Replayable Planning: An Event-Sourced Architecture for the aime Planner Agent
The Planner Agent is responsible for the shape of a learner's instructional journey — what is taught, when, in what order, at what pace, and how assessment is interleaved. Today it operates as a plan-replacement system: every significant educational signal causes a full regeneration of the plan. As plans grow, that pattern becomes costly, opaque and difficult to extend to multiple collaborators. This brief outlines aime's shift to a replayable planning architecture, in which the Planner Agent emits typed educational decisions rather than complete documents, and the current plan is reconstructed by replaying those decisions over a periodic snapshot. The posture extends concepts already proven inside the aime Loom™ Workflow Engine — deterministic event histories, replay-based state reconstruction and first-class audit — and brings the same properties to instructional planning: incremental updates, full historical visibility, explainable plan evolution, and a foundation for human-in-the-loop governance, branching experiments and rollback. The event taxonomy, projection engine design, snapshot strategy, conflict-resolution rules and integration with the rest of the agent stack remain aime's proprietary IP and are shared with partners under NDA.
