budget

Context budget computation — tracks token allocation across the LLM context window to prevent overflow and optimize utilization.

Structs

`ContextBudget`

Token budget allocation for an LLM context window.

Breaks the total context window into reserved zones and computes the remaining space available for conversation history.

┌────────────────────────────────────────────────────┐
│                  Context Window (total)             │
├────────────┬────────────┬────────┬─────────────────┤
│  System    │   Tools    │ Output │   Available     │
│  (fixed)   │  (schemas) │ (gen)  │  for History    │
└────────────┴────────────┴────────┴─────────────────┘

Fields

Field	Type	Description
`total`	`u32`	Total context window in tokens (from ModelCapabilities).
`reserved_output`	`u32`	Tokens reserved for model output generation.
`reserved_system`	`u32`	Tokens consumed by the system prompt.
`reserved_tools`	`u32`	Tokens consumed by tool schema definitions.
`available_for_history`	`u32`	Remaining tokens available for conversation history + memories.

Methods

`new`

fn new(context_window: u32, max_output_tokens: u32, system_message: Option<&str>, tools_json: &[serde_json::Value]) -> Self

Create a new budget from model capabilities and current context.

Parameters

context_window: Total tokens the model can accept
max_output_tokens: Tokens to reserve for generation
system_message: The system prompt text (will be estimated)
tools_json: Tool schema definitions (will be estimated)

`history_usage`

fn history_usage(&self, history_messages: &[serde_json::Value]) -> u32

Compute how many tokens are actually used by a set of history messages.

`would_exceed`

fn would_exceed(&self, history_messages: &[serde_json::Value]) -> bool

Check whether adding the given messages would exceed the history budget.

`utilization`

fn utilization(&self, history_messages: &[serde_json::Value]) -> f32

Utilization ratio (0.0 to 1.0) of the full context window.

`remaining`

fn remaining(&self, history_messages: &[serde_json::Value]) -> u32

Remaining tokens available after current history usage.