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Replicated growable array: head inserts bypass the concurrent-sibling skip · case 02

Concurrent inserts at the start of the document appear in arrival order.

Member previewVariant 2 · 3 implementations · 10 checks per implementation

Case contract

A sequence of [id, char, deleted] where id = (counter, replica). ["ins", id, after, ch] finds the element with id `after` (head when None or unknown), moves one past it, then skips every following element whose id is greater than the new id before inserting. ["del", id] marks the element deleted but keeps it. Return visible text and the number of slots including tombstones.

Why this case matters

RGA orders concurrent insertions deterministically so that every causally valid delivery order yields the same text.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
concurrent head inserts	`{"slots": 3, "text": "cab"}`	`{"slots": 3, "text": "cba"}`	Failed

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