FA-40749 / Heap invariants / Member archive

Min-max trickle repairs the displaced key against the intervening max-level parent · case 04

The bounded minmax grandchild step certificate reports an incorrect grandchild key.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

A minimum-level trickle step receives current key x, chosen grandchild key g, its parent key p, and ids. After swapping x with smaller g, x at the grandchild must also be no greater than its maximum-level parent; if x>p exchange those two. Return root key, grandchild key, parent key, cross-level correction flag, two-step trace, and preserved multiset.

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 1	`{"correction": true, "grandchild_key": 9, "multiset": [2, 7, 9], "parent_key": 9, "root_key": 2, "trace": ["grandchild", "parent"]}`	`{"correction": true, "grandchild_key": 7, "multiset": [2, 7, 9], "parent_key": 9, "root_key": 2, "trace": ["grandchild", "parent"]}`	Failed

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