Inline `!`cmd`` expansion in SKILL.md bodies ran for every skill whenever the
global skills.inline_shell flag was on — a community hub skill and a builtin
were expanded identically. The hub's install gate (INSTALL_POLICY) blocks a
community install on the caution/dangerous verdicts the inline-shell DSL scans
as, but --force or a pre-scanner install puts that skill on disk anyway, and
the next view/slash/preload would auto-execute it on the host.
Gate expansion at the single preprocess_skill_content choke point (all three
surfaces route through it): community-trust hub lock entries never expand;
trusted/builtin hub entries and anything without a hub lock entry (bundled-
synced, user-created, project/external) keep the flag's contract. Lock read
failures skip the gate, like every other provenance consumer.
Fixes#63307
ccff4df98c