Fast-follow for the two code-review findings on #555.
Finding 1 — `all` mode dropped Pi's native skill roots. `mosaic` passes
`--no-skills`, which suppresses Pi's own auto-discovery, so the `all`
catalog must re-enumerate the native roots (`~/.pi/agent/skills/` and
`<cwd>/.pi/skills/`) explicitly or skills living only there vanish.
`discoverPiSkills` now scans those roots too. Also fixes a latent bug:
the old enumerator skipped symlinked entries (`!isDirectory()`), but
synced fleet skills land as symlinks — they were being dropped.
Finding 2 — `discover` mode (which keeps native discovery ON) force-loaded
fleet skills unconditionally, double-registering any skill Pi already finds
natively. It now filters force-loads against the native-root realpath set.
Implementation: realpath-based dedup throughout. New `skillRealPath`,
`piNativeSkillRoots`, `enumerateSkillDirs` (accepts dirs + symlinks, dedup
by realpath), `piNativeSkillRealPaths`. `mergeSkillArgs` dedups by realpath.
`buildPiSkillArgs` gains an injectable 5th param for deterministic tests.
Tests: discover-mode native-filter + intra-set dedup cases, plus real-FS
coverage of `enumerateSkillDirs` (symlink acceptance, cross-root realpath
dedup, SKILL.md gating). 308 pass; typecheck/lint/prettier green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QoYiBeKNh3BiYtAJS5Z587
