Updated Gemini Automatic Code Review Agent

.github/reviewer-rules.md

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+# Code Reviewer Instructions & Domain Knowledge
+
+## Model & Infrastructure Rules
+- We use the `gemini-3.6-flash` model endpoint across our CI/CD workflows. It is valid and working; do not suggest changing model versions.
+
+## FRC Robotics Best Practices
+- **WPILib Command-Based:** Verify subsystems require commands properly (`addRequirements(this)`).
+- **CAN Bus Safety:** Ensure CAN IDs and motor controller configurations avoid blocking calls in periodic loops.
+- **Null Safety:** Check that sensors and encoders initialized in constructor are null-checked before `.get()`.
+- **Educational Tone:** Explain *why* something is an issue rather than just giving a diff.

.github/workflows/gemini-review.yml

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+name: Gemini FRC Code Review
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  issue_comment:
+    types: [created]
+
+jobs:
+  gemini-review:
+    if: |
+      github.event_name == 'pull_request' ||
+      (github.event.issue.pull_request && startsWith(github.event.comment.body, '/gemini'))
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+      issues: write
+
+    steps:
+      # Step 1: Acknowledge Command with Reactions API (if triggered by comment)
+      - name: Acknowledge Command
+        if: ${{ github.event_name == 'issue_comment' }}
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh api "repos/${{ github.repository }}/issues/comments/${{ github.event.comment.id }}/reactions" \
+            -f content="eyes"
+
+      # Step 2: Fetch PR Details, Diff, and Rules
+      - name: Fetch PR Details, Diff, and Rules
+        id: fetch_data
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            PR_NUM="${{ github.event.pull_request.number }}"
+          else
+            PR_NUM="${{ github.event.issue.number }}"
+          fi
+
+          echo "PR_NUMBER=$PR_NUM" >> $GITHUB_ENV
+
+          # Get PR Head Commit SHA (required for inline comments)
+          COMMIT_SHA=$(gh pr view "$PR_NUM" --repo "${{ github.repository }}" --json headRefOid -q .headRefOid)
+          echo "COMMIT_SHA=$COMMIT_SHA" >> $GITHUB_ENV
+
+          # Download PR diff
+          gh pr diff "$PR_NUM" --repo "${{ github.repository }}" > pr_diff.txt
+          head -c 20000 pr_diff.txt > trimmed_diff.txt
+
+          # Fetch reviewer-rules.md if present
+          gh api "repos/${{ github.repository }}/contents/.github/reviewer-rules.md" \
+            -H "Accept: application/vnd.github.raw+json" > rules.txt 2>/dev/null || touch rules.txt
+
+      # Step 3: Run Gemini & Post Inline Review Comments
+      - name: Post Inline Gemini Review
+        env:
+          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          EVENT_NAME: ${{ github.event_name }}
+          USER_COMMENT: ${{ github.event.comment.body }}
+        run: |
+          python3 - << 'EOF'
+          import urllib.request, urllib.error, json, os, sys, time, subprocess
+
+          api_key = os.environ.get('GEMINI_API_KEY', '').strip()
+          pr_number = os.environ.get('PR_NUMBER', '')
+          commit_sha = os.environ.get('COMMIT_SHA', '')
+          repo = os.environ.get('GITHUB_REPOSITORY', '')
+
+          if not api_key:
+              print('Error: GEMINI_API_KEY secret is not set.')
+              sys.exit(1)
+
+          models_to_try = ['gemini-3.6-flash', 'gemini-3.5-flash', 'gemini-2.0-flash']
+
+          try:
+              with open('trimmed_diff.txt', 'r', encoding='utf-8', errors='replace') as f:
+                  diff_text = f.read()
+          except Exception as e:
+              print(f'Error reading diff: {e}')
+              sys.exit(1)
+
+          rules_text = ""
+          if os.path.exists('rules.txt'):
+              with open('rules.txt', 'r', encoding='utf-8', errors='replace') as rf:
+                  content = rf.read().strip()
+                  if content:
+                      rules_text = f"\n\nPROJECT RULES & SKILLS:\n{content}"
+
+          if not diff_text.strip():
+              print('No code changes detected.')
+              sys.exit(0)
+
+          system_prompt = f"""You are a lead mentor for an FRC robotics team reviewing a pull request diff.
+          Provide feedback on WPILib best practices, thread safety, motor safety, logic bugs, and null safety.
+          {rules_text}
+
+          CRITICAL OUTPUT FORMAT:
+          You must respond ONLY with a raw JSON object (no markdown code blocks, no backticks, no extra text) matching this schema:
+          {{
+            "summary": "High-level summary for the PR description",
+            "comments": [
+              {{
+                "path": "path/to/file.java",
+                "line": 42,
+                "body": "Your inline comment or suggestion here."
+              }}
+            ]
+          }}
+
+          NOTE: The 'line' must correspond to a valid line number in the NEW modified file (+ lines in diff). Only comment on lines that need improvement or praise."""
+
+          prompt = f"{system_prompt}\n\nDiff to Review:\n{diff_text}"
+          data = json.dumps({'contents': [{'parts': [{'text': prompt}]}]}).encode('utf-8')
+
+          response_json = None
+          for model in models_to_try:
+              url = f'https://generativelanguage.googleapis.com/v1beta/models/{model}:generateContent'
+              req = urllib.request.Request(
+                  url,
+                  data=data,
+                  headers={
+                      'Content-Type': 'application/json',
+                      'x-goog-api-key': api_key
+                  }
+              )
+              try:
+                  with urllib.request.urlopen(req) as res:
+                      res_data = json.loads(res.read().decode('utf-8'))
+                      raw_text = res_data['candidates'][0]['content']['parts'][0]['text'].strip()
+                      # Clean potential markdown wraps from response
+                      if raw_text.startswith("```json"):
+                          raw_text = raw_text[7:]
+                      if raw_text.startswith("```"):
+                          raw_text = raw_text[3:]
+                      if raw_text.endswith("```"):
+                          raw_text = raw_text[:-3]
+                      response_json = json.loads(raw_text.strip())
+                      break
+              except urllib.error.HTTPError as e:
+                  if e.code in [503, 429, 404]:
+                      time.sleep(1)
+                      continue
+                  else:
+                      print(f'HTTP Error {e.code}')
+                      break
+              except Exception as e:
+                  print(f'Parsing error: {e}')
+                  break
+
+          if not response_json:
+              print('Failed to generate structured review.')
+              sys.exit(0)
+
+          # 1. Post High-level Summary Comment
+          summary = response_json.get('summary', 'PR reviewed.')
+          subprocess.run([
+              'gh', 'pr', 'comment', pr_number,
+              '--repo', repo,
+              '--body', f"🤖 **Gemini Code Review Summary**\n\n{summary}"
+          ])
+
+          # 2. Post Inline Comments
+          comments = response_json.get('comments', [])
+          for c in comments:
+              file_path = c.get('path')
+              line_num = c.get('line')
+              body_msg = c.get('body')
+
+              if file_path and line_num and body_msg:
+                  # Use GitHub REST API for pull request review comments
+                  cmd = [
+                      'gh', 'api',
+                      f'repos/{repo}/pulls/{pr_number}/comments',
+                      '-X', 'POST',
+                      '-f', f'body=🤖 {body_msg}',
+                      '-f', f'commit_id={commit_sha}',
+                      '-f', f'path={file_path}',
+                      '-F', f'line={line_num}',
+                      '-f', 'side=RIGHT'
+                  ]
+                  subprocess.run(cmd)
+
+          EOF