Function unresolvable_approval_routes 

pub fn unresolvable_approval_routes(
    approval: &SopApprovalConfig,
    channel_keys: &HashSet<String>,
) -> Vec<ApprovalRouteIssue>

The configured approval routes (request_route + escalation_route) whose channel key is NOT among channel_keys - the channels the route adapter can actually deliver to (present in its map AND supports_outbound_send). A route names an undeliverable channel when it is absent from the map (e.g. an AMQP SOP-dispatch channel that needs runtime SOP handles the adapter lacks) OR present but inbound-only (its send is a no-op). The daemon logs these at STARTUP so the drift between “configured route” and “deliverable channel” surfaces at boot, not silently on the first parked gate. A route must have non-empty channel:recipient halves; malformed values are also surfaced at startup. Returns one ApprovalRouteIssue per invalid route.