memable 0.2.0

Reusable semantic memory library for LangGraph agents with PostgreSQL/pgvector and SQLite backends

memable 🐘

Long-term semantic memory for AI agents. Elephants never forget.

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Drop-in long-term memory with:

• Durability tiers — core facts vs situational context vs episodic memories
• Temporal awareness — validity windows, expiry, recency weighting
• Version chains — audit trail for memory updates with contradiction handling
• Scoped namespaces — org/user/project hierarchies with priority merging
• Memory consolidation — decay, summarize, and prune old memories
• LangGraph integration — ready-to-use nodes for retrieve/store/consolidate

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Installation

pip install memable

Or for development:

git clone https://github.com/joelash/memable
cd memable
pip install -e ".[dev]"

Quick Start

from memable import build_postgres_store
from memable.graph import build_memory_graph

# Connect to your Neon/Postgres DB (context manager handles connection lifecycle)
with build_postgres_store("postgresql://user:pass@host:5432/dbname") as store:
    store.setup()  # Run migrations (once)

    # Build a graph with memory baked in
    graph = build_memory_graph()
    compiled = graph.compile(store=store.raw_store)

    # Run it
    config = {"configurable": {"user_id": "user_123"}}
    result = compiled.invoke(
        {"messages": [{"role": "user", "content": "I'm Joel, I live in Wheaton."}]},
        config=config,
    )

Memory Schema

Each memory item includes:

{
    "text": "User lives in Wheaton, IL",
    "durability": "core",           # core | situational | episodic
    "valid_from": "2026-02-06",     # when this became true
    "valid_until": None,            # null = permanent
    "confidence": 0.95,
    "source": "explicit",           # explicit | inferred
    "supersedes": None,             # UUID of memory this replaces (version chain)
    "superseded_by": None,          # UUID of memory that replaced this
}

Durability Tiers

Tier	Description	Example	Default TTL
core	Stable facts about the user	"Name is Joel", "Prefers dark mode"	Never expires
situational	Temporary context	"Visiting Ohio this week"	Explicit end date
episodic	Things that happened	"We discussed the API design"	30 days, decays

Features

Version Chains (Contradiction Handling)

When a memory contradicts an existing one, we don't delete — we create a version chain:

# Original: "User lives in Wheaton"
# New info: "User moved to Austin"

# Result:
# - Old memory gets superseded_by = new_memory_id
# - New memory gets supersedes = old_memory_id
# - Retrieval only returns current (non-superseded) memories
# - Audit trail preserved for debugging

Scoped Namespaces

# Retrieval merges across scopes with priority
retrieve_memories(
    store=store,
    scopes=[
        ("org_123", "user_456", "preferences"),  # highest priority
        ("org_123", "shared"),                    # org-wide fallback
    ],
    query="user preferences",
)

Memory Consolidation

from memable import consolidate_memories

# Periodic cleanup job
consolidate_memories(
    store=store,
    user_id="user_123",
    strategy="summarize_and_prune",
    older_than_days=7,
)

LangGraph Nodes

Pre-built nodes for your graph:

from memable.nodes import (
    retrieve_memories_node,
    store_memories_node,
    consolidate_memories_node,
)

builder = StateGraph(MessagesState)
builder.add_node("retrieve", retrieve_memories_node)
builder.add_node("llm", your_llm_node)
builder.add_node("store", store_memories_node)

builder.add_edge(START, "retrieve")
builder.add_edge("retrieve", "llm")
builder.add_edge("llm", "store")
builder.add_edge("store", END)

Performance & Costs

Storage Requirements

Scale	Memories	SQLite	DuckDB	Postgres
Light user	100	~700 KB	~3 MB	~700 KB
Regular user	1,000	~7 MB	~30 MB	~7 MB
Heavy user	10,000	~70 MB	~300 MB	~70 MB
Power user	100,000	~700 MB	~3 GB	~700 MB

Embeddings dominate storage: 1536 dims × 4 bytes = ~6KB per memory

API Costs (text-embedding-3-small)

Usage	Daily Tokens	Daily Cost	Monthly Cost
Light (100 adds, 500 searches)	7,000	$0.0001	$0.00
Medium (500 adds, 2,000 searches)	30,000	$0.0006	$0.02
Heavy (2,000 adds, 10,000 searches)	140,000	$0.0028	$0.08

Extraction Costs (gpt-4.1-mini)

If using LLM-based memory extraction:

Usage	Daily Cost	Monthly Cost
Light (50 extractions)	$0.007	$0.20
Medium (200 extractions)	$0.027	$0.81
Heavy (1,000 extractions)	$0.135	$4.05

Total cost for a typical agent (100 conversations/day): ~$0.08-0.50/month

Run pytest tests/performance/ -v -s to benchmark on your hardware.

Configuration

Environment variables:

OPENAI_API_KEY=sk-...           # For embeddings
DATABASE_URL=postgresql://...    # Postgres connection

Multi-Tenant / Schema Isolation

For multi-tenant deployments where each customer needs isolated data, you can use PostgreSQL schemas:

from memable import build_store

# Each tenant gets their own schema
with build_store("postgresql://...", schema="customer_123") as store:
    store.setup()  # Creates tables in customer_123 schema
    store.add(namespace, memory)

Requirements:

• The schema must already exist in the database (CREATE SCHEMA customer_123;)
• Tables will be created within that schema when setup() is called
• Each schema has its own isolated set of tables

Database Tables

memable uses LangGraph's PostgresStore under the hood, which creates:

Table	Purpose
store	Memory documents with metadata
store_vectors	pgvector embeddings for semantic search
store_migrations	Migration version tracking

Note: Table names are currently fixed by LangGraph. If you need custom table names (e.g., prefixes/suffixes), use schema-based isolation instead, or run each app in a separate PostgreSQL schema.

Alternative pattern: For apps that already use schema-per-tenant, you could combine with a suffix:

-- Example: customer schemas with memory suffix
CREATE SCHEMA customer_123_memories;

with build_store("postgresql://...", schema="customer_123_memories") as store:
    store.setup()

License

MIT