Trait BudgetGuard 

pub trait BudgetGuard: Send + Sync {
    // Provided methods
    fn check_before_llm<'life0, 'life1, 'async_trait>(
        &'life0 self,
        session_id: &'life1 str,
        estimated_prompt_tokens: usize,
    ) -> Pin<Box<dyn Future<Output = BudgetDecision> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
    fn record_after_llm<'life0, 'life1, 'life2, 'async_trait>(
        &'life0 self,
        session_id: &'life1 str,
        usage: &'life2 TokenUsage,
    ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait,
             'life2: 'async_trait { ... }
    fn check_before_tool<'life0, 'life1, 'life2, 'async_trait>(
        &'life0 self,
        session_id: &'life1 str,
        tool_name: &'life2 str,
    ) -> Pin<Box<dyn Future<Output = BudgetDecision> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait,
             'life2: 'async_trait { ... }
}

Host-supplied budget / quota contract.

Implementations are typically wired up by a cluster control plane to enforce cross-session, cross-tenant cost limits. The framework itself ships only the no-op NoopBudgetGuard.

All trait methods default to Allow / no-op so impls only need to override what they actually want to govern.

Provided Methods

fn check_before_llm<'life0, 'life1, 'async_trait>( &'life0 self, session_id: &'life1 str, estimated_prompt_tokens: usize, ) -> Pin<Box<dyn Future<Output = BudgetDecision> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Called immediately before an LLM API call.

estimated_prompt_tokens is a best-effort framework estimate from the message history at call time; impls that want precise accounting should use record_after_llm instead of trusting the estimate.

fn record_after_llm<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, session_id: &'life1 str, usage: &'life2 TokenUsage, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called after every successful LLM call with the actual usage reported by the provider. Lets the impl keep its running spend total in sync with reality.

Failed LLM calls do not invoke this hook.

fn check_before_tool<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, session_id: &'life1 str, tool_name: &'life2 str, ) -> Pin<Box<dyn Future<Output = BudgetDecision> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called immediately before a tool invocation. The framework does not pass tool arguments — impls that need argument-aware caps must wrap the executor via a custom ToolExecutor.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl BudgetGuard for NoopBudgetGuard