Function decide 

pub fn decide(
    evidence: GateEvidence,
    waiver: Option<&NoVerifyWaiver>,
) -> MergeVerdict

The pure acceptance decision. This is the most safety-critical logic in the gate, so it lives here — pure and exhaustively testable — rather than inline in the async orchestrator. Acceptance requires affirmative evidence; every “we don’t know” path resolves to Rejected or Inconclusive.