refactor: enhance pre-commit workflow with improved diff detection and caching

.github/workflows/pre-commit.yml

@@ -14,20 +14,46 @@ jobs:
         with:
           fetch-depth: 0  # Required for detecting diffs
 
+      - name: Fetch main branch
+        run: |
+          # Ensure we have the main branch reference for comparison
+          git fetch origin main:main 2>/dev/null || git fetch origin main 2>/dev/null || true
+
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
           python-version: '3.12'
 
+      - name: Cache pre-commit environments
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pre-commit
+          key: pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}
+          restore-keys: |
+            pre-commit-
+
       - name: Install pre-commit
         run: |
           pip install pre-commit
 
+      - name: Install hook environments (cache)
+        run: |
+          pre-commit install-hooks
+
       - name: Run pre-commit on changed files
         run: |
-          CHANGED_FILES=$(git diff --name-only origin/main...HEAD | tr '\n' ' ')
-          if [ -n "$CHANGED_FILES" ]; then
-            pre-commit run --files $CHANGED_FILES
+          # Use pre-commit's native diff detection with fallback strategies
+          if git show-ref --verify --quiet refs/heads/main; then
+            # Main branch exists locally, use pre-commit's native diff mode
+            echo "Running pre-commit with native diff detection against main branch"
+            pre-commit run --from-ref main --to-ref HEAD
+          elif git show-ref --verify --quiet refs/remotes/origin/main; then
+            # Origin/main exists, use it as reference
+            echo "Running pre-commit with native diff detection against origin/main"
+            pre-commit run --from-ref origin/main --to-ref HEAD
           else
-            echo "No changed files to check."
+            # Fallback: run on all files (for first commits or when main is unavailable)
+            echo "Main branch reference not found, running pre-commit on all files"
+            echo "⚠️  This may take longer and show more issues than normal"
+            pre-commit run --all-files
           fi