Struct ModelPrice 

pub struct ModelPrice {
    pub input: u64,
    pub output: u64,
    pub cache_read: u64,
    pub cache_write: u64,
}

One model’s prices: USD per million tokens, in micro-USD (1e-6 USD).

Integers so a price and a derived Cost stay Eq and serde-stable, and so summary()’s $ is reproducible to the last digit. Default is the all-zero price — a known free model, which is Some(ModelPrice::default()) and never None.

Fields

input: u64

Price of one million uncached prompt tokens.

output: u64

Price of one million completion tokens.

cache_read: u64

Price of one million prompt tokens served from the provider’s cache.

A cached read is a SUBSET of input_tokens on the chat-completions wire (rig maps usage.prompt_tokens_details .cached_tokens, i.e. tokens already inside prompt_tokens), so a cached token is billed at THIS rate instead of input — never on top of it.

cache_write: u64

Price of one million tokens written to the cache. 0 for most providers (models.dev omits the field when the provider does not report it); it is not part of input’s accounting.

Implementations

impl ModelPrice

pub fn cost_numerator(&self, usage: &Usage) -> u128

One turn’s cost numerator: Σ tokens × rate, i.e. micro-USD × 1e6.

Contract:

• cache_read_tokens is billed at ModelPrice::cache_read, the remainder of input_tokens at ModelPrice::input (the subset rule). cache_read_tokens is clamped to input_tokens so a provider that over-reports cannot underflow the remainder.
• cache_write_tokens is billed at ModelPrice::cache_write on top of that; a turn reporting no cache field pays the full input rate.
• the value is the un-truncated numerator so a caller folding many turns sums numerators and divides ONCE (cost_of); one turn’s answer is ModelPrice::micro_usd.

Does NOT promise: tier rates, or that the provider reported usage at all (a Usage::default() turn costs 0 — the caller decides whether a turn counted).

pub fn micro_usd(&self, usage: &Usage) -> u64

One turn’s cost in whole micro-USD, truncated.

micro_usd(u) == (cost_numerator(u) / 1_000_000) as u64 — a sub-micro fraction is dropped, never rounded, so the printed $ agrees with the truncated micro-USD the brief’s §7.2 check computes.

Trait Implementations

impl Clone for ModelPrice

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ModelPrice

impl Debug for ModelPrice

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

Formats the value using the given formatter.

impl Default for ModelPrice

fn default() -> Self

Returns the “default value” for a type.

impl Eq for ModelPrice

impl PartialEq for ModelPrice

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ModelPrice