GHA: Implement LLM code review workflow

.github/workflows/code-review.yaml

@@ -0,0 +1,66 @@
+name: Code Review
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  explain-change:
+    if: ${{ !github.event.pull_request.draft }}
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+
+      - name: Install script deps
+        run: |
+          python -m pip install --upgrade pip
+          pip install git+https://github.com/sbekkerm/llm-code-review.git@main
+
+      - name: Gather PR diff
+        id: diff
+        run: |
+          BASE_SHA="${{ github.event.pull_request.base.sha }}"
+          HEAD_SHA="${{ github.event.pull_request.head.sha }}"
+          git diff --unified=0 "$BASE_SHA" "$HEAD_SHA" > pr.diff || true
+          echo "diff_path=pr.diff" >> "$GITHUB_OUTPUT"
+
+      - name: Run LLM review
+        id: explain
+        env:
+          LLM_API_URL: ${{ secrets.LLM_API_URL }}
+          LLM_API_KEY: ${{ secrets.LLM_API_KEY }}
+          LLM_MODEL_NAME: ${{ secrets.LLM_MODEL_NAME }}
+          LLM_TIMEOUT_SECONDS: 60
+          LLM_MAX_TOKENS: 700
+          LLM_MAX_CHARS_PER_CHUNK: 12000
+        run: |
+          llm-code-review --diff "${{ steps.diff.outputs.diff_path }}" --out review.md
+          echo "review<<EOF" >> $GITHUB_OUTPUT
+          cat review.md >> $GITHUB_OUTPUT
+          echo "EOF" >> $GITHUB_OUTPUT
+
+      - name: Comment on PR with review
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const fs = require('fs');
+            const body = fs.readFileSync('review.md', 'utf8');
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body
+            })