FFmpegEngine and ConcatEngine each carried their own copy of the same `when`, and the copies
had drifted: one preferred the fail stack trace and fell back to the log tail, the other only
ever read the log tail. Neither was tested -- both live inside a callback handed to FFmpegKit,
which does not run on the JVM -- so nothing could see that the two disagreed about what a
failed session says.
sessionOutcome() now holds the rule and each engine maps Success/Cancelled/Failed onto its
continuation. Verified JVM-safe rather than assumed: javap over the committed AAR shows
ReturnCode(int) as a plain public constructor with pure static isSuccess/isCancel and a
<clinit> that loads no native library.
Per #203's decision this unifies on the stack trace, so a join failure now carries the
diagnostics a conversion failure always did. The PREFIX stays per-engine: unifying the
strategy must not unify the sentence, since a join reporting "FFmpeg failed" would be a worse
message than the one it replaces. There is a test for exactly that.
The two message sources are lambdas rather than values, and that is load-bearing.
getFailStackTrace and getAllLogsAsString are calls onto a native session, and only the
failure arm needs either; taking them by value would put both on the happy path of every
successful conversion, which the shape this replaces did not -- it read them inside the else
branch. Same reasoning as capabilitiesFrom taking a Sequence in #194: a seam should not change
what runs when. There is a test that counts the reads, and the eager mutation reddens it.
A null return code is a real input rather than a defensive one -- getReturnCode() is nullable
and a session killed before reporting has none -- so it fails, with "null" where the number
would be.
Nothing asserted the old join text: `grep -rn 'Joining failed|FFmpeg failed' app/src/` returns
only main, plus ConcatWorker.GENERIC_FAILURE_MESSAGE, which is a different constant this does
not touch. Re-run immediately before committing, as the ticket asked.
Mutations, all run and restored:
swap the ifBlank operands 1 red
treat cancellation as a failure 2 red
read both message sources eagerly 1 red
hardcode the prefix 1 red
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5
ec2cae256f