Fix DASH SegmentTimeline negative @r and Pattern, TTML sidecar sets with no contentType, HLS CHANNELS identifiers and Dolby channel masks; test against 408 public DASH/HLS/ISM manifests.
A tag with a region (en-US, es-419) matches only that variant and reports a miss instead of taking another region. A bare tag takes the variant it means (pt -> pt-BR, es -> es-ES) and falls back to any variant only when that one is missing. `orig` prefers the title's own tag, `-sl orig` resolves, forced and SDH subtitles are picked from their own pools, and the track name no longer strips the region from the cached language.
BREAKING CHANGE: -l es-419 no longer selects es-ES, and language_priority, language_tags and muxing.default_language treat a regional tag as exact.
Test servers shut down without the 0.5s poll wait, unit tests refuse non-loopback lookups, and three load-sensitive tests are steadied. Pushes to dev test Python 3.11 only; the docs job builds with uv.
Each keeps one kind of track inside its track type. A run of more than one title skips a title that has no such track. The REST API rejects a non-boolean value for a boolean dl param, and the DASH parser reads audio description from Role elements.
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