DR-246. The strategy used to turn on `is_hls` and `use_html5`, decided in a
command handler on behalf of engines it does not own. That is how "who
renders" came to mean "how do I seek", and why a transcoded seek silently did
nothing the moment native video changed the renderer (DR-238).
Engines now declare `Capabilities::seeks_transcoded_in_place` — true for
hls.js, which seeks within the VOD playlist it was handed and lets the server
catch up; false for mpv, whose HLS demuxer cannot make the server transcode
from a new offset. The command asks whichever engine is rendering. Adding an
engine no longer means editing a shared truth table.
The item's transport is not read at the seek site any more; the compiler
flagged it unused, which is the URL-shape input finally disappearing.
A deviation from the spec, recorded deliberately: it called for the engine to
own the decision outright. It cannot. Re-negotiating a stream needs the
repository, which sits above the engine, so the engine states the ability and
the caller acts on it. That still removes the defect — nobody guesses on
another component's behalf — without pretending an engine can reach upward.
Also fixes a latent race in the conformance suite, found by running it: the
seek case asserted immediately, which passes on an engine that records the
target when it accepts a seek and races on one that waits for the decoder to
move. `Harness::await_seek` polls instead, the way the Android suite already
did. It failed with machine load rather than with the code, which is the kind
of test that teaches people to re-run until green.
MpvPlayer 9/9
LegacyPlayer 8/9 - still only the mute/rate gap in the old trait
789 tests, clippy -D warnings clean with and without the feature.
dtourolle
6b3d853442