FA-9048 / Undo and history / Member archive

Adjacent typing undo coalescing: Explicit undo boundaries fail to split typing groups · case 03

Explicit undo boundaries fail to split typing groups.

Member previewVariant 3 · 3 implementations · 11 checks per implementation

Case contract

Only contiguous insertion edits without explicit boundary coalesce; preserve the first before-state and newest after-state; no-op input creates no history.

Why this case matters

A deterministic model of adjacent typing undo coalescing; 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
boundary	`[["a", "abc"]]`	`[["a", "ab"], ["ab", "abc"]]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

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

Member access is invitation-based. Sign in with your invited account to inspect the sources.