Enum StandardError 

pub enum StandardError {
    BadRequest {
        message: String,
    },
    ValidationFailed {
        errors: Vec<ValidationError>,
    },
    Unauthenticated,
    Forbidden {
        reason: String,
    },
    NotFound,
    Conflict {
        message: String,
    },
    UnprocessableEntity {
        message: String,
    },
    RateLimited {
        retry_after_seconds: u32,
    },
    Internal,
    ServiceUnavailable {
        retry_after_seconds: u32,
    },
    Timeout,
}

Built-in standard errors. Procedures may use these directly or wrap them.

This is a curated set of “common” RPC errors that map cleanly onto well-known HTTP status codes. The full taxonomy is:

Variant	Code	HTTP
BadRequest	bad_request	400
ValidationFailed	validation_error	400
Unauthenticated	unauthenticated	401
Forbidden	forbidden	403
NotFound	not_found	404
Conflict	conflict	409
UnprocessableEntity	unprocessable_entity	422
RateLimited	rate_limited	429
Internal	internal	500
ServiceUnavailable	service_unavailable	503
Timeout	timeout	504

Note: ValidationFailed carries a list of ValidationError entries and is emitted by the server router when input validation rejects a request before the procedure runs. Its discriminant is validation_error (not validation_failed) to match the wire contract.

Design principle

StandardError is intentionally narrow: it covers the cross-cutting concerns every RPC stack tends to hit (auth, rate limiting, transport-shaped failures) and nothing else. Anything domain-specific — business-rule violations, per-procedure failure modes, structured validation results — should be its own error enum with #[derive(taut_rpc::TautError)]. Reaching for StandardError to model domain errors collapses meaningful distinctions into a single bucket and is an anti-pattern.

Per SPEC §8 the unauthenticated discriminant is reserved.

Variants

BadRequest

400 — Malformed or syntactically invalid request.

Fields

message: String

Human-readable description of why the request was rejected.

ValidationFailed

400 — Server-side input validation rejected the request before the procedure ran. Carries the per-field failures that the validator collected. Serializes with the validation_error discriminant.

Fields

errors: Vec<ValidationError>

Per-field validation failures collected by the validator.

Unauthenticated

401 — Caller is not authenticated.

Forbidden

403 — Caller is authenticated but not permitted.

Fields

reason: String

Human-readable explanation of why the caller was denied.

NotFound

404 — Target resource does not exist.

Conflict

409 — State conflict (e.g. unique-key violation, optimistic-lock failure).

Fields

message: String

Human-readable description of the conflict.

UnprocessableEntity

422 — Request was syntactically valid but failed semantic validation.

Fields

message: String

Human-readable description of the semantic failure.

RateLimited

429 — Caller is being rate limited.

Fields

retry_after_seconds: u32

Suggested delay before the caller retries, in seconds.

Internal

500 — Unexpected server-side failure.

ServiceUnavailable

503 — Service is temporarily unavailable (graceful degradation, deploys, etc.).

Fields

retry_after_seconds: u32

Suggested delay before the caller retries, in seconds.

Timeout

504 — Upstream or internal operation timed out.

Trait Implementations

impl Clone for StandardError

fn clone(&self) -> StandardError

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StandardError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for StandardError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for StandardError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl Serialize for StandardError

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl TautError for StandardError

fn code(&self) -> &'static str

Stable, machine-readable code. SHOULD be lowercase snake_case.

fn http_status(&self) -> u16

HTTP status code this error maps to. Default 400.