Enum AppErrorKind 

pub enum AppErrorKind {
    Unauthorized,
    BadRequest,
    NotFound,
    Conflict,
    Internal,
    PayloadTooLarge,
    UnsupportedMediaType,
    MethodNotAllowed,
    ServiceUnavailable,
    FormationCycle,
    FormationMultipleCoordinators,
    FormationNoCoordinator,
    FormationAuthorityNotNarrowing,
    FormationDuplicateMemberId,
}

Stable error identifier. Adding a variant is a non-breaking change; renaming one IS breaking (clients pin on type).

Variants

Unauthorized

BadRequest

NotFound

Conflict

Internal

PayloadTooLarge

FUZZ-WAVE-1 MED-1: axum’s built-in extractors (Json, Path, Query) reject malformed input with text/plain. We catch those rejections in the response-mapping middleware and re-emit them as problem+json under these stable type URIs.

UnsupportedMediaType

MethodNotAllowed

ServiceUnavailable

FUZZ-CRIT-1: the upstream event store (JetStream/NATS) is unreachable or timing out. Distinct from Internal because the HTTP control plane itself is healthy — only the data tier behind /v1/events is degraded.

FormationCycle

Discriminants from ADR-0010 §Enforcement: cellos-server admission gate rejection reasons. Surfaced via application/problem+json so cellctl can switch on type without parsing detail.

FormationMultipleCoordinators

FormationNoCoordinator

FormationAuthorityNotNarrowing

FormationDuplicateMemberId

FUZZ-MED-4: distinct discriminant for duplicate members[*].id. Historically the duplicate-id case rode on multiple-coordinators because the ADR-0010 §Consequences narrative (“two members both named coord”) used the same scenario. Operators reading the problem-type couldn’t distinguish “your manifest declares two coordinators” (a structural design error) from “your manifest declares two members with the same id” (a typo). Both still 400; clients pinning on the old type continue to see 400 + the authority-not-narrowing/cycle chain when applicable. New clients can switch on this discriminant to render a typo-specific hint.

Implementations

impl AppErrorKind

pub fn status(self) -> StatusCode

pub fn type_uri(self) -> &'static str

type URI identifier per RFC 9457 §3.1. We use relative URI references rooted at /problems/ so the server’s deployment URL does not affect the stable identifier.

pub fn title(self) -> &'static str

Trait Implementations

impl Clone for AppErrorKind

fn clone(&self) -> AppErrorKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AppErrorKind

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

Formats the value using the given formatter.

impl Copy for AppErrorKind