ci: enforce no .unwrap(), .expect(), or assert!() in production code (#1087)

Add a diff-based CI job and pre-commit hook check that block
panic-inducing calls (.unwrap(), .expect(), assert!, assert_eq!,
assert_ne!) from entering production Rust code. debug_assert is
excluded (compiled out in release). False positives can be suppressed
with an inline `// safety: <reason>` comment.

- pre-commit-safety.sh: add check 6 (PANIC) for staged diffs
- code_style.yml: add `no-panics` job, wire into roll-up gate
- check-boundaries.sh: extend check 2 to also catch assert!()

Co-authored-by: Claude Opus 4.6 <[email protected]>

.github/workflows/code_style.yml

@@ -78,15 +78,55 @@ jobs:
     - name: Check lints
       run: cargo clippy --all --benches --tests --examples ${{ matrix.flags }} -- -D warnings
 
+  no-panics:
+    name: No panics in production code
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v6
+      with:
+        fetch-depth: 0
+    - name: Check for .unwrap(), .expect(), assert!() in production code
+      run: |
+        BASE="${{ github.event.pull_request.base.sha }}"
+        # Get added lines in .rs files (production only, exclude tests/)
+        ADDED=$(git diff "$BASE"...HEAD -- 'src/**/*.rs' 'crates/**/*.rs' \
+          | grep -E '^\+[^+]' || true)
+
+        if [ -z "$ADDED" ]; then
+          echo "No production Rust changes detected."
+          exit 0
+        fi
+
+        # Match panic-inducing patterns, excluding test code and safety suppressions
+        VIOLATIONS=$(echo "$ADDED" \
+          | grep -E '\.(unwrap|expect)\(|[^_]assert(_eq|_ne)?!' \
+          | grep -Ev 'debug_assert|// safety:|#\[cfg\(test\)\]|#\[test\]|mod tests' \
+          || true)
+
+        if [ -n "$VIOLATIONS" ]; then
+          echo "::error::Found .unwrap(), .expect(), or assert!() in production code."
+          echo "Production code must use proper error handling instead of panicking."
+          echo "Suppress false positives with an inline '// safety: <reason>' comment."
+          echo ""
+          echo "$VIOLATIONS" | head -20
+          echo ""
+          COUNT=$(echo "$VIOLATIONS" | wc -l | tr -d ' ')
+          echo "Total: $COUNT violation(s)"
+          exit 1
+        fi
+
+        echo "OK: No panic-inducing calls in changed production code."
+
   # Roll-up job for branch protection
   code-style:
     name: Code Style (fmt + clippy + deny)
     runs-on: ubuntu-latest
     if: always()
-    needs: [format, clippy, clippy-windows, deny-check]
+    needs: [format, clippy, clippy-windows, deny-check, no-panics]
     steps:
       - run: |
-          if [[ "${{ needs.format.result }}" != "success" || "${{ needs.clippy.result }}" != "success" || "${{ needs.deny-check.result }}" != "success" ]]; then
+          if [[ "${{ needs.format.result }}" != "success" || "${{ needs.clippy.result }}" != "success" || "${{ needs.deny-check.result }}" != "success" || "${{ needs.no-panics.result }}" != "success" ]]; then
             echo "One or more jobs failed"
             exit 1
           fi