Project skills from .claude/skills don't appear in / autocomplete in GitHub-repo sessions (web + desktop) — they load and invoke fine

Project skills committed to a repo's .claude/skills/ load and invoke correctly in sessions attached to a GitHub repo, but they never show up in the / autocomplete menu. Only built-ins are listed (typing /work- offers /workflows and nothing else). Typing the full command, e.g. /work-list, and sending it works fine — the skill runs. So the skills are loaded; it's only the picker that can't see them.

The interesting part is the discriminator: it's not the client, it's how the session is attached to the repo.

• Web (claude.ai/code), session on a GitHub repo: skills invoke, no autocomplete
• Desktop app (macOS), session on a GitHub repo: skills invoke, no autocomplete
• Desktop app (macOS), the same repo checked out on disk and opened as a local folder: autocomplete works normally

Repro:

1. Commit a few skills to a repo as .claude/skills/<name>/SKILL.md with name and description frontmatter (ours are named work-begin, work-list, etc.)
2. Open a session on that GitHub repo from claude.ai/code or the desktop app
3. Type /work- — only built-ins appear
4. Send /work-list in full — the skill executes correctly
5. Open the same repo as a local folder in the desktop app — /work- now lists all the custom skills

Expected: the picker lists project skills in GitHub-repo sessions the same way it does in local folder sessions, since the skills are demonstrably loaded either way.

This matters a lot for teams that ship their tooling as project skills in the repo — non-technical users have no way to discover the available commands. #71584 reports what looks like the same symptom on the mobile app, and #76651 / #76932 look related for Remote Control.