CaptraOne contract for intelligent software.

Build type-safe capabilities, agent loops, adaptive memory, shared state, tools, approvals, and UI without stitching together five frameworks.

Start building

Understand the architecture

View on GitHub

Capability-first

Deterministic functions and autonomous agents share one typed, inspectable contract.

State + memory

Exact reactive state stays separate from scoped, semantic context—with safe coordination across agents.

Full-stack types

The same schemas drive runtime validation, the remote client, structured output, and React rendering.

Durable agents

Events, checkpoints, idempotency, queues, approvals, cancellation, and recovery are runtime primitives.

Integration-ready

Typed tools, lifecycle hooks, versioned plugins, provider adapters, and Web Standard handlers.

Own the interface

Accessible unstyled components and explicit view registries keep generated UI safe and customizable.

A complete product behavior in one contract

tsx

export const refund=capability({
  name:'refund',
  input:RefundInput,
  output:RefundResult,
  memory:['user','project'],
  permissions:['refund:create'],
  approval:'required',
  run:refundPayment,
  view:RefundCard,
})

The contract tells Captra how to validate, authorize, execute, remember, observe, transport, and render the capability.

Install

bash

npx create-captra my-app
cd my-app
npm install
npm run dev

The starter includes a React client, Node runtime, typed transport, scoped memory, component registry, startup animation, and tests.

What makes Captra different?

Many AI libraries help call a model. Captra defines the application boundary around the model: capabilities, exact state, recalled memory, authorized tools, human approvals, durable events, recovery, and UI. Those pieces remain replaceable, but they follow one mental model.

Learn the mental model →Capability, agent, tool, hook, plugin, app, runtime, and view.Design state and memory →Choose the right consistency model for every kind of context.Deploy safely →Mount the runtime and configure durable production infrastructure.