Definition
Durable memory is agent state intentionally retained across runs and made available later. It may contain verified facts, decisions, preferences, project conventions, task history, procedures, or a persistent identity record. "Durable" means the state outlives one process or context window. It does not mean permanent, correct, or impossible to revise.
Durability requires more than writing a file or database row. The system needs a stable identity for the subject and scope, a write authority, persistence guarantees, retrieval or trigger rules, and a lifecycle for supersession, correction, expiration, export, and deletion. A record that survives forever but is never delivered is durable storage, not useful memory.
For auditable systems, preserve the events or documents from which a memory was derived. Summaries, embeddings, and extracted facts can then remain rebuildable projections rather than becoming an unchallengeable second source of truth. Some memory, such as an explicitly chosen preference, is itself a source event and should retain who set it and when.
Distinguish it from nearby terms
- Working memory supports the active task and may disappear at the end of a run.
- Agent memory is the broader capture, storage, selection, and delivery system. Durable memory is the cross-run portion.
- Model parameters persist across calls, but they are learned through training and do not provide an inspectable record of one user's recent decision.
- A knowledge base stores reference material. Durable memory usually adds temporal continuity, subject scope, and mutation rules.
Control and safety
Persistent memory can amplify one bad write across many future runs. Restrict mutation authority, preserve an audit log, separate observation from endorsed fact, and require stronger approval for identity or standing-instruction changes. Jesse Vincent's therapist pattern proposes a dedicated single writer for persistent identity so the active agent cannot silently rewrite its own governing record.
Memory also creates privacy and security obligations. Users need to know what is retained and must be able to correct or delete it. Retention should follow a purpose and policy, not the accidental lifetime of a database.
Check your understanding
An agent stores "deploy directly from a laptop" after one mistaken session. Without provenance, expiry, or a correction path, that error can steer every later deployment. Persistence has multiplied the failure.