[BUG] @ does not allow for selecting context in large monorepos

Environment

• Platform (select one):
• [ ] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify --> LiteLLM claude-3-7-sonnet-20250219
• Claude CLI version: <!-- output of claude --version --> 1.0.55 (Claude Code)
• Operating System: <!-- e.g. macOS 14.3, Windows 11, Ubuntu 22.04 --> macOS 15.3
• Terminal: <!-- e.g. iTerm2, Terminal App --> iTerm 2

Bug Description

<!-- A clear and concise description of the bug -->

Steps to Reproduce

1. Use this as an example script to generate a ton of files simulating a monorepo

import os
import random
import string

def random_dir_name(length=6):
    return ''.join(random.choices(string.ascii_lowercase, k=length))

def generate_nested_path(base_dir, max_depth):
    depth = random.randint(1, max_depth)
    subdirs = [random_dir_name() for _ in range(depth)]
    return os.path.join(base_dir, *subdirs)

def generate_files(target_dir, num_files=60000, max_depth=10):
    print(f"Creating {num_files} files with up to {max_depth} directory levels...")
    os.makedirs(target_dir, exist_ok=True)

    for i in range(num_files):
        nested_path = generate_nested_path(target_dir, max_depth)
        os.makedirs(nested_path, exist_ok=True)

        file_path = os.path.join(nested_path, f"file_{i:05}.txt")
        with open(file_path, "w") as f:
            f.write(f"This is file {i} in {nested_path}")

        if i % 1000 == 0:
            print(f"Created {i} files...")

    print(f"Finished creating all {num_files} files.")

if __name__ == "__main__":
    # Update this path if needed
    output_directory = "/tmp/massive_repo"
    generate_files(output_directory)

1. Run claude in /tmp/massive_repo
2. Try to @ a file or directory—nothing will show up. But this works completely fine with smaller repos.

Expected Behavior

<!-- What you expected to happen -->

The files would show up to be added as context.

Actual Behavior

<!-- What actually happened -->

Nothing shows up when typing @. ripgrep appears briefly at the top of the iTerm 2 window but no errors appear. I verified this happens on other machines as well.

Additional Context

<!-- Add any other context about the problem here, such as screenshots, logs, etc. -->