Codex App SDK

⚡

App-server, handled

Discovery, process lifecycle, typed JSONL transport, authentication, catalogs, history, reconnects, and server requests.

🧵

Truly concurrent threads

Keep several conversations loaded and streaming independently without coupling them to the selected UI thread.

💬

Full conversation UI

Prompt recall, editable queues, double-Escape interruption, tools, approvals, goals, generated media, code copying, Markdown, LaTeX, Mermaid, and native attachments.

🧱

Two narrow host adapters

Electron IPC and framework-neutral WebSockets carry the same renderer-safe snapshots, events, and validated actions.

🧰

Built to extend

Add grouped @ mentions, custom mention rendering, host instructions, opaque context, dynamic tools, app-owned MCP servers, visualization actions, and sub-agent UI without leaking raw protocol into the renderer.

🎨

Product-ready customization

Capabilities, presentation controls, slots, reusable leaf components, scoped styles, semantic tokens, and light/dark themes.

One surface. Five focused packages.

Build your own Codex experience on an Apache-2.0 SDK. Start with the mocked component lab, connect a real app-server, then make the application your own.

Core

Share renderer-safe surface, event, attachment, and host-capability contracts across every runtime.

Backend

Own app-server startup, global state, concurrent conversations, semantic events, extensions, tools, and MCP configuration.

Electron

Project the surface over typed IPC and provide native attachments, clipboard, links, and speech capabilities.

Web

Bind a host-authorized WebSocket without taking ownership of HTTP, authentication, users, or process pooling.

Vue

Drop in the shared sidebar and conversation pane or compose the same messages, composer, tools, media, and menus yourself.

Start with the complete application scaffold, then update the generated project with your own shell, backend modules, tools, and product behavior. The renderer boundary remains intentionally small:

vue

<script setup lang="ts">
import { CodexConversationPane, useCodexSurface } from '@codex-app-sdk/vue';
import '@codex-app-sdk/vue/styles.css';

const surface = useCodexSurface(rendererApi);
</script>

<template>
  <CodexConversationPane :surface="surface" />
</template>

The pane connects through the SDK bridge and renders the active app-server conversation. Your app can add its own conversation list, workspace controls, business UI, or custom tools without recreating the conversation system.

Start with the scaffold, learn from the samples

If you are building…	Start from…
A new Electron + Vue application	Project scaffolder
A web application embedded in an existing site	Web integration
A runnable Express + `ws` web baseline	Basic web sample
A full multi-thread Codex client	Basic sample
A focused, branded chat experience	Spark sample
A business application with model-driven operations	Relay sample
A custom runtime or non-Vue renderer	Surface runtime and surface contracts
A protocol experiment not yet projected by the SDK	Low-level client

If you are building…

Start from…

A new Electron + Vue application

Project scaffolder

A web application embedded in an existing site

Web integration

A runnable Express + ws web baseline

Basic web sample

A full multi-thread Codex client

Basic sample

A focused, branded chat experience

Spark sample

A business application with model-driven operations

Relay sample

A custom runtime or non-Vue renderer

Surface runtime and surface contracts

A protocol experiment not yet projected by the SDK

Low-level client

Design rule

Ordinary application code should speak in conversations, messages, approvals, goals, and events—not thread/*, turn/*, JSON-RPC envelopes, or generated protocol types.

Source and package access

The repository and documentation are public. You can clone the source and run the component lab or samples without package credentials. Starting with 0.14.0, all six scoped packages, including the scaffolder, are public on npm and install without authentication. See installation for setup and migration from the older GitHub Packages releases.

The SDK is pre-1.0. These docs follow main; package releases may lag behind. The JSON-RPC inventory records the checked-in app-server schema version and its coverage.