Add more context to automated reviews (#3891)

.github/workflows/pr-review.yml

@@ -55,7 +55,7 @@ jobs:
       - id: install-deps
         name: Install Dependencies
         run: |
-          pip install google-cloud-aiplatform
+          pip install google-genai
 
       - id: generate-diff
         name: Generate PR Diff
@@ -70,16 +70,36 @@ jobs:
           # Generate the diff between the PR base and the PR head
           git diff "$BASE_SHA"..."$HEAD_SHA" > pr.diff
 
+      - id: fetch-comments
+        name: Fetch PR Comments
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const comments = await github.rest.issues.listComments({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              per_page: 20,
+              sort: 'created',
+              direction: 'desc'
+            });
+            const fs = require('fs');
+            fs.writeFileSync('pr_comments.json', JSON.stringify(comments.data));
+
       - id: run-review
         name: Run Gemini PR Review
         env:
           VERTEX_PROJECT: ${{ vars.REVIEWS_VERTEX_PROJECT }}
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
         run: |
-          # The script prints the review to stdout, which we capture into a file
-
           python3 tools/pr_review.py \
             --project "$VERTEX_PROJECT" \
-            --diff-file pr.diff > review_output.md
+            --diff-file pr.diff \
+            --comments-file pr_comments.json \
+            --base-sha "$BASE_SHA" \
+            --head-sha "$HEAD_SHA" > review_output.md
+
       - id: pr-comment
         name: Post comment to Pull Request
         uses: actions/github-script@v7
@@ -87,7 +107,7 @@ jobs:
           script: |
             const fs = require('fs');
             const reviewContent = fs.readFileSync('review_output.md', 'utf8');
-            const output = `### Automated PR Review 🤖\n\n${reviewContent}`;
+            const output = `### Automated PR Review 🤖\n*(Reviewed commit: ${context.payload.pull_request.head.sha})*\n\n${reviewContent}`;
 
             github.rest.issues.createComment({
               issue_number: context.issue.number,