Enum TaskEndVariant 

pub enum TaskEndVariant {
    Success,
    Unable,
    Failed,
    Unknown,
}

Discriminator for EngineEvent::TaskEnd that tells consumers how a task finished without having to introspect the value payload. Extracted in #206 (Stream 4 follow-up): before this, a caller had to inspect the value for a Value::Unable envelope to distinguish “the agent said I can’t” from a well-typed successful return. Serde-tagged on a "variant" field so new arms ship without wire-shape churn.

#[serde(other)] on TaskEndVariant::Unknown preserves forward-compat: a future engine that adds e.g. Partial (#205) still deserializes on older SDKs — the unknown variant surfaces as Unknown and the stream keeps flowing. Do not match without a wildcard on this enum.

Variants

Success

The task produced a well-typed value that passed every stage of the parse → schema → custom validation pipeline. This is the pre-#206 default and the variant carried when #[serde(default)] fires on payloads that omit the field entirely (older servers).

Unable

The task’s declared return type was T | Unable and the agent emitted a canonical {"unable": {...}} envelope. The value field on EngineEvent::TaskEnd carries the full Value::Unable record so consumers can render reason/missing/category without re-parsing.

Failed

The task ended with a dispatch-level failure — provider error, sandbox timeout, OOM kill, schema-validation budget exhausted, or any other path where the value on EngineEvent::TaskEnd is a Value::FatalError. Consumers grouping by task can use this to render a failure UI without inspecting value. Emitted from the runtime dispatch path; LLM tasks may also adopt it in a follow-up. Older SDKs that don’t know this variant will see it as Unknown via #[serde(other)] and behave as today.

Unknown

Catch-all for future variants the SDK doesn’t know yet. #[serde(other)] routes unknown discriminants here so consumers never crash on a newer engine — e.g. Partial lands in #205 and an older SDK will see it as Unknown until its own upgrade.

Trait Implementations

impl Clone for TaskEndVariant

fn clone(&self) -> TaskEndVariant

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TaskEndVariant

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

Formats the value using the given formatter.

impl Default for TaskEndVariant

fn default() -> TaskEndVariant

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for TaskEndVariant

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for TaskEndVariant

fn eq(&self, other: &TaskEndVariant) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for TaskEndVariant

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for TaskEndVariant

impl Eq for TaskEndVariant

impl StructuralPartialEq for TaskEndVariant