FA-40197 / Heap invariants / Member archive

Leftist meld rewrites both surviving child parent links toward the chosen root · case 02

The bounded leftist meld step certificate reports an incorrect parent assignments.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

A leftist meld unwind record gives chosen root id, left subtree [id,npl,size] or None, returned right subtree similarly, and root key. Orient children by npl (null=-1), retain left on equal rank, set npl to right npl+1, and size to one plus both child sizes.

Why this case matters

This isolates an internal heap representation or priority-structure invariant using deterministic finite records.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression certificate 4	`{"left_id": 1, "npl": 1, "parent_assignments": [[1, 9]], "right_id": 2, "size": 10, "swap": false}`	`{"left_id": 1, "npl": 1, "parent_assignments": [[1, 9], [2, 9]], "right_id": 2, "size": 10, "swap": false}`	Failed

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