1. Runtime Spine

The spine is a continuous event processor. It applies one event at a time, schedules model work into single-flight slots, and starts executor work as owned tasks identified by delegates. The loop body never waits for an executor.

This yields stable ownership:

• the event queue orders facts;
• model slots (fast, surrogate.watch, compress) enforce single-flight constraints;
• delegates identify outstanding executor work;
• wake reasons preserve causality;
• Floor prevents simultaneous user-facing responses.

A slow task and a new user turn can therefore coexist without inventing nested turns or a workflow interpreter.

surrogate.watch is the legacy serialized slot for Proactive selection. Runtime event, origin, wake and telemetry identifiers retain their historical spelling; the current role is Proactive.