diff --git a/packages/adapter-dotnet/src/DotnetDebugAdapter.ts b/packages/adapter-dotnet/src/DotnetDebugAdapter.ts
index ee6eee16..213e4695 100644
--- a/packages/adapter-dotnet/src/DotnetDebugAdapter.ts
+++ b/packages/adapter-dotnet/src/DotnetDebugAdapter.ts
@@ -296,8 +296,8 @@ export class DotnetDebugAdapter extends EventEmitter implements IDebugAdapter {
     const possiblePaths = [
       // Development: running from compiled adapter package dist/
       path.resolve(__dirname, 'utils', 'netcoredbg-bridge.js'),
-      // Bundled NPX distribution (cli.mjs is in dist/, bridge copied alongside)
-      path.resolve(__dirname, '..', 'packages', 'adapter-dotnet', 'dist', 'utils', 'netcoredbg-bridge.js'),
+      // Bundled NPX distribution (cli.mjs is in dist/, bridge copied at dist/packages/adapter-dotnet/dist/utils/)
+      path.resolve(__dirname, 'packages', 'adapter-dotnet', 'dist', 'utils', 'netcoredbg-bridge.js'),
       // Monorepo source tree fallback
       path.resolve(__dirname, '..', '..', '..', '..', 'packages', 'adapter-dotnet', 'dist', 'utils', 'netcoredbg-bridge.js'),
       // CWD-relative fallback
diff --git a/packages/mcp-debugger/scripts/bundle-cli.js b/packages/mcp-debugger/scripts/bundle-cli.js
index afe6534a..555355fa 100644
--- a/packages/mcp-debugger/scripts/bundle-cli.js
+++ b/packages/mcp-debugger/scripts/bundle-cli.js
@@ -211,15 +211,24 @@ async function bundleCLI() {
     console.warn('Run: pnpm -w -F @debugmcp/adapter-rust run build:adapter');
   }
 
-  // Copy netcoredbg bridge script for .NET adapter
-  const bridgeSrc = path.join(repoRoot, 'packages/adapter-dotnet/dist/utils/netcoredbg-bridge.js');
-  if (fs.existsSync(bridgeSrc)) {
-    const bridgeDestDir = path.join(distDir, 'packages', 'adapter-dotnet', 'dist', 'utils');
-    fs.mkdirSync(bridgeDestDir, { recursive: true });
-    fs.cpSync(bridgeSrc, path.join(bridgeDestDir, 'netcoredbg-bridge.js'));
-    console.log('Copied netcoredbg bridge script.');
+  // Copy .NET adapter runtime utils. The bridge entry imports ./netcoredbg-bridge-core.js
+  // at runtime in the spawned child Node process, so the core file must be present on
+  // disk next to the entry — tsup only inlines into cli.mjs, not the spawned worker.
+  const dotnetUtilsSrc = path.join(repoRoot, 'packages/adapter-dotnet/dist/utils');
+  if (fs.existsSync(dotnetUtilsSrc)) {
+    const dotnetUtilsDest = path.join(distDir, 'packages', 'adapter-dotnet', 'dist', 'utils');
+    fs.mkdirSync(dotnetUtilsDest, { recursive: true });
+    fs.cpSync(dotnetUtilsSrc, dotnetUtilsDest, {
+      recursive: true,
+      filter: (src) => {
+        const stat = fs.statSync(src);
+        if (stat.isDirectory()) return true;
+        return src.endsWith('.js');
+      }
+    });
+    console.log('Copied .NET adapter runtime utils (netcoredbg bridge + core).');
   } else {
-    console.warn('Warning: netcoredbg-bridge.js not found; .NET debugging may fail in NPX distribution.');
+    console.warn('Warning: packages/adapter-dotnet/dist/utils/ not found; .NET debugging will fail in NPX distribution.');
   }
 
   // Mirror dist into the package/ directory used by npm pack artifacts.
diff --git a/packages/mcp-debugger/test-bundle.cjs b/packages/mcp-debugger/test-bundle.cjs
index b084dfdc..6a9ee5c7 100644
--- a/packages/mcp-debugger/test-bundle.cjs
+++ b/packages/mcp-debugger/test-bundle.cjs
@@ -40,9 +40,13 @@ console.log('Bundle path:', bundlePath);
     console.log('\nChecking for required runtime assets:');
     const requiredAssets = [
       {
-        name: 'netcoredbg bridge (.NET)',
+        name: 'netcoredbg bridge entry (.NET)',
         path: 'packages/adapter-dotnet/dist/utils/netcoredbg-bridge.js'
       },
+      {
+        name: 'netcoredbg bridge core (.NET)',
+        path: 'packages/adapter-dotnet/dist/utils/netcoredbg-bridge-core.js'
+      },
       {
         name: 'proxy bundle',
         path: 'proxy/proxy-bundle.cjs'