Fix coverage badge workflow for protected branches

Summary:
The coverage workflow was failing to push the badge to `main` due to branch protection rules (CLA check, import status check, PR requirement).

## Changes

1. **Push badge to separate `badges` branch**: Instead of pushing directly to the protected `main` branch, the workflow now pushes the coverage badge to an unprotected `badges` branch. This avoids the branch protection restrictions.

2. **Updated README badge URL**: Changed the badge endpoint from `main` to `badges` branch:
   ```
   # Before
   .../balance/main/.github/badges/coverage.json
   # After
   .../balance/badges/.github/badges/coverage.json
   ```

3. **Conditional execution**: The "Commit coverage badge" step only runs on push events to main (`github.event_name == 'push'`), while coverage extraction still runs on all main branch events (including PRs) for visibility.

Fixes #271

Differential Revision: D90920671

fbshipit-source-id: d2cc0260ba5e84fab9ff1132a36f4b94d7a2bde6

Author: talgalili

.github/workflows/coverage.yml

@@ -13,71 +13,67 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v5
-      
+
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
           python-version: '3.12'
-      
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           pip install .[dev]
-      
+
       - name: Run tests with coverage
         run: |
           python -m pytest --cov=balance --cov-report=xml --cov-report=html --cov-report=term-missing
-      
+
       - name: Upload coverage reports to artifacts
         if: always()
         uses: actions/upload-artifact@v4
         with:
           name: coverage-report
           path: htmlcov/
-      
+
       - name: Upload coverage XML
         if: always()
         uses: actions/upload-artifact@v4
         with:
           name: coverage-xml
           path: coverage.xml
-      
+
       - name: Display coverage percentage
         run: |
           coverage report --precision=2
-      
+
       - name: Extract coverage percentage
         if: github.ref == 'refs/heads/main'
         run: |
           COVERAGE=$(coverage report --precision=2 | grep TOTAL | awk '{print $NF}' | sed 's/%//')
           echo "COVERAGE=$COVERAGE" >> $GITHUB_ENV
           echo "Coverage: $COVERAGE%"
-      
-      - name: Create coverage badge
-        if: github.ref == 'refs/heads/main'
+
+      - name: Commit coverage badge
+        if: github.ref == 'refs/heads/main' && github.event_name == 'push'
         run: |
+          git config --local user.email "github-actions[bot]@users.noreply.github.com"
+          git config --local user.name "github-actions[bot]"
+
+          # Fetch the badges branch or create it as an orphan
+          git fetch origin badges:badges 2>/dev/null || git checkout --orphan badges
+          git checkout badges
+
+          # Create badge directory and file
           mkdir -p .github/badges
           python -c "
-          import os
+          import os, json
           coverage = float(os.environ['COVERAGE'])
           color = 'brightgreen' if coverage >= 80 else 'yellow' if coverage >= 60 else 'orange'
-          badge = {
-              'schemaVersion': 1,
-              'label': 'coverage',
-              'message': f'{coverage}%',
-              'color': color
-          }
-          import json
+          badge = {'schemaVersion': 1, 'label': 'coverage', 'message': f'{coverage}%', 'color': color}
           with open('.github/badges/coverage.json', 'w') as f:
               json.dump(badge, f)
-          print(f'Created badge with {coverage}% coverage in {color}')
           "
-      
-      - name: Commit coverage badge
-        if: github.ref == 'refs/heads/main'
-        run: |
-          git config --local user.email "github-actions[bot]@users.noreply.github.com"
-          git config --local user.name "github-actions[bot]"
+
           git add .github/badges/coverage.json
           git diff --staged --quiet || git commit -m "Update coverage badge [skip ci]"
-          git push
+          git push origin badges

README.md

@@ -7,7 +7,7 @@
 [![Current Release](https://img.shields.io/github/release/facebookresearch/balance.svg)](https://github.com/facebookresearch/balance/releases)
 [![Python 3.9+](https://img.shields.io/badge/Python-3.9+-fcbc2c.svg?logo=python&logoColor=white)](https://www.python.org/downloads/)
 [![Build & Test](https://github.com/facebookresearch/balance/actions/workflows/build-and-test.yml/badge.svg)](https://github.com/facebookresearch/balance/actions/workflows/build-and-test.yml?query=branch%3Amain)
-[![Coverage](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/facebookresearch/balance/main/.github/badges/coverage.json)](https://github.com/facebookresearch/balance/actions/workflows/coverage.yml?query=branch%3Amain)
+[![Coverage](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/facebookresearch/balance/badges/.github/badges/coverage.json)](https://github.com/facebookresearch/balance/actions/workflows/coverage.yml?query=branch%3Amain)
 [![CodeQL](https://github.com/facebookresearch/balance/actions/workflows/codeql.yml/badge.svg)](https://github.com/facebookresearch/balance/actions/workflows/codeql.yml?query=branch%3Amain)
 [![Deploy Website](https://github.com/facebookresearch/balance/actions/workflows/deploy-website.yml/badge.svg)](https://github.com/facebookresearch/balance/actions/workflows/deploy-website.yml?query=branch%3Amain)
 [![Release](https://github.com/facebookresearch/balance/actions/workflows/release.yml/badge.svg)](https://github.com/facebookresearch/balance/actions/workflows/release.yml?query=branch%3Amain)