fix(lotus): denoise restart fallback must not hand LiveKit its own raw track

On a failed restart() the processor set processedTrack to the LiveKit-owned
input track. LiveKit's internalStopProcessor() stops processedTrack and then
republishes _mediaStreamTrack — the same object — so any later
stopProcessor()/teardown killed the live mic for the rest of the session.
Leave processedTrack undefined so LiveKit falls through to its own track.
Unit-tested.

Fixes #2

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/lotus/lotusDenoiseProcessor.test.ts

@@ -0,0 +1,55 @@
+/*
+Copyright 2026 Lotus Guild
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+import { describe, expect, test } from "vitest";
+import { type AudioProcessorOptions } from "livekit-client";
+
+import { LotusDenoiseProcessor } from "./lotusDenoiseProcessor";
+
+function makeProcessor(): LotusDenoiseProcessor {
+  return new LotusDenoiseProcessor({
+    model: "rnnoise",
+    assetBase: "https://example.invalid/denoise/",
+    gate: false,
+    gateThreshold: -45,
+    floor: 0.15,
+  });
+}
+
+describe("LotusDenoiseProcessor.restart", () => {
+  test("falls back to processedTrack = undefined (never the raw LiveKit track) when graph rebuild fails", async () => {
+    const processor = makeProcessor();
+
+    // Stub out the AudioContext/graph plumbing: pretend the context is fine
+    // but the graph rebuild (wasm load / worklet construction) throws, which
+    // is the path this test targets.
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (processor as any).ensureContext = async (): Promise<void> => {
+      await Promise.resolve();
+    };
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (processor as any).buildGraph = async (): Promise<never> => {
+      await Promise.resolve();
+      throw new Error("simulated graph build failure");
+    };
+
+    const rawTrack = {
+      stop: (): void => undefined,
+    } as unknown as MediaStreamTrack;
+
+    await processor.restart({
+      track: rawTrack,
+    } as unknown as AudioProcessorOptions);
+
+    // Must NOT be the raw, LiveKit-owned track: LiveKit's
+    // internalStopProcessor() calls `processor.processedTrack?.stop()` then
+    // re-publishes the same `_mediaStreamTrack` object, which would kill the
+    // live mic on the next stopProcessor()/teardown if we handed it back here.
+    expect(processor.processedTrack).toBeUndefined();
+    expect(processor.processedTrack).not.toBe(rawTrack);
+  });
+});

src/lotus/lotusDenoiseProcessor.ts

@@ -12,11 +12,7 @@ import {
 } from "livekit-client";
 import { logger } from "matrix-js-sdk/lib/logger";
 
-export type LotusDenoiseModel =
-  | "rnnoise"
-  | "speex"
-  | "dtln"
-  | "deepfilternet";
+export type LotusDenoiseModel = "rnnoise" | "speex" | "dtln" | "deepfilternet";
 
 export interface LotusDenoiseConfig {
   model: LotusDenoiseModel;
@@ -111,8 +107,8 @@ function supportsSimd(): boolean {
     // Minimal SIMD module (v128) — validates only where SIMD is supported.
     return WebAssembly.validate(
       new Uint8Array([
-        0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 96, 0, 1, 123, 3, 2, 1, 0, 10,
-        10, 1, 8, 0, 65, 0, 253, 15, 253, 98, 11,
+        0, 97, 115, 109, 1, 0, 0, 0, 1, 5, 1, 96, 0, 1, 123, 3, 2, 1, 0, 10, 10,
+        1, 8, 0, 65, 0, 253, 15, 253, 98, 11,
       ]),
     );
   } catch {
@@ -145,9 +141,10 @@ interface Graph {
  * stopped track on the sender: on failure it degrades to the RAW mic track
  * rather than silence.
  */
-export class LotusDenoiseProcessor
-  implements TrackProcessor<Track.Kind.Audio, AudioProcessorOptions>
-{
+export class LotusDenoiseProcessor implements TrackProcessor<
+  Track.Kind.Audio,
+  AudioProcessorOptions
+> {
   public readonly name = "lotus-denoise";
   public processedTrack?: MediaStreamTrack;
 
@@ -180,10 +177,16 @@ export class LotusDenoiseProcessor
       this.processedTrack = next.track;
     } catch (e) {
       // Never go silent on the A7/device-switch path: fall back to raw audio.
+      // [lotus] IMPORTANT: never assign `opts.track` (LiveKit-owned) here.
+      // LiveKit's internalStopProcessor() does `processor.processedTrack?.stop()`
+      // then re-publishes `_mediaStreamTrack` — the SAME object if we set it as
+      // processedTrack — which kills the live mic on the next stopProcessor()/
+      // teardown. Leaving processedTrack undefined makes LiveKit fall through to
+      // its own `_mediaStreamTrack` instead.
       logger.warn("[lotus] denoise restart failed; using raw mic", e);
       this.disposeGraph(this.graph);
       this.graph = undefined;
-      this.processedTrack = opts.track;
+      this.processedTrack = undefined;
     }
   }
 
@@ -209,7 +212,11 @@ export class LotusDenoiseProcessor
   /** Create (once) the model-rate context + register the flat worklet modules. */
   private async ensureContext(): Promise<void> {
     const rate = sampleRateFor(this.config.model);
-    if (this.ctx && this.ctx.state !== "closed" && this.ctx.sampleRate === rate) {
+    if (
+      this.ctx &&
+      this.ctx.state !== "closed" &&
+      this.ctx.sampleRate === rate
+    ) {
       if (this.ctx.state === "suspended") await resumeCtx(this.ctx);
       return;
     }
@@ -316,7 +323,12 @@ export class LotusDenoiseProcessor
       logger.info(
         `[lotus] denoise processor active (${this.config.model}, floor=${floor})`,
       );
-      return { source, nodes, disposes, track: dest.stream.getAudioTracks()[0] };
+      return {
+        source,
+        nodes,
+        disposes,
+        track: dest.stream.getAudioTracks()[0],
+      };
     } catch (e) {
       // A node constructor / model load can throw mid-build; clean up the
       // partially-built graph so it doesn't leak (init/restart still fall back
@@ -338,15 +350,20 @@ export class LotusDenoiseProcessor
     if (model === "dtln") {
       // Self-contained ESM that resolves its own processor + LiteRT wasm +
       // TFLite models. bypassUntilReady passes raw audio until the model loads.
-      const mod = await import(/* @vite-ignore */ `${base}workadventure/audio-worklet.js`);
+      const mod = await import(
+        /* @vite-ignore */ `${base}workadventure/audio-worklet.js`
+      );
       return (await mod.createNoiseSuppressionAudioWorklet(ctx, {
         bypassUntilReady: true,
       })) as MlNode;
     }
 
     if (model === "deepfilternet") {
-      const dfnBase = new URL(`${base}deepfilternet`, window.location.href).href;
-      const mod = await import(/* @vite-ignore */ `${base}deepfilternet/index.esm.js`);
+      const dfnBase = new URL(`${base}deepfilternet`, window.location.href)
+        .href;
+      const mod = await import(
+        /* @vite-ignore */ `${base}deepfilternet/index.esm.js`
+      );
       const core = new mod.DeepFilterNet3Core({
         sampleRate: 48_000,
         // 60, not 80: full-strength suppression is the main source of the
@@ -379,7 +396,10 @@ export class LotusDenoiseProcessor
       numberOfOutputs: 1,
       processorOptions: { maxChannels: 1, wasmBinary },
     });
-    return { node, dispose: () => void safeCall(() => node.port.postMessage("destroy")) };
+    return {
+      node,
+      dispose: () => void safeCall(() => node.port.postMessage("destroy")),
+    };
   }
 
   private disposeGraph(graph: Graph | undefined): void {