Module capacity 

Names the fixed-capacity internal structures reported by the Capacity variant of the client and server error enums. Names the fixed-capacity internal structures whose exhaustion is reportable through the Capacity variant of client::Error and server::Error.

Those are deliberately not intra-doc links: both modules are behind features, and this one is compiled unconditionally, so linking them fails the --no-default-features and single-feature doc builds.

This lives at the crate root rather than under client or server because both report through it, and a consumer handling capacity exhaustion should not have to learn two different vocabularies for the same condition. Not every kind is reachable from every error type — the server currently only produces CapacityKind::UdpBuffer — and that asymmetry is deliberate: one shared kind keeps the handling code uniform as the server grows others.

Enums

CapacityKind

Which fixed-capacity internal structure overflowed.