Summary-based context compaction.
When the conversation approaches the configured reserve threshold, Alloy preserves the first message, keeps a recent verbatim token window, and replaces older context with a structured handoff summary. If summary generation fails, Alloy falls back to deterministic truncation.
Compaction options live under compaction::
:clear_tool_results- clear old bulky tool-result content before summary generation (defaulttrue):keep_recent_tool_results- newest tool results to preserve verbatim when clearing (default3):summary_system_prompt- system prompt used for summary generation:summary_prompt- user prompt instructions appended after the serialized conversation
Summary
Functions
Compacts messages, preserving the first message and the most recent N messages.
Forces compaction regardless of reserve budget. Used when the provider rejects the prompt as too long.
Compacts state messages when they exceed max_tokens - reserve_tokens.
Prefix used for synthetic handoff summary messages inserted by the compactor.
Functions
@spec compact_messages( [Alloy.Message.t()], keyword() ) :: [Alloy.Message.t()]
Compacts messages, preserving the first message and the most recent N messages.
This helper intentionally stays deterministic and provider-free so it can serve as the fallback truncation strategy.
Options
:keep_recent- number of recent messages to preserve (default 10)
@spec force_compact(Alloy.Agent.State.t()) :: Alloy.Agent.State.t()
Forces compaction regardless of reserve budget. Used when the provider rejects the prompt as too long.
@spec maybe_compact( Alloy.Agent.State.t(), keyword() ) :: {:compacted | :unchanged, Alloy.Agent.State.t()}
Compacts state messages when they exceed max_tokens - reserve_tokens.
Returns {:compacted, state} when compaction occurred, or
{:unchanged, state} when already within budget.
@spec summary_prefix() :: String.t()
Prefix used for synthetic handoff summary messages inserted by the compactor.