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,

test/sanitizer.test.ts

@@ -7,6 +7,7 @@ import {
   normalizeHtmlEntities,
   sanitizeContent,
   stripHtmlComments,
+  redactGitHubTokens,
 } from "../src/github/utils/sanitizer";
 
 describe("stripInvisibleCharacters", () => {
@@ -242,6 +243,109 @@ describe("sanitizeContent", () => {
   });
 });
 
+describe("redactGitHubTokens", () => {
+  it("should redact personal access tokens (ghp_)", () => {
+    const token = "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";
+    expect(redactGitHubTokens(`Token: ${token}`)).toBe(
+      "Token: [REDACTED_GITHUB_TOKEN]",
+    );
+    expect(redactGitHubTokens(`Here's a token: ${token} in text`)).toBe(
+      "Here's a token: [REDACTED_GITHUB_TOKEN] in text",
+    );
+  });
+
+  it("should redact OAuth tokens (gho_)", () => {
+    const token = "gho_16C7e42F292c6912E7710c838347Ae178B4a";
+    expect(redactGitHubTokens(`OAuth: ${token}`)).toBe(
+      "OAuth: [REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should redact installation tokens (ghs_)", () => {
+    const token = "ghs_xz7yzju2SZjGPa0dUNMAx0SH4xDOCS31LXQW";
+    expect(redactGitHubTokens(`Install token: ${token}`)).toBe(
+      "Install token: [REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should redact refresh tokens (ghr_)", () => {
+    const token = "ghr_1B4a2e77838347a253e56d7b5253e7d11667";
+    expect(redactGitHubTokens(`Refresh: ${token}`)).toBe(
+      "Refresh: [REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should redact fine-grained tokens (github_pat_)", () => {
+    const token =
+      "github_pat_11ABCDEFG0example5of9_2nVwvsylpmOLboQwTPTLewDcE621dQ0AAaBBCCDDEEFFHH";
+    expect(redactGitHubTokens(`Fine-grained: ${token}`)).toBe(
+      "Fine-grained: [REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should handle tokens in code blocks", () => {
+    const content = `\`\`\`bash
+export GITHUB_TOKEN=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
+\`\`\``;
+    const expected = `\`\`\`bash
+export GITHUB_TOKEN=[REDACTED_GITHUB_TOKEN]
+\`\`\``;
+    expect(redactGitHubTokens(content)).toBe(expected);
+  });
+
+  it("should handle multiple tokens in one text", () => {
+    const content =
+      "Token 1: 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 and token 2: gho_16C7e42F292c6912E7710c838347Ae178B4a";
+    expect(redactGitHubTokens(content)).toBe(
+      "Token 1: [REDACTED_GITHUB_TOKEN] and token 2: [REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should handle tokens in URLs", () => {
+    const content =
+      "https://api.github.com/user?access_token=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";
+    expect(redactGitHubTokens(content)).toBe(
+      "https://api.github.com/user?access_token=[REDACTED_GITHUB_TOKEN]",
+    );
+  });
+
+  it("should not redact partial matches or invalid tokens", () => {
+    const content =
+      "This is not a token: ghp_short or gho_toolong1234567890123456789012345678901234567890";
+    expect(redactGitHubTokens(content)).toBe(content);
+  });
+
+  it("should preserve normal text", () => {
+    const content = "Normal text with no tokens";
+    expect(redactGitHubTokens(content)).toBe(content);
+  });
+
+  it("should handle edge cases", () => {
+    expect(redactGitHubTokens("")).toBe("");
+    expect(redactGitHubTokens("ghp_")).toBe("ghp_");
+    expect(redactGitHubTokens("github_pat_short")).toBe("github_pat_short");
+  });
+});
+
+describe("sanitizeContent with token redaction", () => {
+  it("should redact tokens as part of full sanitization", () => {
+    const content = `
+      <!-- Hidden comment with token: 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 -->
+      Here's some text with a token: gho_16C7e42F292c6912E7710c838347Ae178B4a
+      And invisible chars: test\u200Btoken
+    `;
+
+    const sanitized = sanitizeContent(content);
+
+    expect(sanitized).not.toContain("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");
+    expect(sanitized).not.toContain("gho_16C7e42F292c6912E7710c838347Ae178B4a");
+    expect(sanitized).not.toContain("<!-- Hidden comment");
+    expect(sanitized).not.toContain("\u200B");
+    expect(sanitized).toContain("[REDACTED_GITHUB_TOKEN]");
+    expect(sanitized).toContain("Here's some text with a token:");
+  });
+});
+
 describe("stripHtmlComments (legacy)", () => {
   it("should remove HTML comments", () => {
     expect(stripHtmlComments("Hello <!-- example -->World")).toBe(