Add/remove/solo tracks

CHANGELOG.md

@@ -8,8 +8,25 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- Per-clip **stereo pan** (`props.pan`, −1…+1) on video/audio clips — inspector
+  slider + keyframes; preview, audio-hold, and Fast export all honor it. Linked
+  stems default to L `−1` / R `+1` / center for other channels; projects saved
+  before pan migrate once via `panSchema` (so omitting `pan: 0` later does not
+  re-hard-pan a centered stem). Compact MCP keeps `pan` on linked stems.
+- Stereo **master meter** (L/R) on the monitor — post-pan program sum in the
+  same RMS / LUFS / Peak modes as the per-track bars; A-tracks + video spill
+  route through one summed path when the meter worklet is active. Per-track
+  bars collapse via **◂** / **▸** beside the master strip (master L/R stay visible).
 - Preview playback speed — a monitor toolbar toggle plus **J**/**K**/**L** shortcuts cycle the preview player through 1×, 1.5×, 2×, and 4× (L faster, J slower, K play/pause and reset to 1×). It rides on top of each clip's own speed and is forced back to 1× during export, so renders always come out at real time.
 
+### Fixed
+- Audio graph teardown on project reload — clip chains
+  (`MediaElementSource → splitter → gain → panner → bus`) are now fully
+  disconnected via `releaseClipEl` instead of only clearing the maps (which
+  left nodes wired to live track buses). Panner attach degrades gracefully if
+  `StereoPannerNode` is unavailable; inspector volume/pan changes refresh
+  audio-hold voices.
+
 ## [1.6.0] - 2026-07-14
 
 ### Added

CLAUDE.md

@@ -157,6 +157,7 @@ Examples in `library/svg/`: `sparkles.svg` (loop), `lower-third.svg`,
   "width": 1280, "height": 720, "fps": 30,   // canvas/export settings
   "background": "#000000",                    // canvas color behind all clips (optional)
   "revision": 7,                              // bump on every write!
+  "panSchema": 1,                             // 1 = pan-aware; omit only on pre-pan projects (UI migrates once)
   "markers": [ { "t": 2.5 }, { "t": 5.0, "label": "drop" } ],
   // ^ beat/cue markers: gold diamonds on the ruler, snap targets for clip edges.
   "inPoint": 10.023, // in timeline marker; paired with outPoint sets the focus on the part of the timeline
@@ -166,7 +167,16 @@ Examples in `library/svg/`: `sparkles.svg` (loop), `lower-third.svg`,
     { "id": "f_broll", "name": "B-roll", "parentId": null, "open": true }
   ],
   "disabledTracks": [ "A2" ],
-  // ^ optional — track ids (V4 V3 V2 V1 A1 A2 A3) omitted from preview/export when listed
+  // ^ optional — track ids (e.g. V4 V3 V2 V1 A1 A2 A3) omitted from preview/export when listed
+  "tracks": [                          // optional — timeline lanes (default V3…V1 + A1…A4)
+    { "id": "V3", "kind": "video" },   // video: higher number drawn on top (V1 under V2 under V3…)
+    { "id": "V2", "kind": "video" },
+    { "id": "V1", "kind": "video" },
+    { "id": "A1", "kind": "audio" },   // audio: A1…An top→bottom; +V/+A in the UI appends Vn+1 / An+1
+    { "id": "A2", "kind": "audio" },
+    { "id": "A3", "kind": "audio" },
+    { "id": "A4", "kind": "audio" }
+  ],
   "media": [
     { "id": "m_abc", "name": "intro.mp4", "kind": "video",  // video|audio|image|svg
       "src": "/media/intro.mp4",             // path under ./media or ./library
@@ -178,12 +188,12 @@ Examples in `library/svg/`: `sparkles.svg` (loop), `lower-third.svg`,
       "id": "c_xyz",             // unique string
       "mediaId": "m_abc",        // null for kind:"text" and kind:"adjust"
       "kind": "video",           // video | audio | image | svg | text | adjust
-      "track": "V1",             // V3 V2 V1 (top→bottom video) | A1 A2 A3 A4 (audio)
+      "track": "V1",             // Vn…V1 (video) | A1…An (audio); extras via UI +V/+A or tracks[]
       "start": 0,                // timeline position, seconds
       "in": 2.5,                 // offset into source media, seconds (0 for image/svg/text)
       "duration": 5,             // clip length on timeline, seconds
       "name": "intro",
-      "linkGroup": "lg_abc",     // OPTIONAL — AV link: video + its L/R audio companions share one id
+      "linkGroup": "lg_abc",     // OPTIONAL — AV link: video + per-channel audio stems share one id
       "props": { /* all optional — see the props reference below */ },
       // OPTIONAL — keyframe animation. Times are seconds RELATIVE TO CLIP START.
       // "ease" sits on the DESTINATION keyframe of each segment:
@@ -250,6 +260,7 @@ Examples in `library/svg/`: `sparkles.svg` (loop), `lower-third.svg`,
 | prop | default | notes |
 |---|---|---|
 | `volume` | 1 | 0–2 |
+| `pan` | 0 | −1 (full left) … 0 (center) … +1 (full right). Linked stems default L `−1` / R `+1` / other `0`. Projects saved before pan migrate once on load (`panSchema`); keep `panSchema: 1` (and explicit `pan` on stems) when rewriting the document so a centered stem is not re-hard-panned. |
 | `speed` | 1 | 0.25–4× playback rate. **Keyframable → speed ramps**: with `keyframes.speed` the engine time-remaps (media time = `in` + ∫speed dt), in preview and in the export audio mix. Static case: source window consumed = `duration × speed`, so `in + duration×speed ≤ media.duration`. |
 
 **Text clips only:**
@@ -315,7 +326,7 @@ footage. Example: 0.3 s impact shake over everything =
 `{kind:"adjust", track:"V3", duration:0.3, props:{shake:18}}`.
 
 **Animatable props** (usable in `keyframes`): x, y, scale, rotation, opacity,
-volume, speed, brightness, contrast, saturation, hue, blur, grayscale, sepia,
+volume, pan, speed, brightness, contrast, saturation, hue, blur, grayscale, sepia,
 invert, temperature, tint, vignette, cornerRadius, shake, rgbSplit, grain,
 fontSize, letterSpacing, glow.
 
@@ -325,14 +336,19 @@ glitch (RGB split + jitter) · pop (overshoot scale — stickers/captions).
 
 ### Semantics
 
-- Rendering order: V1 is drawn first, then V2, V3 on top. SVG/image/text clips
-  go on any V track (V2/V3 are handy overlay lanes).
-- **Audio tracks A1–A4** hold both standalone audio files *and* linked companions
+- Rendering order: V1 is drawn first, then V2, V3, … on top. SVG/image/text clips
+  go on any V track (higher V lanes are handy overlay lanes). Add lanes with the
+  timeline **+V** / **+A** buttons (or by listing them in `tracks`); up to 16 per kind.
+  Right-click an empty track header → **Remove track** (disabled if the lane has
+  clips or is the last video/audio track).
+- **Audio tracks A1–An** hold both standalone audio files *and* linked companions
   for imported video. Dropping a video creates the picture on a V track
-  (`props.volume: 0` so it isn't doubled) plus stereo L/R `kind:"audio"` clips
-  on A1/A2 that share a `linkGroup` (and the same `mediaId` / timing). Standalone
-  music/SFX also live on A1–A4. Linked partners move/trim/split together — edit
-  timing on any member of the group; do not treat A-tracks as music-only.
+  (`props.volume: 0` so it isn't doubled) plus one `kind:"audio"` clip per source
+  channel on consecutive A-tracks that share a `linkGroup` (and the same
+  `mediaId` / timing). Each stem is mono-isolated then placed with `pan` (defaults
+  preserve stereo: L `−1`, R `+1`). Standalone music/SFX also live on A-tracks. Linked partners
+  move/trim/split together — edit timing on any member of the group; do not treat
+  A-tracks as music-only.
 - Media is `fit`-ted to the canvas (default "contain"), then crop → scale/x/y/
   rotation → flips apply.
 - `props` keys are all optional — missing keys get the defaults above.
@@ -425,6 +441,8 @@ of previous durations.
 
 **Music bed**: audio file on A1, `props.volume: 0.3`, trim with `in`/`duration`.
 
+**Center a mono stem**: linked or standalone audio clip with `props.pan: 0` (inspector **Pan** slider, −1…+1). Stereo video stems default to L `−1` / R `+1`; set A1 to `0` to center that channel in the mix.
+
 **Cinematic grade**: `props.filterPreset: "teal-orange"` (tweak with
 `temperature`/`vignette` on top).
 

README.md

@@ -37,11 +37,22 @@ same time.
 
 **Editing**
 
-- 3 video tracks + 4 audio tracks, drag/trim/split/snap, undo/redo
+- Video + audio tracks (default 3+4; add more with **+V** / **+A** in the track
+  header; right-click an empty header → **Remove track**), drag/trim/split/snap,
+  undo/redo
 - **Settings** (cog in the top bar) — optional prefs stored in this browser via
   `localStorage`. Enable **Link timeline and Project bin selection** so picking a
   timeline clip highlights its media in Project, and clicking a Project item
   selects every timeline clip that uses it (off by default).
+- Video + audio tracks (default 3+4), drag/trim/split/snap, undo/redo
+  - **+V** / **+A** in the track header add a video or audio lane (up to 16 each)
+  - Right-click an empty track header → **Remove track** (disabled if the lane
+    has clips, or if it would leave you with zero video/audio tracks)
+  - Track header **S** solos that lane (mutes all others); click again to restore
+    the previous mute state. Using the mute toggle while soloed exits solo.
+  - Dropping a video with more audio channels than A-tracks **adds the missing
+    lanes automatically** (up to 16) and toasts how many were added; each channel
+    becomes a linked stem on its own A-track
 - **Direct manipulation on the monitor** — click a clip or title on the preview to
   move, resize (corner handles), or rotate (top handle, Shift-snap) it directly
 - **Timeline multi-select** — rubber-band marquee (drag on empty track area),