# Compaction

Source: https://customlabs.io/glossary/compaction/
Updated: 2026-09-13

Agents

# Compaction

Compaction summarizes or drops older context to make room in a filling window.

It should run on a published rule, not as an emergency response to overflow.

What a compaction pass is told to protect decides whether it helps or actively harms.

A pass with no instruction to preserve the goal and open commitments will compress those away too.

An agent that forgot its task is a harder failure to spot than one that ran out of room.

[Context Engineering](https://customlabs.io/context-engineering/#surface-history)[Failure mode: Context overflow drops the task](https://customlabs.io/failure-modes/context-overflow-drops-the-task/)

[← Back to the full glossary](https://customlabs.io/glossary/)

## Related terms

[Context Rot Context rot is a model's declining ability to use context well as it fills with stale material.](https://customlabs.io/glossary/context-rot/)[Context Engineering Context engineering decides what occupies a model's context window at every step, and in what order.](https://customlabs.io/glossary/context-engineering/)

## More in Agents

[Agent (Agentic AI) An agent is an LLM given a loop, memory, and tools it can call.](https://customlabs.io/glossary/agent/)[Tool Calling Tool calling lets a model request a structured action instead of only generating text.](https://customlabs.io/glossary/tool-calling/)[Model Context Protocol (MCP) MCP is an open standard for connecting LLM applications to tools and data sources.](https://customlabs.io/glossary/model-context-protocol/)[Tool Contract A tool contract is the schema a tool exposes to a model.](https://customlabs.io/glossary/tool-contract/)