Struct SummaryCompactor 

pub struct SummaryCompactor<M> { /* private fields */ }

LLM-summary Compactor — drops the oldest turns past keep_recent_turns into a single summarised Turn::User, leaving the most recent turns verbatim.

Pair invariant: dropped turns carry their ToolPairs away with them — the retained set keeps every Turn::Assistant’s tools vector intact, so the wire-side codec never sees an unmatched tool block.

Construct with SummaryCompactor::new then chain SummaryCompactor::with_system_prompt / SummaryCompactor::with_keep_recent_turns for tuning. The summariser model is any Runnable<Vec<Message>, Message> — the operator’s ChatModel, a layered model, or a stub for tests.

Implementations

impl<M> SummaryCompactor<M>

pub fn new(model: Arc<M>) -> Self

Construct with the default system prompt and keep-recent count.

pub fn with_system_prompt(self, prompt: impl Into<String>) -> Self

Override the system prompt. Operators with a custom voice or downstream-format requirement (e.g. JSON envelope) point the summariser via this knob.

pub const fn with_keep_recent_turns(self, n: usize) -> Self

Override how many newest turns are retained verbatim. Higher values preserve more recent context at the cost of leaving more budget pressure for the summariser to manage.

Trait Implementations

impl<M> Compactor for SummaryCompactor<M>

where M: Runnable<Vec<Message>, Message> + Send + Sync + 'static,

fn compact<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, events: &'life1 [GraphEvent], _budget_chars: usize, ctx: &'life2 ExecutionContext, ) -> Pin<Box<dyn Future<Output = Result<CompactedHistory>> + Send + 'async_trait>>

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

Compact events to fit within budget_chars. The budget is approximate — implementations measure character length of the rendered text (closest free proxy for token count without pulling a tokenizer dependency). The ExecutionContext carries cancellation + deadline so a long-running summarisation respects the same lifetime as the dispatch that triggered it. Returns Error::Config when the event log violates the pair invariant before compaction (e.g. ToolResult without a preceding ToolCall); a well-formed SessionGraph never hits this path.