`kamu-snap-response`

Framework-agnostic response envelope + error taxonomy for Bank Indonesia SNAP BI.

Part of the kamu-public-crates workspace.

What this crate is

Item	Purpose
`SnapResponse<T>`	Typed envelope + optional typed payload (flat JSON wire shape)
`SnapEnvelope`	`responseCode` + `responseMessage`
`Error`	61-variant SNAP BI taxonomy + feature-gated `Crypto` bridge
`Category`	`Success` / `Message` / `Business` / `System`
`ResponseCode`	Defensive parser + inverse classifier
`ServiceCode`	Validated `0..=99` newtype

The `responseCode` formula

7 digits: HHH SS CC
         │   │  │
         │   │  └── case code (00..=99) — per-variant per-spec
         │   └───── service code (00..=99) — per-endpoint
         └───────── HTTP status (200, 401, 403, 404, 405, 409, 429, 500, 504)

SnapResponse::ok(payload, ServiceCode::new(11).unwrap(), 0) → responseCode = "2001100".

Error::Unauthorized("...".into()).response_code(ServiceCode::new(11).unwrap()) → ResponseCode("4011100").

30-second quickstart — server side

use kamu_snap_response::{Error, ServiceCode, SnapResponse};

let svc = ServiceCode::new(11).unwrap();

// Success
let ok: SnapResponse<MyData> = SnapResponse::ok(my_data, svc, 0);

// Error
let err: SnapResponse<MyData> = SnapResponse::err(Error::InsufficientFunds, svc);

30-second quickstart — client side

use kamu_snap_response::SnapResponse;

let wire: &str = "...";
let resp: SnapResponse<MyData> = serde_json::from_str(wire)?;

// Defensive parsing: malformed responseCode preserves raw()
println!("{}", resp.envelope.response_code.raw());

// Classify back to a typed Error variant for retry policy
if let Some(err) = resp.envelope.response_code.classify() {
    use kamu_snap_response::Category::*;
    match err.category() {
        Business => println!("do not retry: {err}"),
        System => println!("retry with backoff: {err}"),
        _ => {}
    }
}
# Ok::<(), serde_json::Error>(())

Full example: examples/client_parse.rs.

Defensive parsing

ResponseCode::parse is total — never errors. Malformed wire codes preserve raw() while http() / service() / case() return None:

use kamu_snap_response::ResponseCode;

let code = ResponseCode::parse("500000"); // BRI source-doc 6-digit defect
assert_eq!(code.raw(), "500000");
assert_eq!(code.http(), None);

This closes the prior bug where deserialisation hard-failed on a malformed code, losing the entire response.

Inverse classifier

ResponseCode::classify() maps received wire codes back to typed Error variants:

use kamu_snap_response::{Error, ResponseCode};

let code = ResponseCode::parse("4011100");
assert!(matches!(code.classify(), Some(Error::Unauthorized(_))));

String-bearing variants (e.g. Unauthorized(String)) reconstruct with an empty string — the wire responseMessage is still available via envelope.response_message for display.

`#[non_exhaustive]`

Both Error and Category are #[non_exhaustive]. Future SNAP BI variants can add cases without a breaking change.

Feature flags

Feature	Default	Purpose
`crypto`	off	Enables `Error::Crypto(#[from] kamu_snap_crypto::Error)`

Enable when server handlers want to propagate crypto failures into the SNAP error taxonomy.

Framework adapters

Responder (actix-web) and IntoResponse (axum) impls live in:

kamu-snap-response-actix
kamu-snap-response-axum

Both are thin and defensive — no .unwrap() on the response path.

Migration from v1.x

v1.x	v2.0
`SNAPResponse<T>`	`SnapResponse<T>`
`SNAPResponseCommon`	`SnapEnvelope`
`ResponseError` / `Error` aliases	`Error` (one canonical name)
`Error::Unathorized(s)`	`Error::Unauthorized(s)` (typo fixed)
`error.get_http_status_code()`	`error.http_status()`
`error.get_code(svc)`	`error.response_code(ServiceCode::new(svc).unwrap())`
`Error::default()` → `GeneralError`	removed — construct explicitly
`traced_guard!` macro	removed — use `?` + `Error::Crypto(#[from])`
Custom Deserialize silently swallowed payload errors	propagates errors loudly

License

Dual-licensed under either MIT or Apache-2.0 at your option (MIT OR Apache-2.0). Previously MIT-only in pt-immer/lib-snap.

kamu-snap-response 2.2.0

kamu-snap-response