SENTINEL
Watches the other instruments for drift, scope violation and quota anomaly, and reports. It does not enforce.
SENTINEL is the did-anything-go-wrong surface for an always-on suite. It observes other agents and instruments and raises what it sees: a model drifting off its baseline, an agent reaching outside its declared scope, a quota curve that does not look like yesterday's.
The split matters. DISCIPLINE ENGINE enforces and a router gates, but both of those are inside the path of the work. SENTINEL sits outside it and only reports, which is the same separation a data center keeps between a control system and the monitoring that watches the control system.
That habit came straight off the floor. In a hyperscale room the thing that tells you something is wrong is never the thing that caused it.
Data-center operations, Microsoft, T5 Data Centers. Uptime, logging, reversible changes. Read the whole timeline.