Hippo, biologically inspired memory for AI agents
Biological decay mechanics beat vector search for agent memory that actually forgets.
Agentic AI memory with Ebbinghaus forgetting curve decay. +16pp better recall than Mem0 on LoCoMo.
Ebbinghaus forgetting curve cuts token waste 84% while doubling recall versus Zep.
AI agent developers, LLM application builders
Zep · Mem0 · Letta
This implementation experiments with a biological approach by using the Ebbinghaus forgetting curve to manage context as a living substrate. Memories are assigned a "strength" score where each recall reinforces the data and flattens its decay curve (spaced repetition), while unused data eventually hits a threshold and is pruned.
To solve the "logical neighbor" problem where semantic search misses relevant but non-similar nodes, a graph layer is layered over the vector store. Benchmarked against the LoCoMo dataset, this reached 52% Recall@5, nearly double the accuracy of stateless vector stores, while cutting token waste by roughly 84%.
Built as a local first MCP server using DuckDB, the hypothesis is that for agents handling long-running projects, "what to forget" is just as critical as "what to remember." I'd be interested to hear if others are exploring non-linear decay or similar biological constraints for context management.
Biological decay mechanics beat vector search for agent memory that actually forgets.
ACT-R decay and Hebbian learning as native primitives, not vector hacks.
Local RAG for browser LLMs with decay lifecycle, but already competed by Langchain vectors.
Ebbinghaus decay + offline semantic search beats Mem0, Letta, Memori combined.
Ebbinghaus decay prunes memory automatically, unlike standard RAG hoarding.
Thermodynamic memory decay beats passive vector search—90% token reduction claimed.