Struct Usage 

pub struct Usage {
    pub prompt_tokens: u32,
    pub completion_tokens: u32,
    pub total_tokens: u32,
}

Token usage for one conversation.

Field names match the OpenAI wire format; total_tokens follows the vendor’s convention (not necessarily the sum of the other two). Default = all zeros.

Presence is carried by the enclosing type: ChatResponse::usage / StreamEvent::Done::usage are Option<Usage> — None means the endpoint did not report usage for this turn, Some means the reported values. The distinction matters for observability: “not reported” is not the same as “reportedly zero” (the Agent layer also tracks it in RunSummary::usage_omitted).

Fields

prompt_tokens: u32

Input tokens for this turn.

completion_tokens: u32

Output tokens for this turn.

total_tokens: u32

Total for this turn (vendor convention).

Implementations

impl Usage

pub fn new(prompt_tokens: u32, completion_tokens: u32) -> Usage

Constructs from input / output counts; the total is summed automatically.

Trait Implementations

impl AddAssign for Usage

Usage accumulates per turn (the Agent layer sums tokens across turns).

fn add_assign(&mut self, rhs: Usage)

Performs the += operation.

impl Clone for Usage

fn clone(&self) -> Usage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Usage

impl Debug for Usage

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

Formats the value using the given formatter.

impl Default for Usage

fn default() -> Usage

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Usage

fn deserialize<__D>( __deserializer: __D, ) -> Result<Usage, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for Usage

impl PartialEq for Usage

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Usage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Usage