Support Git-backed remote skill sources

What variant of Codex are you using?

CLI

What feature would you like to see?

I would like Codex to support Git-backed remote skill sources that users can register directly, without manually cloning skill repositories into their projects.

Proposed CLI:

codex skill source add GIT_URL --ref main
codex skill source list
codex skill source sync
codex skill source remove SOURCE

Expected behavior:

• Add a persistent git skill source type.
• Store source metadata such as source id/name, Git URL, ref, managed local path, last resolved commit SHA, last checked timestamp, and sync policy.
• Clone sources into an internal Codex-managed directory, not into user project directories.
• Use deterministic managed paths so duplicate URLs with different refs are handled safely.
• Discover skills from the managed clone using the existing local skill discovery mechanism.
• Detect updates by fetching remote metadata and comparing the local resolved commit with the remote ref commit.
• Keep the default behavior safe: manual/check-only/prompt.
• Make auto-sync opt-in only.
• Support removal by deleting source metadata and removing or quarantining the managed clone.

The default behavior should avoid mutating a user's available skills unexpectedly. codex skill source sync could check all registered sources and report pending updates for manual or prompt policies. Only sources explicitly configured with an auto policy should be updated automatically.

Additional information

Remote skill repositories should be treated as untrusted content.

Codex should not execute arbitrary code from a remote skill source during add/list/check. It should only parse supported skill metadata and files. Loading should also prevent path traversal and avoid following symlinks outside the managed source root.

Network failures, deleted refs, invalid refs, and missing local clone directories should not break existing local skills. Missing managed clones should be recoverable through sync or re-add.

This would make sharing and consuming skills easier without requiring users to manually clone repositories, remember local paths, or build their own update process. It would also let Codex provide safer defaults around update detection and synchronization.

Open questions:

• Should the default sync policy be manual or prompt?
• Should sync ever prompt interactively, or only print pending updates in non-interactive CLI contexts?
• Should remote skill source metadata live in user config, a separate registry file under CODEX_HOME, or another existing persistence mechanism?
• Should Codex support only branch/tag refs at first, or also pinned commit SHAs in the initial implementation?
• How should authentication work for private or enterprise Git SCM URLs, such as HTTPS credentials, SSH keys, GitHub/GitLab tokens, existing credential helpers, or Codex-managed auth prompts?