Feature request: support subscription-backed @codex on GitHub Issues

What version of Codex CLI is running?

codex-cli 0.144.6

What subscription do you have?

ChatGPT/Codex subscription authentication. codex doctor --json reports stored ChatGPT tokens: true, stored API key: false, and stored auth mode: chatgpt.

Which model were you using?

gpt-5.6-sol

What platform is your computer?

Linux 6.11.0-1027-oem x86_64 x86_64

What terminal emulator and version are you using?

tmux 3.4, with an xterm.js client (xterm.js(6.1.0-beta.256)).

Codex doctor report

The relevant redacted diagnostics are:

{
  "overallStatus": "ok",
  "codexVersion": "0.144.6",
  "auth": {
    "storedChatGPTTokens": true,
    "storedApiKey": false,
    "mode": "chatgpt"
  },
  "git": {
    "repoDetected": true,
    "branch": "main"
  },
  "terminal": {
    "multiplexer": "tmux 3.4"
  }
}

What issue are you seeing?

I can use Codex CLI through my ChatGPT/Codex subscription, but cannot delegate GitHub Issue work by mentioning @codex without separately provisioning and paying for an OpenAI API key.

The official openai/codex-action@v1 documentation requires an OPENAI_API_KEY GitHub Actions secret. The documented GitHub Cloud integration describes @codex for pull-request comments, not Issue comments. As a result, an explicit, permission-scoped @codex mention on a GitHub Issue has no subscription-backed path.

What steps can reproduce the bug?

1. Authenticate Codex CLI with a ChatGPT/Codex subscription rather than an API key.
2. Confirm with codex doctor --json that ChatGPT tokens are stored and no API key is stored.
3. Try to configure a GitHub Issue-comment workflow that runs only when a trusted collaborator writes @codex.
4. The available Codex Action requires OPENAI_API_KEY; subscription authentication cannot be used by the workflow.

What is the expected behavior?

Provide a supported subscription-backed route for Codex to respond to explicitly invoked GitHub Issue comments (for example, @codex <request>), with trusted-user and least-privilege controls. Alternatively, support ChatGPT/Codex subscription authentication in the Codex GitHub Action.

The trigger should be explicit only: no automatic issue scanning or unsolicited runs.

Additional information

This is a product/integration gap rather than an unauthenticated-execution request. Existing Claude-based issue workflows can be preserved; the request is for an equivalent Codex path that does not require a separate API billing credential.