🤖 Implement Gemini PR Pre-review Reflex

This PR adds a new reflex action to the Gemini CLI Bot that automatically provides high-level pre-reviews for new pull requests. ### Changes: - Created `tools/gemini-cli-bot/reflexes/scripts/pr_pre_review.ts`: A reflex script that uses Gemini to evaluate PRs based on quality, roadmap alignment, "obvious wins," and repository best practices. - Updated `.github/workflows/gemini-cli-bot-pulse.yml`: Added `GEMINI_API_KEY` and ensure the Gemini CLI is bundled before running reflex actions. ### Impact: - **Time to First Response**: Will decrease as the bot provides initial feedback within 30 minutes of PR submission. - **Maintainer Productivity**: High-level assessments and roadmap alignment checks will help maintainers prioritize reviews. - **Contributor Experience**: Immediate feedback on best practices and roadmap alignment. This addresses the request in issue #26471.
2026-05-14 22:02:59 -07:00 · 2026-05-04 22:28:40 +00:00
parent a79da4f3a9
commit 923a692acb
2 changed files with 188 additions and 0 deletions
@@ -34,9 +34,14 @@ jobs:
      - name: 'Install dependencies'
        run: 'npm ci'

+      - name: 'Build Gemini CLI'
+        run: 'npm run bundle'
+
      - name: 'Run Reflex Processes'
        env:
          GITHUB_TOKEN: '${{ secrets.GITHUB_TOKEN }}'
+          GEMINI_API_KEY: '${{ secrets.GEMINI_API_KEY }}'
+          GEMINI_MODEL: 'gemini-3-flash-preview'
        run: |
          if [ -d "tools/gemini-cli-bot/reflexes/scripts" ] && [ "$(ls -A tools/gemini-cli-bot/reflexes/scripts)" ]; then
            for script in tools/gemini-cli-bot/reflexes/scripts/*.ts; do
@@ -0,0 +1,183 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { execFileSync, execSync } from 'node:child_process';
+import { readFileSync, writeFileSync, existsSync, rmSync } from 'node:fs';
+import { join } from 'node:path';
+
+const REVIEW_HEADER = '## 🤖 Gemini Bot Pre-review';
+
+/**
+ * Runs a shell command and returns the output.
+ */
+function runCommand(cmd: string, args: string[], options: any = {}): string {
+  try {
+    return execFileSync(cmd, args, {
+      encoding: 'utf-8',
+      stdio: ['ignore', 'pipe', 'ignore'],
+      ...options,
+    }).trim();
+  } catch (err) {
+    // Silence errors for expected failures or missing data
+    return '';
+  }
+}
+
+async function main() {
+  console.log('Starting Gemini PR Pre-review Reflex...');
+
+  // 1. Get open PRs
+  const prsJson = runCommand('gh', [
+    'pr',
+    'list',
+    '--state',
+    'open',
+    '--limit',
+    '20',
+    '--json',
+    'number,title,body,author,labels',
+  ]);
+
+  if (!prsJson) {
+    console.log('No open PRs found or gh command failed.');
+    return;
+  }
+  
+  let prs;
+  try {
+    prs = JSON.parse(prsJson);
+  } catch (err) {
+    console.error('Failed to parse PR list JSON.');
+    return;
+  }
+
+  for (const pr of prs) {
+    // Skip bot PRs
+    if (pr.author.login.includes('[bot]') || pr.author.login.includes('robot')) {
+      continue;
+    }
+
+    // 2. Check if already reviewed by the bot
+    const commentsJson = runCommand('gh', [
+      'pr',
+      'view',
+      pr.number.toString(),
+      '--json',
+      'comments',
+    ]);
+    if (!commentsJson) continue;
+    
+    let comments;
+    try {
+      comments = JSON.parse(commentsJson).comments;
+    } catch (err) {
+      continue;
+    }
+    
+    const alreadyReviewed = comments.some(
+      (c: any) => c.body && c.body.includes(REVIEW_HEADER),
+    );
+
+    if (alreadyReviewed) {
+      console.log(`PR #${pr.number} already has a Gemini pre-review. Skipping.`);
+      continue;
+    }
+
+    console.log(`Pre-reviewing PR #${pr.number}: ${pr.title}`);
+
+    // 3. Get Diff
+    const diff = runCommand('gh', ['pr', 'diff', pr.number.toString()]);
+    if (!diff) {
+      console.log(`Could not get diff for PR #${pr.number}.`);
+      continue;
+    }
+
+    // 4. Prepare Prompt
+    const roadmapPath = join(process.cwd(), 'ROADMAP.md');
+    const roadmap = existsSync(roadmapPath) ? readFileSync(roadmapPath, 'utf-8') : 'No roadmap found.';
+    
+    const prompt = `
+You are the Gemini CLI Bot. Your task is to perform a pre-review of a Pull Request.
+Provide a high-level assessment based on:
+1. **Objective measures of quality**: (code structure, tests, documentation, performance).
+2. **Alignment with the project roadmap**: (roadmap provided below).
+3. **Identification of "obvious wins"**: (significant improvements, critical bug fixes, "good to go" small PRs).
+4. **Conformity with TypeScript and repository best practices**: (license headers, type safety, naming conventions).
+
+Roadmap:
+${roadmap}
+
+PR Title: ${pr.title}
+PR Body: ${pr.body || 'No description provided.'}
+
+PR Diff:
+${diff.substring(0, 50000)}
+
+Output your review in Markdown. 
+Rules:
+- Start with the header: ${REVIEW_HEADER}
+- Use sections for the 4 points above.
+- If you find a "roadmap match", mention it explicitly.
+- If it's an "obvious win", recommend it for fast-track review.
+- Suggest 1-3 labels if appropriate (e.g., area/core, status/needs-tests, priority/p2).
+- Be concise, professional, and encouraging.
+- Do NOT use tools. Just output the text of the review.
+`;
+
+    // 5. Run Gemini
+    const promptFile = join(process.cwd(), `pr_prompt_${pr.number}.md`);
+    writeFileSync(promptFile, prompt);
+    
+    let review = '';
+    try {
+      const geminiPath = join(process.cwd(), 'bundle', 'gemini.js');
+      if (existsSync(geminiPath)) {
+        review = execFileSync('node', [
+          geminiPath,
+          '--prompt-file', promptFile
+        ], { 
+          encoding: 'utf-8',
+          env: { 
+            ...process.env, 
+            GEMINI_CLI_TRUST_WORKSPACE: 'true',
+            GEMINI_MODEL: process.env.GEMINI_MODEL || 'gemini-3-flash-preview'
+          }
+        });
+      } else {
+        console.error('bundle/gemini.js not found. Cannot perform review.');
+        continue;
+      }
+    } catch (err) {
+      console.error(`Error running Gemini for PR #${pr.number}:`, err);
+      continue;
+    } finally {
+      if (existsSync(promptFile)) rmSync(promptFile);
+    }
+
+    if (!review || review.trim().length === 0) {
+      console.log(`Gemini returned an empty review for PR #${pr.number}.`);
+      continue;
+    }
+
+    // 6. Post Comment
+    const commentFile = join(process.cwd(), `pr_review_${pr.number}.md`);
+    writeFileSync(commentFile, review);
+    
+    try {
+      execFileSync('gh', ['pr', 'comment', pr.number.toString(), '--body-file', commentFile]);
+      console.log(`Successfully posted pre-review for PR #${pr.number}.`);
+    } catch (err) {
+      console.error(`Failed to post comment for PR #${pr.number}:`, err);
+    } finally {
+      if (existsSync(commentFile)) rmSync(commentFile);
+    }
+  }
+}
+
+main().catch((err) => {
+  console.error('Fatal error in PR pre-review reflex:', err);
+  process.exit(1);
+});