Reduce median scene-load latency from ~30-80s to ~17-25s by switching image generation to Runware FLUX.2 [klein] 9B KV and moving per-beat TTS synthesis off the scene response into a new lazy /api/beat-audio endpoint with hard timeout + abort support.
- feat(image): migrate to Runware FLUX.2 [klein] 9B KV — task-array API, $0.001/image, sub-second inference.
- feat(tts): split /api/scene into directScene + image + voicedesign-provisioning; lazily synth per beat via /api/beat-audio with 15s hard timeout + AbortSignal threaded to MiMo so timed-out calls don't keep burning sockets/quota; client fans out per-beat fetches on scene-id change with abort + identity-check finally to prevent cross-scene beat-id collisions.
- refactor(tts): slim BeatAudioRequest to { beat, voice } — ~800KB per-beat upload dropped to ~160KB by sending only the speaker's voice instead of the full session.
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Adds optional Xiaomi MiMo TTS layer on top of the scene/beat engine and a MOCK_IMAGE flag for cheap local TTS iteration.
- Per-character voice provisioning via MiMo voice design → clone, reference audio persisted in session
- Per-line free-form delivery direction (Director writes "鼓起勇气又害羞，声音发颤" style instructions; sent to MiMo's director channel, never read aloud)
- Per-beat audio served with the scene response; frontend plays via hidden <audio> with typewriter synced to audio duration; mute toggle persisted via localStorage lazy initializer
- Graceful degradation: any TTS step failing → silent beat, game continues
- MOCK_IMAGE=true returns a sharp-generated placeholder PNG so local TTS iteration doesn't burn image tokens
- Recommended config in .env.example: MiMo Token Plan covers TEXT/VISION/TTS with one key (mimo-v2.5-pro for text, mimo-v2.5 omni for vision, mimo-v2.5-tts for TTS)
Squashed from #3:
- feat(tts): 小米 MiMo 逐 beat 配音 + 按 session 角色音色 + 自由文本配音指导
- feat(engine): MOCK_IMAGE 占位图便于本地测试
- fix(tts): address Copilot review on PR #3
- fix(tts): Copilot round-2 review feedback
Known limitation: Session.characters carries the full WAV reference audio (~200-300KB/character base64) and round-trips through every /api/scene, /api/vision, /api/insert-beat request. This is intrinsic to MiMo's design→clone model (voice identity IS the audio, no server-side voiceId). Fixing requires server-side storage which is out of scope; documented for future hardening.
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Zonghao Yuan