Struct ContextBudget 

pub struct ContextBudget {
    pub system_prompt_static_tokens: usize,
    pub system_prompt_dynamic_tokens: usize,
    pub tool_schema_tokens: usize,
    pub deferred_tool_tokens: usize,
    pub skill_listing_tokens: usize,
    pub conversation_tokens: usize,
    pub tool_result_tokens: usize,
    pub context_window_size: usize,
    pub static_prefix_cache_hit: bool,
    pub static_prefix_hash: Option<String>,
}

Tracks token usage by component for context optimization.

Each field represents the estimated token count for a specific component of the prompt. This enables:

• Monitoring which components consume the most context
• Triggering compaction when utilization exceeds thresholds
• Informing deferred loading decisions (tools, skills)
• API-side prompt caching optimization

Fields

system_prompt_static_tokens: usize

Static system prompt tokens (cacheable across sessions)

system_prompt_dynamic_tokens: usize

Dynamic system prompt tokens (per-session: env, memory, hooks)

tool_schema_tokens: usize

Tool schema tokens (full schemas for core tools)

deferred_tool_tokens: usize

Deferred tool listing tokens (name + description only)

skill_listing_tokens: usize

Skill listing tokens in system prompt

conversation_tokens: usize

Conversation history tokens (all messages)

tool_result_tokens: usize

Tool result tokens in current turn

context_window_size: usize

Total estimated context window size for the model

static_prefix_cache_hit: bool

Whether the static prompt prefix hash has changed (cache bust)

static_prefix_hash: Option<String>

Hash of the static system prompt prefix for cache tracking

Implementations

impl ContextBudget

pub fn total_tokens(&self) -> usize

Total tokens currently consumed across all components

pub fn utilization(&self) -> f64

Context utilization as a percentage (0.0 - 1.0)

pub fn remaining_tokens(&self) -> usize

Remaining tokens available in the context window

pub fn is_warning(&self) -> bool

Whether context utilization exceeds the warning threshold (80%)

pub fn is_critical(&self) -> bool

Whether context utilization exceeds the critical threshold (90%)

pub fn deferred_savings(&self) -> usize

Tokens saved by deferring tools (vs loading all schemas)

Trait Implementations

impl Clone for ContextBudget

fn clone(&self) -> ContextBudget

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ContextBudget

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

Formats the value using the given formatter.

impl Default for ContextBudget

fn default() -> ContextBudget

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ContextBudget

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ContextBudget

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

where __S: Serializer,

Serialize this value into the given Serde serializer.