fix: improve main module detection for npx compatibility

The previous module detection logic failed when running via npx due to
symlink resolution differences. This caused the server to exit immediately
without starting, resulting in "MCP error -32000: Connection closed".

The fix uses realpathSync() to fully resolve both the module path and
script path before comparison, handling symlinks and path normalization
across different execution contexts (npx, node, direct execution).

Fixes the issue where:
- Connection failed after ~1s with "Connection closed" error
- Server worked in development but failed when installed via npx

Author: claude

package-lock.json

@@ -21,6 +21,7 @@ if (process.env.NODE_ENV !== 'production') {
 import { version } from 'node:process';
 import { fileURLToPath } from 'node:url';
 import { resolve } from 'node:path';
+import { realpathSync } from 'node:fs';
 import { Server } from '@modelcontextprotocol/sdk/server/index.js';
 import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import {
@@ -241,7 +242,17 @@ async function main() {
 // We need to normalize both paths to handle different execution contexts (npx, node, etc.)
 const modulePath = fileURLToPath(import.meta.url);
 const scriptPath = process.argv[1] ? resolve(process.argv[1]) : '';
-const isMainModule = modulePath === scriptPath;
+
+// Resolve both paths fully to handle symlinks and path normalization
+let isMainModule = false;
+try {
+  const realModulePath = realpathSync(modulePath);
+  const realScriptPath = scriptPath ? realpathSync(scriptPath) : '';
+  isMainModule = realModulePath === realScriptPath;
+} catch (error) {
+  // If realpath fails (e.g., file doesn't exist), fall back to simple comparison
+  isMainModule = modulePath === scriptPath;
+}
 
 if (isMainModule) {
   main().catch((error) => {