Module engine 

Schema-agnostic windowing state-machine engines.

Each engine owns the per-(group,window) accumulator state, high-water late rejection, eviction, and diff routing (Insert -> add, Update -> remove(pre) + add(post), Remove -> remove(pre)). The caller (the “face”) owns extraction (row -> (group, coord, contribution)) and output construction; it hands the engine pre-bucketed events and receives WindowResults to translate into diffs.

Modules

config

multi_rolling

rolling

rolling_incremental

tumbling

tumbling_carry

Structs

EmitKey

GroupMeta

Per-group metadata: the highest window start seen, used to drop late events for already-closed windows.

MetaKey

State-cache key for a group’s GroupMeta, tagged so it lives in a distinct keyspace from the per-window accumulators.

RunningKey

WindowResult

A finalized window the engine produced; the face turns it into a diff.

WindowStateKey

Enums

AccumulatorEvent

One contribution routed to a window accumulator.

EmitKind

How a finalized window value should be emitted downstream.

Functions

coord_between_range

coord_due_range

coord_entry_key

coord_row_range

expiry_due_range

expiry_key

is_sealed

meta_key_for

seal_horizon

The seal horizon: window anchors (window start for bucketed engines, the coordinate for rolling ledgers) strictly below this value are sealed - immutable and eligible for state reclamation. Computed by the face as watermark - seal_after, where seal_after folds the window span and the grace duration into one number in coordinate units.