When a fact changes, most agent memory keeps both versions and lets the model guess which is current. Vayl replaces the old value, keeps it in history, and can hold high-stakes changes until a person approves them. It runs locally on SQLite and works with any MCP client: Claude Code, Cursor, Claude Desktop, or your own agent.

_{A real run with gpt-6-luna and the clinical preset. The patient is fictional. Script: assets/demo/clinical_demo.py}

Features

• Reconciles changes. A new value supersedes the old one, and "we stopped X" retracts X. A retired fact is never returned as current.
• Keeps history. Ask what is true now or what was true before. Every change goes on a signed, tamper-evident audit chain.
• Human approval where it matters. Mark slots such as medications as confirm-required, and changes wait in a queue. check_before_act blocks an action that depends on a disputed, stale or just-changed fact.
• Small and local. SQLite by default, Postgres for teams. One model call to store a fact and one to answer. Any OpenAI-compatible model, Anthropic, Groq or a local Ollama model.
• Built-in presets for clinical, support, finance, sales, coding and assistant memory.

Install

pip install vayl-mcp

Add it to Claude Code:

claude mcp add vayl -e LLM_PROVIDER=openai -e OPENAI_API_KEY=sk-... -e VAYL_DB=$HOME/.vayl/vayl.db -- vayl-mcp

For Cursor, Claude Desktop and other clients, see the quickstart. Run vayl-demo to try reconciliation with no API key.

Use it from code

from vayl import Vayl

with Vayl(user_id="cust_5521") as m:
    m.remember("Acme's invoice bounced. Account suspended until payment clears.")
    print(m.recall("Is Acme's account in good standing?"))
    # No. Acme's account is suspended until payment clears.

A TypeScript client (npm i @vayl.dev/client) and adapters for LangGraph, the OpenAI Agents SDK, CrewAI, the Vercel AI SDK and Mastra are in the integration docs.

Documentation

Contributing

See CONTRIBUTING.md. The unit tests run offline, with no API key. Good starting points are labeled good first issue.

Security

Data is encrypted at rest by default, and Vayl sends nothing anywhere except to the model endpoints you configure. Vayl is not certified for clinical use and has not been audited by a third party. Report vulnerabilities as described in SECURITY.md.

License

Apache-2.0