Module rebuild 

Projection rebuild driver interface (KR-003).

The ProjectionTracker is observability only. It records projection health transitions but does NOT execute, schedule, or retry rebuilds. External callers must implement the RebuildDriver trait to drive rebuild execution and report outcomes back to the tracker.

Why a trait instead of built-in execution?

Rebuild execution depends on:

• Which upstream data sources to re-query
• How to batch/throttle rebuilds
• Retry and error handling policies
• Concurrency and resource management

These concerns are owned by the orchestrator, not the runtime. The runtime provides projection health inspection so the driver can make informed decisions, but never initiates work autonomously.

Phase status: KR-003 architecture closure

This trait is the explicit architecture answer to “who drives rebuilds?” The tracker is observability; this trait is the execution contract.

Structs

RebuildOutcome

Outcome of a successful rebuild.

Traits

RebuildDriver

External rebuild driver trait (KR-003).

Functions

rebuild_stale

Drive rebuilds for all stale projections using the provided driver.