feat: add metrics, observability, test fixtures, and scaling playbook artifacts

CHANGELOG.md

@@ -2,6 +2,29 @@
 
 <!-- markdownlint-disable MD024 -->
 
+## [1.0.10] - 2026-08-09
+
+### Added
+
+- **WebSocket summary helper**: Added `scripts/loadtest/summarize-artillery.ps1` to extract counters, rates, and available percentile stats from Artillery JSON output.
+- **Playbook worksheet mapping**: Added artifact-to-worksheet mapping section in `docs/operations/scaling-performance-playbook.md` for WebSocket and Admin API benchmark artifacts.
+- **Test fixture generation docs**: Added ffmpeg commands for generating valid and invalid media fixtures as comments in `backend/playout/src/playlist_test.go`. Phase 1 test fixtures now complete.
+- **R2 cache header support**: `SyncToR2` now sets `CacheControl` and `ContentType` based on file extension:
+  - `.m4s`/`.ts`/`.mp4`/`.m4a` → immutable (max-age=31536000)
+  - `.m3u8` → short-lived (max-age=2s)
+  - unknown → no cache headers
+- **R2 integration tests**: Added `TestSyncToR2_ManifestCacheHeaders` and `TestSyncToR2_NoCacheHeadersForUnknownExt` verifying cache header behavior for segment, manifest, and unknown file types.
+
+### Changed
+
+- **Loadtest runner**: `scripts/loadtest/run-loadtests.ps1` now generates `ws-chat-summary.txt` automatically for `ws` and `all` scenarios.
+- **Loadtest docs**: `scripts/loadtest/README.md` now documents `summarize-artillery.ps1` usage and the new `ws-chat-summary.txt` artifact.
+- **Planning status wording**: Updated `docs/DEVELOPMENT.md` and `.github/instructions/TODO.md` to mark ws/admin benchmark scaffolding complete while benchmark execution remains pending.
+- **Phase 1 complete**: Test fixture creation and ffmpeg documentation marked done.
+- **Phase 4 partially complete**: R2 upload + cache header validation done; edge cache hit/miss validation remains manual.
+- **Phase 2 frontend tests**: Added presence updates (join/leave rendering), private DM flow, and message rendering tests in `main.test.ts` (27 total tests passing).
+- **Phase 3 admin frontend tests**: Added playlist management tests (save via PUT, error handling, sortable rendering) in `admin.test.ts` (31 total tests passing).
+
 ## [1.0.9] - 2026-08-06
 
 ### Added