refactor(core): retire studio solo bridge

Author: vanceingalls

packages/core/src/runtime/init.ts

@@ -43,10 +43,8 @@ import { createColorGradingRuntime, type RuntimeColorGradingApi } from "./colorG
 import { TransportClock } from "./clock";
 import { WebAudioTransport } from "./webAudioTransport";
 import {
-  audioGroupOf,
   ensureAudioGroupInertStyle,
   HF_AUDIO_GROUP_TAG,
-  isAudibleUnderSolo,
   isMemberGroupHidden,
 } from "../audioGroups";
 import { clampNativeMediaVolume } from "../audioGain";
@@ -189,15 +187,7 @@ export function initSandboxRuntimeModular(): void {
   void webAudio.init().then((ok) => {
     webAudioReady = ok;
   });
-  // Keep Studio's session-only "Hear only this" bridge alive until the solo
-  // controls are removed later in the stack. It must not be serialized into
-  // the composition because solo is preview state, not authored state.
-  let soloedIds: ReadonlySet<string> = new Set();
   window.__hf = window.__hf || {};
-  window.__hf.setAudioSolo = (ids) => {
-    soloedIds = new Set(ids);
-    webAudio.setSolo(soloedIds);
-  };
   /** Hidden by an ancestor, or by the BUS this clip belongs to. The bus is
    *  never an ancestor — membership is on the member's `data-audio-group` — so
    *  `closest()` alone could not see a muted group, which the render drops. */
@@ -2122,7 +2112,6 @@ 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)),
         onAutoplayBlocked: () => {
           if (state.mediaAutoplayBlockedPosted) return;
           state.mediaAutoplayBlockedPosted = true;

packages/core/src/runtime/media.ts

@@ -224,9 +224,6 @@ 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. WebAudio-owned
-   * sources apply the same predicate on their dedicated solo gain. */
-  isAudibleUnderSolo?: (el: HTMLMediaElement) => boolean;
   forceSync?: boolean;
 }): void {
   const forceMuteAll = !!(params.outputMuted || params.userMuted);
@@ -343,9 +340,7 @@ export function syncRuntimeMedia(params: {
       // fallback played at full level.
       const silencedByHidden =
         el.closest("[data-hidden]") !== null || isMemberGroupHidden(el.ownerDocument, el);
-      const silencedBySolo = params.isAudibleUnderSolo ? !params.isAudibleUnderSolo(el) : false;
-      const effectiveVolume =
-        silencedByHidden || silencedBySolo ? 0 : clampVolume(authorVolume * userVol);
+      const effectiveVolume = silencedByHidden ? 0 : clampVolume(authorVolume * userVol);
       el.volume = effectiveVolume;
       lastRuntimeAppliedVolume.set(el, effectiveVolume);
       params.onElementVolume?.(el, effectiveVolume, authorVolume);

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

@@ -18,20 +18,11 @@ function createMockAudioContext(currentTime = 100) {
     }),
     _fireEnded: () => endedListeners.forEach((cb) => cb()),
   };
-  // Every createGain call returns a distinct node. Sharing one hides graph
-  // errors because the solo stage can overwrite the authored-volume stage.
-  const gainNodes: Array<{
-    gain: { value: number };
-    connect: ReturnType<typeof vi.fn>;
-    disconnect: ReturnType<typeof vi.fn>;
-  }> = [];
-  const makeGain = () => {
-    const node = { gain: { value: 1 }, connect: vi.fn(), disconnect: vi.fn() };
-    gainNodes.push(node);
-    return node;
+  const gainNode = {
+    gain: { value: 1 },
+    connect: vi.fn(),
+    disconnect: vi.fn(),
   };
-  const gainNode = makeGain();
-  let served = 0;
   const mediaElementSourceNode = {
     connect: vi.fn(),
     disconnect: vi.fn(),
@@ -46,11 +37,11 @@ function createMockAudioContext(currentTime = 100) {
     resume: vi.fn(),
     createBufferSource: vi.fn(() => sourceNode),
     createMediaElementSource: vi.fn(() => mediaElementSourceNode),
-    createGain: vi.fn(() => (served++ === 0 ? gainNode : makeGain())),
+    createGain: vi.fn(() => gainNode),
     destination: {},
     close: vi.fn(),
   };
-  return { ctx, sourceNode, mediaElementSourceNode, gainNode, gainNodes, masterGain, startFn };
+  return { ctx, sourceNode, mediaElementSourceNode, gainNode, masterGain, startFn };
 }
 
 function setupTransport(currentTime = 100) {
@@ -121,9 +112,7 @@ describe("WebAudioTransport", () => {
       expect(mock.ctx.createMediaElementSource).toHaveBeenCalledWith(mockEl);
       expect(mock.ctx.createBufferSource).not.toHaveBeenCalled();
       expect(mock.mediaElementSourceNode.connect).toHaveBeenCalled();
-      const [volumeGain, soloGain] = mock.gainNodes;
-      expect(volumeGain?.connect).toHaveBeenCalledWith(soloGain);
-      expect(soloGain?.connect).toHaveBeenCalledWith(mock.masterGain);
+      expect(mock.gainNode.connect).toHaveBeenCalledWith(mock.masterGain);
       expect(mockEl.muted).toBe(false);
       expect(mockEl.volume).toBe(1);
       expect(mock.gainNode.gain.value).toBe(0.8);
@@ -748,15 +737,15 @@ describe("WebAudioTransport", () => {
       document.body.innerHTML = "";
     });
 
-    it("routes an ungrouped clip to master through its own solo stage", async () => {
+    it("routes an ungrouped clip straight to master through its own gain", async () => {
       const { transport, mock, gen } = setupGroupTransport();
 
       await scheduleGrouped(transport, gen, "lone");
 
-      expect(mock.gainNodes).toHaveLength(2);
-      const [clipGain, soloGain] = mock.gainNodes;
-      expect(clipGain!.connect).toHaveBeenCalledWith(soloGain);
-      expect(soloGain!.connect).toHaveBeenCalledWith(mock.masterGain);
+      // One gain per clip now that solo is gone — it goes straight to master.
+      expect(mock.gainNodes).toHaveLength(1);
+      const [clipGain] = mock.gainNodes;
+      expect(clipGain!.connect).toHaveBeenCalledWith(mock.masterGain);
     });
 
     // The media-element transport is the PRIMARY path for audio — the runtime
@@ -801,9 +790,7 @@ describe("WebAudioTransport", () => {
       await transport.scheduleMediaElementPlayback(el, 0, 0, 0, 1, gen, 1);
 
       const clipGain = mock.gainNodes[0]!;
-      const soloGain = mock.gainNodes[5]!;
-      expect(clipGain.connect).toHaveBeenCalledWith(soloGain);
-      expect(soloGain.connect).toHaveBeenCalledWith(firstGroupInput(mock));
+      expect(clipGain.connect).toHaveBeenCalledWith(firstGroupInput(mock));
       expect(clipGain.connect).not.toHaveBeenCalledWith(mock.masterGain);
     });
 
@@ -813,9 +800,8 @@ describe("WebAudioTransport", () => {
 
       await transport.scheduleMediaElementPlayback(el, 0, 0, 0, 1, gen, 1);
 
-      expect(mock.gainNodes).toHaveLength(2);
-      expect(mock.gainNodes[0]!.connect).toHaveBeenCalledWith(mock.gainNodes[1]);
-      expect(mock.gainNodes[1]!.connect).toHaveBeenCalledWith(mock.masterGain);
+      expect(mock.gainNodes).toHaveLength(1);
+      expect(mock.gainNodes[0]!.connect).toHaveBeenCalledWith(mock.masterGain);
     });
 
     it("two members of the same group land on ONE shared group gain, not master directly", async () => {
@@ -824,23 +810,20 @@ describe("WebAudioTransport", () => {
       await scheduleGrouped(transport, gen, "a", "vo");
       await scheduleGrouped(transport, gen, "b", "vo");
 
-      // Creation order for a: gain(0), group bus(1–4), solo(5). Then b uses
-      // gain(6), solo(7); both solo stages feed the one shared group input.
-      expect(mock.gainNodes.length).toBeGreaterThanOrEqual(8);
+      // Creation order for a: a-gain(0), groupInput(1), groupOutput(2),
+      // muteGain(3), fader(4) — the group bus is built lazily inside a's
+      // schedule call. Then b: b-gain(5).
+      expect(mock.gainNodes.length).toBeGreaterThanOrEqual(6);
       const aGain = mock.gainNodes[0]!;
-      const aSolo = mock.gainNodes[5]!;
       const groupInput = firstGroupInput(mock);
       const groupOutput = mock.gainNodes[2]!;
       const muteGain = mock.gainNodes[3]!;
       const fader = mock.gainNodes[4]!;
-      const bGain = mock.gainNodes[6]!;
-      const bSolo = mock.gainNodes[7]!;
-
-      // Both members feed their own solo stage, then the shared bus.
-      expect(aGain.connect).toHaveBeenCalledWith(aSolo);
-      expect(bGain.connect).toHaveBeenCalledWith(bSolo);
-      expect(aSolo.connect).toHaveBeenCalledWith(groupInput);
-      expect(bSolo.connect).toHaveBeenCalledWith(groupInput);
+      const bGain = mock.gainNodes[5]!;
+
+      // Both members feed the shared bus — neither connects straight to master.
+      expect(aGain.connect).toHaveBeenCalledWith(groupInput);
+      expect(bGain.connect).toHaveBeenCalledWith(groupInput);
       expect(aGain.connect).not.toHaveBeenCalledWith(mock.masterGain);
       expect(bGain.connect).not.toHaveBeenCalledWith(mock.masterGain);
 
@@ -860,11 +843,11 @@ describe("WebAudioTransport", () => {
       const { transport, mock, gen } = setupGroupTransport();
 
       await scheduleGrouped(transport, gen, "a", "vo");
-      const gainCountAfterFirst = mock.gainNodes.length;
+      const gainCountAfterFirst = mock.gainNodes.length; // a-gain + group input/output/mute/fader
       await scheduleGrouped(transport, gen, "b", "vo");
 
-      // Only b's volume and solo gains are new — no second group bus minted.
-      expect(mock.gainNodes.length).toBe(gainCountAfterFirst + 2);
+      // Only b's own gain is new — no second group bus minted.
+      expect(mock.gainNodes.length).toBe(gainCountAfterFirst + 1);
     });
 
     it("a group id with no matching <hf-audio-group> element still gets a flat bus", async () => {
@@ -930,45 +913,6 @@ describe("WebAudioTransport", () => {
       expect(mock.gainNodes.filter((n) => n === groupInput)).toHaveLength(1);
     });
 
-    describe('solo — "Hear only this" compatibility bridge', () => {
-      it("silences non-soloed members without attenuating their shared group bus", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        await scheduleGrouped(transport, gen, "b", "vo");
-
-        transport.setSolo(new Set(["a"]));
-
-        expect(mock.gainNodes[5]!.gain.value).toBe(1);
-        expect(mock.gainNodes[7]!.gain.value).toBe(0);
-        expect(firstGroupInput(mock).gain.value).toBe(1);
-      });
-
-      it("soloing a group keeps every member of that group audible", async () => {
-        const { transport, mock, gen } = setupGroupTransport();
-        await scheduleGrouped(transport, gen, "a", "vo");
-        await scheduleGrouped(transport, gen, "b", "vo");
-
-        transport.setSolo(new Set(["vo"]));
-
-        expect(mock.gainNodes[5]!.gain.value).toBe(1);
-        expect(mock.gainNodes[7]!.gain.value).toBe(1);
-      });
-
-      it("applies an existing solo to newly scheduled clips and restores them when cleared", 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);
-        expect(mock.gainNodes[3]!.gain.value).toBe(0);
-
-        transport.setSolo(new Set());
-        expect(mock.gainNodes[1]!.gain.value).toBe(1);
-        expect(mock.gainNodes[3]!.gain.value).toBe(1);
-      });
-    });
-
     // Surviving stopAll() is the point of the bus — and the trap. Its envelopes
     // were booked against the FIRST pass's absolute context times, so a replay
     // or a seek left the fader holding that pass's last value: 0 after a

packages/core/src/runtime/webAudioTransport.ts

@@ -6,12 +6,7 @@ import {
   type AutomationTiming,
 } from "../audio/audioFxAutomation.js";
 import { VOLUME_RANGE } from "../audioAutomation.js";
-import {
-  audioGroupOf,
-  isAudibleUnderSolo,
-  readAudioGroupVolume,
-  resolveGroupElement,
-} from "../audioGroups.js";
+import { audioGroupOf, readAudioGroupVolume, resolveGroupElement } from "../audioGroups.js";
 import { swallow } from "./diagnostics";
 import { clampAudioGain } from "../audioGain.js";
 import { getDebugSurface } from "./globals.js";
@@ -111,8 +106,6 @@ function scheduleVolumeLane(
 type ScheduledSourceBase = {
   el: HTMLMediaElement;
   gainNode: GainNode;
-  /** Dedicated solo stage so toggles never overwrite authored volume ramps. */
-  soloGain: GainNode;
   /** FX chain spliced between source and gain, when the element carries one. */
   fx?: ElementFxHandle | null;
   compositionStart: number;
@@ -176,8 +169,6 @@ export class WebAudioTransport {
   private _rate = 1;
   private _paused = true;
   private _playGeneration = 0;
-  // Session-only preview state pushed by Studio. Never serialized.
-  private _soloed: ReadonlySet<string> = new Set();
 
   async init(): Promise<boolean> {
     try {
@@ -251,26 +242,6 @@ export class WebAudioTransport {
     return this._playGeneration;
   }
 
-  /** Connect one source through its own solo stage and then into its group bus
-   * (or master for an ungrouped clip). Resolving the group first preserves one
-   * shared bus while solo remains strictly per member. */
-  private connectThroughSolo(
-    ctx: AudioContext,
-    masterGain: GainNode,
-    el: HTMLMediaElement,
-    gainNode: GainNode,
-    timing: { scheduledAt: number; compositionTime: number; rate: number },
-  ): GainNode {
-    const destination =
-      this.resolveDestination(el, timing.scheduledAt, timing.compositionTime, timing.rate) ??
-      masterGain;
-    const soloGain = ctx.createGain();
-    soloGain.gain.value = isAudibleUnderSolo(this._soloed, el.id, audioGroupOf(el)) ? 1 : 0;
-    gainNode.connect(soloGain);
-    soloGain.connect(destination);
-    return soloGain;
-  }
-
   /**
    * Route the browser's pitch-preserving HTMLMediaElement transport through the
    * same FX, automation, element-gain, and master graph used by final audio.
@@ -311,11 +282,9 @@ export class WebAudioTransport {
       // its fallback), so routing it at master would have left every grouped
       // track bypassing the bus whose whole premise is that a group is one
       // signal.
-      const soloGain = this.connectThroughSolo(this._ctx, this._masterGain, el, gainNode, {
-        scheduledAt,
-        compositionTime,
-        rate: safeRate,
-      });
+      gainNode.connect(
+        this.resolveDestination(el, scheduledAt, compositionTime, safeRate) ?? this._masterGain,
+      );
       scheduleVolumeLane(el, gainNode, timing);
 
       this._rate = safeRate;
@@ -328,7 +297,6 @@ export class WebAudioTransport {
         sourceNode,
         sourceKind: "media-element",
         gainNode,
-        soloGain,
         compositionStart,
         mediaStart: _mediaStart,
         scheduledAt,
@@ -515,7 +483,6 @@ export class WebAudioTransport {
       sourceNode.disconnect();
       scheduled.fx?.dispose();
       scheduled.gainNode.disconnect();
-      scheduled.soloGain.disconnect();
     } catch {
       // Already torn down.
     }
@@ -568,11 +535,9 @@ 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.connectThroughSolo(this._ctx, this._masterGain, el, gainNode, {
-        scheduledAt,
-        compositionTime,
-        rate: safeRate,
-      });
+      gainNode.connect(
+        this.resolveDestination(el, scheduledAt, compositionTime, safeRate) ?? this._masterGain,
+      );
 
       scheduleVolumeLane(el, gainNode, timing);
 
@@ -594,7 +559,6 @@ export class WebAudioTransport {
         sourceNode.disconnect();
         fx?.dispose();
         gainNode.disconnect();
-        soloGain.disconnect();
         return null;
       }
 
@@ -608,7 +572,6 @@ export class WebAudioTransport {
         sourceNode,
         sourceKind: "buffer",
         gainNode,
-        soloGain,
         compositionStart,
         mediaStart,
         scheduledAt,
@@ -690,7 +653,6 @@ export class WebAudioTransport {
         source.sourceNode.disconnect();
         source.fx?.dispose();
         source.gainNode.disconnect();
-        source.soloGain.disconnect();
       } catch {
         // already stopped
       }
@@ -735,25 +697,6 @@ export class WebAudioTransport {
     this.applyMasterGain();
   }
 
-  /** Update every active source without rebuilding the graph. Group ids solo
-   * all members through the shared audibility predicate. */
-  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);
-      }
-    }
-  }
-
   private applyMasterGain(): void {
     if (this._masterGain) this._masterGain.gain.value = this._masterMuted ? 0 : this._masterVolume;
   }