feat: [gh skill CLI, v2.90.0+] native session-lifecycle skill sync for Claude Code CLI and Cloud — part of cross-surface remote skill integration (#50148)

Part of the cross-surface gh skill integration proposed in #50148. This issue covers the Claude Code CLI and Cloud session surfaces specifically.

The surface

Claude Code CLI (local) and Cloud both run the same binary and share settings.json for configuration. Session start is the natural lifecycle moment for remote skill sync on these surfaces — skills should be current before the first turn.

What's missing today

Claude Code CLI users who maintain skills in a GitHub repo currently author a SessionStart hook that runs a custom shell script to clone the repo and copy skill directories to ~/.claude/skills/. Claude Code Cloud has no equivalent mechanism at all — remote skills either must be pre-installed or don't exist in Cloud sessions.

The ask for this surface

Honor a skills.sources declaration in settings.json (see #50148) and run the equivalent of gh skill update --all at session start — pulling any updated skills from declared repos into ~/.claude/skills/ before the first turn. No user-authored hook required.

For Cloud specifically, this is the only viable path to remote skills — there's no persistent local filesystem where a bootstrap script can live.

How it connects to other surfaces

The skills.sources config established here should be the same config read by the Claude.ai desktop customize panel, Cowork, and managed settings — so a skill source declared once works everywhere without re-configuration per surface. See #50148 for the full cross-surface picture.

References

• Cross-surface parent: #50148
• gh skill announcement: https://github.blog/changelog/2026-04-16-manage-agent-skills-with-github-cli/
• Agent Skills spec: https://agentskills.io/specification