Add GitHub token redaction to comment tools (#453)

* Add GitHub token redaction to update_claude_comment tool

- Add redactGitHubTokens() function to sanitizer.ts that detects and redacts all GitHub token formats (ghp_, gho_, ghs_, ghr_, github_pat_)
- Update sanitizeContent() to include token redaction in the sanitization pipeline
- Apply sanitization to comment body in github-comment-server.ts before updating comments
- Add comprehensive tests covering all token formats, edge cases, and integration scenarios
- Prevents accidental exposure of GitHub tokens in PR/issue comments while preserving existing functionality

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Add GitHub token redaction to inline comment server

- Apply sanitizeContent() to comment body in github-inline-comment-server.ts before creating inline PR comments
- Ensures consistency in token redaction across all comment creation tools
- Prevents GitHub tokens from being exposed in inline PR review comments

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/github/utils/sanitizer.ts

@@ -58,6 +58,41 @@ export function sanitizeContent(content: string): string {
   content = stripMarkdownLinkTitles(content);
   content = stripHiddenAttributes(content);
   content = normalizeHtmlEntities(content);
+  content = redactGitHubTokens(content);
+  return content;
+}
+
+export function redactGitHubTokens(content: string): string {
+  // GitHub Personal Access Tokens (classic): ghp_XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (40 chars)
+  content = content.replace(
+    /\bghp_[A-Za-z0-9]{36}\b/g,
+    "[REDACTED_GITHUB_TOKEN]",
+  );
+
+  // GitHub OAuth tokens: gho_XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (40 chars)
+  content = content.replace(
+    /\bgho_[A-Za-z0-9]{36}\b/g,
+    "[REDACTED_GITHUB_TOKEN]",
+  );
+
+  // GitHub installation tokens: ghs_XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (40 chars)
+  content = content.replace(
+    /\bghs_[A-Za-z0-9]{36}\b/g,
+    "[REDACTED_GITHUB_TOKEN]",
+  );
+
+  // GitHub refresh tokens: ghr_XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (40 chars)
+  content = content.replace(
+    /\bghr_[A-Za-z0-9]{36}\b/g,
+    "[REDACTED_GITHUB_TOKEN]",
+  );
+
+  // GitHub fine-grained personal access tokens: github_pat_XXXXXXXXXX (up to 255 chars)
+  content = content.replace(
+    /\bgithub_pat_[A-Za-z0-9_]{11,221}\b/g,
+    "[REDACTED_GITHUB_TOKEN]",
+  );
+
   return content;
 }
 

src/mcp/github-comment-server.ts

@@ -6,6 +6,7 @@ import { z } from "zod";
 import { GITHUB_API_URL } from "../github/api/config";
 import { Octokit } from "@octokit/rest";
 import { updateClaudeComment } from "../github/operations/comments/update-claude-comment";
+import { sanitizeContent } from "../github/utils/sanitizer";
 
 // Get repository information from environment variables
 const REPO_OWNER = process.env.REPO_OWNER;
@@ -54,11 +55,13 @@ server.tool(
       const isPullRequestReviewComment =
         eventName === "pull_request_review_comment";
 
+      const sanitizedBody = sanitizeContent(body);
+
       const result = await updateClaudeComment(octokit, {
         owner,
         repo,
         commentId,
-        body,
+        body: sanitizedBody,
         isPullRequestReviewComment,
       });
 

src/mcp/github-inline-comment-server.ts

@@ -3,6 +3,7 @@ import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import { z } from "zod";
 import { createOctokit } from "../github/api/client";
+import { sanitizeContent } from "../github/utils/sanitizer";
 
 // Get repository and PR information from environment variables
 const REPO_OWNER = process.env.REPO_OWNER;
@@ -81,6 +82,9 @@ server.tool(
 
       const octokit = createOctokit(githubToken).rest;
 
+      // Sanitize the comment body to remove any potential GitHub tokens
+      const sanitizedBody = sanitizeContent(body);
+
       // Validate that either line or both startLine and line are provided
       if (!line && !startLine) {
         throw new Error(
@@ -104,7 +108,7 @@ server.tool(
         owner,
         repo,
         pull_number,
-        body,
+        body: sanitizedBody,
         path,
         side: side || "RIGHT",
         commit_id: commit_id || pr.data.head.sha,