Replace shared subprocessStderr with per-subprocess pipes#17
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This test runs a snapshot with --cmd that writes to both stdout and stderr. It currently documents a bug: subprocessStderr is closed before runPostUnpackCmd runs, causing hDuplicate to fail with "Bad file descriptor". Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The shared subprocessStderr pipe caused "Bad file descriptor" crashes when runPostUnpackCmd or RemoteCache.saveCache tried to write after the pipe's write-end was closed. Instead of shuffling close timing, each subprocess now creates its own pipe via withStderrPipe, reads/prefixes its output, and cleans up independently. - Remove subprocessStderr field from AppState - Add withStderrPipe helper to Utils.hs (create-pipe, spawn-handler, run-action, close-and-wait pattern) - Move outputStreamHandler, timeoutStream, ignoreEOF to Utils.hs - Update all callsites: isDirtyAtPaths, getCurrentBranch, getMainBranchCommit, getCurrentCommit, runPostUnpackCmd, hashFileInputs - Update packTar/unpackTar to accept stderr handle parameter - Fix getCurrentCommit TODO (was using raw stderr as workaround) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
zyla
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Mar 14, 2026
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This checks if post-unpack-cmd can use stdout and stderr
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Summary
withStderrPipehelper: each subprocess creates its own pipe, reads/prefixes output, and cleans up independently — no shared state or lifetime issuesgetCurrentCommitTODO (previously fell back to raw stderr as a workaround for the shared pipe problem)timeoutStreamto before success messages are logged, eliminating output ordering race condition which caused flakiness in tests (e.g. https://github.com/restaumatic/taskrunner/actions/runs/23081371040/job/67051182317)🤖 Generated with Claude Code