Function pump_source 

pub fn pump_source(
    db: &AimDb,
    scheme: &str,
    src: impl Source + 'static,
) -> Vec<BoxFuture> 

Inbound pump: a single multiplexed reader future for scheme.

Drives one Source (never one task per topic), fanning each (topic, payload) out to the matching producers via a Router built from collect_inbound_routes.

Backpressure: Router::route drops + logs on a full producer buffer rather than blocking, so one slow record never stalls the shared source. Route errors are non-fatal.