Struct PromptCache 

pub struct PromptCache { /* private fields */ }

Manages prompt caching for the agent turn loop.

PromptCache builds structured system prompts with cache control breakpoints and tracks cache performance metrics.

Implementations

impl PromptCache

pub fn new() -> Self

Creates a new prompt cache with zeroed metrics.

pub fn build_system_prompt( &self, identity: &str, tools: &[ToolDefinition], context: &str, ) -> SystemPrompt

Builds a structured system prompt with cache control breakpoints.

The system prompt is organized into three cacheable sections:

1. Identity — the agent’s identity and behavioral instructions
2. Tool definitions — sorted alphabetically by name for stable ordering
3. Context files — reference materials like AGENTS.md

A dynamic section follows the static prefix, reserved for conversation history that changes each turn.

Arguments

• identity — Agent identity and behavioral instructions.
• tools — List of tool definitions (will be sorted by name).
• context — Context file contents (e.g., AGENTS.md).

Cache Breakpoints

Three breakpoints are inserted:

• After the identity section
• After the tool definitions section
• After the context files section

pub fn track_cache_hit_rate(&mut self, hit: bool)

Records a cache hit or miss for performance tracking.

Arguments

• hit — true if the cache was hit, false if it was a miss.

pub fn cache_hit_rate(&self) -> f64

Returns the cache hit rate as a percentage (0.0 to 100.0).

Returns 0.0 if no cache checks have been recorded.

Trait Implementations

impl Debug for PromptCache

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

Formats the value using the given formatter.

impl Default for PromptCache

fn default() -> Self

Returns the “default value” for a type.