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fix: race in RunWithPrompts truncates output on process exit - #64
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…ompts Wait() closes the stdout pipe as soon as the child exits, racing our own Read on the same fd and occasionally truncating the last chunk of output. Fixes flaky examples/06_prompts.clitest under the new Go 1.27 CI matrix (golang:1.27-alpine), reproduced and verified fixed against that exact image. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Summary
test-ash (1.27)in CI (run 35203905985) fails intermittently atmake examplesonexamples/06_prompts.clitest, missing the script's final "Created user: ..." lineRunWithPrompts(internal/runner/prompts.go) calledcmd.Wait()in a goroutine concurrently with the goroutine readingcmd.StdoutPipe()— a documented anti-pattern (Cmd.Waitcloses the pipe as soon as the child exits, which can race a concurrentReadon the same fd and truncate the last chunk). No application code changed since May; the newgolang:1.27-alpineCI matrix job just shifted timing enough to expose it<-readDone), then callcmd.Wait()once, sequentially, to reap the exit code — timeout now only kills the process, it no longer racesWaitTest plan
go test ./internal/runner/... -run TestRunWithPrompts -race -count=50— passmake test && make e2e && make exampleslocally — passexamples/06_prompts.clitest— 0 failuresmake test && make e2e && make examples) insidegolang:1.27-alpinevia podman, including a 30x stress loop — pass