Struct Step 

pub struct Step {
    pub idx: u32,
    pub kind: StepKind,
    pub name: Option<String>,
    pub prompt_tokens: Option<u32>,
    pub completion_tokens: Option<u32>,
    pub cost_usd: Option<f64>,
    pub input: Value,
    pub output: Value,
    pub error: Option<String>,
    pub latency: Duration,
    pub span_id: Option<String>,
}

One unit of agent work — either an LLM call or a tool call.

Fields

idx: u32

Zero-based index of the step within the run.

kind: StepKind

Discriminator.

name: Option<String>

Tool name (for ToolCall) or model name (for LlmCall); None if unknown.

prompt_tokens: Option<u32>

Prompt-side token count for an LlmCall step; None for other kinds or when the provider did not report a split.

completion_tokens: Option<u32>

Completion-side token count for an LlmCall step; None for other kinds or when the provider did not report a split.

cost_usd: Option<f64>

Estimated USD cost for an LlmCall step, computed by project_with_price_table from the step’s LlmIo and a PriceTable. None for other kinds, when the provider/model/token split is unknown, or when no price matched.

input: Value

JSON inputs (tool args, prompt structure).

output: Value

JSON outputs (tool result, completion text).

error: Option<String>

Error message if this step failed (None on success).

latency: Duration

Wall-clock latency serialised as milliseconds.

span_id: Option<String>

Tracing span id (stringly-typed for now; richer linkage is a Wave 7 carryover).

Trait Implementations

impl Clone for Step

fn clone(&self) -> Step

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Step

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Step

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl JsonSchema for Step

fn schema_name() -> String

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(generator: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn is_referenceable() -> bool

Whether JSON Schemas generated for this type should be re-used where possible using the $ref keyword.

impl Serialize for Step

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

where __S: Serializer,

Serialize this value into the given Serde serializer.