Address review comments + more tests

backend/internal/job/scim_job.go

@@ -17,7 +17,7 @@ func (s *Scheduler) RegisterScimJobs(ctx context.Context, scimService *service.S
 	jobs := &ScimJobs{scimService: scimService}
 
 	// Register the job to run every hour (with some jitter)
-	return s.RegisterJob(ctx, "SyncScim", gocron.DurationJob(24*time.Hour), jobs.SyncScim, true)
+	return s.RegisterJob(ctx, "SyncScim", gocron.DurationJob(time.Hour), jobs.SyncScim, true)
 }
 
 func (j *ScimJobs) SyncScim(ctx context.Context) error {

backend/internal/service/app_lock_service.go

@@ -73,7 +73,10 @@ func (lv *lockValue) Unmarshal(raw string) error {
 // Acquire obtains the lock. When force is true, the lock is stolen from any existing owner.
 // If the lock is forcefully acquired, it blocks until the previous lock has expired.
 func (s *AppLockService) Acquire(ctx context.Context, force bool) (waitUntil time.Time, err error) {
-	tx := s.db.Begin()
+	tx := s.db.WithContext(ctx).Begin()
+	if tx.Error != nil {
+		return time.Time{}, fmt.Errorf("begin lock transaction: %w", tx.Error)
+	}
 	defer func() {
 		tx.Rollback()
 	}()

backend/internal/service/app_lock_service_test.go

@@ -49,6 +49,23 @@ func readLockValue(t *testing.T, db *gorm.DB) lockValue {
 	return value
 }
 
+func lockDatabaseForWrite(t *testing.T, db *gorm.DB) *gorm.DB {
+	t.Helper()
+
+	tx := db.Begin()
+	require.NoError(t, tx.Error)
+
+	// Keep a write transaction open to block other queries.
+	err := tx.Exec(
+		`INSERT INTO kv (key, value) VALUES (?, ?) ON CONFLICT(key) DO NOTHING`,
+		lockKey,
+		`{"expires_at":0}`,
+	).Error
+	require.NoError(t, err)
+
+	return tx
+}
+
 func TestAppLockServiceAcquire(t *testing.T) {
 	t.Run("creates new lock when none exists", func(t *testing.T) {
 		db := testutils.NewDatabaseForTest(t)
@@ -99,6 +116,66 @@ func TestAppLockServiceAcquire(t *testing.T) {
 		require.Equal(t, service.hostID, stored.HostID)
 		require.Greater(t, stored.ExpiresAt, time.Now().Unix())
 	})
+
+	t.Run("force acquisition returns wait duration when stealing active lock", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		existing := lockValue{
+			ProcessID: 99,
+			HostID:    "other-host",
+			LockID:    "other-lock-id",
+			ExpiresAt: time.Now().Add(ttl).Unix(),
+		}
+		insertLock(t, db, existing)
+
+		waitUntil, err := service.Acquire(context.Background(), true)
+		require.NoError(t, err)
+		require.WithinDuration(t, time.Unix(existing.ExpiresAt, 0), waitUntil, time.Second)
+	})
+
+	t.Run("force acquisition does not wait when lock id is unchanged", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		insertLock(t, db, lockValue{
+			ProcessID: 99,
+			HostID:    "other-host",
+			LockID:    service.lockID,
+			ExpiresAt: time.Now().Add(ttl).Unix(),
+		})
+
+		waitUntil, err := service.Acquire(context.Background(), true)
+		require.NoError(t, err)
+		require.True(t, waitUntil.IsZero())
+	})
+
+	t.Run("returns error when existing lock value is invalid JSON", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		raw := "this-is-not-json"
+		err := db.Create(&model.KV{Key: lockKey, Value: &raw}).Error
+		require.NoError(t, err)
+
+		_, err = service.Acquire(context.Background(), false)
+		require.ErrorContains(t, err, "decode existing lock value")
+	})
+
+	t.Run("returns context deadline exceeded when database is locked", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		tx := lockDatabaseForWrite(t, db)
+		defer tx.Rollback()
+
+		ctx, cancel := context.WithTimeout(context.Background(), 150*time.Millisecond)
+		defer cancel()
+
+		_, err := service.Acquire(ctx, false)
+		require.ErrorIs(t, err, context.DeadlineExceeded)
+		require.ErrorContains(t, err, "begin lock transaction")
+	})
 }
 
 func TestAppLockServiceRelease(t *testing.T) {
@@ -134,6 +211,24 @@ func TestAppLockServiceRelease(t *testing.T) {
 		stored := readLockValue(t, db)
 		require.Equal(t, existing, stored)
 	})
+
+	t.Run("returns context deadline exceeded when database is locked", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		_, err := service.Acquire(context.Background(), false)
+		require.NoError(t, err)
+
+		tx := lockDatabaseForWrite(t, db)
+		defer tx.Rollback()
+
+		ctx, cancel := context.WithTimeout(context.Background(), 150*time.Millisecond)
+		defer cancel()
+
+		err = service.Release(ctx)
+		require.ErrorIs(t, err, context.DeadlineExceeded)
+		require.ErrorContains(t, err, "release lock failed")
+	})
 }
 
 func TestAppLockServiceRenew(t *testing.T) {
@@ -186,4 +281,21 @@ func TestAppLockServiceRenew(t *testing.T) {
 		err = service.renew(context.Background())
 		require.ErrorIs(t, err, ErrLockLost)
 	})
+
+	t.Run("returns context deadline exceeded when database is locked", func(t *testing.T) {
+		db := testutils.NewDatabaseForTest(t)
+		service := newTestAppLockService(t, db)
+
+		_, err := service.Acquire(context.Background(), false)
+		require.NoError(t, err)
+
+		tx := lockDatabaseForWrite(t, db)
+		defer tx.Rollback()
+
+		ctx, cancel := context.WithTimeout(context.Background(), 150*time.Millisecond)
+		defer cancel()
+
+		err = service.renew(ctx)
+		require.ErrorIs(t, err, context.DeadlineExceeded)
+	})
 }

backend/resources/migrations/sqlite/20260304090200_indexes.up.sql

@@ -1,6 +1,12 @@
+PRAGMA foreign_keys= OFF;
+BEGIN;
+
 CREATE INDEX IF NOT EXISTS idx_webauthn_sessions_expires_at ON webauthn_sessions (expires_at);
 CREATE INDEX IF NOT EXISTS idx_one_time_access_tokens_expires_at ON one_time_access_tokens (expires_at);
 CREATE INDEX IF NOT EXISTS idx_oidc_authorization_codes_expires_at ON oidc_authorization_codes (expires_at);
 CREATE INDEX IF NOT EXISTS idx_oidc_refresh_tokens_expires_at ON oidc_refresh_tokens (expires_at);
 CREATE INDEX IF NOT EXISTS idx_reauthentication_tokens_expires_at ON reauthentication_tokens (expires_at);
-CREATE INDEX IF NOT EXISTS idx_email_verification_tokens_expires_at ON email_verification_tokens (expires_at);
+CREATE INDEX IF NOT EXISTS idx_email_verification_tokens_expires_at ON email_verification_tokens (expires_at);
+
+COMMIT;
+PRAGMA foreign_keys=ON;