fix: tighten streaming failure handling from re-review

Addresses the CodeRabbit + Codex re-review of the prior commit.

- Normalize a rejected append (channel/handler error, not just a
  { success: false } result) into appendError, so the write queue never
  rejects and isStreaming() stays consistent after a failure (CodeRabbit).
- Handle a rejected open-stream IPC the same as a failed open: fall back
  to in-memory buffering instead of leaving the recorder stuck "pending"
  with an unhandled rejection (CodeRabbit).
- Discard a streamed webcam whose write failed even when the screen save
  succeeds. The cleanup gate is now per-recorder, so a webcam omitted from
  a successful screen-only save no longer leaks its stream and partial
  file (Codex).

Adds tests for the rejected-append and rejected-open paths.

Verified: tsc --noEmit clean; biome clean; vitest 182/182.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/hooks/recorderHandle.test.ts

@@ -90,6 +90,29 @@ describe("createRecorderHandle", () => {
 		expect(decode(await blob.arrayBuffer())).toBe("abc");
 	});
 
+	it("falls back to in-memory buffering when the open IPC call rejects", async () => {
+		const openRecordingStream = vi.fn(async () => {
+			throw new Error("ipc channel closed");
+		});
+		stubElectronAPI({
+			openRecordingStream,
+			appendRecordingChunk: vi.fn(async () => ({ success: true })),
+		});
+
+		const handle = createRecorderHandle({} as MediaStream, { mimeType: "video/webm" }, "rec.webm");
+		const fake = driver(handle);
+
+		fake.emit(new Blob(["a"]));
+		await tick(); // open rejects -> treated as a failed open, keep buffering
+		fake.emit(new Blob(["b"]));
+		fake.stop();
+
+		const blob = await handle.recordedBlobPromise;
+		expect(handle.isStreaming()).toBe(false);
+		expect(blob.size).toBe(2);
+		expect(decode(await blob.arrayBuffer())).toBe("ab");
+	});
+
 	it("waits for in-flight chunk writes before stop resolves (no truncation)", async () => {
 		let releaseAppend: () => void = () => undefined;
 		const appendGate = new Promise<void>((resolve) => {
@@ -142,6 +165,26 @@ describe("createRecorderHandle", () => {
 		expect(handle.isStreaming()).toBe(false);
 	});
 
+	it("treats a rejected append the same as a failed write", async () => {
+		stubElectronAPI({
+			openRecordingStream: vi.fn(async () => ({ success: true })),
+			appendRecordingChunk: vi.fn(async () => {
+				throw new Error("kernel said no");
+			}),
+			closeRecordingStream: vi.fn(async () => ({ success: true })),
+		});
+
+		const handle = createRecorderHandle({} as MediaStream, { mimeType: "video/webm" }, "rec.webm");
+		const fake = driver(handle);
+
+		await tick();
+		fake.emit(new Blob(["a"]));
+		fake.stop();
+
+		await expect(handle.recordedBlobPromise).rejects.toThrow(/kernel said no/);
+		expect(handle.isStreaming()).toBe(false);
+	});
+
 	it("buffers in memory and never opens a stream when no file name is given", async () => {
 		const openRecordingStream = vi.fn(async () => ({ success: true }));
 		stubElectronAPI({

src/hooks/recorderHandle.ts

@@ -61,11 +61,18 @@ export function createRecorderHandle(
 			if (appendError || !fileName || !api?.appendRecordingChunk) {
 				return;
 			}
+			// Capture both outcomes — a `{ success: false }` result and an outright
+			// rejection (channel/handler error) — into appendError, so writeChain
+			// never rejects and isStreaming() stays consistent after a failure.
+			try {
 				const buffer = await chunk.arrayBuffer();
 				const result = await api.appendRecordingChunk(fileName, buffer);
 				if (!result.success) {
 					appendError = new Error(result.error ?? "Failed to write recording chunk to disk");
 				}
+			} catch (error) {
+				appendError = error instanceof Error ? error : new Error(String(error));
+			}
 		});
 	};
 
@@ -74,7 +81,8 @@ export function createRecorderHandle(
 			? api.openRecordingStream(fileName)
 			: Promise.resolve({ success: false });
 
-	void openPromise.then((result) => {
+	void openPromise.then(
+		(result) => {
 			if (result.success) {
 				streamOpened = true;
 				mode = "streaming";
@@ -85,7 +93,13 @@ export function createRecorderHandle(
 			} else {
 				mode = "buffering";
 			}
-	});
+		},
+		() => {
+			// The IPC call itself rejected (channel or handler error). Treat it the
+			// same as a failed open: keep buffering in memory so nothing is lost.
+			mode = "buffering";
+		},
+	);
 
 	const recordedBlobPromise = new Promise<Blob>((resolve, reject) => {
 		recorder.ondataavailable = (event: BlobEvent) => {

src/hooks/useScreenRecorder.ts

@@ -328,10 +328,11 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 			window.electronAPI?.setRecordingState(false);
 
 			void (async () => {
-				// Set once the recording is safely stored. Until then any disk stream
-				// is still open, so the finally block closes it and removes the partial
-				// file on the discard or error paths.
-				let savedToDisk = false;
+				// Each disk stream must end up either saved or explicitly discarded.
+				// store-recorded-session finalizes the streams included in a successful
+				// save; the finally block discards everything else.
+				let storeSucceeded = false;
+				let webcamIncludedInSave = false;
 				try {
 					const screenBlob = await activeScreenRecorder.recordedBlobPromise;
 					if (discardRecordingId.current === activeRecordingId) {
@@ -364,6 +365,7 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 							webcamVideoData = new ArrayBuffer(0);
 						}
 					}
+					webcamIncludedInSave = webcamVideoData !== undefined;
 
 					const result = await window.electronAPI.storeRecordedSession({
 						screen: {
@@ -383,8 +385,8 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 						console.error("Failed to store recording session:", result.message);
 						return;
 					}
-					// store-recorded-session has flushed and closed the disk streams.
-					savedToDisk = true;
+					// store-recorded-session has flushed and closed the saved streams.
+					storeSucceeded = true;
 
 					if (result.session) {
 						await window.electronAPI.setCurrentRecordingSession(result.session);
@@ -396,12 +398,15 @@ export function useScreenRecorder(): UseScreenRecorderReturn {
 				} catch (error) {
 					console.error("Error saving recording:", error);
 				} finally {
-					if (!savedToDisk) {
-						// Discarded, or failed before a successful save — close any
-						// dangling disk streams and remove their partial files so a
-						// cancelled or failed run doesn't leak a descriptor or orphan.
+					// Discard any recorder whose data was not part of a successful save
+					// — a discarded run, a failed save, or a webcam whose disk write
+					// failed (so it was omitted while the screen still saved) — so no
+					// stream or partial file is left open or orphaned.
+					if (!storeSucceeded) {
 						await activeScreenRecorder.discard().catch(() => undefined);
-						await activeWebcamRecorder?.discard().catch(() => undefined);
+					}
+					if (activeWebcamRecorder && !(storeSucceeded && webcamIncludedInSave)) {
+						await activeWebcamRecorder.discard().catch(() => undefined);
 					}
 					if (finalizingRecordingId.current === activeRecordingId) {
 						finalizingRecordingId.current = null;