Invocation is an ordinary session.prompt again: the pre-step gesture
boundary makes it deterministic host-side for every front end, so the
dedicated RPC (handler, wire schema, error codes, client face, fixtures)
and ui-skill's claim machinery are net deletions. The menu keeps decision
21 exactly — a pick lands literal /name text — plus the user-only marker
from skill.list's modelInvocable flag.
The policy scenario now expects the user-only quadrant in the menu with
its marker (riding the description — the hint field is claim-state ghost
text, which the menu never renders), and a new skill-user-invoke scenario
drives /name args through the composer against the real host: the claim
lands skill.invoke, the transcript shows the dedicated card with the
collapsed <skill_content> body, and a paced replay answers the injected
turn deterministically.
