Module replacement 

Available on crate feature alloc only.

TreeSlot: warning/danger/swap lifecycle for tree replacement.

Implements the drift-triggered tree replacement strategy from Gunasekara et al. (2024). Each boosting step owns a “slot” that manages:

• An active tree serving predictions and receiving training samples.
• An optional alternate tree that begins training when a Warning signal is emitted by the drift detector.
• A drift detector monitoring prediction error magnitude.

Lifecycle

  Stable  --> keep training active tree
  Warning --> spawn alternate tree (if not already training)
  Drift   --> replace active with alternate (or fresh tree), reset detector

Structs

TreeSlot

Manages the lifecycle of a single tree in the ensemble.