Microchunk and Model Rejection Relationship

Scope

This note records the current relationship between the streaming microchunk rejection path and the shared model_cavgs_rejection backend.

Current Code State

In this tree, simple_microchunked2D does not call the src/main/cavg_quality backend.

The live stream path is:

1. collect_and_reject detects ABINITIO2D_FINISHED.
2. reject_cavgs reads the chunk project and class averages.
3. reject_cavgs instantiates cluster2D_rejector.
4. cluster2D_rejector applies population, resolution, mask, and local-variance criteria.
5. reject_cavgs writes selected/rejected class-average stacks and propagates states into particles.

The shared class-average quality backend remains available through:

• src/main/cavg_quality
• model_cavgs_rejection

Shared Concepts

The shared model backend mirrors several microchunk principles:

• population and resolution validity gates;
• foreground geometry and connected-component checks;
• local-variance/detail measurements;
• conservative state propagation from class averages to particles.

The two implementations are not identical:

• microchunk streaming currently uses hard, ordered scalar rejection criteria;
• model_cavgs_rejection uses hard validity gates followed by normalized scalar features, learned weights, clustering, and threshold controls.

Ownership Boundary

No backend-selection flag exists in the current stream code.

The stream lifecycle is owned by simple_microchunked2D:

• sentinel handling;
• chunk failure/completion flags;
• selected/rejected stack writing;
• class-to-particle state propagation;
• match finalization and combined output.

The current class-average decision is owned by cluster2D_rejector.