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

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/lib/mobileMemoryGuard.ts

@@ -19,6 +19,8 @@
  * advance, so a benchmark probe would cost more than it saves.
  */
 
+import type { WhisperModel } from "./models";
+
 export interface MobileMemoryHint {
   /** `navigator.userAgent`, or undefined outside a browser (tests, SSR). */
   userAgent: string | undefined;
@@ -86,3 +88,26 @@ export function shouldWarnBeforeLoad(hint: MobileMemoryHint, peakBytes: number):
   }
   return peakBytes > MOBILE_FALLBACK_RISK_THRESHOLD_BYTES;
 }
+
+/**
+ * Desktop-only models (D-WS7a): Parakeet's ~1.3 GB load peak (2 × the
+ * 652 MB int8 encoder, D-027's arithmetic) exceeds every phone budget the
+ * D-029 table considers safe, even at deviceMemory 8 (800 MB). Unlike the
+ * Whisper models — where a confirm lets the user judge their device — it is
+ * not offered at all on phones and tablets: no amount of RAM a phone reports
+ * makes it safe, so a "Continue anyway?" would only invite the crash.
+ */
+export function isModelAllowedOnDevice(
+  model: Pick<WhisperModel, "family">,
+  hint: Pick<MobileMemoryHint, "userAgent" | "maxTouchPoints">,
+): boolean {
+  return model.family !== "parakeet" || !isLikelyMobile(hint);
+}
+
+/** The catalog as offered on this device (order preserved). */
+export function modelsForDevice<T extends Pick<WhisperModel, "family">>(
+  models: readonly T[],
+  hint: Pick<MobileMemoryHint, "userAgent" | "maxTouchPoints">,
+): T[] {
+  return models.filter((model) => isModelAllowedOnDevice(model, hint));
+}