feat: add automatic media normalization, R2 retention cleanup, and seamless playout loops

CHANGELOG.md

@@ -4,6 +4,23 @@
 
 ## [Unreleased]
 
+### Added
+
+- **Automatic media normalization on upload**: Chat backend auto-transcodes non-conforming uploads. New `media.NormalizeVideo` wraps ffmpeg with the Linear Void profile (H.264/AAC, 30fps, 2s keyframes, yuv420p, 48kHz stereo), re-verifies output with ffprobe, and writes `*.normalized.mp4`. Media records gain `normalizing` / `normalization_failed` statuses; `POST /api/admin/media/{id}/normalize` re-triggers manually. Admin UI shows a "Normalize" action with status polling.
+- **R2 segment retention**: Playout `cleanupOldSegments` deletes `hls/r-*/*` objects older than `R2_SEGMENT_RETENTION_HOURS` (default 24h), run hourly + at startup, never touching the live manifest. Exposes `linearvoid_playout_r2_cleanup_objects_total` metric. `.env.example` adds `R2_SEGMENT_RETENTION_HOURS`.
+- **Playout loop metrics**: `linearvoid_playout_loops_total` (clean completions) and `linearvoid_playout_run_duration_seconds` (last run duration).
+
+### Changed
+
+- **Playout seamless looping**: `main()` now only resets HLS output when the playlist changed (SHA-256 `playlistRevision`), on crash/slate recovery, or first run; otherwise it continues segment numbering via `-start_number` and prunes stale segments. Eliminates the viewer gap on clean playlist loops.
+- **Single playout entrypoint**: `start-playout.sh` now runs `/app/playlist-manager -validate` then `exec`s the Go binary, removing the duplicate shell ffmpeg loop. Added a `-validate` mode to `main()`.
+
+### Tests
+
+- Media: `TestNormalizationArgs`, `TestNormalizeVideo_FFmpegError`.
+- Handlers: `TestNormalizeMediaRecord_Success`, `TestNormalizeMediaRecord_Failure`, `TestHandleAdminMediaByID_Normalize`.
+- Playout: `TestCleanupOldSegments`, `TestR2SegmentRetentionHours`, `TestPlaylistFingerprint`, `TestHLSNextStartNumber`.
+
 ## [1.0.12] - 2026-08-11
 
 ### Changed
@@ -13,7 +30,7 @@
 ### Fixed
 
 - **Playout R2 endpoint validation**: `initR2Client()` now validates all required R2 environment variables (`R2_ENDPOINT`, `R2_ACCESS_KEY_ID`, `R2_SECRET_ACCESS_KEY`, `R2_BUCKET_NAME`) before creating the S3 client. Previously, an empty `R2_ENDPOINT` caused cryptic `Custom endpoint '' was not a valid URI` errors on every segment upload attempt. Playout now gracefully degrades when R2 is not configured — local HLS via nginx continues to work.
-- **CD workflow missing R2 secrets**: `.gitea/workflows/cd.yml` "Prepare environment" step now injects all R2_ variables (`R2_ACCESS_KEY_ID`, `R2_SECRET_ACCESS_KEY`, `R2_BUCKET_NAME`, `R2_ENDPOINT`, plus admin variants) from Gitea secrets. Previously the generated `.env` was missing R2 entirely, causing the playout container to start with an empty endpoint.
+- **CD workflow missing R2 secrets**: `.gitea/workflows/cd.yml` "Prepare environment" step now injects all R2\_ variables (`R2_ACCESS_KEY_ID`, `R2_SECRET_ACCESS_KEY`, `R2_BUCKET_NAME`, `R2_ENDPOINT`, plus admin variants) from Gitea secrets. Previously the generated `.env` was missing R2 entirely, causing the playout container to start with an empty endpoint.
 - **Deployment docs**: `docs/DEPLOYMENT.md` now includes explicit R2 and Cloudflare variable lists plus a "Gitea Secrets" table documenting all 15 required secrets.
 
 ## [1.0.11] - 2026-08-10