test(auth): pin the built-in ChatGPT model list to the served catalog

Nothing pinned the list's order or its default, since the other tests
read the constant, so a test now records what GET /codex/models listed
for a ChatGPT Plus account on 2026-11-01.

The comment says where the order comes from and that availability varies
by plan and rollout, so it no longer implies every account is served this
list. It also gives the reason the three models are left out: OpenAI
retired them from Codex with ChatGPT sign-in, and API-key sessions are not
affected.

Author: bwachman

src/auth/codex/constants.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, test } from "bun:test";
+
+import { CODEX_DEFAULT_MODELS } from "./constants.js";
+
+describe("CODEX_DEFAULT_MODELS", () => {
+  // Recorded from GET /codex/models for a ChatGPT Plus account (client_version
+  // 0.165.0, 2026-11-01). Nothing else pins the order or the default: the other
+  // tests read the constant.
+  test("follows the order the Codex backend listed the models in", () => {
+    expect([...CODEX_DEFAULT_MODELS]).toEqual([
+      "gpt-6.1-sol",
+      "gpt-6-astra",
+      "gpt-6.1-terra",
+      "gpt-6-sol",
+      "gpt-6-luna",
+      "gpt-5.6-sol",
+      "gpt-5.6-terra",
+      "gpt-5.6-luna",
+    ]);
+  });
+
+  test("leaves out the models OpenAI retired for ChatGPT sign-in", () => {
+    for (const retired of ["gpt-5.4", "gpt-5.4-mini", "gpt-5.5"]) {
+      expect(CODEX_DEFAULT_MODELS as readonly string[]).not.toContain(retired);
+    }
+  });
+});

src/auth/codex/constants.ts

@@ -21,10 +21,13 @@ export const CODEX_CLIENT_VERSION = "0.50.0";
 // the public Codex CLI originator.
 export const CODEX_ORIGINATOR = "codex_cli_rs";
 
-// The models a ChatGPT sign-in can select, in the Codex backend's priority
-// order (GET /codex/models); the first entry is the ChatGPT default. OpenAI
-// retires models for ChatGPT sign-in on its own schedule, independently of the
-// OpenAI API, so this list and its default do not follow the API-key path.
+// The models a ChatGPT sign-in offers, in the order GET /codex/models listed
+// them for a ChatGPT Plus account (client_version 0.165.0, 2026-11-01); the
+// first entry is the ChatGPT default. Availability varies by plan and rollout,
+// so other accounts may be served a different set. gpt-5.4, gpt-5.4-mini and
+// gpt-5.5 are left out because OpenAI retired them from Codex with ChatGPT
+// sign-in. API-key sessions are not affected, so the API-key path keeps its
+// own list and default.
 export const CODEX_DEFAULT_MODELS = [
   "gpt-6.1-sol",
   "gpt-6-astra",