FA-8219 / Direct manipulation / Member archive

Drag-and-drop list reordering: Dropping an item onto itself destroys the list · case 04

Dropping an item onto itself destroys the list.

Member previewVariant 4 · 3 implementations · 10 checks per implementation

Case contract

Cancellation, missing endpoints and self drops preserve order; otherwise remove the source and insert it immediately before or after the surviving target.

Why this case matters

A deterministic model of drag-and-drop list reordering; this isolates one interface invariant without requiring a browser.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
self	`[]`	`["a", "b"]`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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