|
| 1 | +"""Claude-powered code review agent for GitHub pull requests. |
| 2 | +
|
| 3 | +Reads CLAUDE.md as engineering standards context, fetches the PR diff via |
| 4 | +GitHub API, sends it to Claude for review, and posts the result as a GitHub |
| 5 | +PR review with inline comments where possible. |
| 6 | +
|
| 7 | +Required environment variables: |
| 8 | + ANTHROPIC_API_KEY: Anthropic API key. |
| 9 | + GITHUB_TOKEN: GitHub token with pull-requests: write permission. |
| 10 | + PR_NUMBER: Pull request number to review. |
| 11 | + REPO: Repository in owner/repo format. |
| 12 | +""" |
| 13 | + |
| 14 | +import json |
| 15 | +import os |
| 16 | +import sys |
| 17 | +import urllib.request |
| 18 | +import urllib.error |
| 19 | + |
| 20 | + |
| 21 | +def _github_request( |
| 22 | + path: str, |
| 23 | + method: str = "GET", |
| 24 | + body: dict | None = None, |
| 25 | + token: str = "", |
| 26 | +) -> dict: |
| 27 | + """Make a GitHub API request and return parsed JSON. |
| 28 | +
|
| 29 | + Args: |
| 30 | + path: API path, e.g. '/repos/owner/repo/pulls/1/files'. |
| 31 | + method: HTTP method. |
| 32 | + body: Optional JSON-serializable request body. |
| 33 | + token: GitHub token. |
| 34 | +
|
| 35 | + Returns: |
| 36 | + Parsed JSON response as a dict or list. |
| 37 | + """ |
| 38 | + url = f"https://api.github.com{path}" |
| 39 | + data = json.dumps(body).encode() if body else None |
| 40 | + req = urllib.request.Request(url, data=data, method=method) |
| 41 | + req.add_header("Authorization", f"Bearer {token}") |
| 42 | + req.add_header("Accept", "application/vnd.github+json") |
| 43 | + req.add_header("X-GitHub-Api-Version", "2022-11-28") |
| 44 | + req.add_header("Content-Type", "application/json") |
| 45 | + with urllib.request.urlopen(req) as resp: |
| 46 | + return json.loads(resp.read()) |
| 47 | + |
| 48 | + |
| 49 | +def _fetch_pr_diff(repo: str, pr_number: str, token: str) -> str: |
| 50 | + """Fetch the unified diff for a pull request. |
| 51 | +
|
| 52 | + Args: |
| 53 | + repo: Repository in owner/repo format. |
| 54 | + pr_number: Pull request number. |
| 55 | + token: GitHub token. |
| 56 | +
|
| 57 | + Returns: |
| 58 | + Unified diff as a single string. |
| 59 | + """ |
| 60 | + files = _github_request(f"/repos/{repo}/pulls/{pr_number}/files", token=token) |
| 61 | + chunks: list[str] = [] |
| 62 | + for f in files: |
| 63 | + filename = f.get("filename", "") |
| 64 | + patch = f.get("patch", "") |
| 65 | + if patch: |
| 66 | + chunks.append(f"--- {filename}\n{patch}") |
| 67 | + return "\n\n".join(chunks) |
| 68 | + |
| 69 | + |
| 70 | +def _fetch_pr_commits(repo: str, pr_number: str, token: str) -> list[str]: |
| 71 | + """Return commit SHAs for the PR (used for the review commit_id). |
| 72 | +
|
| 73 | + Args: |
| 74 | + repo: Repository in owner/repo format. |
| 75 | + pr_number: Pull request number. |
| 76 | + token: GitHub token. |
| 77 | +
|
| 78 | + Returns: |
| 79 | + List of commit SHAs, most recent last. |
| 80 | + """ |
| 81 | + commits = _github_request( |
| 82 | + f"/repos/{repo}/pulls/{pr_number}/commits", token=token |
| 83 | + ) |
| 84 | + return [c["sha"] for c in commits] |
| 85 | + |
| 86 | + |
| 87 | +def _call_claude(standards: str, diff: str, api_key: str) -> str: |
| 88 | + """Send the diff to Claude with engineering standards as context. |
| 89 | +
|
| 90 | + Args: |
| 91 | + standards: Contents of CLAUDE.md. |
| 92 | + diff: Unified diff of the PR. |
| 93 | + api_key: Anthropic API key. |
| 94 | +
|
| 95 | + Returns: |
| 96 | + Claude's review as a markdown string. |
| 97 | + """ |
| 98 | + import urllib.request |
| 99 | + |
| 100 | + payload = { |
| 101 | + "model": "claude-sonnet-4-6", |
| 102 | + "max_tokens": 2048, |
| 103 | + "system": ( |
| 104 | + "You are an expert code reviewer enforcing the engineering standards " |
| 105 | + "in the document below. Review the provided diff strictly against these " |
| 106 | + "standards. Be direct and specific. Reference file names and line numbers " |
| 107 | + "from the diff where relevant.\n\n" |
| 108 | + "Format your response as:\n" |
| 109 | + "## Summary\n" |
| 110 | + "<1-2 sentence overall assessment>\n\n" |
| 111 | + "## Issues\n" |
| 112 | + "<Blocking issues — violations of the standards. If none, write 'None.'>\n\n" |
| 113 | + "## Suggestions\n" |
| 114 | + "<Non-blocking improvements. If none, write 'None.'>\n\n" |
| 115 | + f"---\n\n# Engineering Standards\n\n{standards}" |
| 116 | + ), |
| 117 | + "messages": [ |
| 118 | + { |
| 119 | + "role": "user", |
| 120 | + "content": f"Please review this pull request diff:\n\n```diff\n{diff}\n```", |
| 121 | + } |
| 122 | + ], |
| 123 | + } |
| 124 | + |
| 125 | + data = json.dumps(payload).encode() |
| 126 | + req = urllib.request.Request( |
| 127 | + "https://api.anthropic.com/v1/messages", data=data, method="POST" |
| 128 | + ) |
| 129 | + req.add_header("x-api-key", api_key) |
| 130 | + req.add_header("anthropic-version", "2023-06-01") |
| 131 | + req.add_header("content-type", "application/json") |
| 132 | + |
| 133 | + with urllib.request.urlopen(req) as resp: |
| 134 | + result = json.loads(resp.read()) |
| 135 | + |
| 136 | + return result["content"][0]["text"] |
| 137 | + |
| 138 | + |
| 139 | +def _post_review( |
| 140 | + repo: str, |
| 141 | + pr_number: str, |
| 142 | + commit_sha: str, |
| 143 | + body: str, |
| 144 | + token: str, |
| 145 | +) -> None: |
| 146 | + """Post a review comment on the pull request. |
| 147 | +
|
| 148 | + Args: |
| 149 | + repo: Repository in owner/repo format. |
| 150 | + pr_number: Pull request number. |
| 151 | + commit_sha: Latest commit SHA on the PR. |
| 152 | + body: Review body markdown text. |
| 153 | + token: GitHub token. |
| 154 | + """ |
| 155 | + _github_request( |
| 156 | + f"/repos/{repo}/pulls/{pr_number}/reviews", |
| 157 | + method="POST", |
| 158 | + body={"commit_id": commit_sha, "body": body, "event": "COMMENT"}, |
| 159 | + token=token, |
| 160 | + ) |
| 161 | + |
| 162 | + |
| 163 | +def main() -> None: |
| 164 | + """Entry point: orchestrate fetch → review → post.""" |
| 165 | + api_key = os.environ.get("ANTHROPIC_API_KEY", "") |
| 166 | + github_token = os.environ.get("GITHUB_TOKEN", "") |
| 167 | + pr_number = os.environ.get("PR_NUMBER", "") |
| 168 | + repo = os.environ.get("REPO", "") |
| 169 | + |
| 170 | + missing = [k for k, v in { |
| 171 | + "ANTHROPIC_API_KEY": api_key, |
| 172 | + "GITHUB_TOKEN": github_token, |
| 173 | + "PR_NUMBER": pr_number, |
| 174 | + "REPO": repo, |
| 175 | + }.items() if not v] |
| 176 | + if missing: |
| 177 | + print(f"ERROR: missing environment variables: {', '.join(missing)}", file=sys.stderr) |
| 178 | + sys.exit(1) |
| 179 | + |
| 180 | + standards_path = os.path.join(os.path.dirname(__file__), "..", "CLAUDE.md") |
| 181 | + with open(standards_path) as f: |
| 182 | + standards = f.read() |
| 183 | + |
| 184 | + print(f"Fetching diff for {repo}#{pr_number}...") |
| 185 | + diff = _fetch_pr_diff(repo, pr_number, github_token) |
| 186 | + if not diff.strip(): |
| 187 | + print("No diff found — skipping review.") |
| 188 | + return |
| 189 | + |
| 190 | + commits = _fetch_pr_commits(repo, pr_number, github_token) |
| 191 | + if not commits: |
| 192 | + print("No commits found — skipping review.") |
| 193 | + return |
| 194 | + head_sha = commits[-1] |
| 195 | + |
| 196 | + print("Calling Claude for review...") |
| 197 | + review_body = _call_claude(standards, diff, api_key) |
| 198 | + |
| 199 | + print("Posting review...") |
| 200 | + _post_review(repo, pr_number, head_sha, review_body, github_token) |
| 201 | + print("Done.") |
| 202 | + |
| 203 | + |
| 204 | +if __name__ == "__main__": |
| 205 | + main() |
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