Function verify_changes 

pub async fn verify_changes(
    config: &GateConfig,
    changes: &[FileChange],
    footprint: &DeclaredFootprint,
    infra: &SharedInfra,
) -> MergeVerdict

Run the full gate on a worktree’s changes and return a fail-closed verdict. infra provides the shared policy engine (a gating input) and event log (the audit trail). The build/test command runs only if the AST checks passed and policy allowed — integrating a tree we already know is unsafe is wasted work.