Allow checkpoints for empty audio accepted by WhisperX

internal/app/transcribe_checkpoint_recovery_test.go

@@ -18,6 +18,57 @@ import (
 	"gitea.maximumdirect.net/eric/narratio/internal/stage"
 )
 
+func TestExecuteStagesDelegatesEmptyAudioAcceptanceToWhisperX(t *testing.T) {
+	for _, rejected := range []bool{false, true} {
+		name := "accepted"
+		if rejected {
+			name = "rejected"
+		}
+		t.Run(name, func(t *testing.T) {
+			cfg, store := setupTranscribeRecoveryFixture(t, []string{"alice"})
+			paths := artifacts.NewLocalStore(cfg.Pipeline.Workspace.Root).SessionPathsFor(cfg.Session.Campaign, cfg.Session.SessionID)
+			if err := os.WriteFile(filepath.Join(paths.AudioDir, "alice.flac"), nil, 0o644); err != nil {
+				t.Fatal(err)
+			}
+			fake := &whisperx.FakeClient{}
+			if rejected {
+				fake.Err = errors.New("service rejected audio")
+			}
+			transcribe := mustSelectStage(t, "transcribe")
+			_, err := executeStages(context.Background(), cfg, []stage.Stage{transcribe}, RunOptions{
+				Env: &Env{ManifestStore: store, WhisperX: fake},
+			})
+			if !errors.Is(err, fake.Err) {
+				t.Fatalf("transcribe error = %v, want %v", err, fake.Err)
+			}
+			if len(fake.RequestsSnapshot()) != 1 {
+				t.Fatal("empty audio was not sent to service")
+			}
+			m := loadTranscribeRecoveryManifest(t, store, cfg)
+			if rejected {
+				if len(m.Stages["transcribe"].TranscribeSpeakers) != 0 {
+					t.Fatal("rejected audio was checkpointed")
+				}
+				return
+			}
+			record, ok := m.Stages["transcribe"].TranscribeSpeakers["alice"]
+			if !ok || record.AudioSize != 0 {
+				t.Fatalf("missing zero-size checkpoint: %#v", record)
+			}
+			retry := &whisperx.FakeClient{}
+			summary, err := executeStages(context.Background(), cfg, []stage.Stage{transcribe}, RunOptions{
+				Env: &Env{ManifestStore: store, WhisperX: retry},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(summary.Skipped) != 1 || len(retry.RequestsSnapshot()) != 0 {
+				t.Fatal("successful empty-audio result was not reused")
+			}
+		})
+	}
+}
+
 func TestExecuteStagesRetriesOnlyUncommittedTranscribeSpeakers(t *testing.T) {
 	cfg, baseStore := setupTranscribeRecoveryFixture(t, []string{"a", "b", "c", "d"})
 	concurrency := 1