mir-backend-rust-axumlisted

Make It Right (Axum module). Axum + Tower + async Rust specific reliability augmentation. Use alongside mir-backend and mir-backend-rust when the target stack is Axum — it carries the mechanical footguns that the framework-agnostic tiers deliberately omit: extractor ordering (body-consuming extractors must be last), typed State<T> vs Extension<T> and the FromRef sub-state pattern, implementing IntoResponse for error types, and Tower middleware layer ordering (outermost wraps first). TRIGGER only when the Rust backend framework is Axum — building, reviewing, or debugging an Axum handler, router, extractor, or middleware. Always loads TOGETHER WITH mir-backend (the gates) and mir-backend-rust (Tokio runtime concerns: blocking, guard-across-await, cancellation safety, Arc/'static, backpressure, timeouts); this module only adds Axum/Tower library mechanics. SKIP for Actix-web, Warp, Poem, or any non-Axum Rust stack (those get their own mir-backend-rust-<framework> module), and for non-Rust runtimes.
anantbhandarkar/make-it-right · ★ 12 · API & Backend · score 83

Install: claude install-skill anantbhandarkar/make-it-right

# /mir-backend-rust-axum · Make It Right (Axum) Bottom tier of the chain: `mir-backend` (generic gates) → `mir-backend-rust` (Tokio runtime model) → **this** (Axum/Tower library mechanics). Run the gates first; load the Rust runtime tier for blocking/cancellation/Arc concerns; reach for *this* at Gate 5 (design mechanics), Gate 6 (implementation), and Gate 7 review. **Runtime-level concerns (blocking the Tokio runtime, guard-across-await, cancellation safety, bounded channels, timeouts) live in `mir-backend-rust` — not here.** **Stack assumed:** Axum (current stable, 0.7+) · Tower middleware · async Rust on Tokio. Notes apply to `axum` with `tokio` and `tower`/`tower-http`. ## The Axum footguns AI walks into most ### 1. Extractor order — body-consuming extractors MUST be last This is the #1 Axum compile/runtime trap. HTTP request bodies are streams: **reading the body consumes it**. Axum extractors that consume the body (`Json<T>`, `String`, `Bytes`, `Form<T>`, `Multipart`) must be the **last parameter** in the handler signature. Only **one** body-consuming extractor per handler is allowed — the request has one body. Extractors that do NOT consume the body (they read headers, URI, path, query, or app state) can appear in any position: `Path<T>`, `Query<T>`, `State<T>`, `Extension<T>`, `TypedHeader<T>`, `ConnectInfo<T>`. ```rust // WRONG — Json is not last; compilation may succeed but the extractor // that follows Json will see an empty/already-consumed body async fn cr