srt parameter was enabled at synthesis timeflash and instruct_mode paths do not produce SRT).GET /api/tts/stream/{id}: this endpoint is JWT-exempt (app.js:263),auth carrying a 32-character static token, Redis key auth:user:{token}, TTL 7 days.AUTH_FORBIDDEN.Content-Type: text/plain, the body is raw SRT text, not JSON200,{"status": 204}. Judge presence of subtitles by body shape, not by HTTP status alone{ status, code, message, requestId? }. code is always the parent code — sub codes only change message and never appear in the body. requestId is present only on reportable-tier errors, so use the X-Vocu-App-Request-Id response header when troubleshooting (it is written unconditionally on every response). See the "Errors" document for the full code reference.