diff --git a/src/bundles/sound/src/__tests__/recording.test.ts b/src/bundles/sound/src/__tests__/recording.test.ts
index ce4ec3e1b7..0d13fd3078 100644
--- a/src/bundles/sound/src/__tests__/recording.test.ts
+++ b/src/bundles/sound/src/__tests__/recording.test.ts
@@ -9,6 +9,7 @@ beforeEach(() => {
   funcs.setSoundIO(io);
   funcs.globalVars.micPermissionGranted = null;
   funcs.globalVars.activePlayCount = 0;
+  funcs.globalVars.recordingInProgress = false;
 });
 
 describe(funcs.init_record, () => {
@@ -70,6 +71,20 @@ describe('Recording functions', () => {
       expect(() => funcs.record(1)).toThrowError('record: Cannot record while another sound is playing!');
     });
 
+    test('reserves recording state synchronously before startRecording fires', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      funcs.record(1);
+
+      expect(() => funcs.record(1)).toThrowError('record: Cannot record while another recording is in progress!');
+      expect(() => funcs.record_for(1, 1)).toThrowError(
+        'record_for: Cannot record while another recording is in progress!'
+      );
+      expect(io.startRecording).not.toHaveBeenCalled();
+    });
+
     test(`${funcs.record.name} works`, async () => {
       vi.useRealTimers();
       await funcs.init_record();
@@ -94,6 +109,28 @@ describe('Recording functions', () => {
       expect(funcs.get_duration(sound)).toBeCloseTo(samples.length / sampleRate);
       // A mono mic (left === right, same Float32Array) produces a Sound with left=right automatically.
       expect(funcs.get_left_wave(sound)).toBe(funcs.get_right_wave(sound));
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+    });
+
+    test('stop is idempotent and only stops the recording once', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      const samples = new Float32Array([0]);
+      io.stopRecording.mockResolvedValue({ left: samples, right: samples, sampleRate: 8000 });
+
+      const stop = funcs.record(0);
+      await vi.advanceTimersByTimeAsync(300);
+
+      const soundPromise0 = stop();
+      const soundPromise1 = stop();
+      await vi.advanceTimersByTimeAsync(0);
+
+      expect(io.stopRecording).toHaveBeenCalledOnce();
+      expect(soundPromise0()).toBe(soundPromise1());
+      await expect(soundPromise0()).resolves.toBeDefined();
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
     });
 
     test('the sound promise resolves only once processing has actually finished, not immediately', async () => {
@@ -122,6 +159,69 @@ describe('Recording functions', () => {
       expect(resolved).toBe(true);
     });
 
+    test('releases recording state if stopRecording rejects', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      io.stopRecording.mockRejectedValueOnce(new Error('stop failed'));
+
+      const stop = funcs.record(0);
+      await vi.advanceTimersByTimeAsync(300);
+
+      const soundPromise = stop();
+      const recording = soundPromise();
+      void recording.catch(() => undefined);
+      await vi.advanceTimersByTimeAsync(0);
+
+      await expect(recording).rejects.toThrow('stop failed');
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+    });
+
+    test('releases recording state if startRecording rejects before stop is called', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      io.startRecording.mockRejectedValueOnce(new Error('start failed'));
+
+      funcs.record(0);
+      await vi.advanceTimersByTimeAsync(300);
+
+      expect(io.startRecording).toHaveBeenCalledOnce();
+      expect(io.stopRecording).not.toHaveBeenCalled();
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+    });
+
+    test('a stale stop after a failed start cannot release a newer recording', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      io.startRecording.mockRejectedValueOnce(new Error('start failed'));
+
+      const staleStop = funcs.record(0);
+      await vi.advanceTimersByTimeAsync(300);
+
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+
+      const samples = new Float32Array([0]);
+      io.stopRecording.mockResolvedValue({ left: samples, right: samples, sampleRate: 8000 });
+      const currentStop = funcs.record(0);
+
+      const staleSoundPromise = staleStop();
+      await expect(staleSoundPromise()).rejects.toThrow('start failed');
+
+      expect(funcs.globalVars.recordingInProgress).toBe(true);
+
+      await vi.advanceTimersByTimeAsync(300);
+      const currentSoundPromise = currentStop();
+      await vi.advanceTimersByTimeAsync(0);
+
+      await expect(currentSoundPromise()).resolves.toBeDefined();
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+    });
+
     test('a genuinely stereo input device produces a Sound with different left/right channels', async () => {
       vi.useRealTimers();
       await funcs.init_record();
@@ -152,6 +252,20 @@ describe('Recording functions', () => {
       expect(() => funcs.record_for(1, 1)).toThrowError('record_for: Cannot record while another sound is playing!');
     });
 
+    test('reserves recording state synchronously before startRecording fires', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      funcs.record_for(1, 1);
+
+      expect(() => funcs.record(1)).toThrowError('record: Cannot record while another recording is in progress!');
+      expect(() => funcs.record_for(1, 1)).toThrowError(
+        'record_for: Cannot record while another recording is in progress!'
+      );
+      expect(io.startRecording).not.toHaveBeenCalled();
+    });
+
     test(`${funcs.record_for.name} works`, async () => {
       vi.useRealTimers();
       await funcs.init_record();
@@ -170,6 +284,28 @@ describe('Recording functions', () => {
 
       const sound = await promise();
       expect(funcs.get_duration(sound)).toBeCloseTo(samples.length / sampleRate);
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
+    });
+
+    test('the returned promise is idempotent and releases recording state if stopRecording rejects', async () => {
+      vi.useRealTimers();
+      await funcs.init_record();
+      vi.useFakeTimers();
+
+      io.stopRecording.mockRejectedValueOnce(new Error('stop failed'));
+
+      const soundPromise = funcs.record_for(1, 0);
+      const recording0 = soundPromise();
+      const recording1 = soundPromise();
+      expect(recording0).toBe(recording1);
+      void recording0.catch(() => undefined);
+
+      await vi.advanceTimersByTimeAsync(1300);
+
+      expect(io.startRecording).toHaveBeenCalledOnce();
+      expect(io.stopRecording).toHaveBeenCalledOnce();
+      await expect(recording0).rejects.toThrow('stop failed');
+      expect(funcs.globalVars.recordingInProgress).toBe(false);
     });
   });
 });
diff --git a/src/bundles/sound/src/functions.ts b/src/bundles/sound/src/functions.ts
index 0b519d95fe..385d9b7907 100644
--- a/src/bundles/sound/src/functions.ts
+++ b/src/bundles/sound/src/functions.ts
@@ -58,11 +58,17 @@ interface BundleGlobalVars {
    * the mic picking up whatever's playing through the speakers.
    */
   activePlayCount: number;
+  /**
+   * True from the moment record()/record_for() accepts a request until that request either fails
+   * before starting or stopRecording() has settled.
+   */
+  recordingInProgress: boolean;
 }
 
 export const globalVars: BundleGlobalVars = {
   micPermissionGranted: null,
-  activePlayCount: 0
+  activePlayCount: 0,
+  recordingInProgress: false
 };
 
 /**
@@ -72,6 +78,7 @@ export const globalVars: BundleGlobalVars = {
  * on that count itself.
  */
 let playGeneration = 0;
+let recordingGeneration = 0;
 
 let soundIO: SoundTabRpc | undefined;
 
@@ -354,6 +361,25 @@ function assertMicPermission(func_name: string): void {
   }
 }
 
+function reserveRecording(func_name: string): number {
+  if (globalVars.activePlayCount > 0) {
+    throw new EvaluatorRuntimeError(`${func_name}: Cannot record while another sound is playing!`);
+  }
+  if (globalVars.recordingInProgress) {
+    throw new EvaluatorRuntimeError(`${func_name}: Cannot record while another recording is in progress!`);
+  }
+  assertMicPermission(func_name);
+  globalVars.recordingInProgress = true;
+  recordingGeneration += 1;
+  return recordingGeneration;
+}
+
+function releaseRecording(generation: number): void {
+  if (recordingGeneration === generation) {
+    globalVars.recordingInProgress = false;
+  }
+}
+
 /**
  * Records a sound until the returned stop function is called. Takes a buffer duration (in
  * seconds) as argument, and returns a nullary stop function. Calling the stop function returns a
@@ -375,10 +401,7 @@ function assertMicPermission(func_name: string): void {
  */
 export function record(buffer: number): () => () => Promise<Sound> {
   validateDuration('record', buffer);
-  if (globalVars.activePlayCount > 0) {
-    throw new EvaluatorRuntimeError(`${record.name}: Cannot record while another sound is playing!`);
-  }
-  assertMicPermission('record');
+  const generation = reserveRecording(record.name);
 
   const started = (async () => {
     await delay(pre_recording_signal_pause_ms + buffer * 1000);
@@ -386,13 +409,22 @@ export function record(buffer: number): () => () => Promise<Sound> {
     await delay(recording_signal_ms);
     await io().startRecording();
   })();
+  let recordingDone: Promise<Sound> | undefined;
+  void started.catch(() => {
+    if (!recordingDone) {
+      releaseRecording(generation);
+    }
+  });
 
   return () => {
-    const recordingDone: Promise<Sound> = started
-      .then(() => io().stopRecording())
-      .then(({ left, right, sampleRate }) => samplesToSound(left, right, sampleRate));
-    void play_recording_signal();
-    return () => recordingDone;
+    if (!recordingDone) {
+      recordingDone = started
+        .then(() => io().stopRecording())
+        .then(({ left, right, sampleRate }) => samplesToSound(left, right, sampleRate))
+        .finally(() => releaseRecording(generation));
+      void play_recording_signal();
+    }
+    return () => recordingDone!;
   };
 }
 
@@ -420,23 +452,24 @@ export function record(buffer: number): () => () => Promise<Sound> {
 export function record_for(duration: number, buffer: number): () => Promise<Sound> {
   validateDuration('record_for', duration);
   validateDuration('record_for', buffer);
-  if (globalVars.activePlayCount > 0) {
-    throw new EvaluatorRuntimeError(`${record_for.name}: Cannot record while another sound is playing!`);
-  }
-  assertMicPermission('record_for');
+  const generation = reserveRecording(record_for.name);
 
   // order of events for record_for:
   // pre-recording-signal pause | recording signal |
   // pre-recording pause | recording | recording signal
   const recordingDone: Promise<Sound> = (async () => {
-    await delay(pre_recording_signal_pause_ms);
-    await play_recording_signal();
-    await delay(recording_signal_ms + buffer * 1000);
-    await io().startRecording();
-    await delay(duration * 1000);
-    const { left, right, sampleRate } = await io().stopRecording();
-    void play_recording_signal();
-    return samplesToSound(left, right, sampleRate);
+    try {
+      await delay(pre_recording_signal_pause_ms);
+      await play_recording_signal();
+      await delay(recording_signal_ms + buffer * 1000);
+      await io().startRecording();
+      await delay(duration * 1000);
+      const { left, right, sampleRate } = await io().stopRecording();
+      void play_recording_signal();
+      return samplesToSound(left, right, sampleRate);
+    } finally {
+      releaseRecording(generation);
+    }
   })();
 
   return () => recordingDone;