apply_output checked `channels: rgba` against the module before it
applied `webmCodec`, and choosing AV1 then quietly dropped the channels
to RGB. So `render --format webm --webm-codec av1 --channels rgba` (one
renderQueue.add) succeeded and wrote an opaque AV1 stream.
The codec options now apply before Channels, so the existing "has no
alpha channel" error (how an unsupported channels request is already
reported) refuses the combination; for WebM it names the codec: "AV1
WebM has no alpha channel (VP9 WebM has)". Choosing AV1 alone on an
RGBA VP9 item still switches it to RGB, as changing the format does.
Test: av1_webm_refuses_requested_alpha.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
apply_output switched the format whenever the Output To extension mapped
to a different format, and `.mp4` maps to H.264 only, so
renderQueue.setOutput with an .mp4 path (even the item's own default
name) turned an HEVC or AV1 module into H.264 and the render wrote an
H.264 stream.
The extension now changes the format only when the current format
doesn't write it (OutputFormat::extension): HEVC, AV1 and H.264 all write
.mp4, so they stay; `.mov` on H.264 still picks ProRes and `.mp4` on
ProRes still picks H.264.
Test: output_to_keeps_a_format_that_writes_the_extension.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
#154: renderQueue.add (and render.addOutputModule) applied `format`, then
dropped it before applying the output path, so `--format hevc --out
x.mp4` saw the .mp4 extension and switched the module back to H.264
(and ProRes / VP9 for .mov / .webm). An explicit format now wins and a
mismatched extension follows it (x.webm → x.mp4 for AV1), as choosing a
format in the Output Module renames Output To; an extension that agrees
with the format keeps the name as given. The format error lists hevc and
av1 everywhere (one FORMATS string).
#155: a `comp` that names no composition (name or id) failed with "no
active composition". comp_id now reports it as `no composition "Nope"`
(EngineError::NoSuchComp), and comp_for_queue passes that on instead of
collapsing it.
Tests: an_explicit_format_wins_over_the_output_extension and
an_unknown_comp_is_named_in_the_error (engine). Checked with the CLI:
the files are hevc/hvc1 and av1/av01 and decode cleanly with ffmpeg.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
