Struct Step 

pub struct Step {

    pub label: String,
    pub detail: String,
    pub kind: StepKind,
    pub tool_name: Option<String>,
    pub timestamp_ms: Option<u64>,
    pub duration_ms: Option<u64>,
    pub model: Option<String>,
    pub tokens_in: Option<u64>,
    pub tokens_out: Option<u64>,
    pub cache_read: Option<u64>,
    pub cache_create: Option<u64>,
    pub is_fork_root: bool,
    pub tool_call_id: Option<String>,
}

Fields

label: String

detail: String

kind: StepKind

tool_name: Option<String>

timestamp_ms: Option<u64>

duration_ms: Option<u64>

model: Option<String>

Model name for this step, if known. Attached to the first step emitted from each assistant message (see attach_usage_to_first below).

tokens_in: Option<u64>

Input tokens. Anthropic / OpenAI naming: one-time prompt tokens sent to the model for this assistant response.

tokens_out: Option<u64>

Output tokens: tokens the model generated in this assistant response.

cache_read: Option<u64>

Tokens read from the prompt cache (Anthropic). None for providers that don’t support or report cache reads.

cache_create: Option<u64>

Tokens written to the prompt cache in this response (Anthropic).

is_fork_root: bool

True when this step is the root of a conversation branch — i.e. its originating entry shares a parentUuid with at least one other entry in the same session. Only set by the Claude Code parser today (the only format where parentUuid is a first-class field); other parsers leave this false. Powers the TUI fork list overlay and status-bar fork count (Phase 5.1).

tool_call_id: Option<String>

The tool-call ID for ToolUse / ToolResult steps, pairing them across the timeline. Populated by tool_use_step and tool_result_step; every format parser passes this through from its native ID field. Powers Phase 6 trajectory exports (OpenAI fine-tuning format needs the explicit ID on each tool_calls entry and on the matching tool message). None for non-tool step kinds.

Implementations

impl Step

pub fn cost_usd(&self) -> Option<f64>

USD cost for this step, computed from its token counters and model. Returns None when the model is unknown or there are no tokens to cost. Delegates to the pricing table in crate::pricing.

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 Default for Step

fn default() -> Step

Returns the “default value” for a type.

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.