When an integration silently fails for months, your first-principles hypothesis is the suspect — find a working reference implementation in the same ecosystem and triangulate against its actual configuration before committing to a fix. That sentence is the whole lesson from today. The Gemini PR review workflow on claude-code-plugins-plus-skills had been silently failing on community PRs since December. Five contributor PRs were stalled with zero Gemini output. The pipeline's gemini-review step kept reporting green. No one noticed because Gemini's failure mode is "post nothing" — not "throw an error." I had a clean theory for what was wrong, wrote the fix, opened PR #602, and was about to merge. Then I read one paragraph in a different repo's workflow header and reversed the entire change. Below is the journey: the false hypothesis, the reversal, the triangulation method, and the patch that ended the silent fail across all five stalled PRs in under two minutes.…