- 2026-09-30Sentinel: The Watchdog and Derived PointsOne timer wheel for every freshness deadline, why on-change without a heartbeat is a trap, why liveness is a freshness policy rather than a value, and what happens to a derived point whose inputs go stale.17 min
- 2026-09-16Sentinel: The Driver ContractMaking every device look identical to the core while keeping protocol ugliness on the far side of a wire boundary: driver hosts, per-instance supervision, one northbound transport for every protocol, and assignments exported rather than queried.14 min
- 2026-09-09Sentinel: The Semantic ModelIdentity, hierarchy and the point descriptor: why a point ID is a dotted slug rather than a UUID, why a component is the unit of independent failure, and why a point is always scalar.17 min
- 2026-09-02Sentinel: An IntroductionA soil moisture sensor goes quiet for three days, and nothing in the system says so — a reading and a memory of one look identical. Deciding what that costs is what a specification is for, and this is the first of eleven parts publishing one in full, while the system it describes gets built.20 min