Background processes whose command contains `gh pr view --json
statusCheckRollup` or `gh pr checks | jq` now get a runtime hint in
the result pointing at the canonical green-ci-policy snippets. The
homebrew shape has caused at least seven silent CI-watcher failures
in the past two weeks (#31329, #31448, #31695, #31709, #31745,
#32264, #33131) — each one a different jq/awk/grep variation of the
same fundamental problem (stdout buffering, jq null-key edge cases,
conclusion-vs-status confusion, TTY-only banner grepping).
The skill that documents this anti-pattern is excellent, but a skill
only fires if the agent loads it. The tool surface fires on every
misuse. This is the embed-footguns-in-tool-surface pattern from
PR #31289 applied to a recurring failure mode that's outgrown
skill-only enforcement.
Detector is deliberately narrow — flags two specific shapes:
1. Any command containing `statusCheckRollup` (the JSON-API path —
conclusion vs status field semantics keep burning us).
2. `gh pr view` / `gh pr checks` combined with `jq` (gh pr
checks doesn't emit JSON, so any `| jq` here is confused intent;
the canonical column-2 poller uses awk-on-tabs, not jq).
Does NOT flag the blessed column-2 awk-on-tabs poller (which uses
`awk -F"\t" "\==\"pending\""`) or the exit-code-driven
`gh pr checks $PR >/dev/null` snippet.
Hint composes with the existing background-without-notify_on_complete
hint — both can fire on the same call. Each is independently
actionable.
Tests:
- 4 new cases in tests/tools/test_notify_on_complete.py
- test_homebrew_ci_poller_via_statusCheckRollup_emits_hint (positive)
- test_homebrew_ci_poller_via_gh_pr_checks_piped_to_jq_emits_hint (positive)
- test_canonical_column2_awk_poller_does_not_emit_homebrew_hint (negative)
- test_canonical_gh_pr_checks_exit_code_loop_does_not_emit_hint (negative)
- test_non_ci_background_command_does_not_emit_homebrew_hint (negative)
- 30/30 passing (was 26)
