fix(marketing): detect Mac chip on homepage download button

apps/marketing/src/lib/macArch.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { macArchFromGpuRenderer } from "./macArch";
+
+describe("macArchFromGpuRenderer", () => {
+  it("detects explicit Apple Silicon renderers", () => {
+    expect(macArchFromGpuRenderer("Apple M4 Pro")).toBe("arm64");
+  });
+
+  it("prefers an Intel GPU marker even when the renderer also mentions Apple", () => {
+    expect(macArchFromGpuRenderer("ANGLE Metal Renderer: Apple, Intel Iris Plus Graphics")).toBe(
+      "x64",
+    );
+  });
+
+  it("uses x64 for ambiguous Safari and unavailable renderer values", () => {
+    expect(macArchFromGpuRenderer("Apple GPU")).toBe("x64");
+    expect(macArchFromGpuRenderer("")).toBe("x64");
+  });
+});

apps/marketing/src/lib/macArch.ts

@@ -0,0 +1,16 @@
+const INTEL_GPU_PATTERN = /intel|amd|radeon|nvidia|geforce/i;
+const APPLE_SILICON_GPU_PATTERN = /\bapple\s+m\d/i;
+
+export function macArchFromGpuRenderer(renderer: string): "arm64" | "x64" {
+  if (INTEL_GPU_PATTERN.test(renderer)) {
+    return "x64";
+  }
+  if (APPLE_SILICON_GPU_PATTERN.test(renderer)) {
+    return "arm64";
+  }
+
+  // Generic "Apple GPU" renderers are ambiguous on Safari. x64 is the safe
+  // fallback because Apple Silicon can run it through Rosetta, while Intel
+  // Macs cannot run an arm64 build.
+  return "x64";
+}

apps/marketing/src/pages/index.astro

@@ -391,14 +391,33 @@ const mobileEndorsementRows = [
 
 <script>
   import { fetchLatestRelease, RELEASES_URL, type ReleaseAsset } from "../lib/releases";
+  import { macArchFromGpuRenderer } from "../lib/macArch";
 
   type Platform = { os: "mac" | "win" | "linux"; label: string; arch?: string };
 
+  // navigator.userAgent reports "Intel Mac OS X" on both Intel and Apple Silicon
+  // Macs, so probe the GPU renderer instead: Apple Silicon exposes an "Apple" GPU.
+  function detectMacArch(): "arm64" | "x64" {
+    try {
+      const canvas = document.createElement("canvas");
+      const gl = (canvas.getContext("webgl") ||
+        canvas.getContext("experimental-webgl")) as WebGLRenderingContext | null;
+      const debugInfo = gl?.getExtension("WEBGL_debug_renderer_info");
+      if (gl && debugInfo) {
+        const renderer = String(gl.getParameter(debugInfo.UNMASKED_RENDERER_WEBGL) ?? "");
+        return macArchFromGpuRenderer(renderer);
+      }
+    } catch {
+      // fall through to the default below
+    }
+    return macArchFromGpuRenderer("");
+  }
+
   function detectPlatform(): Platform | null {
     const ua = navigator.userAgent;
     if (/Win/i.test(ua)) return { os: "win", label: "Download for Windows" };
     if (/Mac/i.test(ua)) {
-      return { os: "mac", label: "Download for macOS", arch: "arm64" };
+      return { os: "mac", label: "Download for macOS", arch: detectMacArch() };
     }
     if (/Linux/i.test(ua)) return { os: "linux", label: "Download for Linux" };
     return null;