feat: Store benchmark results as git notes (#15)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Marcelo Soares <marcelo.me.soares@gmail.com>

.github/workflows/ci.yaml

@@ -102,11 +102,10 @@ jobs:
   benchmarks:
     needs: generate
     name: run benchmarks
-    if: github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     permissions:
       pull-requests: write
-      contents: read
+      contents: write
     steps:
       - uses: actions/checkout@v4
       - name: Set up Dart
@@ -119,13 +118,31 @@ jobs:
         uses: actions/download-artifact@v4
         with:
           name: generated-code
+      - name: Configure Git
+        run: |
+          git config --global user.name "GitHub Actions"
+          git config --global user.email "actions@github.com"
+      - name: Fetch Existing Benchmark Data
+        run: git fetch origin refs/notes/benchmarks:refs/notes/benchmarks || true
       - name: Run benchmarks
         run: dart benchmark/run.dart --ci > benchmark-results.txt
       - name: Comment on PR
+        if: github.event_name == 'pull_request'
         uses: thollander/actions-comment-pull-request@v3
         with:
           file-path: benchmark-results.txt
           comment-tag: benchmark-results
+      - name: Store Benchmark Data in Git Notes
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            COMMIT_SHA=${{ github.event.pull_request.head.sha }}
+          else
+            COMMIT_SHA=${{ github.sha }}
+          fi
+          git notes --ref=benchmarks add -f -F benchmark-results.txt $COMMIT_SHA
+      - name: Push Benchmark Data
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork != true
+        run: git push origin refs/notes/benchmarks
 
   publish_check:
     needs: generate

benchmark/README.md

@@ -24,6 +24,24 @@ To run the benchmarks:
 dart benchmark/run.dart
 ```
 
+## Accessing Benchmark Results
+
+When running from the CI, benchmark results are automatically stored as git notes on commits. If running on a pull-request, it is also pasted as a comment that is kept up to date on each push. To access historical benchmark data:
+
+```bash
+# Fetch benchmark notes from remote (if not already available)
+git fetch origin refs/notes/benchmarks:refs/notes/benchmarks
+
+# View benchmark results for the latest commit
+git notes --ref=benchmarks show
+
+# View benchmark results for a specific commit
+git notes --ref=benchmarks show <commit-sha>
+
+# View all commits with their benchmark results
+git log --show-notes=benchmark
+```
+
 ## Benchmark Details
 
 ### Table Structure