FA-53764 / Accessibility interaction semantics / Member archive

Attribute run includes its exclusive end character · case 04

Attribute run includes its exclusive end character.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input [length,default_attributes,spans] where spans are [start,end,attributes,priority]. Clamp endpoints to [0,length], discard empty/reversed spans. At each character position merge active spans over defaults by increasing priority, preserving input tie order; None attribute removes that attribute. Build maximal equal adjacent runs [start,end,attributes]. Zero length returns empty. Offsets are codepoints. Dictionary values are strings or None.

Why this case matters

Offline accessibility bridge model with explicit policy; useful for testing semantic API adapters independently of browser implementations.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
contract fixture 1	`[[0, 1, {"lang": "en", "weight": "bold"}], [1, 5, {"lang": "fr", "weight": "bold"}], [5, 6, {"lang": "fr"}]]`	`[[0, 1, {"lang": "en", "weight": "bold"}], [1, 4, {"lang": "fr", "weight": "bold"}], [4, 5, {"lang": "fr"}], [5, 6, {"lang": "en"}]]`	Failed

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