feat: no silent model fallback — explicit failure, gone models, per-profile fallback (#2385)

Co-authored-by: Carlos Florencio <carlosmflorencio@gmail.com>

apps/web/components/settings/model-fallback-settings-shell.test.tsx

@@ -0,0 +1,55 @@
+import { cleanup, fireEvent, render, screen } from "@testing-library/react";
+import { afterEach, describe, expect, it } from "vitest";
+import { ModelFallbackSettingsShell } from "./model-fallback-settings-shell";
+
+afterEach(cleanup);
+
+function renderShell({ autoFallback = false, fallbackModel = "", isDirty = false } = {}) {
+  return render(
+    <ModelFallbackSettingsShell
+      autoFallback={autoFallback}
+      fallbackModel={fallbackModel}
+      isDirty={isDirty}
+      automaticOption={<span>Automatic option</span>}
+      explicitOption={<span>Explicit option</span>}
+    />,
+  );
+}
+
+describe("ModelFallbackSettingsShell", () => {
+  it("starts collapsed with a state summary", () => {
+    renderShell({ fallbackModel: "gpt-5", isDirty: true });
+
+    expect(
+      screen.getByTestId("profile-fallback-settings-trigger").getAttribute("aria-expanded"),
+    ).toBe("false");
+    expect(screen.getByTestId("profile-fallback-settings-summary").textContent).toContain(
+      "Explicit fallback: gpt-5",
+    );
+    expect(
+      screen
+        .getByTestId("profile-fallback-settings")
+        .firstElementChild?.getAttribute("data-settings-dirty"),
+    ).toBe("true");
+    expect(screen.queryByTestId("profile-fallback-settings-grid")).toBeNull();
+  });
+
+  it("reveals both fallback options in the responsive grid", () => {
+    renderShell({ autoFallback: true });
+
+    fireEvent.click(screen.getByTestId("profile-fallback-settings-trigger"));
+
+    expect(
+      screen.getByTestId("profile-fallback-settings-trigger").getAttribute("aria-expanded"),
+    ).toBe("true");
+    expect(screen.getByTestId("profile-fallback-settings-grid").className).toContain(
+      "md:grid-cols-2",
+    );
+    expect(screen.getByTestId("profile-auto-fallback-option").textContent).toContain(
+      "Automatic option",
+    );
+    expect(screen.getByTestId("profile-explicit-fallback-option").textContent).toContain(
+      "Explicit option",
+    );
+  });
+});