External Durable Memory

Version: 1.0.0 | Last updated: 2026-07-16

Purpose

Store cross-session facts, preferences, and task state in durable systems with transactional governance.

Why

External persistence survives context and process failure, but broad shared stores create stale-write, tenant-leakage, and deletion risks.

How

Separate authoritative task state from recall-oriented memory. Use typed schemas, tenant keys, row-level authorization, optimistic concurrency, idempotent writes, encryption, audit events, retention, and backup/restore. Require explicit write criteria and validation; agent outputs enter a pending state until policy approves them. Maintain lineage to every cache, index, and summary.

Tradeoffs

Transactional stores improve correctness but do not provide semantic retrieval by themselves. Add indexes as replaceable derivatives, never as the sole record.

Anti-patterns

• A shared vector store as authoritative state.
• Unversioned upserts and last-write-wins preferences.
• Backups that cannot honor deletion or tenant restore boundaries.

Enterprise Considerations

Define RPO/RTO, residency, key ownership, legal hold, deletion, and tenant-level restore. Exercise failover and corrupt-index rebuilds.

Checklist

• Authoritative and derived stores are distinguished.
• Transactions, versions, idempotency, and audit are enforced.
• Tenant isolation and deletion include backups and derivatives.
• Restore and re-index drills pass.

References

• NIST SP 800-53 Rev. 5
• NIST SP 800-34 Rev. 1

Changelog

• 1.0.0 — 2026-07-16: Initial production standard.