axum-core-state

Overview

Axum delivers shared application state through one type parameter on Router and one extractor. Router<S> means a router that is still missing a state value of type S. Router::with_state(value) supplies that value and the router type becomes Router<()>. Only Router<()> can be served. State wiring is therefore checked entirely at compile time, never at runtime.

State APIs are identical across Axum 0.7 and 0.8: State, with_state, FromRef, and the Router<S> model did not change at the 0.7 to 0.8 boundary. Every pattern in this skill applies to both versions.

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