ACI-003: Correction Erosion After Compaction

Thesis

When a long session triggers context compaction, corrections made earlier in the conversation can be lost. The agent may repeat the exact mistake you already corrected, because the compaction summary did not preserve the correction with enough fidelity. Tracking post-compaction behavior is the only way to detect this.

Story

Agentic coding sessions have a finite context window. When a conversation grows long enough, the system compresses earlier messages into a summary to make room for new ones. This is context compaction, and it is invisible to the user -- there is no notification that it happened.