Enum Error 

#[non_exhaustive]
pub enum Error {
    Json(Error),
    Parse(String),
    Validation {
        errors: ValidationErrors,
    },
    Pointer {
        pointer: String,
        reason: String,
    },
    Binding {
        expression: String,
        reason: String,
    },
    Catalog(String),
    RecoveryExhausted {
        attempts: u32,
        last: ValidationErrors,
    },
}

Everything that can go wrong while producing, validating, or transporting A2UI.

The variants are deliberately coarse: A2UI is a wire protocol, so the useful detail almost always lives in the payload (a crate::validate::ValidationError list, a JSON Pointer, the offending literal) rather than in the discriminant.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Json(Error)

The bytes were not JSON, or were not JSON of the expected shape.

Parse(String)

An LLM response could not be split into conversational text and A2UI blocks, or a block did not contain usable JSON.

Validation

A syntactically well-formed payload that violates A2UI semantics.

Carries the full machine-readable error list so a caller can feed it straight back to a model; see crate::toolkit::recovery.

Fields

errors: ValidationErrors

The full machine-readable error list.

Pointer

A JSON Pointer was malformed, or resolved to a location that cannot be written (for example indexing past the end of an array).

Fields

pointer: String

The offending pointer, exactly as it appeared on the wire.

reason: String

Why it could not be resolved.

Binding

A ${...} expression in a formatString template could not be parsed or evaluated.

Fields

expression: String

The expression body, without the surrounding ${ and }.

reason: String

Why it could not be evaluated.

Catalog(String)

A catalog document could not be interpreted as an A2UI catalog.

RecoveryExhausted

A model failed to produce a valid surface within MAX_A2UI_ATTEMPTS attempts.

Fields

attempts: u32

How many generation attempts were made.

last: ValidationErrors

The validation errors from the final attempt.

Implementations

impl Error

pub fn parse(reason: impl Display) -> Self

Builds a Error::Parse from anything printable.

pub fn catalog(reason: impl Display) -> Self

Builds a Error::Catalog from anything printable.

pub fn pointer(pointer: impl Into<String>, reason: impl Display) -> Self

Builds a Error::Pointer for a pointer that could not be resolved.

pub fn binding(expression: impl Into<String>, reason: impl Display) -> Self

Builds a Error::Binding for an expression that could not be evaluated.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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 From<Error> for Error

fn from(source: Error) -> Self

Converts to this type from the input type.