Introducing Hindsight: Agent Memory That Works Like Human Memory

Chris Latimer•
Introducing Hindsight: Agent Memory That Works Like Human Memory

Today, we’re introducing Hindsight, an open-source memory system for AI agents designed to work the way human memory does — contextual, time-aware, and capable of forming and updating beliefs.

This matters because agents that can’t model memory the way humans do can’t truly learn. They retrieve fragments of the past, but they don’t build understanding over time. Hindsight changes that by treating memory as a first-class substrate for reasoning, enabling agents to learn from experience rather than repeatedly starting from scratch.

In evaluations on long-horizon conversational benchmarks, Hindsight achieves state-of-the-art performance, significantly outperforming existing agent memory systems and full-context baselines. These results validate a simple idea: agents don’t just need more context — they need better memory.

Why Agent Memory Is Holding Agents Back

AI agents are increasingly expected to operate over long time horizons: managing projects, tracking evolving information, maintaining preferences, and explaining decisions. But most agents today are still built on stateless foundations.

The dominant approaches to “memory” rely on:

  • Semantic search over conversation logs
  • Stuffing raw history into the context window
  • Letting the model guess what matters

This works for short interactions, but breaks down as conversations grow longer and reasoning becomes more complex.

Hindsight was built to solve this problem.

What Is Hindsight?

Hindsight is a memory architecture for AI agents that treats memory as a first-class substrate for reasoning, not a thin retrieval layer.

A diagram illustrating the architecture of Hindsight, an open-source memory system for AI agents, showing interactions between an AI Agent, Hindsight API Server, and Memory Bank containing Documents, Memories, and Entities, with arrows indicating operations of retain, recall, and reflect.

It is built around three core operations:

  • Retain — convert interactions into structured, time-aware memory
  • Recall — retrieve the most relevant memories for a task, within a token budget
  • Reflect — reason over memory to answer questions and update beliefs

This allows agents to accumulate experience, maintain consistency, and learn over time.

State-of-the-Art Results

We evaluated Hindsight on what is considered the most relevant memory benchmark, LongMemEval.

MethodModel BackboneOverall Accuracy (%)
Full-contextOSS-20B39.0
Full-contextGPT-4o60.2
ZepGPT-4o71.2
SupermemoryGPT-4o81.6
SupermemoryGPT-584.6
SupermemoryGemini-385.2
HindsightOSS-20B83.6
HindsightOSS-120B89.0
HindsightGemini-391.4

The results are clear. Hindsight improves accuracy by +44.6 points over a full-context baseline, and outperforms other memory systems often using smaller or open source models.

For full details on the evaluation setup and results, see the research paper linked below.

What Makes Hindsight Different

A few architectural choices drive these results:

  • Structured memory, not raw logs

     Memory is organized into distinct networks for facts, experiences, observations, and opinions — separating evidence from inference.
  • Time- and entity-aware recall

     Memories are anchored in time and connected through entities and relationships, enabling multi-session and temporal reasoning.
  • Learning, not just recall

     Agents can form opinions with confidence scores and update those beliefs as new information arrives.
  • Designed for agents

     Retrieval is optimized for downstream reasoning, not generic search or static top-k results.

If you want a deeper dive into the motivation and architecture, we’ve published a deeper technical post here: Hindsight: Building AI Agents That Actually Learn.

Open Source, Available Today

Hindsight is fully open source and available now.

Hindsight is designed to integrate with existing agent frameworks and models, and to be deployable in your own infrastructure.

Research and Coverage

Alongside the open-source release, we’re also publishing:

These materials provide both the technical depth and independent validation behind the system.

What’s Next

We’re also building a hosted cloud version of Hindsight for teams that want managed infrastructure and production-ready features.

You can request early access here: https://vectorize.io/hindsight/cloud

Get Started

If you’re building agents that need to operate over long time horizons, maintain consistency, and learn from experience, Hindsight is built for you.