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Membership maintenance forwards right count changes into left weights · case 04

Membership maintenance forwards right count changes into left weights.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

For a fixed left bag [id,key,multiplicity], apply a right-key count delta batch and emit signed left rows only when right membership crosses zero. Null keys never match. Emit [id,signed-left-multiplicity] in left order; duplicate right updates consolidate before crossing detection.

Why this case matters

A bounded deterministic data engine model makes representation and changelog faults reproducible.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
right duplicate remains	`[[10, -4]]`	`[]`	Failed

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