diff --git a/PLAN.md b/PLAN.md
index a105c98..c785b3f 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -69,8 +69,8 @@ everyone follows the new version.
       "id": "e1",                          // unique, stable
       "kind": "character",                 // character|prop|backdrop|camera|light
       "label": "lady",
-      "source": { "type": "assets",        // assets|upload (upload = client-side only, warn on save)
-                  "path": "characters/pack01/lady.glb" },
+      "source": { "type": "assets",        // assets|upload|none (upload = client-side only, warn on
+                  "path": "characters/pack01/lady.glb" },  //   save; none = needs no bytes: camera/light)
       "params": {},                        // kind-specific, see below
       "transform": { "pos": [0,0,0], "rot": [0,0,0], "scale": 1 },  // rest pose (used when no keys)
       "tracks": {
diff --git a/lanes/A-stage.md b/lanes/A-stage.md
index c99989b..ab27a5f 100644
--- a/lanes/A-stage.md
+++ b/lanes/A-stage.md
@@ -137,3 +137,24 @@ M3-polish list (order):
    whether it's the asset or a loader/material issue (compare in rigroom).
 3. Keep `renderActiveCamera`/`pause`/`resume` stable — the finalRender
    client drives them now (SYNC 3).
+
+### 2026-07-18 — session 3 ACCEPTED (PiP + spec-gloss both verified live).
+**One SYNC 4 regression found & hotfixed by orchestrator, then M4-A unlocked.**
+1. **applyState dropped cameras/lights** on scene load: they carry
+   `source:{type:'upload'}` and applyState skips all upload entities, so a
+   loaded scene silently lost its whole directing rig (verified: 3 of 6
+   entities landed; PiP dead). Hotfix in your stage.js (kind !== camera/light
+   never skipped) — absorb it, then do the clean fix: schema now has
+   `source:{type:'none'}` (PLAN §4.1) — emit it for camera/light in
+   `addEntity` defaults + `captureState`, treat 'none' as always-rebuild in
+   applyState. Keep tolerating legacy 'upload' cams (saved scenes exist).
+2. Your spec-gloss shim + PiP cap verified: lady 26/26 textured on stage and
+   in-render; PiP 178×99 capped 16:9, shows on cut. Nice diagnosis on the
+   CSS aspect-ratio trap and the CC-export extension.
+3. **M4-A — the viseme lane** (last A item in PLAN §5): on character load,
+   detect morph-target dictionaries (`mesh.morphTargetDictionary`); expose
+   `stage.visemeTargets(id)` → canonical viseme names found (A/E/I/O/U/MBP…
+   match loosely, e.g. CC/ARKit names). Inspector shows a 🗣 badge when
+   present, greyed otherwise. Add `stage.setMorph(id, name, weight)` for the
+   timeline to drive. Rhubarb-JSON → keyframes lands on Lane B's side; your
+   deliverable is detection + the setMorph hook + the badge.
diff --git a/lanes/B-timeline.md b/lanes/B-timeline.md
index f9f979a..4cf765e 100644
--- a/lanes/B-timeline.md
+++ b/lanes/B-timeline.md
@@ -120,3 +120,20 @@ frame-exact. Session 3 items:
    `load()` fires onLoad). Add a `setDuration(x)` mutator that clamps
    existing keys' visibility and notifies the UI; wire the dur field to it.
 3. Your listed polish: snapping increment config, keyable-param add UI.
+
+### 2026-07-18 — session 3 ACCEPTED. **M4-B unlocked: audio on the timeline.**
+Good catch fixing the stub's removeEntity-onChange payload — that's the
+honest-stub lesson applied. All three items verified (setDuration bar
+refresh + snap select seen live; tests green). M4-B scope (PLAN §5):
+1. Audio rows in tlui from `scene.audio[]`: one lane per clip, draggable
+   offset (`start`), gain in the inspector-side of the row, add via a 🎵
+   button reading `/assets/tree` audio category; delete.
+2. Web Audio playback synced to the master clock: on `play()` schedule
+   `AudioBufferSourceNode`s at `start - time` offsets; on `seek/pause` stop
+   + reschedule. `step()` NEVER touches audio (deterministic render path —
+   the server muxes from scene.audio, already working end-to-end).
+3. Viseme keyframes (pairs with Lane A's M4-A): a `morphs` track kind —
+   `{t, key: visemeName, value: weight}` evaluated via
+   `stage.setMorph(id, name, weight)` with lerp between keys; plus
+   `importRhubarb(id, rhubarbJson, t0)` mapping mouthShape cues → morph keys.
+   Guard: only offer when `stage.visemeTargets(id).length > 0`.
diff --git a/lanes/C-server.md b/lanes/C-server.md
index 0779c51..5234bbd 100644
--- a/lanes/C-server.md
+++ b/lanes/C-server.md
@@ -124,3 +124,14 @@ verified — no changes needed. Proceed with M4 in this order:
 One render-quality note for your backlog, not urgent: draft webm via
 MediaRecorder is untested in the embedded preview (rAF suspension) — verify
 it once in a real Chrome window before calling it done.
+
+### 2026-07-18 — M4 ACCEPTED. Lane C scope (M1–M4) is COMPLETE.
+Orchestrator verified in the integrated app: audio-muxed finalRender →
+h264+aac mp4, both streams exactly 8.000s; graft_limb `--selftest` green
+under Blender 5.0.1 (both refusal + graft paths); 8 server test groups pass.
+Your blender-path correction noted (it's `/Applications/Blender.app/...`,
+not on PATH — my error). Standing by is fine; remaining work is A/B UI
+(viseme lane, audio rows). One item if you want it: add a `rhubarb` check +
+`/rhubarb?path=` endpoint (subprocess → JSON) IF rhubarb is installed —
+503-with-message otherwise, same pattern as ffmpeg. Log a REQUEST first if
+it needs more than that.
diff --git a/scenegod/web/stage.js b/scenegod/web/stage.js
index 8fc2205..dfb9980 100644
--- a/scenegod/web/stage.js
+++ b/scenegod/web/stage.js
@@ -377,7 +377,10 @@ export class Stage {
   async applyState(sceneJson){
     for(const en of this.entities()) this.removeEntity(en.id);
     for(const d of (sceneJson.entities || [])){
-      if(d.source && d.source.type === 'upload'){ console.warn('skipping upload entity (no bytes):', d.id); continue; }
+      // SYNC4: cameras/lights carry source:'upload' but need no bytes — never skip them,
+      // or scene loads silently lose the whole directing rig (cams + sun).
+      if(d.source && d.source.type === 'upload' && d.kind !== 'camera' && d.kind !== 'light'){
+        console.warn('skipping upload entity (no bytes):', d.id); continue; }
       try { await this.addEntity(d); } catch(err){ console.error('addEntity failed', d.id, err); }
     }
   }