Module planning 

Composable scan planning through explicit IO and CPU state machines.

Planners and morsels are Send and move between threads with the run that owns them; stage-specific phases remain private to those implementations.

Modules

driver

A single-worker driver for the protocol.

morsel

The morsel side of the protocol: array-producing work and its outputs.

next

Handoff between stages: the Next constructor.

planner

The planner side of the protocol: work scopes, object state, and planner outputs.