Reapply "feat: add github copilot gpt-5.3-codex model (#912)"

[mongrelion]

This reverts commit bac557c.

---

This feature had been previously reverted (#920) because the model was not yet generally available.

It seems like the model is now available for all users.

@rversteegen mentions on issue #885

A Github employee commented on Reddit 4 days ago that the rollout to all users is complete.

The Github employee says on Reddit:

All the users should have it now. Make sure you are on latest vscode version. If you still do not see it - let me know what GitHub plan are you on?

Closes

• GPT 5.3 Codex disappeared from model selection list (Github Copilot) #885
• Add GPT-5.3-Codex to GitHub Copilot provider #838

[rekram1-node]

It's not fully rolled out!

You can easily test this urself just do this:

{
  "provider": {
    "opencode": {
      "options": {},
    },
    "github-copilot": {
      "models": {
        "gpt-5.3-codex": {},
      },
    },
  },
}

And youll see:

It's not available outside of their clients

[Khnx-ai]

@rekram1-node it realse and working with copilot cli but not on the opencode please fix this issue ASAP because we have the pro plan of copilot and opus 4.6 cost way more.

[mongrelion]

please fix this issue ASAP

@Khnx-ai You are probably new to the open source world so I will teach you this: the maintainers of this project and any other software that you don't pay for don't owe you anything, so even if you say "please" in this case is still considered rude.

I suggest you remove your comment altogether.