test: assertions the adversarial review found missing -- log lines, immediate saves, snapshot isolation, store and temp-file failures, bounded snippet, identical list (review F9)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/uploads/worker_test.go

@@ -23,8 +23,10 @@ type wStore struct {
 	completed map[string]domain.Transcription
 	failed    map[string]domain.UploadErrorKind
 	startErr  error
-	saves     [][]domain.ProgressStep
-	beats     int
+	// completeErr makes CompleteUpload fail, as a database outage would.
+	completeErr error
+	saves       [][]domain.ProgressStep
+	beats       int
 	// beatDelay makes each heartbeat write slow, so one is still in flight when a job
 	// ends -- which is what proves the worker waits for its heartbeat to finish.
 	beatDelay time.Duration
@@ -44,6 +46,9 @@ func (s *wStore) StartTranscribing(_ context.Context, _, id string) error {
 func (s *wStore) CompleteUpload(_ context.Context, _, id string, t domain.Transcription) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
+	if s.completeErr != nil {
+		return s.completeErr
+	}
 	s.completed[id] = t
 	return nil
 }
@@ -208,6 +213,10 @@ func TestWorkerProcess_FailuresAreTypedAndStillDeleteTheAudio(t *testing.T) {
 	}{
 		{"conversion fails", func(r *wrig) { r.conv.err = errors.New("moov atom not found") }},
 		{"every transcription endpoint fails", func(r *wrig) { r.tr.err = errors.New("iguana down; berget down") }},
+		{"storing the finished transcript fails", func(r *wrig) { r.st.completeErr = errors.New("db down") }},
+		{"the temporary WAV cannot be created", func(r *wrig) {
+			r.w = uploads.NewWorker(r.st, r.conv, r.tr, filepath.Join(r.tmp, "missing"), time.Minute)
+		}},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {