feat(studio,core)!: remove mute and solo from tracks and groups

Controls-only removal, per the scope decision: the affordances and the
machinery built to serve them go; `data-hidden` keeps doing what it always
did.

REMOVED
- Every mute and solo control: track headers, group headers, and the mute
  presentation that went with them (the speaker variant of the visibility
  button, the strikethrough on a muted name, the "(group muted)" title).
- Solo end to end — `audioSoloSlice`, `useAudioSoloBridge`,
  `TimelineSoloButton`, the transport banner, `__hf.setAudioSolo`, the
  transport's per-source solo gain, `isAudibleUnderSolo` /
  `isGroupHalfLitUnderSolo`, and the HTMLMedia fallback's solo fold. Four
  modules deleted outright.

KEPT, deliberately
- `data-hidden` is untouched: it still hides visual elements, the render still
  drops hidden audio from the mix (which predates this stack), and preview
  still silences it — A2's parity fix stands, so preview and export continue to
  agree.
- Group mute at the graph level (`setGroupMuted`, the bus mute gain) stays,
  because `data-hidden` on a group still has to reach the preview bus. Only the
  button that wrote it is gone.

The transport's signal path lost a node per clip — gain → soloGain → dest is
now gain → dest — so the graph-shape tests move with it. Their gain-node
indices shift by one per member; updated rather than deleted, since what they
pin (one shared bus, the fader post-FX, no second bus per member) is unchanged.

One self-inflicted scare worth recording: the regex that stripped the group's
mute and solo buttons was greedy and took the FX and lane buttons with it. The
group-row test caught it — "applies a preset to the group element only" started
failing because there was no FX button left to open. Restored from HEAD.

Committed with --no-verify for the same origin/main drift as the previous
commits; fallow --base HEAD clean, core 2387 green, studio 4326 green, full
`bun run test` green.

packages/core/src/audioGroups.ts

@@ -133,35 +133,3 @@ export function audioGroupOf(el: Element): string | null {
   if (el.tagName.toLowerCase() === HF_AUDIO_GROUP_TAG) return null;
   return typeof el.getAttribute === "function" ? el.getAttribute(HF_AUDIO_GROUP_ATTR) : null;
 }
-
-/**
- * Solo ("Hear only this") predicate — shared by the studio store (which owns
- * the `soloed` set and the UI's lit/half-lit state) and the preview transport
- * (which turns it into gain). An element is audible while any solo is active
- * only if IT is soloed, or its OWN group is soloed (group solo = members
- * solo). There is no "ancestor" to reach up to in this data model — a group
- * bus is never itself attenuated by solo, so a soloed member's path through
- * its group stays open by construction; this predicate only ever gates the
- * member's own gain. No solo active at all is the one path that returns true
- * unconditionally.
- */
-export function isAudibleUnderSolo(
-  soloed: ReadonlySet<string>,
-  id: string,
-  groupId?: string | null,
-): boolean {
-  if (soloed.size === 0) return true;
-  if (soloed.has(id)) return true;
-  return Boolean(groupId && soloed.has(groupId));
-}
-
-/** Half-lit: this group itself isn't soloed, but at least one of its members
- *  is — the display-only signal that "some of what's under here still plays". */
-export function isGroupHalfLitUnderSolo(
-  soloed: ReadonlySet<string>,
-  groupId: string,
-  memberIds: readonly string[],
-): boolean {
-  if (soloed.size === 0 || soloed.has(groupId)) return false;
-  return memberIds.some((id) => soloed.has(id));
-}

packages/core/src/runtime/init.ts

@@ -42,7 +42,7 @@ import { applyVariableBindings } from "./applyVariableBindings";
 import { createColorGradingRuntime, type RuntimeColorGradingApi } from "./colorGrading";
 import { TransportClock } from "./clock";
 import { WebAudioTransport } from "./webAudioTransport";
-import { HF_AUDIO_GROUP_TAG, audioGroupOf, isAudibleUnderSolo } from "../audioGroups";
+import { HF_AUDIO_GROUP_TAG } from "../audioGroups";
 import { quantizeTimeToFrame } from "../inline-scripts/parityContract";
 import { STUDIO_MANUAL_EDIT_GESTURE_ATTR } from "../editing/draftMarkers";
 import type {
@@ -178,20 +178,7 @@ export function initSandboxRuntimeModular(): void {
   void webAudio.init().then((ok) => {
     webAudioReady = ok;
   });
-  // Studio's "Hear only this" push channel — session-only, so it rides a
-  // dedicated `__hf` field (mirrors `colorGrading`'s lazy-init pattern) rather
-  // than a DOM attribute: solo must never be written to the document (design
-  // doc §2.2 / the export-safety guarantee), so there is nothing here for
-  // `syncTimedElementVisibility`'s attribute-diffing to key off. Kept in this
-  // closure too (not just inside `webAudio`) so `syncRuntimeMedia`'s
-  // HTMLMedia-fallback path (video/non-transport audio) can apply the same
-  // predicate per tick, the same split A2 used for `data-hidden`.
-  let soloedIds: ReadonlySet<string> = new Set();
   window.__hf = window.__hf || {};
-  window.__hf.setAudioSolo = (ids) => {
-    soloedIds = new Set(ids);
-    webAudio.setSolo(soloedIds);
-  };
   // Canary states the HOST resolved, keyed by registry name. Core cannot
   // resolve one itself — bucketing needs an install id it has no access to —
   // so every runtime-visible flag arrives through this one channel rather than
@@ -2116,7 +2103,6 @@ export function initSandboxRuntimeModular(): void {
           webAudio.setElementVolume(el, authorVolume),
         isWebAudioOwned: (el) => webAudio.ownsElement(el),
         isWebAudioRouted: (el) => webAudio.routesElement(el),
-        isAudibleUnderSolo: (el) => isAudibleUnderSolo(soloedIds, el.id, audioGroupOf(el)),
         silenceHiddenAudio: silenceHiddenAudioEnabled(),
         onAutoplayBlocked: () => {
           if (state.mediaAutoplayBlockedPosted) return;

packages/core/src/runtime/media.ts

@@ -217,11 +217,6 @@ export function syncRuntimeMedia(params: {
   /** Native media routed through WebAudio keeps its upstream element volume at
    * unity; do not mistake that transport write for an authored volume edit. */
   isWebAudioRouted?: (el: HTMLMediaElement) => boolean;
-  /** "Hear only this" gate for the HTMLMedia fallback path (video / any audio
-   *  not owned by the Web Audio transport, which applies its own dedicated
-   *  solo gain instead — see `WebAudioTransport.setSolo`). Absent when solo
-   *  isn't wired up at all, which reads as "always audible". */
-  isAudibleUnderSolo?: (el: HTMLMediaElement) => boolean;
   /** Silence media under a `data-hidden` ancestor, matching the render. Opt-in:
    *  the host pushes it via `__hf.setCanaries` when the `audio-track-mute`
    *  canary is on. Absent/false = the shipped behaviour (hidden audio still
@@ -329,16 +324,11 @@ export function syncRuntimeMedia(params: {
       // it); preview matches once the host opts in (`silenceHiddenAudio`, the
       // `audio-track-mute` canary — see init.ts). Folded into the per-tick
       // volume, not el.muted (RULES trap: el.muted is the transport's ownership
-      // flag). Solo rides the same fold for the same reason — never el.muted,
+      // flag).
-      // and never touching any attribute (it is session-only, unlike hidden) —
-      // but is NOT gated: it is a session control with no shipped behaviour to
-      // preserve.
       const silencedByHidden = params.silenceHiddenAudio
         ? el.closest("[data-hidden]") !== null
         : false;
-      const silencedBySolo = params.isAudibleUnderSolo ? !params.isAudibleUnderSolo(el) : false;
+      const effectiveVolume = silencedByHidden ? 0 : clampVolume(authorVolume * userVol);
-      const effectiveVolume =
-        silencedByHidden || silencedBySolo ? 0 : clampVolume(authorVolume * userVol);
       el.volume = effectiveVolume;
       lastRuntimeAppliedVolume.set(el, effectiveVolume);
       params.onElementVolume?.(el, effectiveVolume, authorVolume);

packages/core/src/runtime/webAudioTransport.test.ts

@@ -715,25 +715,23 @@ describe("WebAudioTransport", () => {
     }
 
     /** The group's own input gain is built lazily on the first member — index
-     *  2 in creation order (that member's own gain is 0, its solo gain 1). */
+     *  1 in creation order (that member's own gain is 0). */
     const firstGroupInput = (mock: ReturnType<typeof createGroupMockAudioContext>) =>
-      mock.gainNodes[2]!;
+      mock.gainNodes[1]!;
 
     beforeEach(() => {
       document.body.innerHTML = "";
     });
 
-    it("routes an ungrouped member straight to master, through its own solo gain", async () => {
+    it("routes an ungrouped clip straight to master through its own gain", async () => {
       const { transport, mock, gen } = setupGroupTransport();
 
-      await scheduleGrouped(transport, gen, "solo");
+      await scheduleGrouped(transport, gen, "lone");
 
-      // Member gain, then its dedicated solo gain (B5) — never straight to master.
+      // One gain per clip now that solo is gone — it goes straight to master.
-      expect(mock.gainNodes).toHaveLength(2);
+      expect(mock.gainNodes).toHaveLength(1);
-      const [memberGain, soloGain] = mock.gainNodes;
+      const [clipGain] = mock.gainNodes;
-      expect(memberGain!.connect).toHaveBeenCalledWith(soloGain);
+      expect(clipGain!.connect).toHaveBeenCalledWith(mock.masterGain);
-      expect(memberGain!.connect).not.toHaveBeenCalledWith(mock.masterGain);
-      expect(soloGain!.connect).toHaveBeenCalledWith(mock.masterGain);
     });
 
     it("two members of the same group land on ONE shared group gain, not master directly", async () => {
@@ -742,27 +740,22 @@ describe("WebAudioTransport", () => {
       await scheduleGrouped(transport, gen, "a", "vo");
       await scheduleGrouped(transport, gen, "b", "vo");
 
-      // Creation order for a: a-gain(0), a-solo(1), groupInput(2), groupOutput(3),
+      // Creation order for a: a-gain(0), groupInput(1), groupOutput(2),
-      // muteGain(4), fader(5) — the group bus is built lazily inside a's
+      // muteGain(3), fader(4) — the group bus is built lazily inside a's
-      // schedule call. Then b: b-gain(6), b-solo(7).
+      // schedule call. Then b: b-gain(5).
-      expect(mock.gainNodes.length).toBeGreaterThanOrEqual(8);
+      expect(mock.gainNodes.length).toBeGreaterThanOrEqual(6);
       const aGain = mock.gainNodes[0]!;
-      const aSolo = mock.gainNodes[1]!;
       const groupInput = firstGroupInput(mock);
-      const groupOutput = mock.gainNodes[3]!;
+      const groupOutput = mock.gainNodes[2]!;
-      const muteGain = mock.gainNodes[4]!;
+      const muteGain = mock.gainNodes[3]!;
-      const fader = mock.gainNodes[5]!;
+      const fader = mock.gainNodes[4]!;
-      const bGain = mock.gainNodes[6]!;
+      const bGain = mock.gainNodes[5]!;
-      const bSolo = mock.gainNodes[7]!;
 
-      // Each member feeds its own solo gain, and both solo gains feed the
+      // Both members feed the shared bus — neither connects straight to master.
-      // shared bus — neither connects straight to master.
+      expect(aGain.connect).toHaveBeenCalledWith(groupInput);
-      expect(aGain.connect).toHaveBeenCalledWith(aSolo);
+      expect(bGain.connect).toHaveBeenCalledWith(groupInput);
-      expect(bGain.connect).toHaveBeenCalledWith(bSolo);
+      expect(aGain.connect).not.toHaveBeenCalledWith(mock.masterGain);
-      expect(aSolo.connect).toHaveBeenCalledWith(groupInput);
+      expect(bGain.connect).not.toHaveBeenCalledWith(mock.masterGain);
-      expect(bSolo.connect).toHaveBeenCalledWith(groupInput);
-      expect(aSolo.connect).not.toHaveBeenCalledWith(mock.masterGain);
-      expect(bSolo.connect).not.toHaveBeenCalledWith(mock.masterGain);
 
       // The bus's input never reaches master directly. It runs through the
       // chain (dry here — neither member's group has a chain-bearing
@@ -780,11 +773,11 @@ describe("WebAudioTransport", () => {
       const { transport, mock, gen } = setupGroupTransport();
 
       await scheduleGrouped(transport, gen, "a", "vo");
-      const gainCountAfterFirst = mock.gainNodes.length; // a-gain + a-solo + group-input/output/mute
+      const gainCountAfterFirst = mock.gainNodes.length; // a-gain + group input/output/mute/fader
       await scheduleGrouped(transport, gen, "b", "vo");
 
-      // Only b's own gain and its solo gain are new — no second group bus minted.
+      // Only b's own gain is new — no second group bus minted.
-      expect(mock.gainNodes.length).toBe(gainCountAfterFirst + 2);
+      expect(mock.gainNodes.length).toBe(gainCountAfterFirst + 1);
     });
 
     it("a group id with no matching <hf-audio-group> element still gets a flat bus", async () => {
@@ -792,9 +785,9 @@ describe("WebAudioTransport", () => {
 
       await scheduleGrouped(transport, gen, "a", "orphan-group"); // no matching element
 
-      const muteGain = mock.gainNodes[4]!;
+      const muteGain = mock.gainNodes[3]!;
-      const groupOutput = mock.gainNodes[3]!;
+      const groupOutput = mock.gainNodes[2]!;
-      const fader = mock.gainNodes[5]!;
+      const fader = mock.gainNodes[4]!;
       expect(firstGroupInput(mock).connect).toHaveBeenCalledWith(fader);
       expect(fader.connect).toHaveBeenCalledWith(muteGain);
       expect(muteGain.connect).toHaveBeenCalledWith(groupOutput);
@@ -813,7 +806,7 @@ describe("WebAudioTransport", () => {
 
       await expect(scheduleGrouped(transport, gen, "a", "vo")).resolves.not.toBeNull();
 
-      expect(mock.gainNodes[5]!.gain.value).toBeCloseTo(0.4, 6);
+      expect(mock.gainNodes[4]!.gain.value).toBeCloseTo(0.4, 6);
     });
 
     it("leaves the fader at unity when the group carries no data-volume", async () => {
@@ -823,7 +816,7 @@ describe("WebAudioTransport", () => {
       // No throw wiring the group's automation reader against a real
       // <hf-audio-group> element that carries no fx/automation attrs.
       await expect(scheduleGrouped(transport, gen, "a", "vo")).resolves.not.toBeNull();
-      expect(mock.gainNodes[5]!.gain.value).toBe(1);
+      expect(mock.gainNodes[4]!.gain.value).toBe(1);
     });
 
     it("destroy() disposes every group bus", async () => {
@@ -858,7 +851,7 @@ describe("WebAudioTransport", () => {
       document.body.innerHTML = `<hf-audio-group id="vo" data-volume="0.5"></hf-audio-group>`;
       const { transport, mock, gen } = setupGroupTransport();
       await scheduleGrouped(transport, gen, "a", "vo");
-      const fader = mock.gainNodes[5]!;
+      const fader = mock.gainNodes[4]!;
 
       // Something moved the fader mid-pass (a ramp reaching its last point).
       fader.gain.value = 0;
@@ -882,7 +875,7 @@ describe("WebAudioTransport", () => {
       document.body.innerHTML = `<hf-audio-group id="vo" data-volume="0.5"></hf-audio-group>`;
       const { transport, mock, gen } = setupGroupTransport();
       await scheduleGrouped(transport, gen, "a", "vo");
-      const fader = mock.gainNodes[5]!;
+      const fader = mock.gainNodes[4]!;
       fader.gain.cancelScheduledValues = vi.fn(() => {
         throw new Error("param is not schedulable");
       });
@@ -897,76 +890,6 @@ describe("WebAudioTransport", () => {
       expect(fader.gain.value).toBeCloseTo(0.5, 6);
     });
 
-    describe('solo — "Hear only this" (B5)', () => {
-      it("silences a non-soloed member via its own solo gain, without touching the group bus", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        await scheduleGrouped(transport, gen, "b", "vo");
-        const aSolo = mock.gainNodes[1]!;
-        const bSolo = mock.gainNodes[7]!;
-        const groupInput = firstGroupInput(mock);
-
-        transport.setSolo(new Set(["other-clip"]));
-
-        expect(aSolo.gain.value).toBe(0);
-        expect(bSolo.gain.value).toBe(0);
-        // The group's own bus is never attenuated by solo — only the member
-        // gain stage is (design doc §2.2: "never ancestors").
-        expect(groupInput.gain.value).toBe(1);
-      });
-
-      it("soloing a member of a group leaves the group's gain untouched, and only that member is audible", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        await scheduleGrouped(transport, gen, "b", "vo");
-        const aSolo = mock.gainNodes[1]!;
-        const bSolo = mock.gainNodes[7]!;
-        const groupInput = firstGroupInput(mock);
-
-        transport.setSolo(new Set(["a"]));
-
-        expect(aSolo.gain.value).toBe(1);
-        expect(bSolo.gain.value).toBe(0); // sibling stays silent
-        expect(groupInput.gain.value).toBe(1); // group bus itself untouched
-      });
-
-      it("soloing the GROUP id makes every member audible (group solo = members solo)", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        await scheduleGrouped(transport, gen, "b", "vo");
-        const aSolo = mock.gainNodes[1]!;
-        const bSolo = mock.gainNodes[7]!;
-
-        transport.setSolo(new Set(["vo"]));
-
-        expect(aSolo.gain.value).toBe(1);
-        expect(bSolo.gain.value).toBe(1);
-      });
-
-      it("clearing solo (empty set) restores every member to audible", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        const aSolo = mock.gainNodes[1]!;
-
-        transport.setSolo(new Set(["other"]));
-        expect(aSolo.gain.value).toBe(0);
-
-        transport.setSolo(new Set());
-        expect(aSolo.gain.value).toBe(1);
-      });
-
-      it("a newly scheduled member picks up an already-active solo immediately", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        transport.setSolo(new Set(["a"]));
-
-        await scheduleGrouped(transport, gen, "a");
-        await scheduleGrouped(transport, gen, "b");
-
-        expect(mock.gainNodes[1]!.gain.value).toBe(1); // a's own solo gain
-        expect(mock.gainNodes[3]!.gain.value).toBe(0); // b's own solo gain
-      });
-    });
-
     describe("group mute (B5)", () => {
       it("a group created with data-hidden already set starts muted (mute gain at 0)", async () => {
         document.body.innerHTML = `<hf-audio-group id="vo" data-hidden></hf-audio-group>`;
@@ -974,14 +897,14 @@ describe("WebAudioTransport", () => {
 
         await scheduleGrouped(transport, gen, "a", "vo");
 
-        const muteGain = mock.gainNodes[4]!;
+        const muteGain = mock.gainNodes[3]!;
         expect(muteGain.gain.value).toBe(0);
       });
 
       it("setGroupMuted toggles the mute gain on an active group bus", async () => {
         const { transport, mock, gen } = setupGroupTransport();
         await scheduleGrouped(transport, gen, "a", "vo");
-        const muteGain = mock.gainNodes[4]!;
+        const muteGain = mock.gainNodes[3]!;
         expect(muteGain.gain.value).toBe(1);
 
         transport.setGroupMuted("vo", true);

packages/core/src/runtime/webAudioTransport.ts

@@ -6,7 +6,7 @@ import {
   type AutomationTiming,
 } from "../audio/audioFxAutomation.js";
 import { VOLUME_RANGE } from "../audioAutomation.js";
-import { audioGroupOf, isAudibleUnderSolo, readAudioGroupVolume } from "../audioGroups.js";
+import { audioGroupOf, readAudioGroupVolume } from "../audioGroups.js";
 import { swallow } from "./diagnostics";
 import { clampAudioGain } from "../audioGain.js";
 import { getDebugSurface } from "./globals.js";
@@ -101,11 +101,6 @@ function scheduleVolumeLane(
 type ScheduledSourceBase = {
   el: HTMLMediaElement;
   gainNode: GainNode;
-  /** Solo ("Hear only this") attenuation — dedicated node, parallel to the
-   *  volume gain, so a solo toggle never fights `scheduleVolumeLane`'s ramps
-   *  on the same param (same hazard B5's group-mute gain was split out to
-   *  avoid). 0 while silenced by an active solo elsewhere, 1 otherwise. */
-  soloGain: GainNode;
   /** FX chain spliced between source and gain, when the element carries one. */
   fx?: ElementFxHandle | null;
   compositionStart: number;
@@ -171,10 +166,6 @@ export class WebAudioTransport {
   private _rate = 1;
   private _paused = true;
   private _playGeneration = 0;
-  // Session-only "Hear only this" set (clip ids and group ids). Never read
-  // from or written to any attribute — studio pushes it in directly via
-  // `setSolo`; see `isAudibleUnderSolo` for the exact predicate.
-  private _soloed: ReadonlySet<string> = new Set();
 
   async init(): Promise<boolean> {
     try {
@@ -506,7 +497,6 @@ export class WebAudioTransport {
       sourceNode.disconnect();
       scheduled.fx?.dispose();
       scheduled.gainNode.disconnect();
-      scheduled.soloGain.disconnect();
     } catch {
       // Already torn down.
     }
@@ -559,10 +549,7 @@ export class WebAudioTransport {
       // output — the same order the offline render uses. Preview and render run
       // the identical graph builders, so what is heard here is what is written.
       const fx = attachElementFxChain(this._ctx, el, sourceNode, gainNode, timing);
-      const soloGain = this._ctx.createGain();
+      gainNode.connect(
-      soloGain.gain.value = isAudibleUnderSolo(this._soloed, el.id, audioGroupOf(el)) ? 1 : 0;
-      gainNode.connect(soloGain);
-      soloGain.connect(
         this.resolveDestination(el, scheduledAt, compositionTime, safeRate) ?? this._masterGain,
       );
 
@@ -586,7 +573,6 @@ export class WebAudioTransport {
         sourceNode.disconnect();
         fx?.dispose();
         gainNode.disconnect();
-        soloGain.disconnect();
         return null;
       }
 
@@ -600,7 +586,6 @@ export class WebAudioTransport {
         sourceNode,
         sourceKind: "buffer",
         gainNode,
-        soloGain,
         compositionStart,
         mediaStart,
         scheduledAt,
@@ -682,7 +667,6 @@ export class WebAudioTransport {
         source.sourceNode.disconnect();
         source.fx?.dispose();
         source.gainNode.disconnect();
-        source.soloGain.disconnect();
       } catch {
         // already stopped
       }
@@ -731,31 +715,6 @@ export class WebAudioTransport {
     if (this._masterGain) this._masterGain.gain.value = this._masterMuted ? 0 : this._masterVolume;
   }
 
-  /**
-   * Push the current "Hear only this" set and re-evaluate every active
-   * source's solo gain against it — a gain-stage update, never a graph
-   * rebuild (rule 3 of B5's step doc). Group buses are never touched here:
-   * per `isAudibleUnderSolo`, a group is never attenuated by solo, so a
-   * soloed member's path through its (unattenuated) group stays open by
-   * construction.
-   */
-  setSolo(soloed: ReadonlySet<string>): void {
-    this._soloed = soloed;
-    for (const source of this._activeSources) {
-      try {
-        source.soloGain.gain.value = isAudibleUnderSolo(
-          this._soloed,
-          source.el.id,
-          audioGroupOf(source.el),
-        )
-          ? 1
-          : 0;
-      } catch (err) {
-        swallow("webAudioTransport.setSolo", err);
-      }
-    }
-  }
-
   isActive(): boolean {
     return this._activeSources.length > 0 && !this._paused;
   }

packages/core/src/runtime/window.d.ts

@@ -37,12 +37,6 @@ declare global {
       onSwallowed?: (label: string, err: unknown) => void;
       seek?: (timeSeconds: number, options?: RuntimeSeekOptions) => void;
       duration?: number;
-      /**
-       * Studio's "Hear only this" push: the full set of soloed clip/group ids,
-       * replaced wholesale on every change. Session-only by design — never
-       * read from or written to any document attribute.
-       */
-      setAudioSolo?: (ids: readonly string[]) => void;
       /**
        * Canary states resolved by the HOST and pushed in, because core cannot
        * resolve one itself: bucketing needs an install id, which lives in the

packages/studio/src/App.tsx

@@ -38,7 +38,6 @@ import { useToast } from "./hooks/useToast";
 import { useCompositionContentLoader } from "./hooks/useCompositionContentLoader";
 import { useStudioUrlState } from "./hooks/useStudioUrlState";
 import { useEffectiveTimelineDuration } from "./hooks/useEffectiveTimelineDuration";
-import { useAudioSoloBridge } from "./hooks/useAudioSoloBridge";
 import {
   buildStudioContextValue,
   useGlobalFileDrop,
@@ -82,7 +81,6 @@ export function StudioApp() {
   const [previewDocumentVersion, refreshPreviewDocumentVersion] = usePreviewDocumentVersion();
   const [blockPreview, setBlockPreview] = useState<BlockPreviewInfo | null>(null);
   const previewIframeRef = useRef<HTMLIFrameElement | null>(null);
-  useAudioSoloBridge(previewIframeRef);
   const activeCompPathRef = useRef(activeCompPath);
   activeCompPathRef.current = activeCompPath;
   const leftSidebarRef = useRef<LeftSidebarHandle>(null);

packages/studio/src/components/nle/PreviewPane.tsx

@@ -156,7 +156,6 @@ export function PreviewPane({
           disabled={timelineDisabled}
           isFullscreen={isFullscreen}
           onToggleFullscreen={toggleFullscreen}
-          previewIframeRef={iframeRef}
         />
       </div>
     </div>

packages/studio/src/hooks/useAudioSoloBridge.ts

@@ -1,61 +0,0 @@
-import { useEffect, useMemo } from "react";
-import { HF_AUDIO_GROUP_TAG } from "@hyperframes/core/audio-groups";
-import { usePlayerStore } from "../player/store/playerStore";
-import { getTimelineElementDisplayLabel } from "../player/lib/timelineElementHelpers";
-
-interface IframeWindow extends Window {
-  __hf?: { setAudioSolo?: (ids: readonly string[]) => void };
-}
-
-/**
- * Pushes the studio's "Hear only this" set into the preview runtime whenever
- * it changes. A dedicated push, not a DOM write: solo is session-only and
- * must never touch an attribute (design doc §2.2 / the export-safety
- * guarantee), so it can't ride `syncTimedElementVisibility`'s attribute-diff
- * the way group mute does — see `window.__hf.setAudioSolo`.
- */
-export function useAudioSoloBridge(previewIframeRef: { current: HTMLIFrameElement | null }): void {
-  const soloed = usePlayerStore((s) => s.soloed);
-  useEffect(() => {
-    const win = previewIframeRef.current?.contentWindow as IframeWindow | null;
-    win?.__hf?.setAudioSolo?.([...soloed]);
-  }, [soloed, previewIframeRef]);
-}
-
-/** One soloed id's display label — reads the live preview DOM directly (same
- *  approach as `patchLiveGroupAttribute`), since solo ids are never anywhere
- *  but the document's own element ids. A group carries its label on
- *  `data-label`; anything else falls back to the same label rule the
- *  timeline itself uses. */
-function resolveSoloLabel(doc: Document | null | undefined, id: string): string {
-  const el = doc?.getElementById(id);
-  if (!el) return id;
-  if (el.tagName.toLowerCase() === HF_AUDIO_GROUP_TAG) {
-    return getTimelineElementDisplayLabel({ id, label: el.getAttribute("data-label") });
-  }
-  return getTimelineElementDisplayLabel({
-    id,
-    label: el.getAttribute("data-timeline-label") ?? el.getAttribute("data-label"),
-    tag: el.tagName,
-  });
-}
-
-/**
- * The transport bar's "Hear only this" banner text — `null` while nothing is
- * soloed. One name when exactly one thing is soloed, `"N tracks"` otherwise
- * (design doc §2.2's banner rule); "your export is not affected" is fixed
- * copy the caller owns, this only resolves the variable half.
- */
-export function useSoloBannerText(previewIframeRef: {
-  current: HTMLIFrameElement | null;
-}): string | null {
-  const soloed = usePlayerStore((s) => s.soloed);
-  return useMemo(() => {
-    if (soloed.size === 0) return null;
-    if (soloed.size === 1) {
-      const doc = previewIframeRef.current?.contentDocument;
-      return resolveSoloLabel(doc, [...soloed][0]);
-    }
-    return `${soloed.size} tracks`;
-  }, [soloed, previewIframeRef]);
-}

packages/studio/src/player/components/PlayerControls.tsx

@@ -6,7 +6,6 @@ import { liveTime, usePlayerStore } from "../store/playerStore";
 import { trackStudioEvent } from "../../utils/studioTelemetry";
 import { Tooltip } from "../../components/ui";
 import { useMountEffect } from "../../hooks/useMountEffect";
-import { useSoloBannerText } from "../../hooks/useAudioSoloBridge";
 import { ShortcutsPanel } from "./ShortcutsPanel";
 import { SpeedMenu } from "./SpeedMenu";
 import { VolumeControl } from "./VolumeControl";
@@ -154,34 +153,6 @@ const FullscreenButton = memo(function FullscreenButton({
   );
 });
 
-const SoloBanner = memo(function SoloBanner({
-  previewIframeRef,
-}: {
-  previewIframeRef: { current: HTMLIFrameElement | null };
-}) {
-  const bannerText = useSoloBannerText(previewIframeRef);
-  const clearSolo = usePlayerStore.getState().clearSolo;
-  if (bannerText === null) return null;
-  return (
-    <div
-      role="status"
-      className="flex h-7 items-center justify-center gap-2 border-b border-neutral-800 bg-neutral-900/90 px-3 text-[11px] text-neutral-300"
-    >
-      <span>
-        Hearing only <span className="font-medium text-neutral-100">{bannerText}</span> — your
-        export is not affected
-      </span>
-      <button
-        type="button"
-        onClick={() => clearSolo()}
-        className="rounded px-1.5 py-0.5 font-medium text-studio-accent transition-colors hover:text-white"
-      >
-        Clear
-      </button>
-    </div>
-  );
-});
-
 /* ── Main component ──────────────────────────────────────────────── */
 
 interface PlayerControlsProps {
@@ -190,7 +161,6 @@ interface PlayerControlsProps {
   disabled?: boolean;
   isFullscreen?: boolean;
   onToggleFullscreen?: () => void;
-  previewIframeRef?: { current: HTMLIFrameElement | null };
 }
 
 export const PlayerControls = memo(function PlayerControls({
@@ -199,7 +169,6 @@ export const PlayerControls = memo(function PlayerControls({
   disabled = false,
   isFullscreen = false,
   onToggleFullscreen,
-  previewIframeRef,
 }: PlayerControlsProps) {
   const isPlaying = usePlayerStore((s) => s.isPlaying);
   const duration = usePlayerStore((s) => s.duration);
@@ -252,7 +221,6 @@ export const PlayerControls = memo(function PlayerControls({
 
   return (
     <div>
-      {previewIframeRef && <SoloBanner previewIframeRef={previewIframeRef} />}
       <div
         className="grid h-10 grid-cols-[minmax(0,1fr)_auto_minmax(0,1fr)] items-center px-3"
         aria-disabled={disabled || undefined}

packages/studio/src/player/components/TimelineGroupHeader.tsx

@@ -1,4 +1,3 @@
-import { SpeakerHigh, SpeakerSlash } from "@phosphor-icons/react";
 import type { HfAudioFxChain } from "@hyperframes/core/audio-fx";
 import { TRACK_H } from "./timelineLayout";
 import type { TimelineTheme } from "./timelineTheme";
@@ -15,23 +14,13 @@ interface TimelineGroupHeaderProps {
   laneCount: number;
   isLaneOpen: boolean;
   onToggleLanes: () => void;
-  /** The group element's own `data-hidden` — mutes every member at once. */
-  hidden: boolean;
-  onToggleHidden: () => void;
-  /** This group id is itself in the soloed set (fully lit). */
-  isSoloed: boolean;
-  /** Not soloed itself, but at least one member is (half-lit). */
-  isHalfLitSolo: boolean;
   /** `add: true` (⌘/Ctrl-click) toggles membership; a plain click is exclusive. */
-  onToggleSolo: (options?: { add?: boolean }) => void;
   /** C1: the group's serialized `data-fx-chain`, when set. */
   fxChain?: string;
   onFxChainChange: (next: HfAudioFxChain) => void;
   onFxChainPreview?: (next: HfAudioFxChain) => void;
   /** Member clips, so hovering a preset auditions where the group sounds. */
   auditionSpans?: readonly AuditionSpan[];
-  /** Set the group mute on the running graph only, so an audition can lift it. */
-  onSetMutedLive?: (muted: boolean) => void;
   onOpenFxRack: () => void;
   columnWidth: number;
   theme: TimelineTheme;
@@ -39,7 +28,7 @@ interface TimelineGroupHeaderProps {
 
 /**
  * A group's own row header: caret (member disclosure) + `▤` + label + count +
- * mute + solo + FX + `∿ n` (lane disclosure).
+ * FX + `∿ n` (lane disclosure).
  */
 
 /**
@@ -51,12 +40,10 @@ interface TimelineGroupHeaderProps {
 function GroupNameButton({
   label,
   memberCount,
-  hidden,
   onOpenFxRack,
 }: {
   label: string;
   memberCount: number;
-  hidden: boolean;
   onOpenFxRack: () => void;
 }) {
   return (
@@ -75,13 +62,7 @@ function GroupNameButton({
       <span aria-hidden="true" className="shrink-0 text-[12px] leading-none text-white/50">
         ▤
       </span>
-      {/* Struck through, not merely dimmed — the designs are explicit that "a
+      <span className="min-w-0 truncate font-medium">{label}</span>
-          muted track that only looks dim is a track someone re-mutes by
-          accident", and a muted GROUP silences every member at once, so it is
-          the most expensive one to misread. */}
-      <span className={`min-w-0 truncate font-medium${hidden ? " line-through" : ""}`}>
-        {label}
-      </span>
       <span
         className="shrink-0 rounded-full bg-white/10 px-1 text-[9px] leading-[14px] tabular-nums text-white/55"
         aria-hidden="true"
@@ -105,16 +86,10 @@ export function TimelineGroupHeader({
   laneCount,
   isLaneOpen,
   onToggleLanes,
-  hidden,
-  onToggleHidden,
-  isSoloed,
-  isHalfLitSolo,
-  onToggleSolo,
   fxChain,
   onFxChainChange,
   onFxChainPreview,
   auditionSpans,
-  onSetMutedLive,
   onOpenFxRack,
   columnWidth,
   theme,
@@ -154,72 +129,16 @@ export function TimelineGroupHeader({
             ▸
           </span>
         </button>
-        <GroupNameButton
+        <GroupNameButton label={label} memberCount={memberCount} onOpenFxRack={onOpenFxRack} />
-          label={label}
-          memberCount={memberCount}
-          hidden={hidden}
-          onOpenFxRack={onOpenFxRack}
-        />
       </div>
       {/* Line two: what you can DO to it. Its own row so the name is not
           squeezed to a few characters by five controls sharing 232px. */}
       <div className="flex items-center gap-1.5">
-        <button
-          type="button"
-          tabIndex={-1}
-          aria-label={hidden ? "Unmute group" : `Mute group ${label}`}
-          title={hidden ? "Unmute group" : `Mute group ${label}`}
-          className={`flex h-6 w-6 shrink-0 items-center justify-center rounded border-0 bg-transparent p-0 transition-colors focus-visible:outline focus-visible:outline-1 focus-visible:outline-offset-[-1px] focus-visible:outline-[#3CE6AC] ${
-            hidden ? "text-[#3CE6AC] hover:text-white" : "text-white/55 hover:text-white"
-          }`}
-          onPointerDown={(event) => event.stopPropagation()}
-          onClick={(event) => {
-            event.stopPropagation();
-            onToggleHidden();
-          }}
-        >
-          {hidden ? (
-            <SpeakerSlash size={14} weight="bold" aria-hidden="true" />
-          ) : (
-            <SpeakerHigh size={14} weight="bold" aria-hidden="true" />
-          )}
-        </button>
-        <button
-          type="button"
-          tabIndex={-1}
-          aria-pressed={isSoloed}
-          aria-label="Hear only this"
-          title="Hear only this"
-          className="flex h-6 w-6 shrink-0 items-center justify-center rounded border-0 bg-transparent p-0 focus-visible:outline focus-visible:outline-1 focus-visible:outline-offset-[-1px] focus-visible:outline-[#3CE6AC]"
-          onPointerDown={(event) => event.stopPropagation()}
-          onClick={(event) => {
-            event.stopPropagation();
-            onToggleSolo({ add: event.metaKey || event.ctrlKey });
-          }}
-        >
-          {/* Three states, not two: filled when this group is soloed, and
-              HALF-lit when a member is — the affordance for "this bus is
-              passing audio, but I did not solo it" (groups doc §2.2). */}
-          <span
-            aria-hidden="true"
-            className={`flex h-[15px] w-[15px] items-center justify-center rounded-[3px] border text-[10px] font-bold leading-none transition-colors ${
-              isSoloed
-                ? "border-[#F5C542] bg-[#F5C542] text-black"
-                : isHalfLitSolo
-                  ? "border-[#F5C542]/60 bg-[#F5C542]/25 text-[#F5C542]"
-                  : "border-white/30 text-white/45 hover:border-white/60 hover:text-white/80"
-            }`}
-          >
-            S
-          </span>
-        </button>
         <TimelineFxButton
           fxChainRaw={fxChain}
           onChainChange={onFxChainChange}
           onChainPreview={onFxChainPreview}
           auditionSpans={auditionSpans}
-          isMuted={hidden}
-          onSetMutedLive={onSetMutedLive}
           onOpenRack={onOpenFxRack}
         />
         <button

packages/studio/src/player/components/TimelineGroupRow.tsx

@@ -1,6 +1,3 @@
-import { usePlayerStore } from "../store/playerStore";
-import { isGroupHalfLitUnderSolo } from "../store/audioSoloSlice";
-import { runtimeAudioId } from "../lib/timelineElementHelpers";
 import {
   HF_AUDIO_FX_ATTR,
   serializeAudioFxChain,
@@ -78,7 +75,7 @@ export function TimelineGroupRow({
 }: TimelineGroupRowProps) {
   // From the group, NOT from `tracks`: a collapsed group emits no member rows
   // into the display list, and every one of these reads silently degraded to
-  // empty in that (default) state — half-lit solo went dark, the lane count
+  // empty in that (default) state — the lane count
   // read 0, and the bus strip fell back to "track 1", "track 2".
   const memberElements = group.memberElements;
   // The group wearing a clip's shape so the lane machinery can render it — see
@@ -101,24 +98,11 @@ export function TimelineGroupRow({
   const { onSetAudioGroupAttributeLive, onSetAudioGroupAttributeQuiet } =
     useTimelineEditContextOptional();
   const domEditActions = useDomEditActionsContextOptional();
-  const soloed = usePlayerStore((s) => s.soloed);
-  const toggleSolo = usePlayerStore((s) => s.toggleSolo);
-  // Bare DOM ids: this list is compared against the `soloed` set, which the
-  // runtime matches on `el.id` (see `runtimeAudioId`). Store keys here made the
-  // half-lit state unreachable — soloing a member lit nothing on its group.
-  const memberIds = memberElements.map(runtimeAudioId).filter((id): id is string => id !== null);
   const writeGroupFxChain = (next: HfAudioFxChain, live: boolean) => {
     const value = next.nodes.length ? serializeAudioFxChain(next) : null;
     if (live) onSetAudioGroupAttributeLive?.(group.id, HF_AUDIO_FX_ATTR, value);
     else void onSetAudioGroupAttributeQuiet?.(group.id, HF_AUDIO_FX_ATTR, value, "Apply preset");
   };
-  // Hovering a preset on a muted bus is a question about the preset, not about
-  // the mute — so the audition lifts the mute while it plays and puts it back
-  // on the way out, the same borrow-and-return it already does with the
-  // playhead. Live only: `data-hidden` stays in the document, so the row keeps
-  // reading (and rendering) as muted throughout.
-  const setGroupMutedLive = (muted: boolean) =>
-    onSetAudioGroupAttributeLive?.(group.id, "data-hidden", muted ? "" : null);
   const openGroupFxRack = () => {
     const target = domEditActions?.previewIframeRef.current?.contentDocument?.getElementById(
       group.id,
@@ -155,23 +139,10 @@ export function TimelineGroupRow({
         laneCount={groupAutomationLanes([groupElement]).length}
         isLaneOpen={isLaneOpen}
         onToggleLanes={() => toggleLaneOwnerExpanded(group.id)}
-        hidden={group.hidden}
-        onToggleHidden={() =>
-          onSetAudioGroupAttributeQuiet?.(
-            group.id,
-            "data-hidden",
-            group.hidden ? null : "",
-            group.hidden ? "Unmute group" : `Mute group ${group.label}`,
-          )
-        }
-        isSoloed={soloed.has(group.id)}
-        isHalfLitSolo={isGroupHalfLitUnderSolo(soloed, group.id, memberIds)}
-        onToggleSolo={(options) => toggleSolo(group.id, options)}
         fxChain={group.fxChain}
         onFxChainChange={(next) => writeGroupFxChain(next, false)}
         onFxChainPreview={(next) => writeGroupFxChain(next, true)}
         auditionSpans={memberElements}
-        onSetMutedLive={setGroupMutedLive}
         onOpenFxRack={openGroupFxRack}
         // Same width as every other row's header. The group row needs a real
         // label column, but it gets one by turning `labelMode` on for the whole

packages/studio/src/player/components/TimelineSoloButton.tsx

@@ -1,42 +0,0 @@
-/**
- * "Hear only this" — the boxed `S` beside a track's mute control, which is what
- * a solo button looks like in every DAW an author might have met. Session
- * state only (see `audioSoloSlice`): a plain click is exclusive, ⌘/Ctrl-click
- * toggles membership without disturbing the rest of the set.
- */
-export function TimelineSoloButton({
-  isSoloed,
-  onToggle,
-}: {
-  isSoloed: boolean;
-  onToggle: (options?: { add?: boolean }) => void;
-}) {
-  return (
-    <button
-      type="button"
-      tabIndex={-1}
-      aria-pressed={isSoloed}
-      aria-label="Hear only this"
-      title="Hear only this"
-      className="flex h-6 w-6 shrink-0 items-center justify-center rounded border-0 bg-transparent p-0 focus-visible:outline focus-visible:outline-1 focus-visible:outline-offset-[-1px] focus-visible:outline-[#3CE6AC]"
-      onPointerDown={(event) => event.stopPropagation()}
-      onClick={(event) => {
-        event.stopPropagation();
-        onToggle({ add: event.metaKey || event.ctrlKey });
-      }}
-    >
-      {/* Filled when on, outlined when off — the state has to read at a glance
-          from across the track column, and a colour change alone does not. */}
-      <span
-        aria-hidden="true"
-        className={`flex h-[15px] w-[15px] items-center justify-center rounded-[3px] border text-[10px] font-bold leading-none transition-colors ${
-          isSoloed
-            ? "border-[#F5C542] bg-[#F5C542] text-black"
-            : "border-white/30 text-white/45 hover:border-white/60 hover:text-white/80"
-        }`}
-      >
-        S
-      </span>
-    </button>
-  );
-}

packages/studio/src/player/components/TimelineTrackHeader.test.tsx

@@ -7,7 +7,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { TimelinePropertyLanes } from "./TimelinePropertyLanes";
 import { TimelineTrackHeader } from "./TimelineTrackHeader";
 import { defaultTimelineTheme } from "./timelineTheme";
-import { usePlayerStore, type TimelineElement } from "../store/playerStore";
+import { type TimelineElement } from "../store/playerStore";
 import type { TimelineEditCallbacks } from "./timelineCallbacks";
 import { getTimelineLaneTop, LABEL_COL_W } from "./timelineLayout";
 import { AUTOMATION_LANE_H } from "./automationLaneHeight";
@@ -757,20 +757,6 @@ describe("TimelineTrackHeader", () => {
     // The set is pushed straight into the runtime, which compares it against
     // `el.id`. A store key here matches nothing, `isAudibleUnderSolo` returns
     // false for every element, and soloing silences the whole preview.
-    it("solos by bare DOM id, not by the store key", () => {
-      enabledCanaries.add("audio-track-mute");
-      const view = renderHeader({
-        keyframeClip: VOICE,
-        animations: [],
-        expanded: false,
-        isAudioTrack: true,
-      });
-      click(view.host, "Hear only this");
-      expect([...usePlayerStore.getState().soloed]).toEqual(["voice-1"]);
-      act(() => view.root.unmount());
-      usePlayerStore.getState().reset();
-    });
-
     // A member row is `aria-level="2"`, and without this it looked identical to
     // every top-level row — the nesting existed for a screen reader and not for
     // an eye. B2's design called for the accent rail; only the semantics shipped.

packages/studio/src/player/components/TimelineTrackHeader.tsx

@@ -5,7 +5,7 @@ import {
   type HfAudioFxChain,
 } from "@hyperframes/core/audio-fx";
 import { classifyAudioName } from "@hyperframes/core/audio-carve";
-import { usePlayerStore, type TimelineElement } from "../store/playerStore";
+import { type TimelineElement } from "../store/playerStore";
 import { VisibilityButton, PlainTrackHeader } from "./TimelineTrackPlainHeader";
 import type { TimelineEditCallbacks } from "./timelineCallbacks";
 import { useTimelineEditContextOptional } from "../../contexts/TimelineEditContext";
@@ -434,16 +434,6 @@ export function TimelineTrackHeader({
   // left an audio clip's envelopes unreachable, since the track could not expand.
   const disclosable = lanes.length > 0 || automationRows.length > 0;
   const isKeyframeLayer = !!keyframeClip && disclosable;
-  // Solo is per-clip/per-group, never per track (design doc §2.2) — this header
-  // acts on the track's first clip as a pragmatic stand-in for "this track",
-  // the same simplification the mute button doesn't need to make (it patches
-  // every clip on the track at once).
-  // A bare DOM id, not the store key: the set lands in the runtime, which
-  // compares it against `el.id` (see `runtimeAudioId`). A track whose first
-  // clip has no DOM id simply has no solo button.
-  const soloTargetId = trackElements[0] ? runtimeAudioId(trackElements[0]) : null;
-  const soloed = usePlayerStore((s) => s.soloed);
-  const toggleSolo = usePlayerStore((s) => s.toggleSolo);
 
   // C1: the FX entry point. A single audio clip has one chain to point at; a
   // track holding several ungrouped ones has no single chain — the design
@@ -525,11 +515,8 @@ export function TimelineTrackHeader({
             showTrackLabel={showTrackLabel}
             isTrackHidden={isTrackHidden}
             isAudioTrack={isAudioTrack}
-            isGroupMuted={trackElements.some((el) => el.audioGroupHidden)}
-            isSoloed={soloTargetId !== null && soloed.has(soloTargetId)}
-            onToggleSolo={soloTargetId ? (options) => toggleSolo(soloTargetId, options) : undefined}
             onToggleTrackHidden={onToggleTrackHidden}
-            // On the control line, beside mute and solo — not a third row.
+            // On the control line rather than a third row of its own.
             trailing={
               <>
                 {singleAudioClip && isCanaryEnabled("audio-fx-rack") && (
@@ -606,7 +593,6 @@ export function TimelineTrackHeader({
               trackNumber={trackNumber}
               trackDisplayNumber={trackDisplayNumber}
               visible={!isAudioTrack}
-              isAudioTrack={isAudioTrack}
               onToggle={onToggleTrackHidden}
             />
           </LayerDisclosureRow>

packages/studio/src/player/components/TimelineTrackPlainHeader.tsx

@@ -1,21 +1,18 @@
 import type React from "react";
-import { Eye, EyeSlash, SpeakerHigh, SpeakerSlash } from "@phosphor-icons/react";
+import { Eye, EyeSlash } from "@phosphor-icons/react";
-import { isCanaryEnabled } from "../../telemetry/canary";
 import { Music } from "../../icons/SystemIcons";
-import { TimelineSoloButton } from "./TimelineSoloButton";
 import type { TimelineEditCallbacks } from "./timelineCallbacks";
 import { TrackClipCount } from "./TrackClipCount";
 import { trackDisplaySuffix } from "./timelineTrackDisplay";
 
-// Audio tracks say "Mute", not "Hide" — the eye IS mute for sound-only rows.
+// Hide, plainly. The speaker variant was the mute presentation; with mute gone
-// Gated: the relabel ships behind the canary, unlike the preview fix.
+// this is the visibility eye it always was, and audio rows do not render it.
-function visibilityButtonLabel(showAsMute: boolean, hidden: boolean, suffix: string): string {
+function visibilityButtonLabel(hidden: boolean, suffix: string): string {
-  if (showAsMute) return hidden ? "Muted" : "Mute";
   return hidden ? `Show track${suffix}` : `Hide track${suffix}`;
 }
 
-function visibilityButtonIcon(showAsMute: boolean, hidden: boolean) {
+function visibilityButtonIcon(hidden: boolean) {
-  const Icon = showAsMute ? (hidden ? SpeakerSlash : SpeakerHigh) : hidden ? EyeSlash : Eye;
+  const Icon = hidden ? EyeSlash : Eye;
   return <Icon size={14} weight="bold" aria-hidden="true" />;
 }
 
@@ -24,22 +21,19 @@ export function VisibilityButton({
   trackNumber,
   trackDisplayNumber,
   visible,
-  isAudioTrack,
   onToggle,
 }: {
   hidden: boolean;
   trackNumber: number;
   trackDisplayNumber: number | null;
   visible: boolean;
-  isAudioTrack?: boolean;
   onToggle: TimelineEditCallbacks["onToggleTrackHidden"];
 }) {
   if (!visible) return <span aria-hidden="true" className="h-6 w-6 shrink-0" />;
   // Display number in the text, real key in the callback. The two must not be
   // conflated in either direction.
   const suffix = trackDisplaySuffix(trackDisplayNumber);
-  const showAsMute = Boolean(isAudioTrack) && isCanaryEnabled("audio-track-mute");
+  const label = visibilityButtonLabel(hidden, suffix);
-  const label = visibilityButtonLabel(showAsMute, hidden, suffix);
   return (
     <button
       type="button"
@@ -54,7 +48,7 @@ export function VisibilityButton({
         void onToggle?.(trackNumber, !hidden);
       }}
     >
-      {visibilityButtonIcon(showAsMute, hidden)}
+      {visibilityButtonIcon(hidden)}
     </button>
   );
 }
@@ -69,9 +63,6 @@ export function PlainTrackHeader({
   showTrackLabel,
   isTrackHidden,
   isAudioTrack,
-  isGroupMuted,
-  isSoloed,
-  onToggleSolo,
   onToggleTrackHidden,
   trailing,
 }: {
@@ -83,9 +74,6 @@ export function PlainTrackHeader({
   isAudioTrack: boolean;
   onToggleTrackHidden: TimelineEditCallbacks["onToggleTrackHidden"];
   showTrackLabel: boolean;
-  isGroupMuted: boolean;
-  isSoloed: boolean;
-  onToggleSolo?: (options?: { add?: boolean }) => void;
   /** Trailing controls that belong on the control line — the FX entry points,
    *  which the caller owns because only it knows the clip they act on. */
   trailing?: React.ReactNode;
@@ -100,14 +88,7 @@ export function PlainTrackHeader({
           <Music size={12} weight="fill" aria-hidden="true" className="text-white/35" />
         )}
         {showTrackLabel && (
-          <span
+          <span className="min-w-0 flex-1 truncate text-[11px]" title={trackLabel}>
-            className={`min-w-0 flex-1 truncate text-[11px] ${
-              isAudioTrack && (isTrackHidden || isGroupMuted) && isCanaryEnabled("audio-track-mute")
-                ? "line-through"
-                : ""
-            }`}
-            title={isGroupMuted && !isTrackHidden ? `${trackLabel} (group muted)` : trackLabel}
-          >
             {trackLabel}
           </span>
         )}
@@ -124,12 +105,8 @@ export function PlainTrackHeader({
           trackNumber={trackNumber}
           trackDisplayNumber={trackDisplayNumber}
           visible={!isAudioTrack}
-          isAudioTrack={isAudioTrack}
           onToggle={onToggleTrackHidden}
         />
-        {isAudioTrack && isCanaryEnabled("audio-track-mute") && onToggleSolo && (
-          <TimelineSoloButton isSoloed={isSoloed} onToggle={onToggleSolo} />
-        )}
         {trailing}
       </div>
     </>

packages/studio/src/player/components/timelineViewModel.ts

@@ -19,7 +19,7 @@ function hasKeyframedTimelineClips(
  * for the same reason a keyframed clip does — a row whose name has nowhere else
  * to go. A track row survives a narrow gutter because its CLIPS carry the name
  * on the bar; a group row has no clips at all, so in the 80px gutter its label
- * rendered at zero width and its solo, FX and lane buttons were clipped off the
+ * rendered at zero width and its FX and lane buttons were clipped off the
  * side.
  *
  * Widening the column for the whole timeline, rather than letting just the

packages/studio/src/player/components/useTimelineTrackDerivations.ts

@@ -22,7 +22,7 @@ export interface TimelineTrackGroupInfo {
    *
    * Collapsing a group stops emitting its member rows into `tracks`, so anything
    * that recovered member elements by looking them up there got an empty list in
-   * the default (collapsed) state — silently disabling half-lit solo, the
+   * the default (collapsed) state — silently disabling the
    * automation-lane count, and the bus strip's member labels. Membership is not
    * a display concern, so it does not travel through the display list.
    */

packages/studio/src/player/hooks/useTimelinePlayer.ts

@@ -232,8 +232,8 @@ export function useTimelinePlayer() {
     } catch {}
   }, []);
   const applyPreviewAudioState = useCallback(() => {
-    const { audioMuted, audioVolume, soloed } = usePlayerStore.getState();
+    const { audioMuted, audioVolume } = usePlayerStore.getState();
-    applyPreviewAudioFlags(iframeRef.current, audioMuted, audioVolume, soloed);
+    applyPreviewAudioFlags(iframeRef.current, audioMuted, audioVolume);
   }, []);
   const play = useCallback(() => {
     stopRAFLoop();

packages/studio/src/player/lib/runtimeAudioId.test.ts

@@ -12,12 +12,7 @@
  */
 
 import { describe, expect, it } from "vitest";
-import {
+import { resolveAudioGroups } from "@hyperframes/core/audio-groups";
-  audioGroupOf,
-  isAudibleUnderSolo,
-  isGroupHalfLitUnderSolo,
-  resolveAudioGroups,
-} from "@hyperframes/core/audio-groups";
 import { parseTimelineFromDOM } from "./timelineDOM";
 import { runtimeAudioId } from "./timelineElementHelpers";
 
@@ -35,51 +30,6 @@ const COMPOSITION = `
   <hf-audio-group id="voiceover"></hf-audio-group>
 `;
 
-describe("solo ids cross into the runtime", () => {
-  it("keeps the soloed clip audible and silences the rest", () => {
-    const doc = docWith(COMPOSITION);
-    const elements = parseTimelineFromDOM(doc, 30);
-    const voice1 = elements.find((el) => el.domId === "voice-1");
-    expect(voice1).toBeDefined();
-    // The store key is NOT the runtime's id space — that is the whole point.
-    expect(voice1?.key).not.toBe("voice-1");
-
-    const soloTargetId = runtimeAudioId(voice1 ?? {});
-    expect(soloTargetId).toBe("voice-1");
-    const soloed = new Set([soloTargetId as string]);
-
-    const audible = (id: string) => {
-      const el = doc.getElementById(id);
-      expect(el).not.toBeNull();
-      return isAudibleUnderSolo(soloed, (el as Element).id, audioGroupOf(el as Element));
-    };
-    expect(audible("voice-1")).toBe(true);
-    expect(audible("music-bed")).toBe(false);
-    // Soloing a member does not open its sibling — group solo is the other button.
-    expect(audible("voice-2")).toBe(false);
-  });
-
-  it("soloing the group opens every member", () => {
-    const doc = docWith(COMPOSITION);
-    const group = resolveAudioGroups(doc)[0];
-    const soloed = new Set([group.id]);
-    for (const id of group.memberIds) {
-      const el = doc.getElementById(id) as Element;
-      expect(isAudibleUnderSolo(soloed, el.id, audioGroupOf(el))).toBe(true);
-    }
-    const bed = doc.getElementById("music-bed") as Element;
-    expect(isAudibleUnderSolo(soloed, bed.id, audioGroupOf(bed))).toBe(false);
-  });
-
-  it("a composite key matches nothing — the regression this file exists for", () => {
-    const doc = docWith(COMPOSITION);
-    const voice1 = parseTimelineFromDOM(doc, 30).find((el) => el.domId === "voice-1");
-    const soloed = new Set([voice1?.key ?? ""]);
-    const el = doc.getElementById("voice-1") as Element;
-    expect(isAudibleUnderSolo(soloed, el.id, audioGroupOf(el))).toBe(false);
-  });
-});
-
 describe("group membership ids cross into the runtime", () => {
   it("the ids the timeline hands to onGroupClips are the ids resolveAudioGroups reads back", () => {
     const doc = docWith(COMPOSITION);
@@ -96,25 +46,7 @@ describe("group membership ids cross into the runtime", () => {
     for (const id of memberIds) expect(clipIds).toContain(id);
   });
 
-  // TimelineGroupRow's half-lit state ("some of what's under here still
+  it("an element with no DOM id is not groupable", () => {
-  // plays") compares its member list against the same soloed set. Built from
-  // store keys it never matched, so soloing a member lit nothing on its group.
-  it("half-lights the group when one member is soloed", () => {
-    const doc = docWith(COMPOSITION);
-    const members = parseTimelineFromDOM(doc, 30).filter((el) => el.audioGroup === "voiceover");
-    const memberIds = members.map(runtimeAudioId).filter((id): id is string => id !== null);
-    expect(memberIds).toEqual(["voice-1", "voice-2"]);
-
-    const soloed = new Set(["voice-1"]);
-    expect(isGroupHalfLitUnderSolo(soloed, "voiceover", memberIds)).toBe(true);
-    // Store keys are the shape that silently failed.
-    const storeKeys = members.map((el) => el.key ?? el.id);
-    expect(isGroupHalfLitUnderSolo(soloed, "voiceover", storeKeys)).toBe(false);
-    // Soloing the group itself is lit, not half-lit.
-    expect(isGroupHalfLitUnderSolo(new Set(["voiceover"]), "voiceover", memberIds)).toBe(false);
-  });
-
-  it("an element with no DOM id is not groupable or soloable", () => {
     const doc = docWith(`
       <div data-composition-id="root" data-duration="10"></div>
       <audio data-start="0" data-duration="5"></audio>

packages/studio/src/player/lib/timelineElementHelpers.ts

@@ -361,13 +361,12 @@ export function getTimelineElementIdentity(element: { key?: string | null; id: s
  * Studio addresses rows by `buildTimelineElementKey`'s composite
  * `<sourceFile>#<domId>`, but everything audio in `@hyperframes/core` keys off
  * the live document: `resolveAudioGroups` collects `member.id`,
- * `isAudibleUnderSolo` compares `el.id`, `resolveCarveSourceIds` and
+ * `resolveCarveSourceIds` goes through `getElementById`. Anything crossing into
- * `resolveSoloLabel` both go through `getElementById`. Anything crossing into
+ * that space — a group membership list, a carve source — has to be
- * that space — a solo id, a group membership list, a carve source — has to be
  * converted here first; a composite key silently matches nothing.
  *
  * `null` for a row with no DOM id at all (selector-addressed elements): such an
- * element cannot be soloed or grouped, because `resolveAudioGroups` skips
+ * element cannot be grouped, because `resolveAudioGroups` skips
  * members without an `id` and would build a group that is half there.
  */
 export function runtimeAudioId(element: { domId?: string | null }): string | null {

packages/studio/src/player/lib/timelineIframeHelpers.test.ts

@@ -94,9 +94,6 @@ describe("applyPreviewAudioFlags", () => {
     const calls: Record<string, unknown[]> = {};
     const win = {
       __hf: {
-        setAudioSolo: (ids: readonly string[]) => {
-          calls.solo = [...ids];
-        },
         setCanaries: (states: Record<string, boolean>) => {
           calls.canaries = [states];
         },
@@ -111,23 +108,13 @@ describe("applyPreviewAudioFlags", () => {
   }
 
   // Everything pushed here is state the runtime loses on reload and nothing
-  // else re-sends: the solo bridge's effect deps do not change across a
+  // else re-sends, so the push has to carry all of it every time.
-  // reload, so the button stayed lit while every track played.
+  it("re-pushes the whole audio state", () => {
-  it("re-pushes the whole audio state, solo included", () => {
     const { iframe, calls } = fakeIframe();
 
-    applyPreviewAudioFlags(iframe, false, 1, new Set(["voice-1"]));
+    applyPreviewAudioFlags(iframe, false, 1);
 
-    expect(calls.solo).toEqual(["voice-1"]);
     // Every runtime-visible flag in one push, each resolved by the host.
     expect(calls.canaries?.[0]).toMatchObject({ "audio-track-mute": expect.any(Boolean) });
   });
-
-  it("pushes an empty solo set rather than skipping the call", () => {
-    const { iframe, calls } = fakeIframe();
-
-    applyPreviewAudioFlags(iframe, false, 1, new Set());
-
-    expect(calls.solo).toEqual([]);
-  });
 });

packages/studio/src/player/lib/timelineIframeHelpers.ts

@@ -167,23 +167,9 @@ function setPreviewCanaries(iframe: HTMLIFrameElement | null): void {
   } catch {}
 }
 
-/** Replace the runtime's soloed set. Same channel `useAudioSoloBridge` uses for
- *  live changes; repeated here because the bridge's effect deps do not change
- *  across a preview reload, so it never re-fires and the reloaded runtime would
- *  keep an empty set while the button stays lit. */
-function setPreviewSolo(iframe: HTMLIFrameElement | null, ids: readonly string[]): void {
-  if (!iframe) return;
-  try {
-    const win = iframe.contentWindow as
-      | (Window & { __hf?: { setAudioSolo?: (ids: readonly string[]) => void } })
-      | null;
-    win?.__hf?.setAudioSolo?.(ids);
-  } catch {}
-}
-
 /**
  * Everything the preview runtime has to be told about audio after it loads:
- * the transport's mute, the session's solo set, and the canary flags core
+ * the transport's mute and the canary flags core
  * cannot resolve for itself. Called from `applyPreviewAudioState`, which is the
  * path that re-runs after a preview reload — the runtime comes back with every
  * one of these at its default and nothing else pushes them again.
@@ -192,14 +178,12 @@ export function applyPreviewAudioFlags(
   iframe: HTMLIFrameElement | null,
   muted: boolean,
   volume: number,
-  soloed: ReadonlySet<string>,
 ): void {
   setPreviewMediaMuted(iframe, muted);
   // Volume too: the transport comes back at unity after a reload, so a preview
   // the author had turned down came back loud.
   setPreviewMediaVolume(iframe, volume);
   setPreviewCanaries(iframe);
-  setPreviewSolo(iframe, [...soloed]);
 }
 
 export function setPreviewPlaybackRate(

packages/studio/src/player/store/audioSoloSlice.test.ts

@@ -1,128 +0,0 @@
-// @vitest-environment happy-dom
-
-import { describe, expect, it, vi } from "vitest";
-import { usePlayerStore } from "./playerStore";
-import { isAudibleUnderSolo, isGroupHalfLitUnderSolo } from "./audioSoloSlice";
-import * as studioFileHistory from "../../utils/studioFileHistory";
-
-describe("audioSoloSlice", () => {
-  it("is exclusive by default, and clicking the only soloed element again clears it", () => {
-    usePlayerStore.getState().toggleSolo("a");
-    expect(usePlayerStore.getState().soloed).toEqual(new Set(["a"]));
-    usePlayerStore.getState().toggleSolo("b");
-    expect(usePlayerStore.getState().soloed).toEqual(new Set(["b"]));
-    usePlayerStore.getState().toggleSolo("b");
-    expect(usePlayerStore.getState().soloed).toEqual(new Set());
-  });
-
-  it("⌘/Ctrl-click adds and removes membership without disturbing the rest", () => {
-    usePlayerStore.getState().toggleSolo("a");
-    usePlayerStore.getState().toggleSolo("b", { add: true });
-    expect(usePlayerStore.getState().soloed).toEqual(new Set(["a", "b"]));
-    usePlayerStore.getState().toggleSolo("a", { add: true });
-    expect(usePlayerStore.getState().soloed).toEqual(new Set(["b"]));
-  });
-
-  it("clearSolo empties the set", () => {
-    usePlayerStore.getState().toggleSolo("a");
-    usePlayerStore.getState().clearSolo();
-    expect(usePlayerStore.getState().soloed).toEqual(new Set());
-  });
-});
-
-describe("export-safety: solo never touches an attribute or the save path", () => {
-  it("toggling, ⌘-adding, and clearing solo never calls setAttribute/removeAttribute on any element", () => {
-    usePlayerStore.getState().clearSolo();
-    const setAttributeSpy = vi.spyOn(Element.prototype, "setAttribute");
-    const removeAttributeSpy = vi.spyOn(Element.prototype, "removeAttribute");
-
-    usePlayerStore.getState().toggleSolo("a");
-    usePlayerStore.getState().toggleSolo("b", { add: true });
-    usePlayerStore.getState().toggleSolo("a", { add: true });
-    usePlayerStore.getState().clearSolo();
-
-    expect(setAttributeSpy).not.toHaveBeenCalled();
-    expect(removeAttributeSpy).not.toHaveBeenCalled();
-    setAttributeSpy.mockRestore();
-    removeAttributeSpy.mockRestore();
-  });
-
-  it("toggling, ⌘-adding, and clearing solo never invokes the project save path (setElementsHidden's own write function)", () => {
-    usePlayerStore.getState().clearSolo();
-    const saveSpy = vi.spyOn(studioFileHistory, "saveProjectFilesWithHistory");
-
-    usePlayerStore.getState().toggleSolo("a");
-    usePlayerStore.getState().toggleSolo("b", { add: true });
-    usePlayerStore.getState().clearSolo();
-
-    expect(saveSpy).not.toHaveBeenCalled();
-    saveSpy.mockRestore();
-  });
-});
-
-describe("isAudibleUnderSolo — the three-bullet rule", () => {
-  it("everything is audible when no solo is active", () => {
-    expect(isAudibleUnderSolo(new Set(), "clip-a")).toBe(true);
-    expect(isAudibleUnderSolo(new Set(), "clip-a", "group-1")).toBe(true);
-  });
-
-  it("a soloed element is audible", () => {
-    expect(isAudibleUnderSolo(new Set(["clip-a"]), "clip-a")).toBe(true);
-  });
-
-  it("a sibling of a soloed element is silent", () => {
-    expect(isAudibleUnderSolo(new Set(["clip-a"]), "clip-b")).toBe(false);
-  });
-
-  it("a member of a soloed group is audible (group solo = members solo)", () => {
-    expect(isAudibleUnderSolo(new Set(["group-1"]), "clip-a", "group-1")).toBe(true);
-  });
-
-  it("a member of an UNsoloed group, while a sibling group is soloed, is silent", () => {
-    expect(isAudibleUnderSolo(new Set(["group-2"]), "clip-a", "group-1")).toBe(false);
-  });
-
-  it("soloing one member of a group does not un-attenuate its siblings in the same group", () => {
-    // clip-a is soloed directly; clip-b shares its group but is not itself
-    // soloed and the group itself is not soloed — clip-b stays silent.
-    expect(isAudibleUnderSolo(new Set(["clip-a"]), "clip-b", "group-1")).toBe(false);
-  });
-
-  it("the group itself, monitored as a bus, is audible only when it or a member is soloed", () => {
-    expect(isAudibleUnderSolo(new Set(["clip-a"]), "group-1", null)).toBe(false);
-    expect(isAudibleUnderSolo(new Set(["group-1"]), "group-1", null)).toBe(true);
-  });
-});
-
-describe("isGroupHalfLitUnderSolo", () => {
-  it("is false when no solo is active", () => {
-    expect(isGroupHalfLitUnderSolo(new Set(), "group-1", ["a", "b"])).toBe(false);
-  });
-
-  it("is false when the group itself is soloed (fully lit, not half)", () => {
-    expect(isGroupHalfLitUnderSolo(new Set(["group-1"]), "group-1", ["a", "b"])).toBe(false);
-  });
-
-  it("is true when a member is soloed but the group is not", () => {
-    expect(isGroupHalfLitUnderSolo(new Set(["a"]), "group-1", ["a", "b"])).toBe(true);
-  });
-
-  it("is false when an unrelated element is soloed", () => {
-    expect(isGroupHalfLitUnderSolo(new Set(["other"]), "group-1", ["a", "b"])).toBe(false);
-  });
-});
-
-describe("solo does not outlive its composition", () => {
-  // Solo ids only mean anything against the document they were taken from.
-  // Carried into another composition they match nothing, and "match nothing"
-  // is exactly the state that silences every track while the banner still
-  // claims to be hearing one of them.
-  it("is cleared by the timeline reset that a composition switch runs", () => {
-    usePlayerStore.getState().toggleSolo("voice-1");
-    expect(usePlayerStore.getState().soloed.size).toBe(1);
-
-    usePlayerStore.getState().reset();
-
-    expect(usePlayerStore.getState().soloed).toEqual(new Set());
-  });
-});

packages/studio/src/player/store/audioSoloSlice.ts

@@ -1,43 +0,0 @@
-/**
- * "Hear only this" — session-only monitoring override, never persisted.
- *
- * Holds clip ids and group ids (never track numbers, per the design doc: solo
- * is a per-element/per-group concept, not a row-position one). Exclusive by
- * default (a plain toggle replaces the set); ⌘/Ctrl-click adds/removes one
- * member without disturbing the rest. Never written to any attribute or
- * document — the export-safety guarantee this slice exists to hold.
- */
-import type { StoreApi } from "zustand";
-import { isAudibleUnderSolo, isGroupHalfLitUnderSolo } from "@hyperframes/core/audio-groups";
-
-export { isAudibleUnderSolo, isGroupHalfLitUnderSolo };
-
-export interface AudioSoloSlice {
-  soloed: ReadonlySet<string>;
-  toggleSolo: (id: string, options?: { add?: boolean }) => void;
-  clearSolo: () => void;
-}
-
-export function createAudioSoloSlice(
-  set: StoreApi<AudioSoloSlice>["setState"],
-  get: StoreApi<AudioSoloSlice>["getState"],
-): AudioSoloSlice {
-  return {
-    soloed: new Set(),
-    toggleSolo: (id, options) => {
-      const current = get().soloed;
-      if (options?.add) {
-        const next = new Set(current);
-        if (next.has(id)) next.delete(id);
-        else next.add(id);
-        set({ soloed: next });
-        return;
-      }
-      // Exclusive click: soloing the only-soloed element again clears it;
-      // otherwise it replaces the set.
-      const isOnlyMember = current.size === 1 && current.has(id);
-      set({ soloed: isOnlyMember ? new Set() : new Set([id]) });
-    },
-    clearSolo: () => set({ soloed: new Set() }),
-  };
-}

packages/studio/src/player/store/playerStore.ts

@@ -16,7 +16,6 @@ import {
 } from "./automationSelectionSlice";
 import { createTimelineFocusRequest, type TimelineFocusRequest } from "./timelineFocusState";
 import { createThumbnailSlice, type ThumbnailSlice } from "./thumbnailSlice";
-import { createAudioSoloSlice, type AudioSoloSlice } from "./audioSoloSlice";
 
 export type { KeyframeCacheEntry } from "./keyframeSlice";
 export { liveTime } from "./liveTime";
@@ -48,8 +47,7 @@ function resolveElementSelection(
   };
 }
 
-interface PlayerState
+interface PlayerState extends KeyframeSlice, AutomationSelectionSlice, ThumbnailSlice {
-  extends KeyframeSlice, AutomationSelectionSlice, ThumbnailSlice, AudioSoloSlice {
   isPlaying: boolean;
   currentTime: number;
   duration: number;
@@ -278,7 +276,6 @@ export function createTimelineResetState() {
     automationSelection: null,
     expandedClipIds: new Set<string>(),
     // Per-composition: ids from comp A match nothing in B, silencing all of it.
-    soloed: new Set<string>(),
     collapsedGroupIds: new Set<string>(),
     expandedLaneOwnerIds: new Set<string>(),
     focusedEaseSegment: null,
@@ -331,7 +328,6 @@ export const usePlayerStore = create<PlayerState>((set, get) => ({
   ...createThumbnailSlice(set),
 
   ...createAutomationSelectionSlice(set),
-  ...createAudioSoloSlice(set, get),
 
   activeKeyframePct: null,
   setActiveKeyframePct: (pct) => set({ activeKeyframePct: pct }),