Keep Parakeet on WASM unless WebGPU is chosen explicitly, and never offer it on phones

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/mobileMemoryGuard.test.ts

@@ -1,5 +1,11 @@
 import { describe, test, expect } from "bun:test";
-import { isLikelyMobile, shouldWarnBeforeLoad } from "../src/lib/mobileMemoryGuard";
+import {
+  isLikelyMobile,
+  isModelAllowedOnDevice,
+  modelsForDevice,
+  shouldWarnBeforeLoad,
+} from "../src/lib/mobileMemoryGuard";
+import { MODELS, PARAKEET_MODEL_ID } from "../src/lib/models";
 
 // Pure UA/heuristic logic (D-027) — no browser, no navigator.
 
@@ -99,3 +105,27 @@ describe("shouldWarnBeforeLoad", () => {
     ).toBe(false);
   });
 });
+
+describe("desktop-only models (D-WS7a)", () => {
+  const parakeet = MODELS.find((model) => model.id === PARAKEET_MODEL_ID)!;
+  const phone = { userAgent: ANDROID_UA, maxTouchPoints: 5, deviceMemoryGB: 8 };
+  const ipad = { userAgent: IPAD_DESKTOP_UA, maxTouchPoints: 5, deviceMemoryGB: undefined };
+  const desktop = { userAgent: DESKTOP_WINDOWS_UA, maxTouchPoints: 0, deviceMemoryGB: 8 };
+
+  test("Parakeet is never offered on phones or tablets, even high-memory ones", () => {
+    expect(isModelAllowedOnDevice(parakeet, phone)).toBe(false);
+    expect(isModelAllowedOnDevice(parakeet, ipad)).toBe(false);
+    expect(isModelAllowedOnDevice(parakeet, desktop)).toBe(true);
+  });
+
+  test("Whisper models stay allowed everywhere (they get the D-027 confirm instead)", () => {
+    for (const model of MODELS.filter((m) => m.id !== PARAKEET_MODEL_ID)) {
+      expect(isModelAllowedOnDevice(model, phone)).toBe(true);
+    }
+  });
+
+  test("modelsForDevice filters the list, keeping order", () => {
+    expect(modelsForDevice(MODELS, phone)).toEqual(MODELS.filter((m) => m !== parakeet));
+    expect(modelsForDevice(MODELS, desktop)).toEqual([...MODELS]);
+  });
+});