fix: sqlite concurrency defaults

internal/db/sqlite.go

@@ -10,9 +10,14 @@ import (
 
 // Open connects to a sqlite3 database with foreign keys enforced
 func Open(dbFile string) (*sql.DB, error) {
-	db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?_foreign_keys=on", dbFile))
+	// busy_timeout avoids immediate SQLITE_BUSY errors under concurrent access.
+	// foreign_keys ensures FK constraints are enforced for this connection.
+	db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?_foreign_keys=on&_busy_timeout=5000", dbFile))
 	if err != nil {
 		return nil, fmt.Errorf("failed to open db: %w", err)
 	}
+	// WAL improves concurrency between readers and writers.
+	_, _ = db.Exec("PRAGMA journal_mode=WAL;")
+	_, _ = db.Exec("PRAGMA busy_timeout=5000;")
 	return db, nil
 }

internal/episodes/worker.go

@@ -15,14 +15,22 @@ func RegisterWorker(lc fx.Lifecycle, svc domain.EpisodeService, metrics *observa
 	ctx, cancel := context.WithCancel(context.Background())
 
 	lc.Append(fx.Hook{
-		OnStart: func(context.Context) error {
+		OnStart: func(startCtx context.Context) error {
+			// Tie worker lifetime to fx lifecycle start context cancellation.
+			go func() {
+				<-startCtx.Done()
+				cancel()
+			}()
 			go func() {
 				observability.Info("episodes_worker_start", "episodes", "", nil)
 				ticker := time.NewTicker(workerInterval)
 				defer ticker.Stop()
 
 				for {
-					if err := svc.RefreshTrackedDue(ctx, 25); err != nil {
+					tickCtx, tickCancel := context.WithTimeout(ctx, 45*time.Second)
+					err := svc.RefreshTrackedDue(tickCtx, 25)
+					tickCancel()
+					if err != nil {
 						metrics.ObserveWorkerTick("episodes_availability", err)
 						observability.Warn(
 							"episodes_worker_tick_failed",