[ci-scan-feedback] Add fixer freshness/live-leg gate to stop already-fixed & retired-leg PRs

[Copilot]

The ci-failure-fix workflow keeps opening help-wanted PRs for failures that no longer happen — retired legs (#129653, "Mono mobile doesn't run on CI anymore"), already-merged fixes (#130231), and stale KBEs (#130232). This is the dominant closed-unmerged class over the last several ticks, and prior feedback issues (#131644, #131699) flagged it without a guard ever landing.

Changes

.github/workflows/ci-failure-fix.md only — prompt text, no code:

• Step 4, new gate before any fix attempt (inserted as item 2; following items renumbered 3/4). Three checks, first trip ends the KBE with a recorded skip — no PR, no loop-in comment:
  • Recent occurrence — signature checked against the newest completed builds of the definition plus Build Analysis occurrence data in the KBE body; nothing in 14d → skipped: no occurrence in last 14d, likely already fixed or retired
  • Live leg — the leg must appear in the newest completed build's timeline and still be defined in eng/pipelines/** at HEAD; retired Mono-mobile/wasm legs, deleted queues, dropped images → skipped: failing leg retired, no longer runs at HEAD
  • Fix already landed — failing source read at HEAD plus git log since KBE creation; faulty path already removed → skipped: fix already present at HEAD; KBE stale
• Recognized skip reasons list — the three phrasings registered verbatim so the feedback workflow's tally aggregation stays stable.
• One pre-existing trailing space removed (line 192); markdownlint runs repo-wide on any PR touching .md and MD009 is the sole enabled rule.

Placement is deliberate: after Step 3 dedup, before Step 5's fix attempt, mirroring the existing Step 5.1.1 pipeline-category gate. Recorded skip is already a valid outcome in the Step-summary table, so no downstream change is needed.

Notes

No lock-file regeneration: ci-failure-fix.lock.yml pulls the prompt via {{#runtime-import .github/workflows/ci-failure-fix.md}} and stores no hash of the body — only frontmatter changes require a recompile, and the frontmatter is untouched. No other prompt references Step 4 items by number, so the renumbering is contained.

Verified markdownlint-cli clean on the file. Nothing built or tested — there is no code here.

• Fixes [ci-scan-feedback] Add fixer freshness/live-leg gate to stop already-fixed & retired-leg PRs #131873

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[Copilot]

Review details

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• Review effort level: Lite

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