test(ci): [CI-01] checkpoint installed audio and subtitle coverage

packages/artplayer-plugin-multiple-subtitles/ARCHITECTURE.md

@@ -183,3 +183,15 @@ See task09's change/validation record and the core offset change for precise sco
 The matrix is runnable with `yarn test:browser test/browser/multiple-subtitles-combinations.spec.js`;
 do not replace these failures with skips or count boundary observations as acceptance.
 See `../../refactor/baselines/multiple-subtitles-contract.md` for exact historical differences.
+
+## Installed browser coverage
+
+multipleSubtitlesCandidate uses browser-candidate.js for verified installed bytes. An installed map rejects ARTPLAYER_MULTIPLE_SUBTITLES_ARTIFACT overrides. Actual historical plugins and no-plugin controls retain their original inputs.
+
+The shared `yarn test:browser:installed` roster includes this package after preparing
+the nine-package tarballs with `yarn test:package --include=...`; use the exact command
+in ../../scripts/browser-validation/README.md. Attachments identify candidate file,
+archive and source hashes. Missing or stale maps fail without source fallback.
+Without a map, source and deliberate artifact checks retain their existing behavior.
+This is desktop main-entry coverage, not all module forms, physical devices or
+release readiness. See ../../refactor/changes/2026-09-15-CI-01-subtitles-installed.md.