Specification · section 15

Conformance

Level	Requirements
MHP Core	`initialize`, `ping`, `device/describe` (all three tiers and `select`), `resources/*`, `signals/read`, `settings/write` with limit enforcement, error codes in §12.
MHP Actions	Core + `actions/invoke`, `jobs/`, `notifications/jobs/`, interlocks and approval gates, and `methods/*` as specified in §4.5 (answering empty and refusing `save` when no action is method-driven).
MHP Safe	Actions + `safety/estop` that never waits behind ordinary requests, verified `safety/reset`, watchdog, fail-closed state machine with unknown-outcome faults, per-session `session/*` leases with renewal.
MHP Directory (server role)	`initialize` with `role: "directory"`, `directory/search`, `directory/get`, `directory/stats`; indexes cards only.

Devices that carry stored energy or can move SHOULD NOT be exposed below MHP Safe. All device levels MUST support detail and select on device/describe (§3.1).

Conformance is behavioural. The reference suite tests/test_safety_gates.py exercises typed limits, ownership, watchdog silence, rejected approvals, blocked I/O, backend aborts and plan-mode isolation; a conformant implementation should pass equivalent tests.