Memory Architecture

NEW IN 2026 
  Agent memory matured from "pick a vector database" into a benchmarked production discipline in 2026, with dedicated evaluation suites (LoCoMo (Long Conversation Memory)), MemBench, MemoryAgentBench, MemoryArena) and an ecosystem spanning roughly 20+ frameworks and vector stores across managed-cloud, self-hosted, and local-MCP hosting models. 
 
 
 
 
 
 Type 
 
 
 Storage 
 
 
 Layer 
 
 
 Purpose 
 
 
 
 
 Short-Term 
 
 
 Session 
 
 
 In-memory 
 
 
 Conversation state 
 
 
 
 
 Long-Term 
 
 
 Cross-session 
 
 
 Vector DB 
 
 
 Semantic recall 
 
 
 
 
 Graph Memory 
 
 
 Persistent 
 
 
 Graph DB 
 
 
 Relationships 
 
 
 
 
 Episodic 
 
 
 Persistent 
 
 
 DB 
 
 
 Prior tasks / outcomes 
 
 
 
 
 Procedural 
 
 
 Persistent 
 
 
 DB 
 
 
 Learned workflows 
 
 
 
 
 Policy Memory 
 
 
 Persistent 
 
 
 DB 
 
 
 Rules & restrictions 
 
 
 
 
 Audit Memory 
 
 
 Permanent 
 
 
 SQL 
 
 
 Logs & traceability 
 
 
 
 
 
 Three Patterns for Memory Control 
 ●       Pattern A — Context-resident: everything lives in the context window with compression. Simple, but caps out fast on long-running agents. 
 ●       Pattern B — Retrieval-augmented (workhorse pattern): working memory in-context, long-term records in a vector or structured store, injected each step. Recommended default, the engineering burden is manageable and the main challenge is retrieval quality. 
 ●       Pattern C — Tiered memory with learned control: multiple tiers (context, structured DB, vector store, cold archive) managed by a learned or prompted controller. Highest headroom, highest engineering cost — graduate to this only when data shows Pattern B is the bottleneck. 
 Best Practice 
 Memory entries should include: 
 ●       source 
 ●       timestamp 
 ●       confidence 
 ●       owner 
 ●       retention policy 
 ●       trust score 
 Known open problem across 2026 memory systems: selective forgetting. Most benchmarked systems handle retrieval and test-time learning reasonably well but still fail conspicuously at deciding what to evict. Budget explicit engineering time for eviction policy, not just ingestion.