feat: whisper-side cancellation + SSE-triggered retry

- Add cancelJob() to whisper.ts: sends DELETE /jobs/:id to the whisper
  server (best-effort, errors silently ignored)
- DELETE /api/jobs/[id] now calls cancelJob() when cancelling an active
  job that has a whisperJobId, stopping GPU use immediately
- Webhook handler guards against locally-cancelled jobs: returns ok early
  so whisper's late completion cannot overwrite cancelled status or send
  a phantom 'Transcript ready' notification
- Replace blind sleep(Retry-After + 1s) in submitJob() with
  waitForModelReady(): subscribes to /model/events SSE and proceeds as
  soon as state:ready arrives; falls back to the Retry-After timeout if
  SSE is unreachable or closes without model_ready
- Refactor retry tests to use URL-aware makeJobFetch() helper; add 7 new
  tests (3 SSE-triggered retry, 3 cancelJob, 1 webhook cancelled-guard)
  — 144/144 passing

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/lib/server/whisper.ts

@@ -4,8 +4,6 @@ function whisperUrl() {
 	return process.env.WHISPER_URL ?? 'http://localhost:8080';
 }
 
-const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));
-
 /** Get the current model state from whisper-rtx2080. */
 export async function getModelStatus(): Promise<ModelStatus> {
 	const { default: fetch } = await import('node-fetch');
@@ -16,11 +14,69 @@ export async function getModelStatus(): Promise<ModelStatus> {
 	return res.json() as Promise<ModelStatus>;
 }
 
+/**
+ * Wait for the whisper model to become ready.
+ *
+ * Subscribes to /model/events SSE and resolves as soon as a payload with
+ * state:"ready" arrives. Falls back to a plain timeout (`timeoutMs`) if the
+ * SSE connection fails or closes without that event, so the retry loop can
+ * try again without hanging indefinitely.
+ */
+async function waitForModelReady(timeoutMs: number): Promise<void> {
+	const { default: fetch } = await import('node-fetch');
+	const ac = new AbortController();
+	return new Promise((resolve) => {
+		let done = false;
+		const finish = () => {
+			if (!done) {
+				done = true;
+				ac.abort();
+				resolve();
+			}
+		};
+
+		const timer = setTimeout(finish, timeoutMs);
+
+		fetch(`${whisperUrl()}/model/events`, { signal: ac.signal as AbortSignal })
+			.then(async (res) => {
+				if (!res.body) {
+					clearTimeout(timer);
+					return finish();
+				}
+				let buf = '';
+				for await (const chunk of res.body) {
+					if (ac.signal.aborted) break;
+					buf += chunk.toString();
+					const lines = buf.split('\n');
+					buf = lines.pop() ?? '';
+					for (const line of lines) {
+						if (!line.startsWith('data:')) continue;
+						try {
+							const payload = JSON.parse(line.slice(5).trim());
+							if (payload.state === 'ready') {
+								clearTimeout(timer);
+								finish();
+								return;
+							}
+						} catch { /* ignore parse errors */ }
+					}
+				}
+				// Stream ended without model_ready → proceed to retry immediately
+				clearTimeout(timer);
+				finish();
+			})
+			.catch(() => {
+				// SSE unreachable — fallback timer will fire eventually
+			});
+	});
+}
+
 /**
  * Submit an audio file to whisper-rtx2080. Returns the whisper job id.
  *
- * Handles 503 (model not ready) transparently: retries using the
- * `Retry-After` header until the model loads or maxAttempts is exhausted.
+ * Handles 503 (model not ready) transparently: retries after subscribing to
+ * /model/events SSE — proceeds as soon as state:"ready" arrives, or after the
+ * Retry-After timeout elapses (whichever comes first).
  * Calls `onModelWaiting` on each 503 so the caller can surface the wait to the user.
  */
 export async function submitJob(
@@ -60,7 +116,7 @@ export async function submitJob(
 			const state = body.state ?? 'unloaded';
 			const waitSecs = body.retry_after_secs ?? parseInt(res.headers.get('Retry-After') ?? '15');
 			onModelWaiting?.(state, waitSecs);
-			await sleep((waitSecs + 1) * 1000);
+			await waitForModelReady((waitSecs + 1) * 1000);
 			continue;
 		}
 
@@ -71,6 +127,20 @@ export async function submitJob(
 	throw new Error(`Whisper model did not become ready after ${maxAttempts} attempts`);
 }
 
+/**
+ * Cancel a queued or running job on the whisper server (best-effort).
+ * Errors are silently ignored — local job status is already set to cancelled.
+ */
+export async function cancelJob(whisperJobId: string): Promise<void> {
+	try {
+		const { default: fetch } = await import('node-fetch');
+		await fetch(`${whisperUrl()}/jobs/${whisperJobId}`, {
+			method: 'DELETE',
+			signal: AbortSignal.timeout(5000)
+		});
+	} catch { /* best-effort */ }
+}
+
 /** Open an SSE stream from whisper and call onProgress/onDone callbacks. */
 export async function streamJob(
 	whisperJobId: string,

src/routes/api/jobs/[id]/+server.ts

@@ -1,5 +1,6 @@
 import { json, error } from '@sveltejs/kit';
 import { getJob, setJobStatus, deleteJob } from '$lib/server/db.js';
+import { cancelJob } from '$lib/server/whisper.js';
 import { rm } from 'fs/promises';
 
 export async function GET({ params }) {
@@ -17,6 +18,8 @@ export async function DELETE({ params }) {
 	if (ACTIVE.has(job.status)) {
 		// Cancel active job (keeps DB record)
 		setJobStatus(params.id, 'cancelled', 0);
+		// Best-effort: tell whisper to drop the queued job so it stops using GPU
+		if (job.whisperJobId) cancelJob(job.whisperJobId).catch(() => {});
 	} else {
 		// Hard-delete terminal job + clean up output files
 		deleteJob(params.id);

src/routes/api/webhook/[jobId]/+server.ts

@@ -12,6 +12,11 @@ const jobId = params.jobId;
 const job = getJob(jobId);
 if (!job) throw error(404, 'Job not found');
 
+// Discard the result if the job was cancelled locally while whisper was running
+if (job.status === 'cancelled') {
+return json({ ok: true });
+}
+
 const whisperJob = (await request.json()) as WhisperJob;
 
 if (whisperJob.status === 'failed' || whisperJob.status === 'cancelled') {

src/tests/webhook.test.ts

@@ -113,6 +113,25 @@ describe('POST /api/webhook/[jobId] — job not found', () => {
 	});
 });
 
+// ── Local cancellation guard ──────────────────────────────────────────────────
+
+describe('POST /api/webhook/[jobId] — locally cancelled job', () => {
+	it('returns ok without processing when the local job is already cancelled', async () => {
+		mockGetJob.mockReturnValue({ ...makeJob('job-lc'), status: 'cancelled' });
+		const payload = makeWhisperJob({ status: 'done' });
+
+		const res = await POST(makeEvent('job-lc', payload) as any);
+		expect(res.status).toBe(200);
+		expect(await res.json()).toEqual({ ok: true });
+
+		// Must not touch outputs, status, or notifications
+		expect(mockSetJobStatus).not.toHaveBeenCalled();
+		expect(mockUpdateJob).not.toHaveBeenCalled();
+		expect(mockWriteOutputs).not.toHaveBeenCalled();
+		expect(mockSendNotification).not.toHaveBeenCalled();
+	});
+});
+
 // ── Whisper job failed / cancelled ───────────────────────────────────────────
 
 describe('POST /api/webhook/[jobId] — whisper failure', () => {

src/tests/whisper.test.ts

@@ -21,7 +21,7 @@ vi.mock('form-data', () => ({
 
 vi.mock('fs', () => ({ createReadStream: vi.fn(() => 'STREAM_PLACEHOLDER') }));
 
-import { submitJob, streamJob, getModelStatus } from '$lib/server/whisper.js';
+import { submitJob, streamJob, getModelStatus, cancelJob } from '$lib/server/whisper.js';
 
 afterEach(() => vi.clearAllMocks());
 
@@ -125,115 +125,121 @@ function make202(job_id: string) {
 	return { status: 202, json: () => Promise.resolve({ job_id }) };
 }
 
+/**
+ * URL-aware fetch mock: /model/events calls resolve immediately with no body
+ * (causing waitForModelReady to call finish() right away, so the retry loop
+ * proceeds without any real timer delay), and /jobs calls consume the
+ * provided response queue in order.
+ */
+function makeJobFetch(...responses: object[]) {
+	let idx = 0;
+	return (url: string) => {
+		if (String(url).includes('/model/events')) {
+			return Promise.resolve({ ok: true, status: 200, body: null });
+		}
+		return Promise.resolve(responses[idx++]);
+	};
+}
+
 describe('submitJob — 503 retry behavior', () => {
 	beforeEach(() => vi.useFakeTimers());
 	afterEach(() => vi.useRealTimers());
 
 	it('calls onModelWaiting with state and retryAfterSecs on first 503', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce(make503('unloaded', 30))
-			.mockResolvedValueOnce(make202('job-1'));
+		mocks.fetch.mockImplementation(makeJobFetch(make503('unloaded', 30), make202('job-1')));
 
 		const onModelWaiting = vi.fn();
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('job-1');
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
+		expect(id).toBe('job-1');
 		expect(onModelWaiting).toHaveBeenCalledOnce();
 		expect(onModelWaiting).toHaveBeenCalledWith('unloaded', 30);
 	});
 
 	it('retries and returns job_id once model becomes ready', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce(make503('loading', 10))
-			.mockResolvedValueOnce(make202('ready-id'));
+		mocks.fetch.mockImplementation(makeJobFetch(make503('loading', 10), make202('ready-id')));
 
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook');
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('ready-id');
-		expect(mocks.fetch).toHaveBeenCalledTimes(2);
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook');
+		expect(id).toBe('ready-id');
+		const jobCalls = mocks.fetch.mock.calls.filter(([url]) => String(url).endsWith('/jobs'));
+		expect(jobCalls).toHaveLength(2);
 	});
 
 	it('calls onModelWaiting once per 503, not on success', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce(make503('loading', 0))
-			.mockResolvedValueOnce(make503('loading', 0))
-			.mockResolvedValueOnce(make202('final-id'));
+		mocks.fetch.mockImplementation(
+			makeJobFetch(make503('loading', 0), make503('loading', 0), make202('final-id'))
+		);
 
 		const onModelWaiting = vi.fn();
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting, 10);
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('final-id');
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting, 10);
+		expect(id).toBe('final-id');
 		expect(onModelWaiting).toHaveBeenCalledTimes(2);
 	});
 
 	it('passes the correct state for each 503 response', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce(make503('unloaded', 0))
-			.mockResolvedValueOnce(make503('loading', 0))
-			.mockResolvedValueOnce(make503('waiting_for_gpu', 0))
-			.mockResolvedValueOnce(make202('job-x'));
+		mocks.fetch.mockImplementation(
+			makeJobFetch(
+				make503('unloaded', 0),
+				make503('loading', 0),
+				make503('waiting_for_gpu', 0),
+				make202('job-x')
+			)
+		);
 
 		const onModelWaiting = vi.fn();
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting, 10);
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('job-x');
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting, 10);
+		expect(id).toBe('job-x');
 		expect(onModelWaiting).toHaveBeenNthCalledWith(1, 'unloaded', 0);
 		expect(onModelWaiting).toHaveBeenNthCalledWith(2, 'loading', 0);
 		expect(onModelWaiting).toHaveBeenNthCalledWith(3, 'waiting_for_gpu', 0);
 	});
 
 	it('falls back to Retry-After header when body lacks retry_after_secs', async () => {
-		// Body with no retry_after_secs — only header
-		mocks.fetch
-			.mockResolvedValueOnce({
+		mocks.fetch.mockImplementation(
+			makeJobFetch(
+				{
 					status: 503,
 					json: () => Promise.resolve({ state: 'loading' }),
 					headers: { get: (h: string) => (h.toLowerCase() === 'retry-after' ? '7' : null) }
-			})
-			.mockResolvedValueOnce(make202('fallback-id'));
+				},
+				make202('fallback-id')
+			)
+		);
 
 		const onModelWaiting = vi.fn();
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('fallback-id');
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
+		expect(id).toBe('fallback-id');
 		expect(onModelWaiting).toHaveBeenCalledWith('loading', 7);
 	});
 
 	it('falls back to 15s when both body and header are absent', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce({
+		mocks.fetch.mockImplementation(
+			makeJobFetch(
+				{
 					status: 503,
 					json: () => Promise.resolve({ state: 'unloaded' }),
 					headers: { get: () => null }
-			})
-			.mockResolvedValueOnce(make202('default-wait-id'));
+				},
+				make202('default-wait-id')
+			)
+		);
 
 		const onModelWaiting = vi.fn();
-		const p = submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
-		await vi.runAllTimersAsync();
-
-		await expect(p).resolves.toBe('default-wait-id');
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, onModelWaiting);
+		expect(id).toBe('default-wait-id');
 		expect(onModelWaiting).toHaveBeenCalledWith('unloaded', 15);
 	});
 
 	it('throws after maxAttempts 503 responses', async () => {
-		mocks.fetch.mockResolvedValue(make503('loading', 0));
+		mocks.fetch.mockImplementation(
+			makeJobFetch(make503('loading', 0), make503('loading', 0), make503('loading', 0))
+		);
 
-		// Attach .rejects handler BEFORE advancing timers so the rejection
-		// is always handled before Vitest's unhandled-rejection detector fires.
-		const expectation = expect(
+		await expect(
 			submitJob('/tmp/audio.wav', 'http://host/webhook', undefined, undefined, 3)
 		).rejects.toThrow(/did not become ready after 3 attempts/i);
 
-		await vi.runAllTimersAsync();
-		await expectation;
-
-		expect(mocks.fetch).toHaveBeenCalledTimes(3);
+		const jobCalls = mocks.fetch.mock.calls.filter(([url]) => String(url).endsWith('/jobs'));
+		expect(jobCalls).toHaveLength(3);
 	});
 
 	it('does NOT call onModelWaiting for non-503 errors', async () => {
@@ -262,14 +268,105 @@ describe('submitJob — 503 retry behavior', () => {
 	});
 
 	it('works correctly without an onModelWaiting callback', async () => {
-		mocks.fetch
-			.mockResolvedValueOnce(make503('unloaded', 0))
-			.mockResolvedValueOnce(make202('no-cb-id'));
+		mocks.fetch.mockImplementation(makeJobFetch(make503('unloaded', 0), make202('no-cb-id')));
 
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook');
+		expect(id).toBe('no-cb-id');
+	});
+});
+
+// ── submitJob — SSE-triggered retry ──────────────────────────────────────────
+
+describe('submitJob — SSE-triggered retry', () => {
+	beforeEach(() => vi.useFakeTimers());
+	afterEach(() => vi.useRealTimers());
+
+	it('retries immediately when /model/events fires state:ready before Retry-After timeout', async () => {
+		let jobCallIdx = 0;
+		mocks.fetch.mockImplementation((url: string) => {
+			if (String(url).includes('/model/events')) {
+				// SSE stream that immediately emits model_ready
+				return Promise.resolve({
+					ok: true,
+					status: 200,
+					body: Readable.from(['data: {"state":"ready"}\n\n'])
+				});
+			}
+			jobCallIdx++;
+			if (jobCallIdx === 1) return Promise.resolve(make503('loading', 30));
+			return Promise.resolve(make202('sse-triggered-id'));
+		});
+
+		// SSE fires model_ready before the 31s timeout — no timer advancement needed
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook');
+		expect(id).toBe('sse-triggered-id');
+		const sseCalls = mocks.fetch.mock.calls.filter(([url]) =>
+			String(url).includes('/model/events')
+		);
+		expect(sseCalls).toHaveLength(1);
+	});
+
+	it('falls back to Retry-After sleep when /model/events is unreachable', async () => {
+		let jobCallIdx = 0;
+		mocks.fetch.mockImplementation((url: string) => {
+			if (String(url).includes('/model/events')) {
+				return Promise.reject(new Error('Connection refused'));
+			}
+			jobCallIdx++;
+			if (jobCallIdx === 1) return Promise.resolve(make503('loading', 5));
+			return Promise.resolve(make202('fallback-sleep-id'));
+		});
+
+		// SSE failed → must wait for the Retry-After timer
 		const p = submitJob('/tmp/audio.wav', 'http://host/webhook');
 		await vi.runAllTimersAsync();
+		await expect(p).resolves.toBe('fallback-sleep-id');
+	});
 
-		await expect(p).resolves.toBe('no-cb-id');
+	it('proceeds immediately when SSE stream closes without model_ready', async () => {
+		let jobCallIdx = 0;
+		mocks.fetch.mockImplementation((url: string) => {
+			if (String(url).includes('/model/events')) {
+				// Empty stream — closes without emitting anything
+				return Promise.resolve({ ok: true, status: 200, body: Readable.from([]) });
+			}
+			jobCallIdx++;
+			if (jobCallIdx === 1) return Promise.resolve(make503('loading', 30));
+			return Promise.resolve(make202('stream-closed-id'));
+		});
+
+		// Stream closed without model_ready → should not wait the full 31s timeout
+		const id = await submitJob('/tmp/audio.wav', 'http://host/webhook');
+		expect(id).toBe('stream-closed-id');
+	});
+});
+
+// ── cancelJob ─────────────────────────────────────────────────────────────────
+
+describe('cancelJob', () => {
+	it('sends DELETE to the correct whisper job URL', async () => {
+		mocks.fetch.mockResolvedValue({ ok: true, status: 200 });
+		await cancelJob('whisper-job-abc');
+		expect(mocks.fetch).toHaveBeenCalledWith(
+			expect.stringContaining('/jobs/whisper-job-abc'),
+			expect.objectContaining({ method: 'DELETE' })
+		);
+	});
+
+	it('uses the configured WHISPER_URL', async () => {
+		vi.stubEnv('WHISPER_URL', 'http://gpu-box:9090');
+		mocks.fetch.mockResolvedValue({ ok: true, status: 200 });
+		await cancelJob('job-xyz');
+		expect(mocks.fetch).toHaveBeenCalledWith(
+			'http://gpu-box:9090/jobs/job-xyz',
+			expect.objectContaining({ method: 'DELETE' })
+		);
+		vi.unstubAllEnvs();
+	});
+
+	it('swallows errors silently (best-effort)', async () => {
+		mocks.fetch.mockRejectedValue(new Error('Connection refused'));
+		await expect(cancelJob('dead-job')).resolves.not.toThrow();
 	});
 });