Session-Level Memory vs. Fragment Memory: Why AI Coding Agents Hallucinate About the Past

Description and use

<p>Ask your AI coding agent a simple question: <em>"Why did we choose PostgreSQL over MySQL?"</em></p> <p>If you settled that decision three weeks ago in a different session, you'll get one of three responses — and all three are failure modes:</p> <ol> <li> <strong>"I don't have context on that."</strong> Amnesia. Everything you discussed is gone.</li> <li> <strong>A confident, plausible-sounding rationale.</strong> Hallucination. It's inventing reasons that were never discussed.</li> <li> <strong>A memory shard that says "the user prefers PostgreSQL."</strong> Technically true, functionally u

Problem

<p>Ask your AI coding agent a simple question: <em>"Why did we choose PostgreSQL over MySQL?"</em></p> <p>If you settled that decision three weeks ago in a different session, you'll get one of three responses — and all three are failure modes:</p> <ol> <li> <strong>"I don't have context on that."</strong> Amnesia. Everything you discussed is gone.</li> <li> <strong>A confident, plausible-sounding rationale.</strong> Hallucination. It's inventing reasons that were never discussed.</li> <li> <strong>A memory shard that says "the user prefers PostgreSQL."</strong> Technically true, functionally u

Outcome

<p>Ask your AI coding agent a simple question: <em>"Why did we choose PostgreSQL over MySQL?"</em></p> <p>If you settled that decision three weeks ago in a different session, you'll get one of three responses — and all three are failure modes:</p> <ol> <li> <strong>"I don't have context on that."</strong> Amnesia. Everything you discussed is gone.</li> <li> <strong>A confident, plausible-sounding rationale.</strong> Hallucination. It's inventing reasons that were never discussed.</li> <li> <strong>A memory shard that says "the user prefers PostgreSQL."</strong> Technically true, functionally u

Evidence

Session-Level Memory vs. Fragment Memory: Why AI Coding Agents Hallucinate About the Past

Source