Large repository snapshot warning doesn't take nested .gitignore into account

What version of Codex is running?

codex-cli 0.63.0

What subscription do you have?

Plus

Which model were you using?

gpt-5.1-codex-max medium

What platform is your computer?

Linux 6.17.8-2-cachyos x86_64 unknown (Arch Linux)

What issue are you seeing?

I get the following warning when working on my project for a directory that's clearly been .gitignored

⚠ Repository snapshot encountered large untracked directories: packages/utilities/mst/mst-test-suite/tests/diff/exhaustive (16384
  files). This can slow Codex; consider adding these paths to .gitignore or disabling undo in your config.

What steps can reproduce the bug?

# Create a new repository
mkdir test-repo/
cd test-repo/
git init

# Create a test/ directory containing .gitignore and a dozens/ directory containing dozens of files
mkdir -p test/dozens/
echo "/dozens/*.txt" > test/.gitignore
for i in {1..16384}; do touch test/dozens/file_$i.txt; done

# Confirm that Git ignores the files in dozens
git status --short --untracked-files=all

# now open Codex
codex

What is the expected behavior?

Repository snapshot should not be complaining about a large untracked directory

Additional information

For a real repository to test with, clone this repository and run the generate-tests script in packages/utilities/mst