Reading additional input from stdin...
OpenAI Codex v0.153.4
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workdir: /tmp/harnessfacts-dBUElk/fixture
model: gpt-6-astra
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR]
reasoning effort: none
reasoning summaries: none
session id: 01a0803d-159b-73d3-b728-76d02cbe3acc
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user
Write exactly HEADLESS into result.txt in the current directory.
codex
I’ll write `HEADLESS` to `result.txt`.

exec
/bin/bash -lc 'printf %s HEADLESS > result.txt' in /tmp/harnessfacts-dBUElk/fixture
 succeeded in 0ms: