docs(ci): the attribution guarantee promised more than the gate delivers #5601

§2 was headed "Our failure never blocks your merge". The code has never done that.

decideCiGate returns passed: false for every infrastructure conclusion — it blocks, with CI did not complete — re-run the workflow rather than CI failed. It blocks, and always did.

The code is right and the wording was the overstatement, so the wording changed. A run that didn't finish hasn't judged anyone's code, and a gate that waved it through would do exactly what this document exists to refuse: score a check that could not be performed as one that passed.

What §2 promises now is narrower and worth more — the reason names us, the block clears itself via the requeue path (once per workflow+commit), and it doesn't count against the repo's health.

§4 had the same problem in miniature

"An outage of ours never blocks a merge on a check we could not run" — while its own body correctly said a skipped CI check, a skipped security scan and a disabled AI review are all still refused.

Narrowed to "our own advisory service", with the distinction now argued rather than asserted:

• AI review is something we add on top of your tests. Blocking on our outage punishes you for it.
• CI is your tests. A run that didn't complete means nothing checked your code.

Same sentence decides both — "we could not look" is not "we looked and it was fine" — different stakes, different answer.

A test now pins the document to the gate

This was found by hand while chasing something else, and a document does not fail a build. That makes it the same defect class as everything else found today — something reporting a state it does not have — except this one is the file we'd point a customer at.

The check reads headings only, deliberately: the body legitimately quotes the old wording while explaining why it was wrong, and forbidding the phrase outright would force the honest correction note to be written around it.

Its first version passed against the mutation — "blocks your merge" does not contain "block your merge" — so the assertion meant to catch that exact sentence would have caught nothing. Fixed and re-verified: restoring the old heading now fails.