Whenever you test, verify, smoke-test, QA, or debug anything in a repo, capture what you learned as a repo-local runbook entry so the next session does not rediscover it. Maintains docs/testing-runbook.md as a living recipe book — read it before testing, follow the existing recipe, and fix it in the same session when reality differs. Use on testing or verification activity in a real project repo — one that has or warrants docs/testing-runbook.md — not for scratch work or one-off scripts; the user does not need to say "runbook".
