feat(codex-oauth): fetch model list from ChatGPT backend on demand

- Add `get_codex_oauth_models` Tauri command reusing the managed OAuth
  access token to hit `chatgpt.com/backend-api/codex/models`; HTTP and
  multi-shape JSON parsing live in `services::codex_oauth_models` so the
  command stays thin.
- Unify the Claude form's "fetch models" button across normal / Copilot /
  Codex OAuth presets, drop the auto-load effect for Copilot in favor of
  explicit clicks, and guard against stale responses with a requestId ref.
- Add Vitest coverage for both Copilot and Codex OAuth paths asserting no
  request on mount and the correct account id on click; add Rust unit
  tests for the four model-list payload shapes.

tests/components/ClaudeFormFields.test.tsx

@@ -0,0 +1,168 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import type { ComponentProps, PropsWithChildren } from "react";
+import { useForm } from "react-hook-form";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { ClaudeFormFields } from "@/components/providers/forms/ClaudeFormFields";
+import { Form } from "@/components/ui/form";
+
+const copilotApiMock = vi.hoisted(() => ({
+  copilotGetModels: vi.fn(),
+  copilotGetModelsForAccount: vi.fn(),
+}));
+
+const modelFetchApiMock = vi.hoisted(() => ({
+  fetchCodexOauthModels: vi.fn(),
+  fetchModelsForConfig: vi.fn(),
+  showFetchModelsError: vi.fn(),
+}));
+
+vi.mock("@/lib/api/copilot", () => ({
+  copilotGetModels: copilotApiMock.copilotGetModels,
+  copilotGetModelsForAccount: copilotApiMock.copilotGetModelsForAccount,
+}));
+
+vi.mock("@/lib/api/model-fetch", () => ({
+  fetchCodexOauthModels: modelFetchApiMock.fetchCodexOauthModels,
+  fetchModelsForConfig: modelFetchApiMock.fetchModelsForConfig,
+  showFetchModelsError: modelFetchApiMock.showFetchModelsError,
+}));
+
+vi.mock("@/components/providers/forms/CopilotAuthSection", () => ({
+  CopilotAuthSection: () => <div data-testid="copilot-auth-section" />,
+}));
+
+vi.mock("@/components/providers/forms/CodexOAuthSection", () => ({
+  CodexOAuthSection: () => <div data-testid="codex-oauth-section" />,
+}));
+
+type ClaudeFormFieldsProps = ComponentProps<typeof ClaudeFormFields>;
+
+const FormShell = ({ children }: PropsWithChildren) => {
+  const form = useForm();
+
+  return <Form {...form}>{children}</Form>;
+};
+
+const renderCopilotForm = (overrides: Partial<ClaudeFormFieldsProps> = {}) => {
+  const props: ClaudeFormFieldsProps = {
+    shouldShowApiKey: false,
+    apiKey: "",
+    onApiKeyChange: vi.fn(),
+    category: "official",
+    shouldShowApiKeyLink: false,
+    websiteUrl: "",
+    isCopilotPreset: true,
+    usesOAuth: true,
+    isCopilotAuthenticated: true,
+    selectedGitHubAccountId: "gh-1",
+    onGitHubAccountSelect: vi.fn(),
+    isCodexOauthPreset: false,
+    isCodexOauthAuthenticated: false,
+    selectedCodexAccountId: null,
+    onCodexAccountSelect: vi.fn(),
+    codexFastMode: false,
+    onCodexFastModeChange: vi.fn(),
+    templateValueEntries: [],
+    templateValues: {},
+    templatePresetName: "",
+    onTemplateValueChange: vi.fn(),
+    shouldShowSpeedTest: false,
+    baseUrl: "",
+    onBaseUrlChange: vi.fn(),
+    isEndpointModalOpen: false,
+    onEndpointModalToggle: vi.fn(),
+    onCustomEndpointsChange: vi.fn(),
+    autoSelect: false,
+    onAutoSelectChange: vi.fn(),
+    showEndpointTools: true,
+    shouldShowModelSelector: true,
+    claudeModel: "",
+    defaultHaikuModel: "",
+    defaultHaikuModelName: "",
+    defaultSonnetModel: "claude-sonnet",
+    defaultSonnetModelName: "Claude Sonnet",
+    defaultOpusModel: "",
+    defaultOpusModelName: "",
+    onModelChange: vi.fn(),
+    speedTestEndpoints: [],
+    apiFormat: "anthropic",
+    onApiFormatChange: vi.fn(),
+    apiKeyField: "ANTHROPIC_AUTH_TOKEN",
+    onApiKeyFieldChange: vi.fn(),
+    isFullUrl: false,
+    onFullUrlChange: vi.fn(),
+    ...overrides,
+  };
+
+  return render(
+    <FormShell>
+      <ClaudeFormFields {...props} />
+    </FormShell>,
+  );
+};
+
+const renderCodexOauthForm = (overrides: Partial<ClaudeFormFieldsProps> = {}) =>
+  renderCopilotForm({
+    isCopilotPreset: false,
+    isCopilotAuthenticated: false,
+    selectedGitHubAccountId: null,
+    isCodexOauthPreset: true,
+    isCodexOauthAuthenticated: true,
+    selectedCodexAccountId: "chatgpt-1",
+    ...overrides,
+  });
+
+describe("ClaudeFormFields", () => {
+  beforeEach(() => {
+    copilotApiMock.copilotGetModels.mockResolvedValue([]);
+    copilotApiMock.copilotGetModelsForAccount.mockResolvedValue([]);
+    modelFetchApiMock.fetchCodexOauthModels.mockResolvedValue([]);
+    modelFetchApiMock.fetchModelsForConfig.mockResolvedValue([]);
+  });
+
+  it("不会在 Copilot 表单打开时自动获取模型列表", () => {
+    renderCopilotForm();
+
+    expect(copilotApiMock.copilotGetModels).not.toHaveBeenCalled();
+    expect(copilotApiMock.copilotGetModelsForAccount).not.toHaveBeenCalled();
+  });
+
+  it("点击获取模型列表后才请求当前 Copilot 账号的模型", async () => {
+    renderCopilotForm();
+
+    fireEvent.click(
+      screen.getByRole("button", {
+        name: "providerForm.fetchModels",
+      }),
+    );
+
+    await waitFor(() => {
+      expect(copilotApiMock.copilotGetModelsForAccount).toHaveBeenCalledWith(
+        "gh-1",
+      );
+    });
+    expect(copilotApiMock.copilotGetModels).not.toHaveBeenCalled();
+  });
+
+  it("不会在 Codex OAuth 表单打开时自动获取模型列表", () => {
+    renderCodexOauthForm();
+
+    expect(modelFetchApiMock.fetchCodexOauthModels).not.toHaveBeenCalled();
+  });
+
+  it("点击获取模型列表后才请求当前 Codex OAuth 账号的模型", async () => {
+    renderCodexOauthForm();
+
+    fireEvent.click(
+      screen.getByRole("button", {
+        name: "providerForm.fetchModels",
+      }),
+    );
+
+    await waitFor(() => {
+      expect(modelFetchApiMock.fetchCodexOauthModels).toHaveBeenCalledWith(
+        "chatgpt-1",
+      );
+    });
+  });
+});