Struct TokenUsage 

pub struct TokenUsage {
    pub input_tokens: u32,
    pub output_tokens: u32,
    pub cache_read_tokens: Option<u32>,
    pub cache_creation_tokens: Option<u32>,
    pub actual_cost_usd: Option<f64>,
    pub estimated_cost_usd: Option<f64>,
}

Token usage statistics

Tracks token consumption per LLM call including cache tokens for cost optimization. Cache tokens are provider-specific:

• OpenAI: cache_read_tokens from prompt_tokens_details.cached_tokens
• Anthropic: cache_read_tokens from cache_read_input_tokens, cache_creation_tokens from cache_creation_input_tokens

Fields

input_tokens: u32

Number of input/prompt tokens

output_tokens: u32

Number of output/completion tokens

cache_read_tokens: Option<u32>

Number of tokens read from cache (reduces cost)

cache_creation_tokens: Option<u32>

Number of tokens written to cache (Anthropic-specific)

actual_cost_usd: Option<f64>

Actual cost of this generation in USD, as reported by the provider inline (e.g. OpenRouter’s usage.cost, which reflects real post-routing/BYOK/cache pricing). None for providers that do not return a cost.

estimated_cost_usd: Option<f64>

Estimated cost of this generation in USD, derived from the model’s static price-table profile. Computed whenever a profile with cost data exists, independently of actual_cost_usd, so estimate-vs-actual drift can be reconciled. None when there is no profile cost data for the model.

Implementations

impl TokenUsage

pub fn new(input_tokens: u32, output_tokens: u32) -> Self

Create a new TokenUsage with just input and output tokens

pub fn with_cache( input_tokens: u32, output_tokens: u32, cache_read_tokens: Option<u32>, cache_creation_tokens: Option<u32>, ) -> Self

Create a TokenUsage with cache tokens

pub fn with_cost( self, actual_cost_usd: Option<f64>, estimated_cost_usd: Option<f64>, ) -> Self

Set the actual (provider-reported) and estimated (price-table) USD costs, returning self for chaining. The two are tracked independently so an authoritative charge stays distinguishable from an estimate.

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

Best-effort cost of this generation in USD: the actual provider-reported cost when present, otherwise the price-table estimate. None when neither is available. Actual takes priority.

pub fn total_tokens(&self) -> u32

Get total tokens (input + output)

pub fn add(&mut self, other: &TokenUsage)

Add another TokenUsage to this one (for aggregation)

Trait Implementations

impl Clone for TokenUsage

fn clone(&self) -> TokenUsage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TokenUsage

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

Formats the value using the given formatter.

impl Default for TokenUsage

fn default() -> TokenUsage

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for TokenUsage

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for TokenUsage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.