Struct MemorySynthesizer 

pub struct MemorySynthesizer { /* private fields */ }

Smarter alternative to MemoryWriter — distil the session’s assistant turns into 1..=max_facts atomic durable facts using a cheap “synthesizer” model, instead of persisting the verbatim final answer.

Wire either MemoryWriter or MemorySynthesizer, not both — MemorySynthesizer is a superset of the writer’s behaviour with the extra distillation step.

Behaviour:

• On PostModel, appends out.text (when present, non-empty) to an internal buffer.
• On TaskCompleted, tokio::spawns a synthesis task: calls synth_model.complete() with a fixed prompt that asks for a JSON array of {content, tags} objects, parses the response, and writes each one via Memory::write.
• Model errors / parse failures fall back to saving the raw response as a single entry tagged "synth-raw" so the session’s information isn’t lost entirely.
• On BudgetExhausted (no TaskCompleted fires), nothing is written.

The synth model should be cheap (deepseek-v4-flash, gpt-5-nano, etc.). Constructed independently from the main model so you can use a small summariser even when the reasoning model is large.

Implementations

impl MemorySynthesizer

pub fn new(memory: Arc<dyn Memory>, synth_model: Arc<dyn Model>) -> Self

Construct a synthesizer that uses synth_model to distil the session into at most 3 facts.

pub async fn flush_pending(&self)

Await all background synthesis tasks that have been kicked off so far. Call this before your process exits if you want to guarantee the last session’s memory is on disk — otherwise the tokio runtime may be dropped while the spawn is mid-flight.

pub fn with_source(self, source: impl Into<String>) -> Self

pub fn with_base_tags( self, tags: impl IntoIterator<Item = impl Into<String>>, ) -> Self

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

Cap how many facts the synthesizer is allowed to emit. Default 3.

Trait Implementations

impl Hook for MemorySynthesizer

fn name(&self) -> &str

fn matches(&self, ev: &Event<'_>) -> bool

fn fire(&self, ev: &Event<'_>, _w: &mut World) -> HookOutcome