Add configurable Axum buffered JSON body limits

CHANGELOG.md

@@ -2,6 +2,20 @@
 
 ## Unreleased
 
+### Axum buffered JSON limits and body API
+
+Axum now defaults framework-managed JSON buffering to 2 MiB, exactly 2,097,152 bytes.
+Set `EDGEZERO__ADAPTER__JSON_BODY_LIMIT_BYTES` for standalone hosting, or use the fallible
+`with_json_body_limit_bytes` builder on `AxumRunOptions` or `AxumDevServer`. Explicit
+application caps may tighten the ceiling. Overflow is typed HTTP 413; malformed JSON remains
+400. Taken streams, forwarding, manual collection, and other providers' defaults are unchanged.
+
+Public `Body` adds an opaque `Managed` variant and is now `#[non_exhaustive]`. Both changes
+break downstream exhaustive matches. Prefer logical-content accessors or match the exhaustive
+`BodyContent` returned by `Body::into_content` for transport branching. Raw `Body` matches
+outside core require a wildcard. Native policy and cache provenance survive context reconstruction
+independently of mutable headers and extensions; transport handoff removes that metadata.
+
 ### Outbound content encoding
 
 `ContentEncoding::Passthrough` is now `Passthrough(PassthroughReason)`, and the public decoder

Cargo.toml

@@ -72,6 +72,7 @@ log = "0.4"
 miniz_oxide = { version = "=0.8.9", default-features = false, features = ["simd", "with-alloc"] }
 log-fastly = "=0.13.1"
 matchit = "0.9"
+mime = "0.3"
 once_cell = "1"
 redb = "4.1.0"
 reqwest = { version = "=0.13.4", default-features = false, features = ["rustls", "blocking", "json"] }

crates/edgezero-adapter-axum/Cargo.toml

@@ -21,6 +21,7 @@ axum = [
     "dep:http-body",
     "dep:hyper",
     "dep:hyper-util",
+    "dep:mime",
     "dep:reqwest",
     "dep:redb",
 ]
@@ -51,6 +52,7 @@ http-body = { workspace = true, optional = true }
 hyper = { workspace = true, optional = true }
 hyper-util = { workspace = true, optional = true }
 log = { workspace = true }
+mime = { workspace = true, optional = true }
 redb = { workspace = true, optional = true }
 reqwest = { workspace = true, optional = true }
 serde = { workspace = true, optional = true }