# Progress — Explorer 1 (Milestone M4: Concat, Audio Mastering & EBU R128 Architecture)

Last visited: 2026-10-09T07:55:00Z

## Status
- [x] Initialized DISPATCH.md, BRIEFING.md, progress.md with UTC timestamps
- [x] Mandatory reading complete: ORIGINAL_REQUEST.md, PROJECT.md, AGENTS.md §4-6, CINEMATIC_AUDIO_PIPELINE.md
- [x] Objective 1: Inspect `concat_scene_shots` in `production_orchestrator.py` & verify FFmpeg filter_complex syntax
- [x] Objective 2: Inspect `audio_continuity_engine.py` & `master_scene_audio`, verify 2-pass linear loudnorm (-14 LUFS, TP -1.0 dBTP, LRA 9-11 LU, 48kHz stereo AAC) & 4-stem mixing + dynamic ducking
- [x] Objective 3: Audit audio assets in `04_Assets/audio/` and `04_Assets/audio_sfx/` (`scene01_bgm.m4a`, `ep01_scene04_festival_crowd_ambience_120s.wav`)
- [x] Objective 4: Design `assemble_episode_master("ep01")` stitching all 10 scene masters into `06_Exports/ep01_full_feature_master_v1.mp4`
- [x] Author comprehensive blueprint `m4_concat_audio_blueprint.md`
- [x] Author 5-component handoff report `handoff.md`
- [x] Notify parent orchestrator via send_message