Intermediate · Systems

Context Evolution

Visual diagram · (in preparation) · Math · (in preparation) · Worked example · 3 difficulty levels.

TL;DR. How an agent's context changes over the course of a task as steps, observations, and summaries accumulate and replace one another.

Technical Definition

How an agent's context changes over the course of a task as steps, observations, and summaries accumulate and replace one another.

How it works

Context evolution describes the trajectory of an agent's working context across a task. Early turns are dominated by instructions and goal framing; middle turns fill with tool calls, observations, and intermediate artifacts; late turns depend on compacted summaries because raw history no longer fits. Designing this trajectory deliberately — deciding when to summarize, when to re-anchor on the original goal, and when to evict stale observations — prevents the common failure where an agent slowly forgets its objective while its window fills with noise.

Related Concepts

• Agentic Context — The full set of information an agent has available when it decides its next action — goals, state, tools, memory, and retrieved data.
• Context Drift — The gradual divergence of an agent's working context from the actual task or world state, degrading its decisions over time.
• Context Compaction — Compressing accumulated history into a smaller, higher-density representation so an agent can keep working within its token budget.
• Context Lifecycle — The stages a piece of context passes through: acquisition, validation, injection, use, compaction, persistence, and expiry.