Keep AI jobs alive during processing

internal/worker/worker.go

@@ -113,6 +113,9 @@ func (w *Worker) tick(ctx context.Context) {
 }
 
 func (w *Worker) process(ctx context.Context, job *model.Job) {
+	stopHeartbeat := w.startHeartbeat(ctx, job)
+	defer stopHeartbeat()
+
 	if job.TaskType == TaskTranscription {
 		w.processTranscription(ctx, job)
 		return
@@ -168,6 +171,41 @@ func (w *Worker) fail(ctx context.Context, job *model.Job, code, message string)
 	}
 }
 
+func (w *Worker) startHeartbeat(ctx context.Context, job *model.Job) func() {
+	heartbeatCtx, cancel := context.WithCancel(ctx)
+	done := make(chan struct{})
+	ticker := time.NewTicker(w.heartbeatInterval())
+	go func() {
+		defer close(done)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-heartbeatCtx.Done():
+				return
+			case <-ticker.C:
+				if err := w.store.HeartbeatJob(heartbeatCtx, job.ID); err != nil {
+					slog.Warn("heartbeat job failed", "job_id", job.ID, "error", err)
+				}
+			}
+		}
+	}()
+	return func() {
+		cancel()
+		<-done
+	}
+}
+
+func (w *Worker) heartbeatInterval() time.Duration {
+	interval := w.leaseTimeout / 3
+	if interval < 10*time.Second {
+		return 10 * time.Second
+	}
+	if interval > time.Minute {
+		return time.Minute
+	}
+	return interval
+}
+
 func classifyTranscriptionError(err error) string {
 	if err == nil {
 		return "unknown"