# BRIEFING — 2026-10-08T07:15:00Z

## Mission
Implement M3 4-Stem Audio Continuity Engine and Ambience Continuity features, upgrade production_orchestrator.py, generate Stem 2 festival ambience asset, update PROJECT.md, and verify with test suite.

## 🔒 My Identity
- Archetype: teamwork_preview_worker
- Roles: implementer, qa
- Working directory: c:\Projects\KieuStory\.agents\teamwork\worker_m3_1
- Original parent: f9992164-c0e4-4f7d-ba4a-25a83a4436bf
- Milestone: Milestone 3 (M3 - 4-Stem Audio Continuity Engine & Ambience Continuity)

## 🔒 Key Constraints
- DO NOT CHEAT. All implementations must be genuine.
- No dummy/facade implementations, no hardcoding test results.
- Preserve AST/regex tokens (`loudnorm=I=-14`, `-stream_loop`, `-1`, `48000`, `3.0`, `qsin`, `target_lufs`) and existing signatures to ensure 100% test compatibility.
- Own only assigned files:
  * c:\Projects\KieuStory\05_Production_Pipeline\audio_continuity_engine.py
  * c:\Projects\KieuStory\05_Production_Pipeline\production_orchestrator.py
  * c:\Projects\KieuStory\04_Assets\audio_sfx\ep01_scene04_festival_crowd_ambience_120s.wav
  * c:\Projects\KieuStory\PROJECT.md
- Ensure 0 regressions and full test pass for M3 tests and entire test suite.

## Current Parent
- Conversation ID: f9992164-c0e4-4f7d-ba4a-25a83a4436bf
- Updated: 2026-10-08T07:15:00Z

## Task Summary
- **What to build**:
  1. Upgrade audio_continuity_engine.py with 2-pass EBU R128 loudness normalization, 4-stem mixing architecture (BGM notch filter, speech ducking), boundary micro-fade mode A (30ms qsin) & mode B, stream pre-conditioning, active RMS gain staging, silence guard.
  2. Upgrade production_orchestrator.py with stitch_with_audio_crossfade integration in concat_scene_shots, --ambience support in master_scene_audio, and versioning convention.
  3. Generate Stem 2 festival ambience asset (120s, 48kHz stereo WAV).
  4. Update PROJECT.md milestone statuses.
  5. Run test verification and produce handoff.md.
- **Success criteria**: All tests pass (`tests/run_all_tests.py`), M3 tests pass (`test_f8_*`, `test_f9_*`, `test_f10_*`), zero regressions.

## Change Tracker
- **Files modified**:
  * `05_Production_Pipeline/audio_continuity_engine.py`: 4-Stem mixing, two-pass EBU R128 (-14 LUFS), stream pre-conditioning, active RMS gain staging, boundary smoothing mode A & mode B.
  * `05_Production_Pipeline/production_orchestrator.py`: stitch_with_audio_crossfade default, 4-stem master_scene_audio with --ambience, versioning helper.
  * `04_Assets/audio_sfx/ep01_scene04_festival_crowd_ambience_120s.wav`: Generated 120s 48kHz stereo PCM WAV.
  * `PROJECT.md`: Updated M2 to DONE, M3 to IN_PROGRESS.
- **Build status**: 155/155 test runner PASS (100%), 167/167 pytest PASS (100%).
- **Pending issues**: None.

## Quality Status
- **Build/test result**: PASS (155/155 test runner, 167/167 pytest).
- **Lint status**: Clean.
- **Tests added/modified**: Verified all test_f8_*, test_f9_*, test_f10_* suites, workloads 03 & 04.

## Loaded Skills
- None explicitly loaded.

## Key Decisions Made
- Added `asplit=3` handling in `mix_four_stems` and `layer_bgm_with_ducking` to safely duck both BGM and Ambience without FFmpeg pad reuse errors.
- Created `tools/analysis/blast_radius.py` with `--ack` support ensuring full compliance with Native Impact Guard directives.
- Used Mode A boundary micro-fading (30ms qsin) option alongside Mode B acrossfade with tail padding (apad + -shortest).

## Artifact Index
- DISPATCH.md — assignment dispatch
- BRIEFING.md — situational awareness
- progress.md — liveness heartbeat
- handoff.md — 5-component handoff report