Struct Budget 

pub struct Budget {
    pub kind: BudgetKind,
    pub limit: f64,
}

A budget limit: which dimension, and the ceiling set for it.

Minimal on purpose. Budget enforcement owns the richer model; this type exists only so Event::BudgetExceeded can name what was crossed. limit is interpreted in the units implied by kind.

Why every dimension is an f64

BudgetKind::CostUsd and BudgetKind::WallTime are inherently fractional, so they need a float. BudgetKind::Tokens and BudgetKind::Steps are integral in nature, yet they ride the wire as f64 too, and that is a deliberate, kept decision rather than an oversight.

The concern with a float for a counter is silent rounding. It does not arise here: an IEEE 754 double represents every integer exactly up to 2^53, which is 9_007_199_254_740_992 (about 9.0e15). A run’s token and step counts do not approach that bound. A billion-token run is 1e9, six orders of magnitude below the point where consecutive integers stop being exactly representable, and a step is one model turn. So a limit or an observed value that is integral in these dimensions round-trips through the wire and through every comparison exactly. The one caller-facing rule is that a declared token or step limit stay under 2^53, which no realistic budget violates.

The alternative, splitting the type so integral dimensions carried a u64 and fractional ones an f64, was weighed and declined: it would fracture one uniform budget value into two, complicate the single crossing-check comparison that treats every dimension the same way, and change the wire format (with the snapshot and stored-log churn that implies) for no practical gain, since f64 already holds these integers exactly. The uniform f64 is the honest representation given the bound above.

Fields

kind: BudgetKind

The dimension this limit applies to.

limit: f64

The ceiling, in the units implied by kind. An f64 for every dimension; integral for Tokens/Steps and exact there up to 2^53 (see the type docs).

Trait Implementations

impl Clone for Budget

fn clone(&self) -> Budget

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Budget

impl Debug for Budget

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Budget

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Budget

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for Budget

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 Budget