Add find-regression-risk skill and gh-aw workflow

.github/aw/actions-lock.json

@@ -15,6 +15,11 @@
       "version": "v0.62.2",
       "sha": "20045bbd5ad2632b9809856c389708eab1bd16ef"
     },
+    "github/gh-aw-actions/setup@v0.62.5": {
+      "repo": "github/gh-aw-actions/setup",
+      "version": "v0.62.5",
+      "sha": "dc50be57c94373431b49d3d0927f318ac2bb5c4c"
+    },
     "github/gh-aw/actions/setup@v0.43.19": {
       "repo": "github/gh-aw/actions/setup",
       "version": "v0.43.19",

.github/skills/find-regression-risk/SKILL.md

@@ -0,0 +1,95 @@
+---
+name: find-regression-risk
+description: "Detects if a PR modifies or reverts code from a recent bug-fix PR, which could re-introduce a previously-fixed bug. Use when reviewing any PR, before approving, or when asked 'check for regression risks', 'could this revert a fix', 'regression cross-reference'."
+metadata:
+  author: dotnet-maui
+  version: "1.0"
+compatibility: Requires git, PowerShell, and gh CLI.
+---
+
+# Find Regression Risk
+
+Detects if a PR's changes could re-introduce previously-fixed bugs by cross-referencing the diff against recently-merged bug-fix PRs.
+
+## Why This Exists
+
+PRs that fix one bug can silently re-introduce another if they modify or revert lines from a prior fix.
+
+**Real-world example:** PR #33908 removed `|| parent is IMauiRecyclerView` from `MauiWindowInsetListener.cs` — a line that PR #32278 had specifically added to fix issue #32436 (increasing gap at bottom while scrolling). The agent approved PR #33908 without detecting this revert, and the exact same bug reappeared as issue #34634.
+
+## When to Use
+
+- ✅ Before approving any PR that modifies platform code
+- ✅ When asked "check for regression risks" or "could this revert a fix"
+- ✅ As part of the `pr-review` skill's Pre-Flight phase
+- ✅ When a PR touches high-churn files (safe area, CollectionView handlers, inset listeners)
+
+## Workflow
+
+### Step 1: Run the Script
+
+```bash
+# Auto-detect implementation files from PR diff
+pwsh .github/skills/find-regression-risk/scripts/Find-RegressionRisks.ps1 -PRNumber XXXXX
+
+# Or specify files manually
+pwsh .github/skills/find-regression-risk/scripts/Find-RegressionRisks.ps1 \
+  -PRNumber XXXXX \
+  -FilePaths @("src/Core/src/Platform/iOS/MauiView.cs","src/Core/src/Platform/Android/MauiWindowInsetListener.cs")
+```
+
+### Step 2: Interpret Results
+
+| Risk Level | Meaning | Action |
+|------------|---------|--------|
+| 🔴 **REVERT DETECTED** | PR removes/modifies lines from a recent bug-fix PR | **MUST** verify the previously-fixed bug doesn't reappear before approving |
+| 🟡 **OVERLAP** | PR modifies the same file as a recent bug-fix but different lines | Note as lower-risk concern |
+| 🟢 **CLEAN** | No recent bug-fix PRs touched these files | No action needed |
+
+### Step 3: Act on Findings
+
+**If 🔴 REVERT DETECTED:**
+
+1. Identify the at-risk issues — the script reports which issues were fixed by the reverted code
+2. Verify the fix still holds — run the test from the original fix PR, or manually verify
+3. Document in PR review — note the revert risk and the verification result
+4. **Do NOT approve** until the risk is mitigated
+
+## What the Script Does
+
+For each implementation file in the PR diff:
+
+1. **Finds recent PRs** — queries `git log` for the last 6 months of changes to that file
+2. **Identifies bug fixes** — checks PR labels AND linked issue labels for `i/regression`, `t/bug`, `p/0`, `p/1`
+3. **Compares diffs** — checks if lines ADDED by a fix PR are being REMOVED by the current PR
+4. **Reports risks** — structured output with file, PR, issue, and reverted line details
+
+## Output Format
+
+Post results using the following format:
+
+```markdown
+## 🔍 Regression Risk Analysis
+
+**PR:** #XXXXX
+**Risk Level:** [🟢 Clean | 🟡 Overlaps Found | 🔴 Revert Risks Detected]
+
+[Summary sentence]
+
+> 👍 / 👎 — Was this analysis helpful? React to let us know!
+
+<details>
+<summary>📊 Expand Full Analysis</summary>
+
+### Risks Found
+
+| File | Recent Fix PR | Fixed Issue | Risk | Details |
+|------|--------------|-------------|------|---------|
+| ... | ... | ... | ... | ... |
+
+### Recommendations
+
+- ...
+
+</details>
+```