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Replacement selection ends a run only when no active replacement remains · case 03

The bounded replacement selection certificate reports an incorrect run ended.

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Case contract

A replacement-selection external-sort heap receives last emitted key and new records [id,key]. Keys >=last remain active for current run; smaller keys freeze for next run. Return active ids, frozen ids, active sorted order, frozen sorted order, next current-run key, and end-run flag. Equal keys stay active.

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	`{"active": [], "active_order": [], "frozen": ["a", "b", "c"], "frozen_order": ["b", "a", "c"], "next": null, "run_ended": false}`	`{"active": [], "active_order": [], "frozen": ["a", "b", "c"], "frozen_order": ["b", "a", "c"], "next": null, "run_ended": true}`	Failed

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