Module cluster_tree 

Execution coordinator: walks an AxisPlan and dispatches to the per-strategy clusterers, recursing on within for two-axis (and deeper) nesting (§5.5).

Dispatch covers the categorical strategies Strategy::Exact, Strategy::Prefix, Strategy::Top, the numeric strategies Strategy::Bands, Strategy::Quantiles, Strategy::Natural, and explicit algorithmic string clustering Strategy::Similar. The catchall FaceError::Unsupported arm remains as a #[non_exhaustive] safety net for variants added later before their dispatch arms land.

Memory model

build_tree materializes the full record vector and clusters synchronously. Streaming-eligible strategies (Exact, Prefix, Top, Bands-with-fixed-thresholds per §12) could be lifted to a streaming API later; the current API stays simple and buffered.

Structs

AxisPlan

One node in the user’s grouping plan: an axis to cluster on, plus a (possibly empty) list of sub-plans describing how to further cluster the records that fall into each top-level cluster.

Functions

build_tree

Cluster items according to plan, dispatching per-axis to the appropriate strategy and recursing on within.