* perf: 3-phase retain pipeline — fix deadlocks, cap temporal links, query-time entity expansion
Major retain pipeline overhaul addressing deadlocks, write amplification,
and TimeoutErrors. Restructures retain into three phases:
Phase 1: Entity resolution on separate connection (read-heavy)
Phase 2: Core write transaction (atomic) — facts, unit_entities, links
Phase 3: Best-effort display data (error-isolated) — entity viz links, stats
Key changes:
- Sorted bulk INSERT FROM unnest() prevents deadlocks
- Temporal links capped to top-20 per unit (95% reduction)
- Batched semantic ANN via temp table + LATERAL
- Query-time entity expansion via unit_entities self-join
- Entity viz links moved to Phase 3 (post-transaction)
- HINDSIGHT_API_RETAIN_MAX_CONCURRENT config (default: 32)
* fix: increase semantic link top_k from 5 to 20
The hardcoded top_k=5 was artificially limiting semantic link creation.
Link expansion retrieval can consume up to budget (50-200) semantic
neighbors per seed set, but each fact only had 5 outgoing edges — making
the bidirectional graph very sparse.
Increasing to 20 gives retrieval 4x more edges to work with. The ANN
probe cost is unchanged (same HNSW traversal per fact, just returning
more rows). INSERT cost is negligible (~14k rows via bulk INSERT).
Also: all 18 TimeoutErrors in the latest benchmark (beam-1m-u20) were
from Gemini LLM calls, zero from the database — confirming the entity
resolution split eliminated DB timeouts entirely.
* perf: move semantic ANN search to Phase 1 to avoid transaction timeouts
The batched LATERAL ANN query (700 HNSW probes) was the last remaining
source of DB TimeoutErrors — all 29 in the latest benchmark were from
create_semantic_links_batch inside the Phase 2 write transaction.
Split semantic link creation into three phases:
- Phase 1 (separate conn, autocommit): ANN search via temp table + LATERAL.
No transaction locks, no contention with concurrent writers.
- Phase 2 (write transaction): within-batch numpy similarities (instant) +
INSERT of both within-batch and Phase 1 ANN results. No DB reads.
- Phase 3 (flush_pending_stats): future hook point for re-checking ANN
results after commit to catch links missed by concurrent batches.
Also adds 7 unit tests for compute_semantic_links_within_batch covering
empty input, identical/orthogonal embeddings, threshold filtering, top_k
cap, and tuple structure validation.
* fix: handle placeholder unit_ids in Phase 1 ANN search (not valid UUIDs)
* test: add Phase 1 ANN cross-batch test + configurable test PG port
- New test_semantic_links_phase1_ann_cross_batch verifies that the Phase 1
ANN search with placeholder unit IDs correctly creates cross-batch
semantic links after remapping to real IDs.
- Test PG port now configurable via HINDSIGHT_TEST_PG_PORT env var
(default: 5556) to avoid conflicts with running benchmark daemons.
* perf: remove retry_with_backoff from retain, set semaphore default to 4
Remove retry_with_backoff from _run_db_work and _run_delta_db_work:
- Deadlocks are prevented by sorted bulk INSERT (no need for retry)
- Transient timeouts are handled by the worker poller's task-level retry
(3 attempts, 60s spacing) which is better than rapid internal retries
that amplify I/O pressure during contention storms
Set HINDSIGHT_API_RETAIN_MAX_CONCURRENT default from 32 to 4:
- The semaphore gates Phase 1 (ANN + entity resolution) + Phase 2 (writes)
- At 4 concurrent, HNSW index I/O is manageable; at 10+ concurrent the
probes saturate disk and cause cascading timeouts
- LLM extraction still runs at full parallelism (semaphore acquired after)
* fix: add fact_type filter to Phase 1 ANN query to use per-bank HNSW indexes
The LATERAL ANN query was falling back to sequential scan + sort (90ms/probe)
because the per-bank HNSW indexes are partial indexes filtered on fact_type.
Without fact_type in the WHERE clause, PostgreSQL couldn't use them.
Fix: iterate over ('world', 'experience') and run one HNSW-indexed ANN per
type. EXPLAIN shows 8ms/probe (was 90ms) — 11x faster.
700 probes × 8ms × 2 types = ~11s total (was ~63s via seq scan).
* fix: scope temporal links by fact_type + add integration tests
Temporal links now filter by fact_type in the LATERAL query — world facts
only link to world facts, experience to experience. This matches how
retrieval filters results and avoids wasted cross-type link rows.
New integration tests:
- test_semantic_ann_uses_hnsw_index: verifies Phase 1 ANN creates
cross-batch semantic links (tests fact_type filter + placeholder remap)
- test_temporal_links_scoped_by_fact_type: verifies world facts get
temporal links to other world facts but NOT to experience facts
* fix: tolerate individual chunk LLM failures instead of failing entire batch
Changed asyncio.gather(*tasks) to asyncio.gather(*tasks, return_exceptions=True)
in both chunk-level and content-level fact extraction. A single chunk timeout
(e.g., Gemini >90s) no longer discards all other successfully extracted facts.
For a 50MB document with 17k chunks, even a 2% chunk failure rate previously
caused 0 completions (entire batch discarded). Now 16,700 facts are extracted
and only the 300 failed chunks are skipped with a warning log.
* fix: batch temporal LATERAL query for large documents (16k+ chunks)
The LATERAL query for temporal links passed all unit_ids at once into
unnest(), causing PostgreSQL timeouts on documents with 16k+ chunks.
Split into batches of 500 units per query to keep each under the
command_timeout.
Also identified: HNSW index creation on shared pg0 instances with
50k+ existing units exceeds the 60s command_timeout. This is a
test infrastructure issue (shared pg0 accumulates data) but also
affects production when creating new banks on large instances.
* feat: streaming chunk batching for large documents (RETAIN_CHUNK_BATCH_SIZE)
Process chunks in mini-batches of N (default 500), committing each batch
to the DB before starting the next. This prevents OOM kills on large
documents (50MB / 17k+ chunks) by keeping only ~500 facts + embeddings
in memory at a time instead of 50k+.
Each mini-batch goes through the full Phase 1 → 2 → 3 pipeline
independently, sharing the same document_id. On recovery (process dies
mid-way), delta retain detects already-committed chunks via content_hash
and skips them — only remaining chunks get re-extracted.
Config: HINDSIGHT_API_RETAIN_CHUNK_BATCH_SIZE (default: 500, 0 to disable)
Per-bank configurable via the hierarchical config system.
Tests:
- test_streaming_chunk_batching_produces_same_facts
- test_streaming_chunk_batching_recovery (delta retain skips committed chunks)
- test_streaming_disabled_for_small_docs
* perf(retain): producer-consumer pipeline + deferred semantic ANN
Replace the sequential streaming loop with a producer-consumer pipeline:
- LLM producer fires concurrent chunk extractions (semaphore-bounded)
- DB consumer drains queue in batches, runs Phase 1+2+3 per batch
- LLM and DB work overlap instead of running sequentially
Defer semantic links to a single final ANN pass after all batches commit:
- Remove within-batch semantic links from Phase 2 (was 2.6s/batch)
- Run parallel ANN (4 connections) after all facts committed
- top_k reduced from 50 to 20 (recall uses at most 20 neighbors)
- Recovery via operation result_metadata checkpoint
Additional optimizations:
- skip_exists_check on temporal/causal link INSERT (saves ~0.5s/batch)
- WHERE EXISTS guard on semantic link INSERT (handles document upsert)
- timeout=300s on ANN queries and bulk INSERT for large banks
- Demote [ANN] debug logs to logger.debug()
- Fix docstring typos (agent_id → bank_id)
- Fix content_index remapping in producer-consumer batches
- Fix delta retain passing contents vs delta_contents
50MB benchmark (mock LLM): 9.2 min (was 23 min) — 2.5x faster.
BEAM 10m benchmark: zero deadlocks, zero DB errors.
* refactor(retain): remove legacy fallback code paths
- Remove process_entities_batch (legacy single-connection entity processing)
- Remove extract_entities_batch_optimized (only caller was the above)
- Remove fallback entity processing inside Phase 2 transaction
- Remove legacy ANN inline fallback in create_semantic_links_batch
- Remove fallback entity_links direct-insert path in Phase 3
- Make resolved_entity_ids/entity_to_unit/unit_to_entity_ids required params
* refactor(retain): replace tuple returns with dataclasses, remove dead code
- Add EntityResolutionResult and Phase1Result dataclasses in types.py
- Replace 4-tuple return from _pre_resolve_phase1 with Phase1Result
- Remove dead `entity_links = []` variables in retain_batch and _try_delta_retain
- Remove unused `confidence_score` parameter from orchestrator.retain_batch
and _retain_batch_async_internal (was accepted but never used)
* fix(entity-resolver): remove LIKE full-scan fallbacks, use index-only trigram matching
The entity resolution query had LIKE '%...' substring conditions that bypassed
the GIN trigram index, causing full sequential scans of the entities table.
On banks with 10k+ entities, this caused TimeoutErrors (observed in BEAM 10m).
Changes:
- Remove LIKE fallbacks, use trigram % operator only (GIN index-based)
- Lower similarity threshold from 0.3 to 0.15 to catch substring relationships
- Use LOWER() on both sides for case-insensitive matching
- Migration: recreate GIN trigram index on LOWER(canonical_name)
* fix: remove schema prefix from index names in trigram migration
* fix(delta-retain): use same chunk_size as streaming path (3000 vs 120000)
_chunk_contents_for_delta defaulted to chunk_size=120000 while the streaming
path used 3000. On retry, delta re-chunked the document with different
boundaries, found 0 matching chunks, and fell through to full re-extraction.
This wasted all LLM calls on already-committed chunks.
Fix: use the same default (3000) so chunk hashes match on recovery.
* fix(retain): persist generated document_id in operation metadata for retry recovery
When no document_id is provided, retain generates a UUID. On retry, a new UUID
was generated, making delta retain and streaming chunk-hash recovery unable to
find previously committed chunks. All LLM extraction was wasted on retry.
Fix: resolve document_id early in retain_batch (before delta), persist it to
operation result_metadata, and recover it on retry. Both delta and streaming
paths now see the same document_id across attempts.
* refactor(retain): unify into single streaming pipeline, remove non-streaming path
All retains now go through the producer-consumer streaming pipeline,
regardless of document size. Small documents are processed as a single batch.
This eliminates the maintenance burden of two separate code paths.
Also fix document upsert: compare content hash to distinguish recovery
(same content, partially committed) from update (different content, needs
cascade-delete). Previously, existing chunks always triggered recovery mode.
* refactor(retain): remove dead code, replace raw dicts with Phase3Context dataclass
- Remove dead _handle_zero_facts_documents (no callers after path unification)
- Remove unused imports: defaultdict, EntityLink
- Replace raw dict phase3_context with typed Phase3Context dataclass
- Update _build_and_insert_entity_links_phase3 to use typed parameter
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| .claude/skills/code-review | ||
| .claude-plugin | ||
| .githooks | ||
| .github | ||
| cookbook | ||
| docker | ||
| helm/hindsight | ||
| hindsight-all | ||
| hindsight-all-slim | ||
| hindsight-api | ||
| hindsight-api-slim | ||
| 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 | ||
| deno.lock | ||
| 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, lmstudio, and minimax. 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








