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Repeated scatter targets keep the earliest selected write · case 05

Repeated scatter targets keep the earliest selected write.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Apply an ordered scatter update to a column using [target-index,value,is-valid,is-selected] records. Unselected writes do nothing; selected null writes clear validity. Repeated targets use the final selected write, and untouched lanes retain both payload visibility and validity.

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
repeated target	`[5, 7]`	`[5, 8]`	Failed

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