Review round 4, Minor 3. A configHome descriptor can nest a second,
independently-resolved descriptor (skillsHome -> resolveSkillsBaseFromDescriptor)
carrying its own env array, and the derivation walked configHome.env alone —
the identical walk-one-field gap-shape rounds 2-3 closed for the registry
and the non-registry set. Inert today (only kilo declares skillsHome, with
env: []), closed before it is live rather than after.
The guard's root enumeration deliberately does NOT gain the skills base:
getGlobalSkillsBase returns a skills directory (codex: ~/.agents/skills),
not a config root, and the snapshot applies the config-root layout beneath
every root — adding it false-positives on <skillsBase>/gsd-core while
missing a real <skillsBase>/gsd-help write (found by this round's pre-push
adversarial review). Watching skills bases needs its own layout, like
resolveExtraWatchTargets; a comment in resolveLiveConfigRoots records the
non-action.
New derivation test asserts both skillsHome rungs land in TEST_ENV_BASE,
with an anti-vacuity check that at least one runtime actually declares the
field.