FA-17667 / Time representation / Member archive

Civil multiplicity collapses two valid instants · case 02

The decoded time state disagrees with the explicit regression oracle for count.

Member previewVariant 2 · 3 implementations · 11 checks per implementation

Case contract

A stipulated backward offset transition at UTC T changes larger old offset to smaller new offset. Candidate UTC coordinates local-offset are admitted on their owning sides (<T old, >=T new). Return sorted unique candidates, ambiguity flag, selected instant under earlier/later/reject policy, selected offset and civil roundtrip. No timezone database is modeled.

Why this case matters

Clock transfer and timestamp consumers require preserved coordinate, phase, validity and elapsed-time semantics.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
fixture 2	`[[90, 100], false, 90, 20, 110]`	`[[90, 100], true, 90, 20, 110]`	Failed

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

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