Recommended skills fail to load with outdated system git (< 2.19)

What version of the Codex App are you using (From “About Codex” dialog)?

260205.1301

What subscription do you have?

Pro

What issue are you seeing?

Recommended skills section fails to load. This issue has been present
since the very first release of the Codex App.

The root cause is that the app uses git clone --filter=blob:none
(partial clone), which requires git >= 2.19. macOS ships with git 2.15.0
via Command Line Tools, which does not support the --filter flag.

Error displayed:
"Unable to load recommended skills"
git clone failed: error: unknown option filter=blob:none

After upgrading git to a modern version via Homebrew, the original error
is resolved but a secondary issue appears:
"git fetch failed: fatal: shallow file has changed since we read it"

This is caused by stale/corrupted skills cache left from the old git version.

Full workaround:

1. Upgrade git: brew install git (restart terminal)
2. Clear skills cache: rm -rf ~/.codex/skills_cache
3. Restart Codex App

Installed/user-created skills are unaffected — only the Recommended
section fails.

What steps can reproduce the bug?

1. Have a Mac with default Apple Command Line Tools git (2.15.0)
2. Open the Codex App
3. Navigate to Skills panel
4. Scroll to "Recommended" section
5. Observe: "Unable to load recommended skills" with git clone error

After upgrading git without clearing cache:

1. Upgrade git via Homebrew (brew install git)
2. Restart Codex App
3. Observe: error changes to "git fetch failed: fatal: shallow file

has changed since we read it"

After clearing cache:

1. Run rm -rf ~/.codex/skills_cache
2. Restart Codex App
3. Recommended skills now load correctly

Suggestion: The app should either check git version and show a
meaningful error ("Please upgrade git to >= 2.19"), or fall back
to a full clone without --filter when partial clone is not supported.

What is the expected behavior?

_No response_

Additional information

_No response_