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fix(cli): stop typegen stdin feed hanging on an early-exit tool - #6948
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Under CPU contention, writing the tool's stdin could lose its scheduling race against the pipe's own EPIPE error, leaving the write stuck waiting on a drain event that a reader which already exited will never send. Race the stdin feed against the child's own exit, which is always observable, so the wait is bounded without depending on wall-clock timing.
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🤖 AI Review
Both independent reviews were available. No production defect was confirmed. Claude’s minor concern about test scheduling remains uncertain; dependencies are not installed, so runtime verification was unavailable.
Findings
| Severity | Location | Category | Sources | Claim |
|---|---|---|---|---|
| 🟡 MINOR | apps/cli/src/commands/gen/types/types.typegen-host.ts:70 |
test-coverage |
claude | Racing stdin consumption against the fake spawner’s immediately successful exitCode may interrupt consumption before the existing stdin assertion’s expected document is recorded, making the test depend on fiber scheduling. |
Stats
Claude findings: 1 · Codex findings: 0 · Confirmed: 0 · Refuted: 0 · Uncertain: 1
Models: claude-opus-5-5 + gpt-6.1-sol · Trigger: auto · Workflow run
This review runs once per PR. A maintainer can request another with a /ai-review comment.
The fake tool now exits only after it has read its stdin, like a real tool, so the stdin assertion no longer depends on fiber scheduling now that the feed races the exit. A new case has the tool exit while stdin stays blocked; it hangs without the exit race.
avallete
approved these changes
Oct 2, 2026
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types.typegen-host.integration.test.ts› "survives a tool that exits before reading a large stdin" intermittently hit its 5s timeout when the machine was busy.The typegen host writes the request to the tool's stdin and waits for that write to finish. When the write hits backpressure, it waits for a
drainthat never comes once the reader has exited. The only way out is the pipe'serror(EPIPE) event. Under load, that event can be delivered before the listener for it is attached, so the feed hangs even though the tool's exit code, stdout and stderr have all resolved.The stdin feed is now raced against the child's exit, which is always observable once the tool is gone, so the wait no longer depends on winning that scheduling race. Under the same CPU load, the test failed 2 times in 50 before the change and 0 times in 50 after.
The stack's
CommandRunnerstdin path already races its feed against process exit, and it stays settled when several MB of stdin are fed to a psql that exits immediately.