assert!(!s2.is_dirty());
-
-    // Hand-edited times past the end or before the start land on the last or first frame.
-    let mut file: serde_json::Value = serde_json::from_str(&std::fs::read_to_string(&path).unwrap()).unwrap();
-    file["compTimes"] = json!({cid.0.to_string(): i64::MAX, b.0.to_string(): -5});
-    std::fs::write(&path, file.to_string()).unwrap();
-    let mut s3 = Session::default();
-    s3.execute("file.open", json!({"path": path})).unwrap();
-    let c = s3.project.comp(cid).unwrap();
-    assert_eq!(s3.time(), c.frame_rate.snap_nearest(c.duration - c.frame_duration()));
-    assert_eq!(s3.time(), c.frame_rate.snap_nearest(c.duration - c.frame_duration()));
-    assert_eq!(s3.state.times.get(&b).copied(), Some(Tick::ZERO));
-}
+mod session;
+mod three_d;
+mod anim_presets;
+mod anim_tools;
+mod camera_track;
+mod codec_options;
+mod color_view;
+mod crypto_pick;
+mod delete_keys;
+mod disk_cache;
+mod effects;
+mod essential;
+mod essential_more;
+mod face;
+mod fidelity;
+mod frame_export;
+mod fuzz_open;
+mod import_project;
+mod key_metadata_order;
+mod keylight;
+mod limits;
+mod lottie;
+mod m137;
+mod m145;
+mod markers;
+mod mask_warp;
+mod menu_cmds;
+mod model3d;
+mod motion_blur_depth;
+mod project_items;
+mod proxy;
+mod quick_offset;
+mod replace_source;
+mod rig3d;
+mod sequence;
+mod settings;
+mod shortcut_cmds;
+pub(crate) mod stubs;
+mod styles;
+mod tail;
+mod text;
+mod text_edit;
+mod timeline;
+mod timeline_interchange;
+pub(crate) mod track;
+mod vector_import;
+mod viewer;
+mod history;
+mod models;
+mod paint;
+mod panels;
+pub(crate) mod roto;
+mod key_time;
diff --git a/crates/engine/src/tests_anim_presets.rs b/crates/engine/src/tests/anim_presets.rs
similarity index 100%
rename from crates/engine/src/tests_anim_presets.rs
rename to crates/engine/src/tests/anim_presets.rs
diff --git a/crates/engine/src/tests_anim_tools.rs b/crates/engine/src/tests/anim_tools.rs
similarity index 99%
rename from crates/engine/src/tests_anim_tools.rs
rename to crates/engine/src/tests/anim_tools.rs
index 69b6afa06..06d194001 100644
--- a/crates/engine/src/tests_anim_tools.rs
+++ b/crates/engine/src/tests/anim_tools.rs
@@ -3,7 +3,7 @@
 use effectcraft_keyframe::evaluate;
 use serde_json::json;
 
-use crate::tests_timeline::{animate, prop, setup};
+use crate::tests::timeline::{animate, prop, setup};
 
 fn select(s: &mut crate::Session, layer: u64, path: &str) {
     s.execute("prop.select", json!({"layer": layer, "path": path})).unwrap();
diff --git a/crates/engine/src/tests_camera_track.rs b/crates/engine/src/tests/camera_track.rs
similarity index 99%
rename from crates/engine/src/tests_camera_track.rs
rename to crates/engine/src/tests/camera_track.rs
index 5bd5539c1..cc6378c4e 100644
--- a/crates/engine/src/tests_camera_track.rs
+++ b/crates/engine/src/tests/camera_track.rs
@@ -11,7 +11,7 @@ use effectcraft_track::camtrack::linalg::{self, M3, V3};
 use serde_json::{Value, json};
 
 use crate::Session;
-use crate::tests_track::{H, W, frame_time, setup, texture};
+use crate::tests::track::{H, W, frame_time, setup, texture};
 
 const F: f64 = 260.0;
 
diff --git a/crates/engine/src/tests_codec_options.rs b/crates/engine/src/tests/codec_options.rs
similarity index 100%
rename from crates/engine/src/tests_codec_options.rs
rename to crates/engine/src/tests/codec_options.rs
diff --git a/crates/engine/src/tests_color_view.rs b/crates/engine/src/tests/color_view.rs
similarity index 100%
rename from crates/engine/src/tests_color_view.rs
rename to crates/engine/src/tests/color_view.rs
diff --git a/crates/engine/src/tests_crypto_pick.rs b/crates/engine/src/tests/crypto_pick.rs
similarity index 100%
rename from crates/engine/src/tests_crypto_pick.rs
rename to crates/engine/src/tests/crypto_pick.rs
diff --git a/crates/engine/src/tests_delete_keys.rs b/crates/engine/src/tests/delete_keys.rs
similarity index 100%
rename from crates/engine/src/tests_delete_keys.rs
rename to crates/engine/src/tests/delete_keys.rs
diff --git a/crates/engine/src/tests_disk_cache.rs b/crates/engine/src/tests/disk_cache.rs
similarity index 99%
rename from crates/engine/src/tests_disk_cache.rs
rename to crates/engine/src/tests/disk_cache.rs
index 3091964ad..4204b8238 100644
--- a/crates/engine/src/tests_disk_cache.rs
+++ b/crates/engine/src/tests/disk_cache.rs
@@ -30,7 +30,7 @@ fn project(s: &mut Session) -> effectcraft_project::ItemId {
 
 #[test]
 fn disk_cache_settings_persistence_and_invalidation() {
-    crate::tests_roto::hold_roto_cache_test_lock();
+    crate::tests::roto::hold_roto_cache_test_lock();
     let dir = folder("persist");
     let mut s = session(&dir);
     let st = s.execute_checked("cache.diskStats", json!({})).unwrap();
diff --git a/crates/engine/src/tests_effects.rs b/crates/engine/src/tests/effects.rs
similarity index 100%
rename from crates/engine/src/tests_effects.rs
rename to crates/engine/src/tests/effects.rs
diff --git a/crates/engine/src/tests_essential.rs b/crates/engine/src/tests/essential.rs
similarity index 100%
rename from crates/engine/src/tests_essential.rs
rename to crates/engine/src/tests/essential.rs
diff --git a/crates/engine/src/tests_essential_more.rs b/crates/engine/src/tests/essential_more.rs
similarity index 100%
rename from crates/engine/src/tests_essential_more.rs
rename to crates/engine/src/tests/essential_more.rs
diff --git a/crates/engine/src/tests_face.rs b/crates/engine/src/tests/face.rs
similarity index 99%
rename from crates/engine/src/tests_face.rs
rename to crates/engine/src/tests/face.rs
index 9e713ff8b..2a45da98f 100644
--- a/crates/engine/src/tests_face.rs
+++ b/crates/engine/src/tests/face.rs
@@ -6,7 +6,7 @@ use effectcraft_track::face::{FaceParams, LANDMARKS, MEASUREMENTS, render_synthe
 use serde_json::json;
 
 use crate::mask_track::MaskMethod;
-use crate::tests_track::{H, W, frame_time, setup};
+use crate::tests::track::{H, W, frame_time, setup};
 
 fn face(f: u32) -> FaceParams {
     let t = f as f64;
diff --git a/crates/engine/src/tests_fidelity.rs b/crates/engine/src/tests/fidelity.rs
similarity index 100%
rename from crates/engine/src/tests_fidelity.rs
rename to crates/engine/src/tests/fidelity.rs
diff --git a/crates/engine/src/tests_frame_export.rs b/crates/engine/src/tests/frame_export.rs
similarity index 100%
rename from crates/engine/src/tests_frame_export.rs
rename to crates/engine/src/tests/frame_export.rs
diff --git a/crates/engine/src/tests_fuzz_open.rs b/crates/engine/src/tests/fuzz_open.rs
similarity index 100%
rename from crates/engine/src/tests_fuzz_open.rs
rename to crates/engine/src/tests/fuzz_open.rs
diff --git a/crates/engine/src/tests_history.rs b/crates/engine/src/tests/history.rs
similarity index 100%
rename from crates/engine/src/tests_history.rs
rename to crates/engine/src/tests/history.rs
diff --git a/crates/engine/src/tests_import_project.rs b/crates/engine/src/tests/import_project.rs
similarity index 100%
rename from crates/engine/src/tests_import_project.rs
rename to crates/engine/src/tests/import_project.rs
diff --git a/crates/engine/src/tests_key_metadata_order.rs b/crates/engine/src/tests/key_metadata_order.rs
similarity index 100%
rename from crates/engine/src/tests_key_metadata_order.rs
rename to crates/engine/src/tests/key_metadata_order.rs
diff --git a/crates/engine/src/tests_key_time.rs b/crates/engine/src/tests/key_time.rs
similarity index 99%
rename from crates/engine/src/tests_key_time.rs
rename to crates/engine/src/tests/key_time.rs
index d42d6d4a0..b5ec3a159 100644
--- a/crates/engine/src/tests_key_time.rs
+++ b/crates/engine/src/tests/key_time.rs
@@ -4,7 +4,7 @@ use effectcraft_project::LayerId;
 use effectcraft_time::Tick;
 use serde_json::{Value, json};
 
-use crate::{Session, tests_timeline::prop};
+use crate::{Session, tests::timeline::prop};
 
 fn offset_layer(start: f64, stretch: f64) -> (Session, u64) {
     let mut s = Session::default();
diff --git a/crates/engine/src/tests_keylight.rs b/crates/engine/src/tests/keylight.rs
similarity index 100%
rename from crates/engine/src/tests_keylight.rs
rename to crates/engine/src/tests/keylight.rs
diff --git a/crates/engine/src/tests_limits.rs b/crates/engine/src/tests/limits.rs
similarity index 100%
rename from crates/engine/src/tests_limits.rs
rename to crates/engine/src/tests/limits.rs
diff --git a/crates/engine/src/tests_lottie.rs b/crates/engine/src/tests/lottie.rs
similarity index 100%
rename from crates/engine/src/tests_lottie.rs
rename to crates/engine/src/tests/lottie.rs
diff --git a/crates/engine/src/tests_m137.rs b/crates/engine/src/tests/m137.rs
similarity index 100%
rename from crates/engine/src/tests_m137.rs
rename to crates/engine/src/tests/m137.rs
diff --git a/crates/engine/src/tests_m145.rs b/crates/engine/src/tests/m145.rs
similarity index 99%
rename from crates/engine/src/tests_m145.rs
rename to crates/engine/src/tests/m145.rs
index 68b897617..ce0cb34d4 100644
--- a/crates/engine/src/tests_m145.rs
+++ b/crates/engine/src/tests/m145.rs
@@ -345,7 +345,7 @@ fn render_queue_uses_default_folder_bit_depth_names_and_segments() {
 fn every_wired_setting_is_live_and_display_only_ones_are_documented() {
     let todo = crate::prefs::todo_keys();
     assert_eq!(todo, ["general.useSystemColorPicker", "composition.hardwareAcceleratePanels", "scripting.enableJsDebugger"]);
-    let docs = include_str!("../../../docs/preferences.md");
+    let docs = include_str!("../../../../docs/preferences.md");
     assert!(docs.contains("### Display-only settings"));
     assert!(!docs.contains("Not wired yet"));
 }
diff --git a/crates/engine/src/tests_markers.rs b/crates/engine/src/tests/markers.rs
similarity index 99%
rename from crates/engine/src/tests_markers.rs
rename to crates/engine/src/tests/markers.rs
index afe4b9890..66aac5694 100644
--- a/crates/engine/src/tests_markers.rs
+++ b/crates/engine/src/tests/markers.rs
@@ -3,7 +3,7 @@
 
 use serde_json::json;
 
-use crate::tests_timeline::setup;
+use crate::tests::timeline::setup;
 
 #[test]
 fn comp_marker_dialog_fields_and_undo() {
diff --git a/crates/engine/src/tests_mask_warp.rs b/crates/engine/src/tests/mask_warp.rs
similarity index 99%
rename from crates/engine/src/tests_mask_warp.rs
rename to crates/engine/src/tests/mask_warp.rs
index 137feb1cb..e20ec7cb6 100644
--- a/crates/engine/src/tests_mask_warp.rs
+++ b/crates/engine/src/tests/mask_warp.rs
@@ -11,7 +11,7 @@ use effectcraft_track::Homography;
 use serde_json::json;
 
 use crate::Session;
-use crate::tests_track::{FPS, H, W, frame_time, patch_frames, rotating_pose, setup, texture};
+use crate::tests::track::{FPS, H, W, frame_time, patch_frames, rotating_pose, setup, texture};
 
 fn pose_h(f: u32) -> Homography {
     let (c, rot, sc) = rotating_pose(f);
diff --git a/crates/engine/src/tests_menu_cmds.rs b/crates/engine/src/tests/menu_cmds.rs
similarity index 99%
rename from crates/engine/src/tests_menu_cmds.rs
rename to crates/engine/src/tests/menu_cmds.rs
index 5131bf3f4..eb99d809f 100644
--- a/crates/engine/src/tests_menu_cmds.rs
+++ b/crates/engine/src/tests/menu_cmds.rs
@@ -641,7 +641,7 @@ fn work_area_stays_ordered_when_the_start_passes_the_end() {
 
 #[test]
 fn label_group_purge_and_edit_original() {
-    crate::tests_roto::hold_roto_cache_test_lock();
+    crate::tests::roto::hold_roto_cache_test_lock();
     let mut s = comp();
     let a = solid(&mut s, "#ff0000");
     let b = solid(&mut s, "#00ff00");
diff --git a/crates/engine/src/tests_model3d.rs b/crates/engine/src/tests/model3d.rs
similarity index 100%
rename from crates/engine/src/tests_model3d.rs
rename to crates/engine/src/tests/model3d.rs
diff --git a/crates/engine/src/tests_models.rs b/crates/engine/src/tests/models.rs
similarity index 98%
rename from crates/engine/src/tests_models.rs
rename to crates/engine/src/tests/models.rs
index 66111eb34..21d316e75 100644
--- a/crates/engine/src/tests_models.rs
+++ b/crates/engine/src/tests/models.rs
@@ -28,7 +28,7 @@ fn wait_loaded(s: &mut Session, task: Task) {
 
 #[test]
 fn models_are_listed_chosen_and_verified() {
-    crate::tests_roto::hold_roto_cache_test_lock();
+    crate::tests::roto::hold_roto_cache_test_lock();
     let (mut s, d) = session("list");
     std::fs::create_dir_all(&d).unwrap();
     let bogus = d.join("bogus.bin");
diff --git a/crates/engine/src/tests_motion_blur_depth.rs b/crates/engine/src/tests/motion_blur_depth.rs
similarity index 100%
rename from crates/engine/src/tests_motion_blur_depth.rs
rename to crates/engine/src/tests/motion_blur_depth.rs
diff --git a/crates/engine/src/tests_paint.rs b/crates/engine/src/tests/paint.rs
similarity index 100%
rename from crates/engine/src/tests_paint.rs
rename to crates/engine/src/tests/paint.rs
diff --git a/crates/engine/src/tests_panels.rs b/crates/engine/src/tests/panels.rs
similarity index 100%
rename from crates/engine/src/tests_panels.rs
rename to crates/engine/src/tests/panels.rs
diff --git a/crates/engine/src/tests_project_items.rs b/crates/engine/src/tests/project_items.rs
similarity index 100%
rename from crates/engine/src/tests_project_items.rs
rename to crates/engine/src/tests/project_items.rs
diff --git a/crates/engine/src/tests_proxy.rs b/crates/engine/src/tests/proxy.rs
similarity index 100%
rename from crates/engine/src/tests_proxy.rs
rename to crates/engine/src/tests/proxy.rs
diff --git a/crates/engine/src/tests_quick_offset.rs b/crates/engine/src/tests/quick_offset.rs
similarity index 100%
rename from crates/engine/src/tests_quick_offset.rs
rename to crates/engine/src/tests/quick_offset.rs
diff --git a/crates/engine/src/tests_replace_source.rs b/crates/engine/src/tests/replace_source.rs
similarity index 100%
rename from crates/engine/src/tests_replace_source.rs
rename to crates/engine/src/tests/replace_source.rs
diff --git a/crates/engine/src/tests_rig3d.rs b/crates/engine/src/tests/rig3d.rs
similarity index 100%
rename from crates/engine/src/tests_rig3d.rs
rename to crates/engine/src/tests/rig3d.rs
diff --git a/crates/engine/src/tests_roto.rs b/crates/engine/src/tests/roto.rs
similarity index 99%
rename from crates/engine/src/tests_roto.rs
rename to crates/engine/src/tests/roto.rs
index 33500b4ec..423af1d2f 100644
--- a/crates/engine/src/tests_roto.rs
+++ b/crates/engine/src/tests/roto.rs
@@ -8,7 +8,7 @@ use effectcraft_track::roto::rle;
 use serde_json::{Value, json};
 
 use crate::Session;
-use crate::tests_track::{H, W, frame_time, setup};
+use crate::tests::track::{H, W, frame_time, setup};
 
 /// Keep cache/model mutation tests from clearing segmentations under another fixture.
 /// Libtest runs each test on its own thread; the guard lives until that thread exits.
diff --git a/crates/engine/src/tests_sequence.rs b/crates/engine/src/tests/sequence.rs
similarity index 100%
rename from crates/engine/src/tests_sequence.rs
rename to crates/engine/src/tests/sequence.rs
diff --git a/crates/engine/src/tests/session.rs b/crates/engine/src/tests/session.rs
new file mode 100644
index 000000000..b3f0602b3
--- /dev/null
+++ b/crates/engine/src/tests/session.rs
@@ -0,0 +1,735 @@
+use serde_json::json;
+
+use crate::Session;
+
+fn demo() -> Session {
+    let mut s = Session::default();
+    s.execute("file.openDemoProject", json!({})).unwrap();
+    s
+}
+
+#[test]
+fn demo_opens_and_renders() {
+    let s = demo();
+    let cid = s.active_comp_id().unwrap();
+    let img = s.render(cid, s.time(), effectcraft_render::RenderOpts { scale: 0.25, ..Default::default() });
+    assert_eq!((img.width, img.height), (480, 270));
+    let lit = img.data.iter().filter(|p| p[3] > 0.99).count();
+    assert!(lit > 100_000, "{lit}");
+}
+
+/// The session's layer cache never changes pixels: scrubbing the demo (including back and
+/// forth, and across an edit made through a command) matches cache-less renders exactly.
+#[test]
+fn demo_layer_cache_is_transparent() {
+    let mut s = demo();
+    let cid = s.active_comp_id().unwrap();
+    let opts = effectcraft_render::RenderOpts { scale: 0.25, ..Default::default() };
+    let uncached = |s: &Session, t: f64| {
+        let mut r = effectcraft_render::Renderer::new(&s.project, s.footage.as_ref(), opts);
+        r.expr = s.expr.as_deref();
+        r.comp_frame(cid, effectcraft_time::Tick::from_seconds_f64(t))
+    };
+    let check = |s: &Session, t: f64| {
+        let a = s.render(cid, effectcraft_time::Tick::from_seconds_f64(t), opts);
+        let b = uncached(s, t);
+        assert!(a.data.iter().zip(&b.data).all(|(p, q)| (0..4).all(|c| (p[c] - q[c]).abs() < 1e-6)), "t={t}");
+    };
+    for t in [0.5, 1.0, 3.0, 3.0334, 6.0, 3.0, 0.5] {
+        check(&s, t);
+    }
+    assert!(s.layer_cache.stats().hits > 0);
+    // Edit the title's glow through the command layer, then scrub again.
+    let title = s.project.comp(cid).unwrap().layers.iter().find(|l| l.name == "EFFECTCRAFT").map(|l| l.id.0).unwrap();
+    s.execute("prop.set", json!({"layer": title, "path": "effects/#1/radius", "value": 5.0})).unwrap();
+    for t in [3.0, 0.5] {
+        check(&s, t);
+    }
+}
+
+/// `layer.addItem` puts the layer at `index` (1-based) in the stack and starts it at `time`, as a
+/// drop in the Timeline does (#89).
+#[test]
+fn add_item_at_a_stack_index_and_time() {
+    let mut s = Session::default();
+    let clip = s.execute("comp.new", json!({"name": "Clip", "width": 16, "height": 16, "frameRate": 30, "duration": 1})).unwrap()["comp"].as_u64().unwrap();
+    s.execute("comp.new", json!({"name": "Main", "width": 32, "height": 32, "frameRate": 30, "duration": 4})).unwrap();
+    for name in ["C", "B", "A"] {
+        s.execute("layer.newSolid", json!({"name": name})).unwrap();
+    }
+    let names = |s: &Session| s.active_comp().unwrap().layers.iter().map(|l| l.name.clone()).collect::<Vec<_>>();
+    s.execute("layer.addItem", json!({"item": clip, "index": 2, "time": 1.01})).unwrap();
+    assert_eq!(names(&s), ["A", "Clip", "B", "C"]);
+    let l = &s.active_comp().unwrap().layers[1];
+    assert_eq!(l.in_point, effectcraft_time::Tick::from_seconds_f64(1.0), "on the nearest frame");
+    // Past the bottom: the bottom.
+    s.execute("layer.addItem", json!({"item": clip, "index": 99})).unwrap();
+    assert_eq!(names(&s).last().map(String::as_str), Some("Clip 2"));
+    assert!(s.execute("layer.addItem", json!({"item": clip, "index": 0})).is_err(), "1-based");
+}
+
+/// Files dropped on the Timeline or the Composition viewer (`file.import {addToComp}`) become
+/// layers of the comp that was active, one under the other, where they were dropped (#85, #89).
+#[test]
+fn imported_files_go_into_the_comp_where_they_were_dropped() {
+    use effectcraft_project::{Footage, FootageKind};
+    struct Probe;
+    impl crate::Importer for Probe {
+        fn probe(&self, path: &str) -> Result<Footage, String> {
+            Ok(Footage { path: path.into(), kind: FootageKind::Still, width: 64, height: 32, has_video: true, ..Default::default() })
+        }
+    }
+    let mut s = Session { importer: Some(std::sync::Arc::new(Probe)), ..Default::default() };
+    s.execute("comp.new", json!({"name": "Main", "width": 320, "height": 180, "frameRate": 30, "duration": 4})).unwrap();
+    s.execute("layer.newSolid", json!({"name": "Bg"})).unwrap();
+    let params = json!({"paths": ["/drop/a.png", "/drop/b.png"], "addToComp": true, "position": [40.0, 50.0], "index": 1, "time": 1.0});
+    s.execute("file.import", params).unwrap();
+    let comp = s.active_comp().unwrap();
+    assert_eq!(comp.layers.iter().map(|l| l.name.as_str()).collect::<Vec<_>>(), ["a.png", "b.png", "Bg"]);
+    for l in &comp.layers[..2] {
+        assert_eq!(l.props.prop("transform/position").map(|p| p.value.clone()), Some(effectcraft_keyframe::Value::Vec3([40.0, 50.0, 0.0])));
+        assert_eq!(l.in_point, effectcraft_time::Tick::from_seconds_f64(1.0));
+    }
+    // Without `addToComp` they only import.
+    s.execute("file.import", json!({"paths": ["/drop/c.png"]})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers.len(), 3);
+    assert!(s.execute("layer.addItem", json!({"item": "a.png", "position": [1.0]})).is_err(), "position needs x and y");
+}
+
+/// #270: files dropped or picked in the Import dialog (`file.import {background}`) are probed in
+/// a background job that says which file it is reading and how many are left; then they arrive
+/// in one undo step, all selected, with a count. The same file imported again arrives again.
+#[test]
+fn background_imports_report_progress_and_select_what_arrived() {
+    use effectcraft_project::{Footage, FootageKind, ItemId};
+    use std::sync::Arc;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    /// Probes file k once `allow` > k (a slow video; 5 s at most, so an import that waits for it
+    /// fails the test instead of hanging it); `.xyz` files fail.
+    struct Gated {
+        started: AtomicUsize,
+        allow: Arc<AtomicUsize>,
+    }
+    impl crate::Importer for Gated {
+        fn probe(&self, path: &str) -> Result<Footage, String> {
+            let k = self.started.fetch_add(1, Ordering::SeqCst);
+            let until = std::time::Instant::now() + std::time::Duration::from_secs(5);
+            while self.allow.load(Ordering::SeqCst) <= k && std::time::Instant::now() < until {
+                std::thread::sleep(std::time::Duration::from_millis(1));
+            }
+            if path.ends_with(".xyz") {
+                return Err("unsupported file".into());
+            }
+            Ok(Footage { path: path.into(), kind: FootageKind::Still, width: 64, height: 32, has_video: true, ..Default::default() })
+        }
+    }
+    let allow = Arc::new(AtomicUsize::new(1));
+    let mut s = Session { importer: Some(Arc::new(Gated { started: AtomicUsize::new(0), allow: allow.clone() })), ..Default::default() };
+    s.execute("comp.new", json!({"name": "Main", "width": 320, "height": 180, "frameRate": 30, "duration": 4})).unwrap();
+    let undo = s.history.undo.len();
+    let r = s.execute("file.import", json!({"paths": ["/drop/a.png", "/drop/b.png", "/drop/a.png"], "background": true})).unwrap();
+    let job = r["job"].as_str().unwrap().to_string();
+    // The first file is through; the second is being read.
+    let running = |s: &mut Session| s.execute("jobs.list", json!({})).unwrap()["running"].as_array().unwrap().clone();
+    let deadline = std::time::Instant::now() + std::time::Duration::from_secs(10);
+    while running(&mut s)[0]["done"] != json!(1) && std::time::Instant::now() < deadline {
+        std::thread::sleep(std::time::Duration::from_millis(2));
+    }
+    let row = running(&mut s)[0].clone();
+    assert_eq!(row["id"], json!(job));
+    assert_eq!(row["label"], json!("Importing 3 files"));
+    assert_eq!(row["message"], json!("b.png (2 of 3)"));
+    assert_eq!((row["done"].as_u64(), row["total"].as_u64()), (Some(1), Some(3)));
+    assert!(s.project.items.values().all(|i| i.name != "a.png"), "nothing is added before the import finishes");
+    allow.store(usize::MAX, Ordering::SeqCst);
+    s.execute("jobs.wait", json!({})).unwrap();
+    let names = |s: &Session, ids: &[ItemId]| ids.iter().map(|i| s.project.item(*i).unwrap().name.clone()).collect::<Vec<_>>();
+    assert_eq!(names(&s, &s.state.project_selection), ["a.png", "b.png", "a.png"], "everything imported is selected, the same file twice too");
+    assert_eq!(s.history.undo.len(), undo + 1, "one undo step");
+    let rec = s.job_log.last().unwrap();
+    assert_eq!((rec.status.as_str(), rec.message.as_str()), ("done", "Imported 3 items"));
+    assert!(s.drain_events().iter().any(|e| matches!(e, crate::Event::Toast { message, .. } if message == "Imported 3 items")));
+    // Dropped on the viewer: they become layers too; a file that can't be read is reported.
+    s.execute("file.import", json!({"paths": ["/drop/c.png", "/drop/d.xyz"], "background": true, "addToComp": true, "position": [10.0, 20.0]})).unwrap();
+    s.execute("jobs.wait", json!({})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers.iter().map(|l| l.name.as_str()).collect::<Vec<_>>(), ["c.png"]);
+    assert_eq!(s.job_log.last().unwrap().message, "Imported 1 item. /drop/d.xyz: unsupported file");
+    // Agents and scripts import at once by default.
+    let r = s.execute("file.import", json!({"paths": ["/drop/e.png"]})).unwrap();
+    assert_eq!(r["items"].as_array().map(Vec::len), Some(1));
+}
+
+/// Audio, Lock and Shy don't change pixels: toggling them keeps the cached layers (#103).
+#[test]
+fn audio_lock_and_shy_keep_cached_layers() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "C", "width": 160, "height": 90, "frameRate": 30, "duration": 1})).unwrap();
+    s.execute("layer.newSolid", json!({"color": "#3080ff", "width": 80, "height": 40})).unwrap();
+    s.execute("effect.apply", json!({"layer": "#1", "effect": "Gaussian Blur"})).unwrap();
+    s.execute("prop.set", json!({"layer": "#1", "path": "effects/#1/blurriness", "value": 12})).unwrap();
+    let cid = s.active_comp_id().unwrap();
+    let t = s.time();
+    s.render(cid, t, Default::default());
+    let before = s.layer_cache.stats();
+    for sw in ["audio", "lock", "shy"] {
+        s.execute("layer.setSwitch", json!({"layers": ["#1"], "switch": sw, "value": sw != "audio"})).unwrap();
+    }
+    s.render(cid, t, Default::default());
+    let after = s.layer_cache.stats();
+    assert_eq!(after.misses, before.misses, "no layer rendered again");
+    assert!(after.hits > before.hits);
+}
+
+#[test]
+fn every_command_has_unique_id_and_runs_or_reports() {
+    let mut ids = std::collections::HashSet::new();
+    for c in crate::command_specs() {
+        assert!(ids.insert(c.id), "duplicate {}", c.id);
+    }
+    assert!(ids.len() >= 90, "{}", ids.len());
+}
+
+#[test]
+fn layer_workflow_with_undo() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "Test", "width": 640, "height": 360, "frameRate": 30, "duration": 4})).unwrap();
+    let r = s.execute("layer.newSolid", json!({"color": "#336699"})).unwrap();
+    let lid = r["layer"].as_u64().unwrap();
+    s.execute("prop.set", json!({"layer": lid, "path": "transform/opacity", "value": 50})).unwrap();
+    let tree = s.execute("layer.tree", json!({"layer": lid})).unwrap();
+    assert!(tree.to_string().contains("\"value\":50.0"));
+    s.execute("prop.toggleAnimation", json!({"layer": lid, "path": "transform/position"})).unwrap();
+    s.execute("time.set", json!({"time": 2.0})).unwrap();
+    s.execute("prop.set", json!({"layer": lid, "path": "transform/position", "value": [100, 100]})).unwrap();
+    let comp = s.active_comp().unwrap();
+    let pos = comp.layers[0].props.prop("transform/position").unwrap();
+    assert_eq!(pos.keys.len(), 2);
+    s.execute("prop.select", json!({"layer": lid, "path": "transform/position"})).unwrap();
+    assert_eq!(s.state.selected_keys.len(), 2);
+    s.execute("keys.easyEase", json!({})).unwrap();
+    s.execute("keys.move", json!({"delta": 0.5})).unwrap();
+    let pos = s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().clone();
+    assert!((pos.keys[0].time.seconds() - 0.5).abs() < 0.02);
+    assert_eq!(pos.keys[0].out_interp, effectcraft_keyframe::Interp::Bezier);
+    // undo back to before the move
+    s.execute("edit.undo", json!({})).unwrap();
+    let pos = s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().clone();
+    assert!(pos.keys[0].time.seconds().abs() < 0.02);
+    s.execute("effect.apply", json!({"layer": lid, "effect": "Gaussian Blur"})).unwrap();
+    s.execute("prop.set", json!({"layer": lid, "path": "effects/#1/blurriness", "value": 12})).unwrap();
+    // Applying selects the new effect (Edit ▸ Duplicate would duplicate it); select the layer.
+    s.execute("layer.select", json!({"layers": [lid]})).unwrap();
+    s.execute("edit.duplicate", json!({})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers.len(), 2);
+    s.execute("layer.precompose", json!({"layers": [1, 2], "name": "Pre"})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers.len(), 1);
+}
+
+#[test]
+fn text_shape_mask_matte_parent() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"width": 800, "height": 450, "duration": 3})).unwrap();
+    let t = s.execute("layer.newText", json!({"text": "Hello", "size": 90})).unwrap()["layer"].as_u64().unwrap();
+    s.execute("layer.addTextAnimator", json!({"layer": t, "properties": ["position", "opacity"]})).unwrap();
+    let sh = s.execute("layer.newShape", json!({"kind": "star", "fill": "#ffcc00"})).unwrap()["layer"].as_u64().unwrap();
+    s.execute("layer.addShapeItem", json!({"layer": sh, "kind": "trim"})).unwrap();
+    s.execute("layer.addMask", json!({"layer": sh, "shape": "ellipse"})).unwrap();
+    s.execute("layer.setMask", json!({"layer": sh, "mask": 1, "mode": "Subtract", "inverted": true})).unwrap();
+    s.execute("layer.setTrackMatte", json!({"layer": sh, "matte": t, "kind": "luma"})).unwrap();
+    s.execute("layer.setParent", json!({"layers": [sh], "parent": t})).unwrap();
+    assert!(s.execute("layer.setParent", json!({"layers": [t], "parent": sh})).is_err());
+    s.execute("layer.setBlendMode", json!({"layers": [sh], "mode": "Screen"})).unwrap();
+    s.execute("layer.setSwitch", json!({"layers": [sh], "switch": "threeD"})).unwrap();
+    let cid = s.active_comp_id().unwrap();
+    let _ = s.render(cid, s.time(), Default::default());
+    let info = s.execute("comp.info", json!({})).unwrap();
+    assert_eq!(info["layers"].as_array().unwrap().len(), 2);
+}
+
+/// The toolbar's Fill / Stroke change a selected shape layer's paint (#205): a shape drawn
+/// without a stroke gets one, later edits change it, and the Contents "Add:" items (#206) include
+/// an empty Path and a Gradient Stroke that render.
+#[test]
+fn toolbar_fill_and_stroke_paint_selected_shape_layers() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
+    let sh = s.execute("layer.newShape", json!({"kind": "rect", "fill": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
+    let paint = |s: &mut Session| s.execute("shape.fillStroke", json!({})).unwrap();
+    assert_eq!(paint(&mut s)["stroke"], serde_json::Value::Null, "drawn without a stroke");
+    s.execute("shape.fillStroke", json!({"stroke": "#00ff00", "strokeWidth": 6})).unwrap();
+    let p = paint(&mut s);
+    assert_eq!((p["stroke"][1].as_f64(), p["strokeWidth"].as_f64()), (Some(1.0), Some(6.0)), "{p}");
+    s.execute("shape.fillStroke", json!({"fill": "#0000ff", "strokeWidth": 3})).unwrap();
+    let p = paint(&mut s);
+    assert_eq!((p["fill"][2].as_f64(), p["strokeWidth"].as_f64()), (Some(1.0), Some(3.0)), "{p}");
+    // One stroke, before the fill (paths, stroke, fill), and each change is one undo step.
+    let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap().clone();
+    let group = l.props.group("contents/group").unwrap();
+    let order: Vec<&str> = group.sub("contents").unwrap().groups().map(|g| g.match_id.as_str()).collect();
+    assert_eq!(order, ["rect", "stroke", "fill"]);
+    s.execute("edit.undo", json!({})).unwrap();
+    assert_eq!(paint(&mut s)["strokeWidth"].as_f64(), Some(6.0));
+    // Only shape layers.
+    s.execute("layer.newSolid", json!({"color": "#808080"})).unwrap();
+    assert!(s.execute("shape.fillStroke", json!({"fill": "#ffffff"})).is_err());
+    for kind in ["path", "gstroke"] {
+        let r = s.execute("layer.addShapeItem", json!({"layer": sh, "kind": kind})).unwrap();
+        assert!(r["path"].as_str().is_some_and(|p| p.starts_with("contents/")), "{r}");
+    }
+    let cid = s.active_comp_id().unwrap();
+    let _ = s.render(cid, s.time(), Default::default());
+}
+
+/// The toolbar's Fill Options / Stroke Options change a selected shape layer's paint kind (#732):
+/// None switches the fill off, a gradient turns the Fill into a Gradient Fill that keeps its
+/// opacity, Solid Color turns it back, and a Stroke kind adds a stroke where there is none.
+#[test]
+fn toolbar_fill_and_stroke_kinds_change_selected_shape_layers() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
+    let sh = s.execute("layer.newShape", json!({"kind": "rect", "fill": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
+    let items = |s: &Session| -> Vec<(String, bool)> {
+        let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap();
+        l.props.group("contents/group/contents").unwrap().groups().map(|g| (g.match_id.clone(), g.enabled)).collect()
+    };
+    let kinds = |s: &mut Session| {
+        let p = s.execute("shape.fillStroke", json!({})).unwrap();
+        (p["fillType"].as_str().unwrap().to_string(), p["strokeType"].as_str().unwrap().to_string())
+    };
+    assert_eq!(kinds(&mut s), ("solid".into(), "none".into()));
+    let cid = s.active_comp_id().unwrap();
+    let centre = |s: &Session| s.render(cid, s.time(), Default::default()).get(200, 150);
+    let red = centre(&s);
+    // None switches the fill off: nothing is drawn, and the item stays.
+    s.execute("shape.fillStroke", json!({"fillType": "none"})).unwrap();
+    assert_eq!(items(&s), [("rect".into(), true), ("fill".into(), false)]);
+    assert_eq!(kinds(&mut s).0, "none");
+    assert_ne!(centre(&s), red, "the fill is off");
+    // A radial gradient: the Fill becomes a Gradient Fill (switched on) that keeps its opacity.
+    s.execute("shape.fillStroke", json!({"fillType": "solid", "fill": "#ff0000"})).unwrap();
+    assert_eq!(centre(&s), red);
+    let opacity = |s: &Session, m: &str| {
+        let l = s.active_comp().unwrap().layer(effectcraft_project::LayerId(sh)).unwrap();
+        l.props.group(&format!("contents/group/contents/{m}")).unwrap().get("opacity").unwrap().value.as_f64()
+    };
+    s.execute("prop.set", json!({"layer": sh, "path": "contents/group/contents/fill/opacity", "value": 40})).unwrap();
+    s.execute("shape.fillStroke", json!({"fillType": "radial"})).unwrap();
+    assert_eq!(items(&s), [("rect".into(), true), ("gfill".into(), true)]);
+    assert_eq!((kinds(&mut s).0.as_str(), opacity(&s, "gfill")), ("radial", 40.0));
+    s.execute("shape.fillStroke", json!({"fillType": "linear"})).unwrap();
+    assert_eq!(kinds(&mut s).0, "linear");
+    s.execute("shape.fillStroke", json!({"fillType": "solid", "fill": "#00ff00"})).unwrap();
+    assert_eq!(items(&s), [("rect".into(), true), ("fill".into(), true)]);
+    assert_eq!(opacity(&s, "fill"), 40.0);
+    // A Stroke kind adds a stroke (before the fill); None switches it off again; undo is per step.
+    s.execute("shape.fillStroke", json!({"strokeType": "linear"})).unwrap();
+    assert_eq!(items(&s), [("rect".into(), true), ("gstroke".into(), true), ("fill".into(), true)]);
+    s.execute("shape.fillStroke", json!({"strokeType": "none"})).unwrap();
+    assert_eq!(kinds(&mut s), ("solid".into(), "none".into()));
+    s.execute("edit.undo", json!({})).unwrap();
+    assert_eq!(kinds(&mut s), ("solid".into(), "linear".into()));
+    assert!(s.execute("shape.fillStroke", json!({"fillType": "plaid"})).is_err());
+}
+
+/// Selecting a mask in the Timeline (its row or its Mask Path) selects all of its points, so the
+/// viewer drags the whole mask (#203); a shape's Path item works the same way.
+#[test]
+fn selecting_a_mask_selects_its_points() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"width": 400, "height": 300, "duration": 2})).unwrap();
+    let l = s.execute("layer.newSolid", json!({"color": "#808080"})).unwrap()["layer"].as_u64().unwrap();
+    let m1 = s.execute("layer.addMask", json!({"layer": l, "shape": "rect"})).unwrap()["mask"].as_u64().unwrap();
+    let m2 = s.execute("layer.addMask", json!({"layer": l, "shape": "ellipse"})).unwrap()["mask"].as_u64().unwrap();
+    let points = |s: &Session, m: u64| s.state.selected_vertices.iter().filter(|v| v.mask == m).count();
+    s.execute("prop.select", json!({"layer": l, "prop": m1, "selectKeys": false})).unwrap();
+    assert_eq!((points(&s, m1), s.state.selected_vertices.len()), (4, 4));
+    // Mask Path selects them too; Shift-adding another mask keeps the first.
+    let path = s.active_comp().unwrap().layer(effectcraft_project::LayerId(l)).unwrap().props.find_group(m2).unwrap().get("path").unwrap().uid;
+    s.execute("prop.select", json!({"layer": l, "prop": path, "add": true})).unwrap();
+    assert_eq!((points(&s, m1), points(&s, m2)), (4, 4));
+    // Another mask replaces them; another property deselects them.
+    s.execute("prop.select", json!({"layer": l, "prop": m2})).unwrap();
+    assert_eq!((points(&s, m1), points(&s, m2)), (0, 4));
+    // Delete removes the selected mask (not only its points).
+    s.execute("edit.clear", json!({})).unwrap();
+    let masks = |s: &Session| s.active_comp().unwrap().layer(effectcraft_project::LayerId(l)).unwrap().masks().unwrap().children.len();
+    assert_eq!(masks(&s), 1);
+    s.execute("prop.select", json!({"layer": l, "path": "transform/opacity"})).unwrap();
+    assert!(s.state.selected_vertices.is_empty());
+    let sh = s.execute("layer.newShape", json!({"kind": "star"})).unwrap()["layer"].as_u64().unwrap();
+    let star = s.execute("layer.addShapeItem", json!({"layer": sh, "kind": "path"})).unwrap()["uid"].as_u64().unwrap();
+    s.execute("prop.select", json!({"layer": sh, "prop": star})).unwrap();
+    assert_eq!(s.state.selected_vertices.len(), 0, "an empty Path has no points");
+}
+
+#[test]
+fn save_and_open_roundtrip() {
+    let mut s = demo();
+    let dir = std::env::temp_dir().join(format!("ec-test-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("demo.ecproj").to_string_lossy().to_string();
+    s.execute("file.saveAs", json!({"path": path})).unwrap();
+    let before = s.project.clone();
+    let mut s2 = Session::default();
+    s2.execute("file.open", json!({"path": path})).unwrap();
+    assert_eq!(*before, *s2.project);
+    let _ = std::fs::remove_dir_all(dir);
+}
+
+#[test]
+fn help_links_emit_urls() {
+    let mut s = Session::default();
+    let r = s.execute("help.discord", json!({})).unwrap();
+    assert_eq!(r["url"], "https://discord.gg/artcraft");
+    assert!(s.drain_events().iter().any(|e| matches!(e, crate::Event::OpenUrl(u) if u.contains("discord"))));
+    assert_eq!(s.execute("help.github", json!({})).unwrap()["url"], "https://github.com/storytold/effectcraft");
+}
+
+#[test]
+fn time_navigation() {
+    let mut s = demo();
+    s.execute("time.start", json!({})).unwrap();
+    let r = s.execute("time.nextKey", json!({})).unwrap();
+    assert!(r["time"].as_f64().unwrap() > 0.0);
+    s.execute("time.set", json!({"frame": 45})).unwrap();
+    assert_eq!(s.execute("time.step", json!({"frames": 5})).unwrap()["frame"], 50);
+}
+
+#[test]
+fn time_navigation_per_property() {
+    let mut s = demo();
+    // An animated property and the comp times of its keys.
+    let comp = s.active_comp().unwrap().clone();
+    let mut found = None;
+    for l in &comp.layers {
+        l.props.walk("", &mut |_, pr| {
+            if found.is_none() && pr.keys.len() >= 2 {
+                found = Some((pr.uid, pr.keys.iter().map(|k| l.comp_time(k.time)).collect::<Vec<_>>()));
+            }
+        });
+    }
+    let (uid, times) = found.expect("demo has an animated property");
+    s.set_time(effectcraft_time::Tick::ZERO);
+    let half = comp.frame_duration().0 / 2;
+    let expect = times.iter().copied().filter(|t| t.0 > half).min().unwrap();
+    s.execute("time.go", json!({"to": "nextKey", "prop": uid})).unwrap();
+    let snap = |t| comp.frame_rate.snap(t);
+    assert_eq!(s.time(), snap(expect));
+    // Going back from past the last key lands on the last key.
+    s.set_time(comp.duration);
+    s.execute("time.go", json!({"to": "prevKey", "prop": uid})).unwrap();
+    assert_eq!(s.time(), snap(*times.iter().max().unwrap()));
+}
+
+#[test]
+fn set_text_paragraph_fill_and_leading() {
+    use effectcraft_keyframe::{Justify, Value as KValue};
+    let mut s = demo();
+    let t = s.execute("layer.newText", json!({"text": "Hi"})).unwrap()["layer"].as_u64().unwrap();
+    let doc = |s: &Session| {
+        let l = s.active_comp().unwrap().layer(crate::project::LayerId(t)).unwrap().clone();
+        match &l.props.prop("text/sourceText").unwrap().value {
+            KValue::Text(d) => (**d).clone(),
+            v => panic!("{v:?}"),
+        }
+    };
+    for (key, j) in [
+        ("justifyLeft", Justify::JustifyLastLeft),
+        ("justifyCenter", Justify::JustifyLastCenter),
+        ("justifyRight", Justify::JustifyLastRight),
+        ("justifyAll", Justify::JustifyAll),
+        ("center", Justify::Center),
+    ] {
+        s.execute("layer.setText", json!({"layer": t, "justify": key})).unwrap();
+        assert_eq!(doc(&s).justify, j, "{key}");
+    }
+    s.execute("layer.setText", json!({"layer": t, "leading": 50, "applyFill": false, "applyStroke": true})).unwrap();
+    let d = doc(&s);
+    assert_eq!((d.leading, d.apply_fill, d.apply_stroke), (Some(50.0), false, true));
+    s.execute("layer.setText", json!({"layer": t, "leading": "auto"})).unwrap();
+    assert_eq!(doc(&s).leading, None);
+    s.execute("layer.setText", json!({"layer": t, "hScale": 120, "vScale": 80, "baselineShift": 4, "smallCaps": true, "strokeOverFill": true})).unwrap();
+    let d = doc(&s);
+    assert_eq!((d.h_scale, d.v_scale, d.baseline_shift, d.small_caps, d.stroke_over_fill), (120.0, 80.0, 4.0, true, true));
+}
+
+#[test]
+fn property_groups_report_actionable_errors() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "T"})).unwrap();
+    let l = s.execute("layer.newText", json!({"text": "Hi"})).unwrap()["layer"].as_u64().unwrap();
+    let uid = s.active_comp().unwrap().layer(crate::project::LayerId(l)).unwrap().props.group("text/pathOptions").unwrap().uid;
+    for selector in [json!({"path": "text"}), json!({"path": "text/pathOptions"}), json!({"path": format!("@{uid}")}), json!({"prop": uid})] {
+        let mut params = selector;
+        params["layer"] = json!(l);
+        for cmd in ["prop.get", "prop.set"] {
+            let err = s.execute(cmd, params.clone()).unwrap_err().to_string();
+            assert!(err.contains("is a property group"), "{cmd}: {err}");
+            assert!(err.contains("get_layer"), "{cmd}: {err}");
+        }
+    }
+    assert!(s.execute("prop.get", json!({"layer": l, "path": "text/sourceText"})).is_ok());
+    let err = s.execute("prop.get", json!({"layer": l, "path": "missing"})).unwrap_err().to_string();
+    assert!(err.contains("no property `missing`"), "{err}");
+}
+
+#[test]
+fn prop_get_and_render_rgba8() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "T", "width": 320, "height": 180, "duration": 2.0, "frameRate": 30})).unwrap();
+    let l = s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
+    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 0.0, "value": [0, 0]})).unwrap();
+    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 1.0, "value": [100, 50]})).unwrap();
+    let v = s.execute("prop.get", json!({"layer": l, "path": "transform/position", "time": 1.0})).unwrap();
+    assert_eq!(v["animated"], true);
+    assert_eq!(v["keys"].as_array().unwrap().len(), 2);
+    assert_eq!(v["value"][0].as_f64().unwrap(), 100.0);
+    let cid = s.resolve_comp(Some(&json!("T"))).unwrap();
+    let (w, h, rgba) = s.render_rgba8(cid, effectcraft_time::Tick::ZERO, 160).unwrap();
+    assert_eq!((w, h), (160, 90));
+    assert_eq!(rgba.len(), (w * h * 4) as usize);
+}
+
+#[test]
+fn params_docs_parse() {
+    use crate::commands::accepted_params;
+    let k = |d: &str| accepted_params(d).unwrap();
+    assert_eq!(k("{layers: [id|name|#n], add?, toggle?}"), ["layers", "add", "toggle"]);
+    assert_eq!(k("{time? (s) | frame? | timecode?}"), ["time", "frame", "timecode"]);
+    assert_eq!(k("{interpolation?|in?|out?: linear|bezier|hold, autoBezier?}"), ["interpolation", "in", "out", "autoBezier"]);
+    assert_eq!(k("{keys: [{layer, prop, time}], add?}"), ["keys", "add"]);
+    assert_eq!(k("{label: Red|Yellow|Aqua|…, layers?}"), ["label", "layers"]);
+    assert_eq!(k("{name?, background? [r,g,b]|#hex, open?}"), ["name", "background", "open"]);
+    assert!(k("{}").is_empty());
+    assert!(accepted_params("free text").is_none());
+    // Every registered command documents its params as a parseable key list.
+    for c in crate::command_specs() {
+        assert!(accepted_params(c.params).is_some(), "{}: {}", c.id, c.params);
+    }
+}
+
+#[test]
+fn execute_checked_rejects_unknown_params() {
+    let mut s = demo();
+    let e = s.execute_checked("layer.select", json!({"index": 2})).unwrap_err().to_string();
+    assert!(e.contains("`index`") && e.contains("layers, add, toggle"), "{e}");
+    s.execute_checked("layer.select", json!({"layers": ["#2"]})).unwrap();
+    assert_eq!(s.state.selected_layers.len(), 1);
+    // Aliases and always-accepted keys.
+    s.execute_checked("layer.select", json!({"layer": "#1", "comp": s.active_comp_id().unwrap().0})).unwrap();
+    s.execute_checked("time.set", json!({"frame": 3})).unwrap();
+    assert!(s.execute_checked("edit.undo", json!({"steps": 2})).is_err());
+    // Non-object params are not validated; the unchecked path stays lenient.
+    s.execute("layer.select", json!({"layers": ["#1"], "index": 2})).unwrap();
+}
+
+#[test]
+fn layer_tree_paths_resolve() {
+    let mut s = demo();
+    s.execute("effect.apply", json!({"layer": 1, "effect": "Gaussian Blur"})).unwrap();
+    let comp = s.execute("comp.info", json!({})).unwrap();
+    let mut checked = 0;
+    for l in comp["layers"].as_array().unwrap() {
+        let tree = s.execute("layer.tree", json!({"layer": l["id"]})).unwrap();
+        let mut stack = vec![tree["properties"].clone()];
+        while let Some(n) = stack.pop() {
+            if let Some(ch) = n["children"].as_array() {
+                stack.extend(ch.iter().cloned());
+                continue;
+            }
+            let path = n["path"].as_str().unwrap();
+            let got = s.execute("prop.get", json!({"layer": l["id"], "path": path})).unwrap();
+            assert_eq!(got["uid"], n["uid"], "path {path} on layer {}", l["name"]);
+            checked += 1;
+        }
+    }
+    assert!(checked > 20, "{checked}");
+}
+
+#[test]
+fn comp_settings_anchor_start_timecode_renderer() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "A", "width": 100, "height": 100, "duration": 2.0})).unwrap();
+    let l = s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap()["layer"].as_u64().unwrap();
+    s.execute("prop.addKey", json!({"layer": l, "path": "transform/position", "time": 0.0, "value": [10, 20]})).unwrap();
+    let pos = |s: &Session| {
+        let pr = s.active_comp().unwrap().layer(crate::project::LayerId(l)).unwrap().props.prop("transform/position").unwrap().clone();
+        pr.keys[0].value.components()
+    };
+    // Center anchor: grow by 100x50 → shift by half.
+    s.execute("comp.settings", json!({"width": 200, "height": 150})).unwrap();
+    assert_eq!(pos(&s)[..2], [60.0, 45.0]);
+    // Top-left anchor: no shift. Bottom-right: full shift.
+    s.execute("comp.settings", json!({"width": 300, "anchor": 0})).unwrap();
+    assert_eq!(pos(&s)[..2], [60.0, 45.0]);
+    s.execute("comp.settings", json!({"width": 200, "height": 100, "anchor": 8})).unwrap();
+    assert_eq!(pos(&s)[..2], [-40.0, -5.0]);
+    s.execute("comp.settings", json!({"startTimecode": "0:00:01:00", "renderer": "advanced3D"})).unwrap();
+    let c = s.active_comp().unwrap();
+    assert_eq!(c.display_start, c.frame_rate.tick_of(30));
+    assert_eq!(c.renderer, crate::project::Renderer::Advanced3D);
+}
+
+/// `advanced3D` is a value of `renderer`, not a key: comp.new / comp.settings don't advertise it
+/// in their schemas and reject it as unknown instead of ignoring it (#177).
+#[test]
+fn renderer_values_are_not_parameter_keys() {
+    let mut s = Session::default();
+    for (id, p) in [("comp.new", json!({"name": "A"})), ("comp.settings", json!({}))] {
+        let spec = crate::command_specs().iter().find(|c| c.id == id).unwrap();
+        let keys = crate::commands::accepted_params(spec.params).unwrap();
+        assert!(keys.contains(&"renderer".to_string()) && !keys.contains(&"advanced3D".to_string()), "{id}: {keys:?}");
+        let mut bad = p.clone();
+        bad["advanced3D"] = json!(true);
+        let e = s.execute_checked(id, bad).unwrap_err().to_string();
+        assert!(e.contains("unknown parameter(s) `advanced3D`"), "{id}: {e}");
+        let mut good = p;
+        good["renderer"] = json!("advanced3D");
+        s.execute_checked(id, good).unwrap();
+        assert_eq!(s.active_comp().unwrap().renderer, crate::project::Renderer::Advanced3D, "{id}");
+        s.execute("comp.renderer", json!({"renderer": "classic3d"})).unwrap();
+    }
+}
+
+#[test]
+fn comp_rejects_zero_and_negative_frame_rates() {
+    let mut s = Session::default();
+    for fps in [0.0, -30.0, 0.0001] {
+        assert!(s.execute("comp.new", json!({"frameRate": fps})).is_err(), "{fps}");
+    }
+    s.execute("comp.new", json!({"frameRate": 30, "duration": 1})).unwrap();
+    assert!(s.execute("comp.settings", json!({"frameRate": 0})).is_err());
+    assert_eq!(s.active_comp().unwrap().frame_rate, crate::time::FrameRate::FPS_30);
+}
+
+#[test]
+fn render_queue_add_accepts_documented_settings_when_checked() {
+    let mut s = demo();
+    let r = s.execute_checked(
+        "renderQueue.add",
+        json!({"format": "gif", "output": "/tmp/x.gif", "resolution": "quarter", "timeSpan": "custom", "start": 0.0, "end": 0.5, "quality": "draft", "loop": true}),
+    );
+    // Without an exporter the add itself still succeeds (rendering is what needs one).
+    assert!(r.is_ok(), "{r:?}");
+    assert!(s.execute_checked("renderQueue.add", json!({"bogus": 1})).is_err());
+}
+
+#[test]
+fn new_text_rejects_malformed_positions_without_creating_a_layer() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "C", "width": 64, "height": 64, "duration": 1})).unwrap();
+    for position in [json!([]), json!([10]), json!(["x", 20]), json!([null, 20])] {
+        let err = s.execute("layer.newText", json!({"text": "Hello", "position": position})).unwrap_err();
+        assert!(err.to_string().contains("position: [x, y]"), "{err}");
+        assert!(s.active_comp().unwrap().layers.is_empty());
+    }
+    s.execute("layer.newText", json!({"name": "Valid", "text": "Hello", "position": [10, 20]})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers[0].props.prop("transform/position").unwrap().value, effectcraft_keyframe::Value::Vec3([10.0, 20.0, 0.0]));
+    s.execute("layer.newText", json!({"text": "No explicit position"})).unwrap();
+    assert_eq!(s.active_comp().unwrap().layers.len(), 2);
+}
+
+/// The active comp and the open comp tabs are saved with the project and restored on open (#748).
+#[test]
+fn reopening_a_project_restores_its_active_comp() {
+    use effectcraft_project::ItemId;
+    let dir = std::env::temp_dir().join(format!("ec-test-748-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("view.ecproj").to_string_lossy().to_string();
+    let mut s = Session::default();
+    let a = s.execute("comp.new", json!({"name": "CompA"})).unwrap()["comp"].as_u64().unwrap();
+    let b = s.execute("comp.new", json!({"name": "CompB"})).unwrap()["comp"].as_u64().unwrap();
+    let c = s.execute("comp.new", json!({"name": "CompC"})).unwrap()["comp"].as_u64().unwrap();
+    s.execute("comp.open", json!({"comp": "CompB"})).unwrap();
+    s.state.open_comps.retain(|id| id.0 != c);
+    s.execute("file.saveAs", json!({"path": path})).unwrap();
+    let mut s2 = Session::default();
+    s2.execute("file.open", json!({"path": path})).unwrap();
+    assert_eq!(s2.state.active_comp, Some(ItemId(b)));
+    assert_eq!(s2.state.open_comps, vec![ItemId(a), ItemId(b)]);
+    assert!(!s2.is_dirty());
+
+    // A file from before the view was saved opens on its first comp, as it always did.
+    let text = std::fs::read_to_string(&path).unwrap();
+    let mut old: serde_json::Value = serde_json::from_str(&text).unwrap();
+    let obj = old.as_object_mut().unwrap();
+    obj.remove("activeComp");
+    obj.remove("openComps");
+    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
+    let mut s3 = Session::default();
+    s3.execute("file.open", json!({"path": path})).unwrap();
+    assert_eq!((s3.state.active_comp, s3.state.open_comps.clone()), (Some(ItemId(a)), vec![ItemId(a)]));
+
+    // Ids that no longer name a comp (edited by hand, or written by another tool) fall back.
+    obj_set(&mut old, json!(999), json!([999, b, "x"]));
+    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
+    let mut s4 = Session::default();
+    s4.execute("file.open", json!({"path": path})).unwrap();
+    assert_eq!((s4.state.active_comp, s4.state.open_comps.clone()), (Some(ItemId(b)), vec![ItemId(b)]));
+    obj_set(&mut old, json!(999), json!([]));
+    std::fs::write(&path, serde_json::to_string_pretty(&old).unwrap()).unwrap();
+    let mut s5 = Session::default();
+    s5.execute("file.open", json!({"path": path})).unwrap();
+    assert_eq!((s5.state.active_comp, s5.state.open_comps.clone()), (Some(ItemId(a)), vec![ItemId(a)]));
+
+    // XML copies carry it too.
+    let xml = dir.join("view.ecprojx").to_string_lossy().to_string();
+    s.execute("file.saveAs", json!({"path": xml})).unwrap();
+    let mut s6 = Session::default();
+    s6.execute("file.open", json!({"path": xml})).unwrap();
+    assert_eq!(s6.state.active_comp, Some(ItemId(b)));
+    let _ = std::fs::remove_dir_all(dir);
+
+    fn obj_set(v: &mut serde_json::Value, active: serde_json::Value, open: serde_json::Value) {
+        let o = v.as_object_mut().unwrap();
+        o.insert("activeComp".into(), active);
+        o.insert("openComps".into(), open);
+    }
+}
+
+/// Layer times are saved as exact ticks and read back unchanged, and each comp reopens at the
+/// current time it was saved at, not at 0, where a layer starting later shows nothing (#1714).
+#[test]
+fn reopening_a_project_restores_layer_times_and_current_time() {
+    use effectcraft_project::ItemId;
+    use effectcraft_time::{FrameRate, Tick};
+    let dir = std::env::temp_dir().join(format!("ec-test-1714-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("times.ecproj").to_string_lossy().to_string();
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "C", "width": 108, "height": 192, "duration": 60})).unwrap();
+    s.execute("layer.newSolid", json!({"name": "crown"})).unwrap();
+    let cid = s.active_comp_id().unwrap();
+    let comp = std::sync::Arc::make_mut(&mut s.project).comp_mut(cid).unwrap();
+    comp.frame_rate = FrameRate::FPS_59_94;
+    // The layer from the issue: 34f, 315f and 3033f at 59.94 fps.
+    let l = comp.layers.first_mut().unwrap();
+    (l.start_time, l.in_point, l.out_point) = (Tick(144_086_342_400), Tick(1_334_917_584_000), Tick(12_853_349_308_800));
+    s.execute("time.set", json!({"time": 6.0})).unwrap();
+    let t = s.time();
+    // A second comp keeps its own time.
+    let b = ItemId(s.execute("comp.new", json!({"name": "B"})).unwrap()["comp"].as_u64().unwrap());
+    s.execute("time.set", json!({"time": 2.0})).unwrap();
+    let tb = s.time();
+    s.execute("comp.open", json!({"comp": "C"})).unwrap();
+    s.execute("file.saveAs", json!({"path": path})).unwrap();
+
+    let mut s2 = Session::default();
+    s2.execute("file.open", json!({"path": path})).unwrap();
+    let l = s2.project.comp(cid).unwrap().layers.first().unwrap();
+    assert_eq!((l.start_time, l.in_point, l.out_point), (Tick(144_086_342_400), Tick(1_334_917_584_000), Tick(12_853_349_308_800)));
+    assert_eq!((s2.time(), s2.state.times.get(&b).copied()), (t, Some(tb)));
+    assert!(l.in_point <= s2.time() && s2.time() < l.out_point, "the layer shows at the reopened time");
+    assert!(!s2.is_dirty());
+
+    // Hand-edited times past the end or before the start land on the last or first frame.
+    let mut file: serde_json::Value = serde_json::from_str(&std::fs::read_to_string(&path).unwrap()).unwrap();
+    file["compTimes"] = json!({cid.0.to_string(): i64::MAX, b.0.to_string(): -5});
+    std::fs::write(&path, file.to_string()).unwrap();
+    let mut s3 = Session::default();
+    s3.execute("file.open", json!({"path": path})).unwrap();
+    let c = s3.project.comp(cid).unwrap();
+    assert_eq!(s3.time(), c.frame_rate.snap_nearest(c.duration - c.frame_duration()));
+    assert_eq!(s3.time(), c.frame_rate.snap_nearest(c.duration - c.frame_duration()));
+    assert_eq!(s3.state.times.get(&b).copied(), Some(Tick::ZERO));
+}
diff --git a/crates/engine/src/tests_settings.rs b/crates/engine/src/tests/settings.rs
similarity index 99%
rename from crates/engine/src/tests_settings.rs
rename to crates/engine/src/tests/settings.rs
index c35d4f3a4..620bc3eeb 100644
--- a/crates/engine/src/tests_settings.rs
+++ b/crates/engine/src/tests/settings.rs
@@ -181,7 +181,7 @@ fn every_schema_key_exists_and_docs_list_the_todo_settings() {
             assert!(ids.contains(&page), "{path:?} opens unknown page {page}");
         }
     }
-    let docs = include_str!("../../../docs/preferences.md");
+    let docs = include_str!("../../../../docs/preferences.md");
     for k in crate::prefs::todo_keys() {
         assert!(docs.contains(&format!("`{k}`")), "docs/preferences.md must list the not-yet-wired setting `{k}`");
     }
diff --git a/crates/engine/src/tests_shortcut_cmds.rs b/crates/engine/src/tests/shortcut_cmds.rs
similarity index 100%
rename from crates/engine/src/tests_shortcut_cmds.rs
rename to crates/engine/src/tests/shortcut_cmds.rs
diff --git a/crates/engine/src/tests_stubs.rs b/crates/engine/src/tests/stubs.rs
similarity index 100%
rename from crates/engine/src/tests_stubs.rs
rename to crates/engine/src/tests/stubs.rs
diff --git a/crates/engine/src/tests_styles.rs b/crates/engine/src/tests/styles.rs
similarity index 100%
rename from crates/engine/src/tests_styles.rs
rename to crates/engine/src/tests/styles.rs
diff --git a/crates/engine/src/tests_tail.rs b/crates/engine/src/tests/tail.rs
similarity index 100%
rename from crates/engine/src/tests_tail.rs
rename to crates/engine/src/tests/tail.rs
diff --git a/crates/engine/src/tests_text.rs b/crates/engine/src/tests/text.rs
similarity index 99%
rename from crates/engine/src/tests_text.rs
rename to crates/engine/src/tests/text.rs
index 84f88fd33..3980c7bb5 100644
--- a/crates/engine/src/tests_text.rs
+++ b/crates/engine/src/tests/text.rs
@@ -198,7 +198,7 @@ fn cached_text_presets_keep_the_catalog_and_application_independent() {
 #[ignore = "warm text-preset listing benchmark"]
 fn text_preset_listing_benchmark() {
     let old = || {
-        let v: serde_json::Value = serde_json::from_str(include_str!("../presets/text_animators.json")).unwrap();
+        let v: serde_json::Value = serde_json::from_str(include_str!("../../presets/text_animators.json")).unwrap();
         let presets = v["presets"].as_array().unwrap().clone();
         presets.iter().map(|p| (p["id"].as_str().unwrap().to_string(), p["name"].as_str().unwrap().to_string())).collect::<Vec<_>>()
     };
diff --git a/crates/engine/src/tests_text_edit.rs b/crates/engine/src/tests/text_edit.rs
similarity index 100%
rename from crates/engine/src/tests_text_edit.rs
rename to crates/engine/src/tests/text_edit.rs
diff --git a/crates/engine/src/tests_3d.rs b/crates/engine/src/tests/three_d.rs
similarity index 100%
rename from crates/engine/src/tests_3d.rs
rename to crates/engine/src/tests/three_d.rs
diff --git a/crates/engine/src/tests_timeline.rs b/crates/engine/src/tests/timeline.rs
similarity index 100%
rename from crates/engine/src/tests_timeline.rs
rename to crates/engine/src/tests/timeline.rs
diff --git a/crates/engine/src/tests_timeline_interchange.rs b/crates/engine/src/tests/timeline_interchange.rs
similarity index 100%
rename from crates/engine/src/tests_timeline_interchange.rs
rename to crates/engine/src/tests/timeline_interchange.rs
diff --git a/crates/engine/src/tests_track.rs b/crates/engine/src/tests/track.rs
similarity index 100%
rename from crates/engine/src/tests_track.rs
rename to crates/engine/src/tests/track.rs
diff --git a/crates/engine/src/tests_vector_import.rs b/crates/engine/src/tests/vector_import.rs
similarity index 100%
rename from crates/engine/src/tests_vector_import.rs
rename to crates/engine/src/tests/vector_import.rs
diff --git a/crates/engine/src/tests_viewer.rs b/crates/engine/src/tests/viewer.rs
similarity index 100%
rename from crates/engine/src/tests_viewer.rs
rename to crates/engine/src/tests/viewer.rs