FA-12470 / Molecular graph representation / Member archive

Materialized hydrogens are counted twice · case 05

Materialized hydrogens are counted twice.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

Annotation total is either None or total attached hydrogen count including materialized H neighbors. Return total if present, otherwise explicit neighbor H count; counts are nonnegative and present totals are at least explicit count.

Why this case matters

Controlled molecular graph interchange model; tests isolate atom or bond representation errors without claiming chemical validity or production toolkit equivalence.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
mixed explicit implicit	`7`	`6`	Failed

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