* perf: replace window-function retrieval with UNION ALL + per-bank HNSW indexes The previous retrieve_semantic_bm25_combined() used ROW_NUMBER() OVER (PARTITION BY fact_type ...) which forced a full sequential scan — pgvector cannot use HNSW indexes when a window function partitions on the same column as the ORDER BY. Changes: - retrieval.py: rewrite to UNION ALL of per-fact_type subqueries; each arm has its own ORDER BY embedding <=> $1 LIMIT n, enabling partial HNSW index scans. Semantic arms over-fetch 5x (min 100) for HNSW approximation; trimmed in Python. - memory_engine.py: set hnsw.ef_search=200 at pool init (persistent per-connection, no per-query SET/RESET overhead). - bank_utils.py: add create_bank_hnsw_indexes / drop_bank_hnsw_indexes for per-(bank_id, fact_type) partial HNSW index lifecycle management. - fact_storage.py / bank_utils.py: create per-bank indexes on fresh bank insert. - memory_engine.py delete_bank: drop per-bank indexes via DELETE...RETURNING to avoid a separate round-trip. - Migration a3b4c5d6e7f8: add interim fact_type-only partial indexes. - Migration d5e6f7a8b9c0: add internal_id UUID UNIQUE to banks, replace fact_type-only indexes with per-(bank, fact_type) partial HNSW indexes, drop the global idx_memory_units_embedding that competed with them. Why per-(bank, fact_type) not just per-fact_type: The idx_memory_units_bank_id B-tree index always wins over fact_type-only partial indexes when bank_id appears in the WHERE clause. Including bank_id in the partial index predicate removes the B-tree from consideration and lets the planner choose HNSW. The global HNSW index must also be dropped to avoid competing for the larger fact_type partitions (world, observation). * refactor: collapse two HNSW migrations into one * refactor: generate bank internal_id in Python before insert Instead of relying on DEFAULT gen_random_uuid() and RETURNING internal_id, generate the UUID in application code before the INSERT. This means we always know the value upfront and can call create_bank_hnsw_indexes immediately without needing a DB round-trip to retrieve the assigned ID. Also adds tests for HNSW index lifecycle and retrieve_semantic_bm25_combined. * fix: correct migration and prevent global HNSW index recreation Migration fixes: - Add text() wrappers for raw SQL in d5e6f7a8b9c0 (SQLAlchemy 2.0 compat) - Drop stale fact_type-only partial indexes (idx_mu_emb_world/observation/experience) that may exist from prior migrations on the same DB migrations.py fix: - Skip global HNSW index creation when per-bank partial HNSW indexes already exist on memory_units (idx_mu_emb_* pattern). Without this, the post-migration vector index check detects no %embedding% named index and recreates the global idx_memory_units_embedding, which defeats the per-bank index strategy. Verified with EXPLAIN ANALYZE on 66K-row bank: all three fact_type arms use their per-bank HNSW index scan (idx_mu_emb_worl/expr/obsv_<uid16>). * fix: use correct embeddings.encode() in test |
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| .githooks | ||
| .github | ||
| cookbook | ||
| docker | ||
| helm/hindsight | ||
| hindsight | ||
| hindsight-api | ||
| hindsight-cli | ||
| hindsight-clients | ||
| hindsight-control-plane | ||
| hindsight-dev | ||
| hindsight-docs | ||
| hindsight-embed | ||
| hindsight-integration-tests | ||
| hindsight-integrations | ||
| monitoring/grafana/dashboards | ||
| scripts | ||
| skills | ||
| .dockerignore | ||
| .env.example | ||
| .gitignore | ||
| .python-version | ||
| .sesskey | ||
| AGENTS.md | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| hindsight-favicon.png | ||
| LICENSE | ||
| package-lock.json | ||
| package.json | ||
| pyproject.toml | ||
| README.md | ||
| SECURITY.md | ||
| uv.lock | ||
What is Hindsight?
Hindsight™ is an agent memory system built to create smarter agents that learn over time. Most agent memory systems focus on recalling conversation history. Hindsight is focused on making agents that learn, not just remember.
It eliminates the shortcomings of alternative techniques such as RAG and knowledge graph and delivers state-of-the-art performance on long term memory tasks.
Memory Performance & Accuracy
Hindsight is the most accurate agent memory system ever tested according to benchmark performance. It has achieved state-of-the-art performance on the LongMemEval benchmark, widely used to assess memory system performance across a variety of conversational AI scenarios. The current reported performance of Hindsight and other agent memory solutions as of January 2026 is shown here:
The benchmark performance data for Hindsight has been independently reproduced by research collaborators at the Virginia Tech Sanghani Center for Artificial Intelligence and Data Analytics and The Washington Post. Other scores are self-reported by software vendors.
Hindsight is being used in production at Fortune 500 enterprises and by a growing number of AI startups.
Adding Hindsight to Your AI Agents
The easiest way to use Hindsight with an existing agent is with the LLM Wrapper. You can add memory to your agent with 2 lines of code. That will swap your current LLM client out with the Hindsight wrapper. After that, memories will be stored and retrieved automatically as you make LLM calls.
If you need more control over how and when your agent stores and recalls memories, there's also a simple API you can integrate with using the SDKs or directly via HTTP.
🤖 Using a coding agent? Install the Hindsight documentation skill for instant access to docs while you code:
npx skills add https://github.com/vectorize-io/hindsight --skill hindsight-docsWorks with Claude Code, Cursor, and other AI coding assistants.
Quick Start
Docker (recommended)
export OPENAI_API_KEY=sk-xxx
docker run --rm -it --pull always -p 8888:8888 -p 9999:9999 \
-e HINDSIGHT_API_LLM_API_KEY=$OPENAI_API_KEY \
-v $HOME/.hindsight-docker:/home/hindsight/.pg0 \
ghcr.io/vectorize-io/hindsight:latest
You can modify the LLM provider by setting HINDSIGHT_API_LLM_PROVIDER. Valid options are openai, anthropic, gemini, groq, ollama, and lmstudio. The documentation provides more details on supported models.
Docker (external PostgreSQL)
export OPENAI_API_KEY=sk-xxx
export HINDSIGHT_DB_PASSWORD=choose-a-password
cd docker/docker-compose
docker compose up
Client
pip install hindsight-client -U
# or
npm install @vectorize-io/hindsight-client
Python
from hindsight_client import Hindsight
client = Hindsight(base_url="http://localhost:8888")
# Retain: Store information
client.retain(bank_id="my-bank", content="Alice works at Google as a software engineer")
# Recall: Search memories
client.recall(bank_id="my-bank", query="What does Alice do?")
# Reflect: Generate disposition-aware response
client.reflect(bank_id="my-bank", query="Tell me about Alice")
Node.js / TypeScript
npm install @vectorize-io/hindsight-client
const { HindsightClient } = require('@vectorize-io/hindsight-client');
const main = async () => {
const client = new HindsightClient({ baseUrl: 'http://localhost:8888' });
await client.retain('my-bank', 'Alice loves hiking in Yosemite');
const results = await client.recall('my-bank', 'What does Alice like?');
console.log(results);
}
main();
Python Embedded (no server required)
pip install hindsight-all -U
import os
from hindsight import HindsightServer, HindsightClient
with HindsightServer(
llm_provider="openai",
llm_model="gpt-5-mini",
llm_api_key=os.environ["OPENAI_API_KEY"]
) as server:
client = HindsightClient(base_url=server.url)
client.retain(bank_id="my-bank", content="Alice works at Google")
results = client.recall(bank_id="my-bank", query="Where does Alice work?")
Use Cases
Hindsight is built to support conversational AI agents as well as agents that are intended to perform tasks autonomously. The ideal use case for Hindsight are agents that require a blend of these features such as AI employees that need to handle open-ended tasks, change behavior based on user feedback, and learn to perform complex tasks to automate work at a level that approximates a human work. Hindsight can be used with simple AI workflows like those built with n8n and other similar tools, but may be overkill for such applications.
Per-User Memories and Chat History
One of the simpler use cases you can use Hindsight for is to personalize AI chatbots and other conversational agents by storing and recalling memories associated with individual users.
The requirements for this use case usually look something like this:
Satisfying these requirements in Hindsight is straightforward. When new user inputs and tool calls are ingested into Hindsight using the retain operation, custom metadata can be used to enrich the new memories. Metadata provides a convenient way to isolate memories that need to be restricted to a given user. Once these are fed into the retain operation, any raw memories and mental models that get created can be filtered when retrieving relevant memories.
Architecture & Operations
Most agent memory implementations rely on basic vector search or sometimes use a knowledge graph. Hindsight uses biomimetic data structures to organize agent memories in a way that is more like how human memory works:
- World: Facts about the world ("The stove gets hot")
- Experiences: Agent's own experiences ("I touched the stove and it really hurt")
- Mental Models: Learned understanding of the agent's world formed by reflecting on raw memories and experiences.
Memories in Hindsight are stored in banks (i.e. memory banks). When memories are added to Hindsight, they are pushed into either the world facts or experiences memory pathway. They are then represented as a combination of entities, relationships, and time series with sparse/dense vector representations to aid in later recall.
Hindsight provides three simple methods to interact with the system:
- Retain: Provide information to Hindsight that you want it to remember
- Recall: Retrieve memories from Hindsight
- Reflect: Reflect on memories and experiences to generate new observations and insights from existing memories.
Retain
The retain operation is used to push new memories into Hindsight. It tells Hindsight to retain the information you pass in as an input.
from hindsight_client import Hindsight
client = Hindsight(base_url="http://localhost:8888")
# Simple
client.retain(
bank_id="my-bank",
content="Alice works at Google as a software engineer"
)
# With context and timestamp
client.retain(
bank_id="my-bank",
content="Alice got promoted to senior engineer",
context="career update",
timestamp="2025-06-15T10:00:00Z"
)
Behind the scenes, the retain operation uses an LLM to extract key facts, temporal data, entities, and relationships. It passes these through a normalization process to transform extracted data into canonical entities, time series, and search indexes along with metadata. These representations create the pathways for accurate memory retrieval in the recall and reflect operations.
Recall
The recall operation is used to retrieve memories. These memories can come from any of the memory types (world, experiences, etc.)
from hindsight_client import Hindsight
client = Hindsight(base_url="http://localhost:8888")
# Simple
client.recall(bank_id="my-bank", query="What does Alice do?")
# Temporal
client.recall(bank_id="my-bank", query="What happened in June?")
Recall performs 4 retrieval strategies in parallel:
- Semantic: Vector similarity
- Keyword: BM25 exact matching
- Graph: Entity/temporal/causal links
- Temporal: Time range filtering
The individual results from the retrievals are merged, then ordered by relevance using reciprocal rank fusion and a cross-encoder reranking model.
The final output is trimmed as needed to fit within the token limit.
Reflect
The reflect operation is used to perform a more thorough analysis of existing memories. This allows the agent to form new connections between memories and build a more thorough understanding of its world.
For example, the reflect operation can be used to support use cases such as:
- An AI Project Manager reflecting on what risks need to be mitigated on a project.
- A Sales Agent reflecting on why certain outreach messages have gotten responses while others haven't.
- A Support Agent reflecting on opportunities where customers have questions not answered by current product documentation.
The reflect operation can also be used to handle on-demand question answering or analysis which require more deep thinking.
from hindsight_client import Hindsight
client = Hindsight(base_url="http://localhost:8888")
client.reflect(bank_id="my-bank", query="What should I know about Alice?")
Resources
Documentation:
Clients:
Community:
Star History
Contributing
See CONTRIBUTING.md.
License
MIT — see LICENSE
Built by Vectorize.io








