Codex skill discovery silently misses global skill when entry file is SKILL.MD

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

Version 26.422.62136 (2180)

What subscription do you have?

Pro

What platform is your computer?

Darwin 25.4.0 arm64 arm

What issue are you seeing?

Codex appeared not to discover a globally installed skill when the skill entry file was named SKILL.MD instead of exactly SKILL.md.

The skill was listed by the generic skills CLI using npx skills ls -g --json. It included better-auth-security-best-practices.

But the skill did not appear in Codex’s available skills for the session, while neighboring skills in the same directory did.

The global skill existed at ~/.agents/skills/better-auth-security-best-practices/SKILL.MD.

Other discovered skills used ~/.agents/skills/<skill-name>/SKILL.md.

After renaming SKILL.MD to SKILL.md, the skill became discoverable by exact SKILL.md scans.

What steps can reproduce the bug?

1. Install or create a global skill under ~/.agents/skills, for example ~/.agents/skills/example-skill/SKILL.MD.
2. Ensure the file is named SKILL.MD, not SKILL.md.
3. Confirm the skill is registered/listed by running npx skills ls -g --json.
4. Start or use Codex and check the available skills list for the session.
5. Observe that the skill may be absent from Codex’s available skills, while other skills with exact SKILL.md files are present.
6. Rename the file from SKILL.MD to SKILL.md.
7. Check discovery again after refresh/restart.

In my case, the affected path was ~/.agents/skills/better-auth-security-best-practices/SKILL.MD.

I did not prove whether a fresh Codex restart would have loaded SKILL.MD; the observed issue was that the current Codex session did not list the skill while the skills CLI did.

What is the expected behavior?

Codex should either discover skill entry files case-insensitively, at least on macOS, or show a warning when a registered skill folder exists but does not contain an exact SKILL.md.

A registered skill should not be silently absent from Codex’s available skills when the only apparent issue is filename casing.

Additional information

Environment details:

OS: macOS
Platform: Darwin 25.4.0 arm64 arm
Global skills location: ~/.agents/skills
Codex native skills location: ~/.codex/skills
Workaround used:

Renamed SKILL.MD to SKILL.md
Symlinked the global skill folders into ~/.codex/skills
After that, exact scans using find -L ~/.codex/skills -maxdepth 2 -type f -name SKILL.md resolved the skill correctly.