Barrel documentation

Start here.

• Features: what Barrel does today, what is opt-in, what is planned.

Guides

• Embed barrel in an Erlang app: the barrel API.
• Record mode: policy-driven vector indexing over documents.
• Query with BQL: one query language over documents, vectors, and keyword search.
• Run the REST server: barrel_server over HTTP.
• Embed the barrel server in a livery app: mount barrel's routes into a host livery service, under a sub-path.
• Synchronization: replication between databases.
• Timeline: branch a database, work in isolation, merge back (incl. PITR).
• Encryption at rest: per-database keys over every store and index file.
• Audit and provenance: who wrote what, when, and past versions.
• Spaces, sessions, and handoffs: the agent layer with capability tokens.
• MCP endpoint: tools, resources, and live queries for MCP clients.
• barrel-lite (browser client): an offline-first TypeScript client that syncs over the wire.
• Distribute the umbrella apps: Hex packages, git mirrors, and consuming an app elsewhere.

Architecture

• Vision: what barrel is becoming (the database for agents) and the settled decisions.
• Overview: how the umbrella is split and why.
• Responsibilities: per-app responsibilities.