FA-139 / Storage and queries / Member archive

A prefix range scan misses negative secondary keys · case 04

A composite index lookup omits some rows for its leading key or leaks rows from the next leading key.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input rows are sorted unique tuples [integer_tenant,integer_secondary,payload_string]. Return all rows for the requested tenant in index order. Secondary keys can be any integer. The model assumes integer, not string, leading keys.

Why this case matters

Exercises lexicographic B-tree range-bound construction without claiming to implement a physical index. It covers short-tuple ordering and invalid sentinel assumptions rather than cursor pagination.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
entire composite prefix	`[]`	`[[4, -4, "negative"], [4, 0, "zero"], [4, 4, "positive"]]`	Failed

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