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Bundle Tool Timeout Fix

Problem

The MCP bundle tool would hang indefinitely when called by AI models, causing the entire MCP server to become unresponsive.

Root Cause

subprocess.run() in mcp_stdio.py:148-155 had no timeout parameter:

process = subprocess.run(
    ["node", str(script_path)],
    cwd=str(mcp_server_root),
    env=env,
    capture_output=True,
    text=True,
    check=False,
    # ❌ Missing timeout parameter!
)

If the Node.js bundler script hung for any reason:

  • File I/O deadlock
  • Infinite loop in dependency resolution
  • Unhandled promise rejection
  • Node.js process stuck

...the Python subprocess would wait forever, blocking the MCP tool call indefinitely.

Solution

Added 10-second hard timeout with proper exception handling:

try:
    process = subprocess.run(
        ["node", str(script_path)],
        cwd=str(mcp_server_root),
        env=env,
        capture_output=True,
        text=True,
        check=False,
        timeout=10.0,  # ✓ Guaranteed exit after 10s
    )
except subprocess.TimeoutExpired as e:
    raise RuntimeError(
        f"Bundle operation timed out after 10 seconds.\n"
        f"project_dir: {env.get('PROJECT_DIR')}\n"
        f"This usually indicates:\n"
        f"  1. Infinite loop in bundler script\n"
        f"  2. Hanging file I/O operation\n"
        f"  3. Node.js process stuck\n"
        f"Captured output before timeout:\n"
        f"stdout: {e.stdout.decode('utf-8') if e.stdout else '<none>'}\n"
        f"stderr: {e.stderr.decode('utf-8') if e.stderr else '<none>'}"
    )

Verification of bundle-and-deploy.js Safety

Checked for potential infinite loop risks:

✓ Circular Dependency Protection

Lines 159-161 handle circular deps:

if (stack.has(normalizedEntry)) {
  circularDeps.add(normalizedEntry);
  return; // Exits recursion
}

✓ Visited Set Prevention

Lines 164-166:

if (visited.has(normalizedEntry)) {
  return; // Prevents re-processing
}

✓ Regex Loop Safety

Line 102 uses proper regex exec pattern:

while ((match = requirePattern.exec(content)) !== null) {
  requires.push(match[1]);
}

Global regex resets properly with exec() in while loops.

✓ Async Operations

All file I/O uses fs.promises with proper await, no blocking operations.

What This Guarantees

  1. MCP tool will exit within 10 seconds, even if bundler hangs
  2. AI models won't get stuck waiting for unresponsive tool calls
  3. Diagnostic info captured - timeout exception includes partial stdout/stderr
  4. Process killed - subprocess.TimeoutExpired terminates the child process

Testing

To test timeout behavior:

# Simulate hanging bundler by adding sleep in bundle-and-deploy.js:
# setTimeout(() => {}, 60000);  // 60s sleep

Expected result: RuntimeError raised after exactly 10 seconds with timeout message.