Remote/phone composer does not surface repo-local skills as slash commands

Problem

Repo-local skills under .agents/skills are not surfacing in the remote/phone composer through /.

Observed behavior:

• A repo-local skill exists under .agents/skills/morning-brief/ with a valid SKILL.md and agents/openai.yaml.
• In the remote/phone Codex experience, typing / does not show the skill as an invocation option.
• Typing @ is treated as a file mention, not a native skill/command invocation.
• @ is not a workable fallback on phone because it depends on file mention UX and is not as portable or ergonomic as a native command.

Expected behavior:

• Repo-local skills should be discoverable/invocable from the / surface in remote/phone contexts, matching the intended skill invocation experience.
• If remote/phone skill invocation is intentionally unsupported, the support matrix should be documented clearly.

Why this matters:

• Skills are useful for personal-assistant workflows that often start away from desktop, such as a morning planning brief.
• The desired interaction is something like: open Codex on phone, type /morning-brief, and have the agent load the repo-local skill.
• Without remote/phone support, repo-local skills are much less useful for mobile-triggered workflows.

Example structure

.agents/skills/morning-brief/SKILL.md
.agents/skills/morning-brief/agents/openai.yaml

The skill validates locally, but the remote/phone composer does not expose it through /.

Possible fixes

• Add / skill discovery for repo-local skills in remote/phone composers.
• Add another phone-safe explicit skill invocation syntax that does not rely on file mentions.
• Document current limitations if this is not planned behavior yet.