pr-narrator-mcp: Instructions file for GitHub Copilot

Repository-Wide Code Review Instructions

Security (Highest Priority)

• Verify validateRepoPath() is called before any simple-git operation on user-supplied paths
• Check for path traversal vulnerabilities in any function accepting file or repo paths
• Verify all user-supplied regex patterns are validated via validateRegexPattern() before use
• Ensure no hardcoded secrets, API keys, or credentials anywhere in the codebase
• Check that diff and output sizes are bounded — look for MAX_DIFF_SIZE usage or equivalent limits
• Flag any use of child_process, exec, execSync, or spawn — this project uses simple-git exclusively
• Reject any code that writes to the git repository — all operations must be read-only
• Verify that null byte injection is prevented in path handling

Git Operation Safety

• All git operations must go through simple-git with a validated path from validateRepoPath()
• Never execute arbitrary git commands via shell
• Always handle git operation failures gracefully with try/catch — return null or empty defaults
• Verify that new git operations do not modify the repository (no commits, checkouts, or resets)
• Ensure createGit(validatedPath) is used, not raw simpleGit() calls

MCP Protocol Compliance

• Tool handlers must never throw exceptions — return { success: false, errors: [...] }
• Tool definitions must have name (snake_case), description, and inputSchema (JSON Schema object)
• Input schemas use Zod with .optional() and .describe() for all parameters
• Config is always the second parameter to handlers, never imported directly in tool files
• Tool results are serialized as { type: "text", text: JSON.stringify(result, null, 2) }
• New tools must be registered in src/index.ts: imports, tools array, and CallToolRequestSchema switch

Error Handling

• Functions must not throw — return result objects with errors: string[] and success: boolean
• Use error instanceof Error ? error.message : String(error) for safe error extraction in catch blocks
• Git failures return null or empty defaults, never crash the server
• Zod parse errors are caught and reported as tool errors, not re-thrown
• The index.ts handler wraps all calls in try/catch as a safety net — tools should still handle their own errors