# codex-app-server

`codex app-server` is the harness Codex uses to power rich interfaces such as the [Codex VS Code extension](https://marketplace.visualstudio.com/items?itemName=openai.chatgpt). The message schema is currently unstable, but those who wish to build experimental UIs on top of Codex may find it valuable.

## Protocol

Similar to [MCP](https://modelcontextprotocol.io/), `codex app-server` supports bidirectional communication, streaming JSONL over stdio. The protocol is JSON-RPC 2.0, though the `"jsonrpc":"2.0"` header is omitted.

## Message Schema

Currently, you can dump a TypeScript version of the schema using `codex generate-ts`. It is specific to the version of Codex you used to run `generate-ts`, so the two are guaranteed to be compatible.

```
codex generate-ts --out DIR
```

## Auth endpoints (v2)

The v2 JSON-RPC auth/account surface exposes request/response methods plus server-initiated notifications (no `id`). Use these to determine auth state, start or cancel logins, logout, and inspect ChatGPT rate limits.

### Quick reference
- `account/read` — fetch current account info; optionally refresh tokens.
- `account/login/start` — begin login (`apiKey` or `chatgpt`).
- `account/login/completed` (notify) — emitted when a login attempt finishes (success or error).
- `account/login/cancel` — cancel a pending ChatGPT login by `loginId`.
- `account/logout` — sign out; triggers `account/updated`.
- `account/updated` (notify) — emitted whenever auth mode changes (`authMode`: `apikey`, `chatgpt`, or `null`).
- `account/rateLimits/read` — fetch ChatGPT rate limits; updates arrive via `account/rateLimits/updated` (notify).

### 1) Check auth state

Request:
```json
{ "method": "account/read", "id": 1, "params": { "refreshToken": false } }
```

Response examples:
```json
{ "id": 1, "result": { "account": null, "requiresOpenaiAuth": false } } // no auth needed
{ "id": 1, "result": { "account": null, "requiresOpenaiAuth": true } }  // auth needed
{ "id": 1, "result": { "account": { "type": "apiKey" }, "requiresOpenaiAuth": true } }
{ "id": 1, "result": { "account": { "type": "chatgpt", "email": "user@example.com", "planType": "pro" }, "requiresOpenaiAuth": true } }
```

Field notes:
- `refreshToken` (bool): set `true` to force a token refresh.
- `requiresOpenaiAuth` reflects the active provider; when `false`, Codex can run without OpenAI credentials.

### 2) Log in with an API key

1. Send:
   ```json
   { "method": "account/login/start", "id": 2, "params": { "type": "apiKey", "apiKey": "sk-…" } }
   ```
2. Expect:
   ```json
   { "id": 2, "result": { "type": "apiKey" } }
   ```
3. Notifications:
   ```json
   { "method": "account/login/completed", "params": { "loginId": null, "success": true, "error": null } }
   { "method": "account/updated", "params": { "authMode": "apikey" } }
   ```

### 3) Log in with ChatGPT (browser flow)

1. Start:
   ```json
   { "method": "account/login/start", "id": 3, "params": { "type": "chatgpt" } }
   { "id": 3, "result": { "type": "chatgpt", "loginId": "<uuid>", "authUrl": "https://chatgpt.com/…&redirect_uri=http%3A%2F%2Flocalhost%3A<port>%2Fauth%2Fcallback" } }
   ```
2. Open `authUrl` in a browser; the app-server hosts the local callback.
3. Wait for notifications:
   ```json
   { "method": "account/login/completed", "params": { "loginId": "<uuid>", "success": true, "error": null } }
   { "method": "account/updated", "params": { "authMode": "chatgpt" } }
   ```

### 4) Cancel a ChatGPT login

```json
{ "method": "account/login/cancel", "id": 4, "params": { "loginId": "<uuid>" } }
{ "method": "account/login/completed", "params": { "loginId": "<uuid>", "success": false, "error": "…" } }
```

### 5) Logout

```json
{ "method": "account/logout", "id": 5 }
{ "id": 5, "result": {} }
{ "method": "account/updated", "params": { "authMode": null } }
```

### 6) Rate limits (ChatGPT)

```json
{ "method": "account/rateLimits/read", "id": 6 }
{ "id": 6, "result": { "rateLimits": { "primary": { "usedPercent": 25, "windowDurationMins": 15, "resetsAt": 1730947200 }, "secondary": null } } }
{ "method": "account/rateLimits/updated", "params": { "rateLimits": { … } } }
```

Field notes:
- `usedPercent` is current usage within the OpenAI quota window.
- `windowDurationMins` is the quota window length.
- `resetsAt` is a Unix timestamp (seconds) for the next reset.

### Dev notes

- `codex generate-ts --out <dir>` emits v2 typings under `v2/`.
- See [“Authentication and authorization” in the config docs](../../docs/config.md#authentication-and-authorization) for configuration knobs.