/api/phase/run guards itself (phases._phase_card refuses a non-phase);
/api/agent/start has no phase check at all, so a stale tab launched an
ordinary work agent on card 53 and it implemented both members itself.
The gate that was missing is on the older feature — the usual shape:
a new capability guards its own front door and leaves the neighbour's
open.
istos
21a819080a