fix(ci): implement unique branch strategy for pre-commit hooks workflow

Replace complex branch reuse logic with timestamped unique branches.
Remove stash/pop operations that caused 'nothing to commit' issues.
Simplify workflow by always creating fresh PRs instead of updating existing ones.
Add timestamp suffix to branch names for guaranteed uniqueness.
Eliminate Git conflicts from attempting to checkout existing branches with local changes.

This resolves the workflow failures where existing branches already contained
the same updates, resulting in empty commits and merge conflicts.

Author: mrz1836

.github/workflows/update-pre-commit-hooks.yml

@@ -128,8 +128,13 @@ jobs:
             exit 1
           fi
 
+          # Create unique branch name with timestamp to avoid conflicts
+          TIMESTAMP=$(date -u +%Y%m%d-%H%M)
+          UNIQUE_BRANCH_NAME="${BRANCH_NAME}-${TIMESTAMP}"
+          
           # Set as environment variables for all subsequent steps
-          echo "BRANCH_NAME=$BRANCH_NAME" >> $GITHUB_ENV
+          echo "BRANCH_NAME=$UNIQUE_BRANCH_NAME" >> $GITHUB_ENV
+          echo "BASE_BRANCH_NAME=$BRANCH_NAME" >> $GITHUB_ENV
           echo "CONFIG_FILE=$CONFIG_FILE" >> $GITHUB_ENV
           echo "PR_LABELS=$PR_LABELS" >> $GITHUB_ENV
           echo "PR_ASSIGNEE=$PR_ASSIGNEE" >> $GITHUB_ENV
@@ -151,7 +156,8 @@ jobs:
           # Log configuration
           echo "🔍 Configuration loaded:"
           echo "  📁 Config file: $CONFIG_FILE"
-          echo "  🌿 Update branch: $BRANCH_NAME"
+          echo "  🌿 Base branch pattern: $BRANCH_NAME"
+          echo "  🌿 Unique branch name: $UNIQUE_BRANCH_NAME"
           echo "  📁 Pip directory: $PIP_DIR"
           echo "  🔀 Create PR: ${{ env.CREATE_PR }}"
           echo "  🧪 Test hooks: ${{ env.TEST_HOOKS }}"
@@ -317,33 +323,26 @@ jobs:
           git config --global user.email "41898282+github-actions[bot]@users.noreply.github.com"
 
       # ————————————————————————————————————————————————————————————————
-      # Check if PR branch already exists
+      # Check for existing PRs with base branch pattern
       # ————————————————————————————————————————————————————————————————
-      - name: 🔍 Check for existing PR branch
+      - name: 🔍 Check for existing PRs
         id: check_branch
         if: steps.check_changes.outputs.has_changes == 'true' && env.CREATE_PR == 'true'
         run: |
-          echo "🔍 Checking for existing branch and PR..."
-
-          # Check if branch exists remotely
-          if git ls-remote --exit-code --heads origin "${{ env.BRANCH_NAME }}" >/dev/null 2>&1; then
-            echo "🌿 Branch ${{ env.BRANCH_NAME }} already exists remotely"
-            echo "branch_exists=true" >> $GITHUB_OUTPUT
-
-            # Check if there's already an open PR
-            pr_number=$(gh pr list --head "${{ env.BRANCH_NAME }}" --json number --jq '.[0].number // empty')
-            if [ -n "$pr_number" ]; then
-              echo "📋 Open PR already exists: #$pr_number"
-              echo "pr_exists=true" >> $GITHUB_OUTPUT
-              echo "pr_number=$pr_number" >> $GITHUB_OUTPUT
-            else
-              echo "🌿 Branch exists but no open PR found"
-              echo "pr_exists=false" >> $GITHUB_OUTPUT
-            fi
+          echo "🔍 Checking for existing PRs with similar branch pattern..."
+
+          # Since we use unique timestamped branches, this branch is always new
+          echo "🆕 Using unique branch: ${{ env.BRANCH_NAME }}"
+          echo "branch_exists=false" >> $GITHUB_OUTPUT
+          echo "pr_exists=false" >> $GITHUB_OUTPUT
+          
+          # Check if there are other open PRs for pre-commit updates (for info only)
+          existing_prs=$(gh pr list --head "${{ env.BASE_BRANCH_NAME }}*" --json number,title,headRefName --jq '.[] | select(.headRefName | startswith("${{ env.BASE_BRANCH_NAME }}")) | .number' || echo "")
+          if [ -n "$existing_prs" ]; then
+            echo "ℹ️ Found existing pre-commit update PRs: $existing_prs"
+            echo "💡 These will remain open - consider closing them if this update supersedes them"
           else
-            echo "🆕 Branch ${{ env.BRANCH_NAME }} does not exist"
-            echo "branch_exists=false" >> $GITHUB_OUTPUT
-            echo "pr_exists=false" >> $GITHUB_OUTPUT
+            echo "✅ No existing pre-commit update PRs found"
           fi
         env:
           GH_TOKEN: ${{ secrets.GH_PAT_TOKEN || secrets.GITHUB_TOKEN }}
@@ -356,34 +355,9 @@ jobs:
         run: |
           echo "🌿 Preparing to commit changes..."
 
-          # Create or switch to the branch
-          if [ "${{ steps.check_branch.outputs.branch_exists }}" = "true" ]; then
-            echo "🔄 Switching to existing branch..."
-            # Stash any local changes to avoid checkout conflicts
-            if ! git diff --quiet || ! git diff --cached --quiet; then
-              echo "💾 Stashing local changes..."
-              git stash push -m "Pre-commit workflow: temporary stash for branch checkout"
-              STASH_CREATED=true
-            else
-              STASH_CREATED=false
-            fi
-            
-            # Fetch and checkout the existing branch
-            git fetch origin "${{ env.BRANCH_NAME }}"
-            git checkout "${{ env.BRANCH_NAME }}"
-            
-            # Apply stashed changes if we created a stash
-            if [ "$STASH_CREATED" = "true" ]; then
-              echo "📤 Applying stashed changes..."
-              git stash pop || echo "⚠️ Stash pop failed - changes may need manual resolution"
-            fi
-            
-            # Merge with main to get latest changes
-            git merge origin/main --no-edit || echo "⚠️ Merge conflicts may need manual resolution"
-          else
-            echo "🆕 Creating new branch..."
-            git checkout -b "${{ env.BRANCH_NAME }}"
-          fi
+          # Create unique timestamped branch (always new)
+          echo "🆕 Creating unique timestamped branch: ${{ env.BRANCH_NAME }}"
+          git checkout -b "${{ env.BRANCH_NAME }}"
 
           # Stage the changes
           git add "${{ env.CONFIG_FILE }}"
@@ -443,8 +417,8 @@ jobs:
       # ————————————————————————————————————————————————————————————————
       # Create a new pull request using GitHub CLI
       # ————————————————————————————————————————————————————————————————
-      - name: 🔀 Create new pull request
-        if: steps.check_changes.outputs.has_changes == 'true' && env.CREATE_PR == 'true' && steps.check_branch.outputs.pr_exists != 'true'
+      - name: 🔀 Create pull request
+        if: steps.check_changes.outputs.has_changes == 'true' && env.CREATE_PR == 'true'
         run: |
           echo "🔀 Creating new pull request..."
 
@@ -481,6 +455,7 @@ jobs:
           2. **Check CI status** - automated tests will verify compatibility
           3. **Test locally** with \`pre-commit run --all-files\` if desired
           4. **Merge when ready** - no manual action needed unless issues arise
+          5. **Close older pre-commit PRs** if this update supersedes them
 
           ### 🔐 Security Notes
           - All Python packages installed use hash verification (\`--require-hashes\`)
@@ -490,6 +465,7 @@ jobs:
           ### 🤖 Automation Details
           - **Workflow:** \`${{ github.workflow }}\`
           - **Trigger:** ${{ github.event_name }}
+          - **Branch:** \`${{ env.BRANCH_NAME }}\` (timestamped for uniqueness)
           - **Run ID:** [${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})
 
           ---
@@ -537,34 +513,6 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.GH_PAT_TOKEN || secrets.GITHUB_TOKEN }}
 
-      # ————————————————————————————————————————————————————————————————
-      # Update existing PR if changes detected
-      # ————————————————————————————————————————————————————————————————
-      - name: 🔄 Update existing PR
-        if: steps.check_changes.outputs.has_changes == 'true' && env.CREATE_PR == 'true' && steps.check_branch.outputs.pr_exists == 'true'
-        run: |
-          pr_number="${{ steps.check_branch.outputs.pr_number }}"
-
-          echo "🔄 Updating existing PR #$pr_number with new changes..."
-
-          # Add comment about the update
-          gh pr comment "$pr_number" --body "### 🔄 Pre-commit Hooks Updated Again
-
-          New changes detected and committed to this PR:
-          - Updated on $(date -u '+%Y-%m-%d %H:%M:%S UTC')
-          - Number of hooks updated: **${{ steps.analyze_changes.outputs.hooks_updated }}**
-          - Run ID: [${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})
-
-          ### Latest Changes:
-          \`\`\`diff
-          $(git diff HEAD~1 -- "${{ env.CONFIG_FILE }}" | head -50)
-          \`\`\`
-
-          The PR now contains the most recent hook versions available."
-
-          echo "✅ Existing PR #$pr_number updated with new changes"
-        env:
-          GH_TOKEN: ${{ secrets.GH_PAT_TOKEN || secrets.GITHUB_TOKEN }}
 
   # ----------------------------------------------------------------------------------
   # Generate Workflow Summary Report
@@ -602,13 +550,8 @@ jobs:
             BRANCH_NAME=$(echo "$ENV_JSON" | jq -r '.UPDATE_PRE_COMMIT_HOOKS_BRANCH')
 
             echo "| **Config File** | \`$CONFIG_FILE\` |" >> $GITHUB_STEP_SUMMARY
-            echo "| **Branch** | \`$BRANCH_NAME\` |" >> $GITHUB_STEP_SUMMARY
-
-            if [ "${{ needs.update-hooks.outputs.pr_exists }}" = "true" ]; then
-              echo "| **Action** | Updated existing PR #${{ needs.update-hooks.outputs.pr_number }} |" >> $GITHUB_STEP_SUMMARY
-            else
-              echo "| **Action** | Created new pull request |" >> $GITHUB_STEP_SUMMARY
-            fi
+            echo "| **Branch Pattern** | \`$BRANCH_NAME\` |" >> $GITHUB_STEP_SUMMARY
+            echo "| **Action** | Created new timestamped pull request |" >> $GITHUB_STEP_SUMMARY
           else
             echo "## ℹ️ No Updates Available" >> $GITHUB_STEP_SUMMARY
             echo "" >> $GITHUB_STEP_SUMMARY
@@ -634,11 +577,7 @@ jobs:
           echo "=== 🪝 Pre-commit Hooks Update Summary ==="
           if [ "${{ needs.update-hooks.result }}" = "success" ]; then
             if [ "${{ needs.update-hooks.outputs.has_changes }}" = "true" ]; then
-              if [ "${{ needs.update-hooks.outputs.pr_exists }}" = "true" ]; then
-                echo "✅ Status: Updated existing PR #${{ needs.update-hooks.outputs.pr_number }}"
-              else
-                echo "✅ Status: Created new pull request"
-              fi
+              echo "✅ Status: Created new timestamped pull request"
               echo "📊 Hooks updated: ${{ needs.update-hooks.outputs.hooks_updated }}"
             else
               echo "ℹ️ Status: No changes detected - hooks are up to date"