- Make host-user authority unforgeable. `{ kind: 'user' }` was a bare
discriminant, so any plugin holding `ctx.subagents` — including
model-generated cordis_mount code, which the advanced ACP composition ships
alongside continuable subagents — could construct it and skip the
direct-parent check for any known child id. It now carries an opaque grant
that only SubagentService.userAuthority() mints, which composition hands to
trusted host adapters; a model-facing tool uses parent authority from its own
execution context.
- Reconcile a delivery discarded inside its own admission window. An enqueue
listener that cancels fires the discard before followup() returns, so the
discard listener could not clear an id it had not seen; submit() retained it
and residency stayed `running` until an explicit drain.
- Recheck the caller signal after materialization. An abort landing between
publication and inbox acceptance still submitted the prompt and returned both
ids; it now rolls the child back.
- Stop promising the model transcript access that no shipped continuable config
mounts. The tools now state only that a background child does not report back.
- Restate the implemented note as shipped state rather than a proposal, so it
works as current authority.