Struct CompactionConfig 

pub struct CompactionConfig {
    pub threshold_prompt_tokens: u32,
    pub keep_recent_turns: u32,
    pub compactor_model: String,
    pub max_summary_tokens: u32,
}

Configuration for natural-language history compaction.

When set on RunOptions::compaction, the agent loop monitors the previous turn’s prompt_tokens and — once it crosses threshold_prompt_tokens — replaces the middle of the conversation with a single synthetic system message containing a compacted summary produced by a separate (typically cheaper) DeepSeek call.

Cost trade-off

Compaction costs one extra API call (input = serialized middle slice, output ≤ max_summary_tokens) and invalidates the prompt cache prefix for subsequent turns because the front of the message vector changes. DeepSeek’s cache-hit input price is ~25% of the cache-miss price, so:

• For short loops (a few turns): leave RunOptions::compaction = None — cache hits already make resending cheap.
• For long loops where prompt_tokens crosses ~30K: one compaction call on deepseek-chat costs ~$0.008, but saves resending ~30K tokens × each remaining turn at the cache-hit rate. Break-even is roughly four future turns.

Defaults are tuned for the long-loop case; tune threshold_prompt_tokens deliberately if your workload is short.

Fields

threshold_prompt_tokens: u32

Trigger compaction when the previous turn’s prompt_tokens >= this.

keep_recent_turns: u32

Number of complete recent turns to keep verbatim after the summary. A “turn” is one assistant message plus its associated tool-result group (if the assistant requested tool calls). Tool-call/result pairs are never split — compaction may keep one extra turn to preserve atomicity.

compactor_model: String

Model used for the compaction call. Default: deepseek-chat (cheapest input rate).

max_summary_tokens: u32

Soft cap on summary completion tokens.

Trait Implementations

impl Clone for CompactionConfig

fn clone(&self) -> CompactionConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CompactionConfig

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

Formats the value using the given formatter.

impl Default for CompactionConfig

fn default() -> Self

Returns the “default value” for a type.