bug mcp normalise stdin and http for standlone npx

Author: igorcosta

src/mcp/commandNormalization.ts

@@ -21,6 +21,59 @@ function hasNpxYesFlag(args: string[] | undefined): boolean {
   return args.some(arg => arg === '-y' || arg === '--yes');
 }
 
+function hasFlag(args: string[], flag: string): boolean {
+  return args.some(arg => arg === flag || arg.startsWith(`${flag}=`));
+}
+
+function findNpxCommandIndex(args: string[]): number | null {
+  for (let i = 0; i < args.length; i++) {
+    const token = args[i];
+
+    if (token === '--') {
+      return i + 1 < args.length ? i + 1 : null;
+    }
+
+    if (!token.startsWith('-') || token === '-') {
+      return i;
+    }
+
+    const consumesNextValue = token === '-p'
+      || token === '--package'
+      || token === '-c'
+      || token === '--call';
+    if (consumesNextValue) {
+      i++;
+    }
+  }
+
+  return null;
+}
+
+function isChromeDevtoolsMcpPackage(spec: string): boolean {
+  const normalized = spec.toLowerCase();
+  return normalized === 'chrome-devtools-mcp' || normalized.startsWith('chrome-devtools-mcp@');
+}
+
+function addKnownNonInteractiveServerFlags(args: string[]): string[] {
+  const normalizedArgs = [...args];
+  const commandIndex = findNpxCommandIndex(normalizedArgs);
+  if (commandIndex === null || commandIndex >= normalizedArgs.length) {
+    return normalizedArgs;
+  }
+
+  const packageSpec = normalizedArgs[commandIndex];
+  if (!isChromeDevtoolsMcpPackage(packageSpec)) {
+    return normalizedArgs;
+  }
+
+  // Prevent startup prompts that block MCP initialize handshake.
+  if (!hasFlag(normalizedArgs, '--no-usage-stats')) {
+    normalizedArgs.push('--no-usage-stats');
+  }
+
+  return normalizedArgs;
+}
+
 function sanitizePathSegment(value: string): string {
   const sanitized = value
     .toLowerCase()
@@ -87,10 +140,11 @@ export function normalizeMcpCommandForSpawn(
   if (!hasNpxYesFlag(normalizedArgs)) {
     normalizedArgs.unshift('-y');
   }
+  const spawnSafeArgs = addKnownNonInteractiveServerFlags(normalizedArgs);
 
   return {
     command,
-    args: normalizedArgs.length > 0 ? normalizedArgs : undefined,
+    args: spawnSafeArgs.length > 0 ? spawnSafeArgs : undefined,
   };
 }
 

tests/mcpCliCommands.spec.ts

@@ -168,7 +168,7 @@ describe('MCP CLI subcommands', () => {
         name: 'chrome-devtools',
         transport: 'stdio',
         command: 'npx',
-        args: ['-y', 'chrome-devtools-mcp@latest'],
+        args: ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats'],
       });
     });
 

tests/mcpCommandNormalization.spec.ts

@@ -17,15 +17,26 @@ describe('MCP command normalization', () => {
     const normalized = normalizeMcpCommandForSpawn('npx', ['chrome-devtools-mcp@latest']);
     expect(normalized).toEqual({
       command: 'npx',
-      args: ['-y', 'chrome-devtools-mcp@latest'],
+      args: ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats'],
     });
   });
 
   it('does not duplicate existing -y flag', () => {
     const normalized = normalizeMcpCommandForSpawn('npx', ['-y', 'chrome-devtools-mcp@latest']);
     expect(normalized).toEqual({
       command: 'npx',
-      args: ['-y', 'chrome-devtools-mcp@latest'],
+      args: ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats'],
+    });
+  });
+
+  it('does not duplicate chrome-devtools non-interactive flag', () => {
+    const normalized = normalizeMcpCommandForSpawn(
+      'npx',
+      ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats']
+    );
+    expect(normalized).toEqual({
+      command: 'npx',
+      args: ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats'],
     });
   });
 
@@ -53,6 +64,14 @@ describe('MCP command normalization', () => {
     });
   });
 
+  it('adds chrome-devtools non-interactive flag for config normalization', () => {
+    const normalized = normalizeMcpCommandForConfig('npx', ['chrome-devtools-mcp@latest']);
+    expect(normalized).toEqual({
+      command: 'npx',
+      args: ['-y', 'chrome-devtools-mcp@latest', '--no-usage-stats'],
+    });
+  });
+
   it('detects npx command names across platforms', () => {
     expect(isNpxCommand('npx')).toBe(true);
     expect(isNpxCommand('npx.cmd')).toBe(true);