feat: add automated PR review agent that summarizes changes as a comment

.github/workflows/pr-review-agent.yml

@@ -0,0 +1,140 @@
+name: PR Review Agent
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  summarize-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Summarize PR and post comment
+        uses: actions/github-script@v7
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const pr_number = context.payload.pull_request.number;
+            const { owner, repo } = context.repo;
+
+            // Fetch PR metadata
+            const { data: pr } = await github.rest.pulls.get({
+              owner, repo, pull_number: pr_number,
+            });
+
+            // Fetch changed files (up to 100)
+            const { data: files } = await github.rest.pulls.listFiles({
+              owner, repo, pull_number: pr_number, per_page: 100,
+            });
+
+            // Build a compact file-change list
+            const fileLines = files.map(
+              f => `- \`${f.filename}\` (${f.status}): +${f.additions} −${f.deletions}`
+            );
+
+            // Collect diff patches for the first 15 text files
+            const patches = files
+              .filter(f => f.patch)
+              .slice(0, 15)
+              .map(f => `### \`${f.filename}\`\n\`\`\`diff\n${f.patch.slice(0, 2000)}\n\`\`\``)
+              .join('\n\n');
+
+            const userPrompt = [
+              'You are a senior engineer reviewing a pull request for AccessHub, a TypeScript',
+              'internal developer platform (Express + Prisma + SQLite API, React + Vite frontend).',
+              '',
+              'PR title: ' + pr.title,
+              'PR description: ' + (pr.body || '(none)'),
+              '',
+              'Changed files (' + files.length + ' total):',
+              fileLines.join('\n'),
+              '',
+              'Diff excerpts:',
+              patches || '(no text patches available)',
+              '',
+              'Write a concise PR summary using these sections:',
+              '## Summary',
+              'One or two sentences describing what this PR does.',
+              '',
+              '## Changes',
+              'Bullet-point list of the most important changes.',
+              '',
+              '## Potential concerns',
+              'Flag any security, architecture, or testing issues relevant to this codebase.',
+              'If there are none, say "None identified."',
+            ].join('\n');
+
+            let body;
+
+            try {
+              const token = process.env.GITHUB_TOKEN;
+              const resp = await fetch('https://models.inference.ai.azure.com/chat/completions', {
+                method: 'POST',
+                headers: {
+                  'Authorization': 'Bearer ' + token,
+                  'Content-Type': 'application/json',
+                },
+                body: JSON.stringify({
+                  model: 'gpt-4o-mini',
+                  messages: [{ role: 'user', content: userPrompt }],
+                  max_tokens: 1024,
+                }),
+              });
+
+              if (!resp.ok) {
+                const text = await resp.text();
+                throw new Error('Models API ' + resp.status + ': ' + text);
+              }
+
+              const json = await resp.json();
+              const aiSummary = json.choices[0].message.content.trim();
+              body = '## \uD83E\uDD16 PR Review Agent\n\n' + aiSummary +
+                     '\n\n---\n*Generated automatically by the PR Review Agent.*';
+            } catch (err) {
+              // Fallback: structured summary without AI
+              core.warning('AI summarization unavailable (' + err.message + '); using structured fallback.');
+              body = [
+                '## \uD83E\uDD16 PR Review Agent',
+                '',
+                '## Summary',
+                'This PR — **' + pr.title + '** — modifies ' + files.length + ' file(s).',
+                '',
+                '## Changes',
+                fileLines.join('\n'),
+                '',
+                '## Potential concerns',
+                '_AI summarization was unavailable; please review manually._',
+                '',
+                '---',
+                '*Generated automatically by the PR Review Agent.*',
+              ].join('\n');
+            }
+
+            // Remove any previous bot summary comment to keep the thread clean
+            const { data: comments } = await github.rest.issues.listComments({
+              owner, repo, issue_number: pr_number,
+            });
+            for (const c of comments) {
+              if (
+                c.user?.type === 'Bot' &&
+                c.body?.includes('PR Review Agent')
+              ) {
+                await github.rest.issues.deleteComment({
+                  owner, repo, comment_id: c.id,
+                });
+              }
+            }
+
+            // Post the new summary
+            await github.rest.issues.createComment({
+              owner, repo, issue_number: pr_number, body,
+            });