Implement real transcribe stage

internal/adapters/whisperx/fake.go

@@ -1,6 +1,12 @@
 package whisperx
 
-import "context"
+import (
+	"context"
+	"os"
+	"path/filepath"
+)
+
+var minimalTranscriptJSON = []byte(`{"schema":"speaker_transcript.v1","segments":[]}`)
 
 // NoopClient is a deterministic no-op WhisperX adapter.
 type NoopClient struct{}
@@ -10,6 +16,9 @@ func (n *NoopClient) Transcribe(ctx context.Context, req TranscribeRequest) (Tra
 	if err := ctx.Err(); err != nil {
 		return TranscribeResult{}, err
 	}
+	if err := writeMinimalJSON(req.OutputRawTranscriptPath); err != nil {
+		return TranscribeResult{}, err
+	}
 	return TranscribeResult{
 		OutputRawTranscriptPath: req.OutputRawTranscriptPath,
 		Attempts:                1,
@@ -22,9 +31,10 @@ func (n *NoopClient) Transcribe(ctx context.Context, req TranscribeRequest) (Tra
 
 // FakeClient captures requests and returns deterministic responses for tests.
 type FakeClient struct {
-	Requests []TranscribeRequest
-	Err      error
-	Result   TranscribeResult
+	Requests     []TranscribeRequest
+	Err          error
+	Result       TranscribeResult
+	TranscribeFn func(ctx context.Context, req TranscribeRequest) (TranscribeResult, error)
 }
 
 // Transcribe records the request and returns either configured error or result.
@@ -33,6 +43,9 @@ func (f *FakeClient) Transcribe(ctx context.Context, req TranscribeRequest) (Tra
 		return TranscribeResult{}, err
 	}
 	f.Requests = append(f.Requests, req)
+	if f.TranscribeFn != nil {
+		return f.TranscribeFn(ctx, req)
+	}
 	if f.Err != nil {
 		return TranscribeResult{}, f.Err
 	}
@@ -46,5 +59,18 @@ func (f *FakeClient) Transcribe(ctx context.Context, req TranscribeRequest) (Tra
 	if res.Metadata == nil {
 		res.Metadata = map[string]any{"fake": true}
 	}
+	if err := writeMinimalJSON(res.OutputRawTranscriptPath); err != nil {
+		return TranscribeResult{}, err
+	}
 	return res, nil
 }
+
+func writeMinimalJSON(path string) error {
+	if path == "" {
+		return nil
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	return os.WriteFile(path, minimalTranscriptJSON, 0o644)
+}