Pre-fix `loadSkills` in `extensibility/skills.ts` gated the OMP-native
`agents` provider (the canonical `~/.agent[s]/skills` and project-walkup
`.agent[s]/skills`) on the `anyBuiltInSkillSourceEnabled` fall-through —
the OR of `enableCodexUser`/`enableClaudeUser`/`enableClaudeProject`/
`enablePiUser`/`enablePiProject`. A user who turned off the named
third-party toggles to clean noise from other CLIs silently lost their
own canonical OMP-native skills, so typing `/` showed no `/skill:<name>`
entries for `~/.agents/skills/*/SKILL.md`.
- Added `skills.enableAgentsUser` and `skills.enableAgentsProject` to
the settings schema (default true) and to the `SkillsSettings` shape.
- Routed `isSourceEnabled` to the new toggles for `provider === "agents"`
(per level). The fall-through still covers providers without a
dedicated toggle (`claude-plugins`, `opencode`, `gemini`, `github`, …);
agents joins claude/codex/native at the named-source layer where it
always belonged.
- Updated `docs/skills.md` to document the new toggles and the corrected
enablement rule.
- Refactored `test/skills.test.ts` to share a `DISABLE_ALL_BUILTIN_SKILLS`
helper (so the isolation tests stay correct when new toggles are
added) and added two regression tests: one asserting that the
pre-fix scenario (named third-party toggles off, agents defaulted) now
loads `~/.agents/skills/<name>/SKILL.md`, and one pinning the explicit
`enableAgentsUser: false` opt-out.
Fixes#2401