SignInWithCodex

SignInWithCodex is a Swift package for ChatGPT OAuth, Keychain storage, model discovery, and streamed Codex responses.

This package uses the ChatGPT subscription transport from the Codex CLI. It does not use the public OpenAI Responses API.

This transport is not a stable public API. See COMPATIBILITY.md for the pinned Codex revision and fallback model.

Warning — read before shipping

This package authenticates as the Codex CLI: it uses OpenAI's Codex OAuth client ID, sends the Codex originator and version headers, and calls the private chatgpt.com/backend-api/codex endpoints. It is not an OpenAI product and is not endorsed by OpenAI.

• OpenAI's terms restrict how ChatGPT subscriptions may be used outside of OpenAI's own clients. Using this package may violate those terms. Your users' ChatGPT accounts can be rate-limited, flagged, or banned.
• The transport can change or be blocked at any time without notice. Any release can stop working overnight.

No guarantees

This software is provided "as is", without warranty of any kind, express or implied. The authors accept no liability for account actions, data loss, service interruption, or any other damages arising from its use. There is no commitment to maintain compatibility with future Codex revisions. Use at your own risk, and disclose this risk to your users.

Add the package

Add this repository as a Swift package. Select the SignInWithCodex library product.

Enable local network access for OAuth callbacks:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsLocalNetworking</key>
    <true/>
</dict>

Create a session

Keep one session for the application lifetime:

import SignInWithCodex
import SwiftUI

@main
struct ExampleApp: App {
    @StateObject private var codex = CodexSession()

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(codex)
        }
    }
}

The session restores its Keychain credential. Its default service name derives from the application bundle identifier.

If several targets share credentials, pass a fixed service name:

let codex = CodexSession(keychainService: "com.example.app.codex")

Present sign-in

The supplied button and sheet are iOS-only. On macOS, the package still signs in, stores credentials, and streams; present session.authorization?.authorizationURL yourself (for example with NSWorkspace.shared.open) after calling session.signIn(), and call session.cancelSignIn() if the user abandons the flow.

Use the supplied button:

CodexSignInButton(session: codex)

For a custom button, use the supplied sheet modifier:

Button("Connect Codex") {
    codex.signIn()
}
.codexSignInSheet(session: codex)

Stream a response

Stream a prompt with the default model:

Task {
    for try await event in codex.stream(prompt: "Explain this function") {
        switch event {
        case let .responseStarted(model):
            print("Model:", model)
        case let .textDelta(delta):
            output += delta
        case let .completed(response):
            print("Complete:", response.model)
        }
    }
}

CodexRequest also supports conversation history, exact model identifiers, custom instructions, and reasoning effort.

Each request carries a threadID. Reuse one value for every turn of a conversation and create a new UUID() for each new conversation; Codex scopes its session and prompt-cache identifiers to it.

A stream that ends before Codex sends response.completed throws SignInWithCodexError.streamClosedBeforeCompletion. Deltas that were already delivered are partial output, not a finished answer. A response that consists only of a refusal throws SignInWithCodexError.refused with the model's stated reason.

History is text only. The package does not replay reasoning items between turns, so multi-turn requests carry the visible conversation and nothing else.

session.signOut() ends every active stream and discards any token refresh that completes afterwards.

Demo application

If project.yml changes, regenerate the project:

xcodegen generate

Open the demo project:

open SignInWithCodexDemo.xcodeproj

Select a code-sign team for a physical device. Run the SignInWithCodexDemo scheme.

Security

The package stores OAuth credentials in Keychain with kSecAttrAccessibleWhenUnlockedThisDeviceOnly.

Do NOT log CodexCredential, authorization callbacks, request headers, or response headers. These values can contain credentials or account identifiers.

Call try session.signOut() to remove the Keychain credential.