diff --git a/plans/audio-review-fixes-handoff.md b/plans/audio-review-fixes-handoff.md
index 3b553cffce..0e30c3eae0 100644
--- a/plans/audio-review-fixes-handoff.md
+++ b/plans/audio-review-fixes-handoff.md
@@ -4,13 +4,14 @@ Written 2026-08-08 so a fresh session can continue without re-deriving anything.
 Everything here was verified in this worktree unless it says otherwise.
 
 **Worktree:** `~/src/wt/hyperframes/webaudio-fx`
-**Working branch:** `wa-19-review-fixes` — 21 commits, **local only, never pushed**
+**Working branch:** `wa-19-review-fixes` — 25 commits, **local only, never pushed**
 **Branched from:** `wa-18-lane-stretch` @ `4bcc7e188`
 
-> **Second session (2026-08-08 afternoon) added 10 commits.** All four of §4a is
-> done, plus six of §4b. See §3b. Baselines moved: studio **3662**, core
-> **1669**, engine **736** (src/services), producer **534** passing with 50
-> pre-existing collect failures (files importing `bun:test` under vitest).
+> **Second session (2026-08-08 afternoon) added 14 commits.** All four of §4a
+> is done, six of the eight in §4b, and 4 of the 9 in §4c. See §3b and the
+> per-section notes. Everything left carries a written reason for being left.
+> Baselines moved: studio **3662**, core **1672**, engine **736**
+> (src/services), producer **534** under vitest plus **203** under bun test.
 
 ---
 
@@ -19,7 +20,7 @@ Everything here was verified in this worktree unless it says otherwise.
 | Branch | State |
 | --- | --- |
 | `wa-18-lane-stretch` | **pushed**, matches remote. PR **#3058** open, ready for review, base `wa-17-lane-clipboard` |
-| `wa-19-review-fixes` | 21 commits, **local only**. The review fixes. |
+| `wa-19-review-fixes` | 25 commits, **local only**. The review fixes. |
 | `carve-reconcile-wip` | 1 commit (`7b57000a1`), **local only**. Working feature, but it breaks undo — see §5. |
 
 Every other `wa-*` branch is in sync with its remote. The handoff §6 warning about
@@ -30,7 +31,7 @@ plain fast-forward.
 
 ```
 packages/studio    3662 passing, 18 todo, 1 file skipped
-packages/core      1669 passing
+packages/core      1672 passing
 packages/engine     736 passing, 3 skipped (src/services)
 packages/producer   534 passing under vitest, 203 under bun test (see below)
 ```
@@ -211,15 +212,54 @@ match nothing); they are inert and out of scope here.
 
 ### 4c. Cleanup list
 
-- `audioFxRender.ts:43` duplicates `parseWavLayout`
-- `propertyPanelFxControls.tsx:51` re-implements FlatSlider/FlatToggle/FlatSelectRow, losing their throttle, pointer capture, Escape-revert and design telemetry
-- `PropertyPanelFlat.tsx:549` reads via hardcoded `"fx-chain"` literals while writing via constants
-- `audioMixer.ts:328` re-rolls curve sampling at 30/s vs the scheduler's 100/s while `sampleAutomationCurve` names it as a consumer
-- `build-audio-fx-runtime.ts` is a near-verbatim clone of `build-position-edits-render.ts`
-- `audioFxGraph.ts:279`/`:352` four hand-rolled wet/dry shells whose dispose lists have already drifted
-- `audioFxGraph.ts:448` enabled-node filter restated 3× while `enabledAudioFxNodes()` goes unused
-- `audioFxGraph.ts:494` dead `shapeOf` recomputation on every observer tick
-- `PropertyPanelFlat.tsx:624` a `doc!` non-null assertion plus an `as` cast laundering `undefined`; `audioAutomation.ts:122` a cast after the guard already narrowed — both against the repo's "avoid `any`/`as T`" rule and the standing no-`!` rule
+**Done — 4 of the 9 items, in 3 commits:**
+
+| Commit | What |
+| --- | --- |
+| `ac0e37247` | the `doc!` assertion and two `as` casts the guards already covered |
+| `ce7c9e486` | one enabled-node helper instead of three restatements; dead `shapeOf` recompute dropped |
+| `5a2247435` | dataset keys derived from their attributes instead of four loose literals |
+
+The `enabledAudioFxNodes` consolidation was not cosmetic: lining the three call
+sites up exposed that `buildFxChain`'s `update()` filter had **no test**, and
+the failure it protects against is silent — a bypassed node shifts every later
+node's parameters into its neighbour, and the shape is identical either way so
+nothing forces a rebuild that would show it. Now covered.
+
+**Not done, with reasons:**
+
+- `audioFxRender.ts:44 readWavChunks` vs `audioVolumeEnvelope.ts:41
+  parseWavLayout`. Real duplication — the same word-aligned chunk walk twice —
+  but they are **not** the same function. `readWavChunks` breaks at the first
+  `data` chunk, returns a slice, checks no format, and skips the `WAVE` check;
+  `parseWavLayout` scans every chunk, returns offsets (it edits in place),
+  rejects anything that is not 16-bit PCM, and does check `WAVE`. Unifying
+  means picking one behaviour for each of those four, in the parser every
+  render's audio goes through, for a cosmetic win. Deliberately not attempted
+  at the end of a long session. If taken up: the shared walk wants its own
+  module — `audioFxRender` already imports `audioVolumeEnvelope`, so putting it
+  in the former makes a cycle.
+- `propertyPanelFxControls.tsx:51` re-implements FlatSlider/FlatToggle/
+  FlatSelectRow, losing their throttle, pointer capture, Escape-revert and
+  design telemetry. The biggest item left in 4c and the one most likely to
+  change behaviour: the local versions grew a commit/preview split
+  (`onChainPreview` while dragging, `onChainChange` on release) and an
+  `edited` guard that the shared controls do not have, so this is a merge of
+  two behaviours, not a swap. Needs the FlatSlider throttle question settled
+  first — see the note about PR #2190 in the project memory, where a
+  throttle fix was held back because the same bug reproduced in the published
+  studio.
+- `audioFxGraph.ts:279`/`:352` four hand-rolled wet/dry shells whose dispose
+  lists have already drifted. Mechanical but touches every modulated effect's
+  teardown; worth doing right after the LFO-phase rework (4b) rather than
+  twice, since that rework rebuilds two of the four anyway.
+- `audioMixer.ts:328` re-rolls curve sampling at 30/s against the scheduler's
+  100/s while `sampleAutomationCurve` names it as a consumer. Untouched: the
+  rate is a deliberate budget for the PCM baker (`CURVED_SEGMENT_SAMPLES_PER_SEC`)
+  and reconciling it is an audio-changing decision, not a cleanup.
+- `build-audio-fx-runtime.ts` is a near-verbatim clone of
+  `build-position-edits-render.ts`. Build scripts; no consumer risk, no
+  behaviour to protect, just nobody's afternoon yet.
 
 ---