axum-core-state

What problem does it solve?

This Skill prevents common Axum state-wiring failures where handlers extract shared state but the router never provides it, or where application-wide resources are injected via Extension and silently fail at runtime.

Core Features & Use Cases

• Compile-time correct state wiring: Use Router<S> with Router::with_state to make only Router<()> serveable, catching missing wiring before deployment.
• State extraction and substate composition: Use State<S> plus FromRef and derive(FromRef) to pull per-handler substates from a larger AppState.
• Performance and correctness guardrails: Ensure state is Clone, wrap heavy immutable data in Arc, and use tokio::sync::Mutex (or scope std::sync::Mutex) to avoid !Send futures caused by holding a mutex guard across .await.

Quick Start

Ask Claude to show how to restructure your Axum router to provide AppState via Router::with_state and extract only the needed fields with State and derive(FromRef), fixing both the Extension 500 trap and any Handler is not satisfied errors.