fix(analytics): send download stats via sendBeacon (v1.0.4)

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "ttrpg-player-landing",
   "private": true,
-  "version": "1.0.3",
+  "version": "1.0.4",
   "description": "Marketing landing for TTRPG Player (НРИ Плеер)",
   "type": "module",
   "scripts": {

src/lib/trackDownload.test.ts

@@ -3,10 +3,30 @@ import { afterEach, describe, it, mock } from "node:test";
 
 import {
   DEFAULT_LICENSE_TRACKING_BASE,
+  buildTrackDownloadPayload,
   resolveTrackDownloadUrl,
   trackDownload,
 } from "./trackDownload";
 
+type BeaconCall = { url: string; blob: Blob };
+
+function installNavigatorMock(sendBeaconImpl: () => boolean): {
+  calls: BeaconCall[];
+} {
+  const calls: BeaconCall[] = [];
+  const sendBeacon = (url: string, data: Blob) => {
+    calls.push({ url, blob: data });
+    return sendBeaconImpl();
+  };
+
+  Object.defineProperty(globalThis, "navigator", {
+    value: { sendBeacon },
+    configurable: true,
+  });
+
+  return { calls };
+}
+
 describe("trackDownload", () => {
   afterEach(() => {
     mock.restoreAll();
@@ -26,12 +46,36 @@ describe("trackDownload", () => {
     );
   });
 
-  it("POSTs platform with keepalive and swallows errors", async () => {
-    const fetchMock = mock.fn(() => Promise.reject(new Error("network down")));
+  it("builds JSON payload for platform", () => {
+    assert.equal(
+      buildTrackDownloadPayload("linux"),
+      JSON.stringify({ platform: "linux" }),
+    );
+  });
+
+  it("sends platform via sendBeacon as text/plain", async () => {
+    const { calls } = installNavigatorMock(() => true);
+    const fetchMock = mock.fn(() => Promise.resolve(new Response()));
     globalThis.fetch = fetchMock;
 
     trackDownload("macos");
 
+    assert.equal(calls.length, 1);
+    const call = calls[0];
+    assert.ok(call);
+    assert.equal(call.url, "https://license.ttrpgplayer.ru/v1/track/download");
+    assert.equal(call.blob.type.toLowerCase(), "text/plain;charset=utf-8");
+    assert.equal(await call.blob.text(), JSON.stringify({ platform: "macos" }));
+    assert.equal(fetchMock.mock.calls.length, 0);
+  });
+
+  it("falls back to fetch keepalive when sendBeacon returns false", async () => {
+    installNavigatorMock(() => false);
+    const fetchMock = mock.fn(() => Promise.reject(new Error("network down")));
+    globalThis.fetch = fetchMock;
+
+    trackDownload("windows");
+
     await new Promise((resolve) => setTimeout(resolve, 0));
 
     assert.equal(fetchMock.mock.calls.length, 1);
@@ -41,7 +85,9 @@ describe("trackDownload", () => {
     assert.equal(url, "https://license.ttrpgplayer.ru/v1/track/download");
     assert.equal(init.method, "POST");
     assert.equal(init.keepalive, true);
-    assert.deepEqual(init.headers, { "Content-Type": "application/json" });
-    assert.equal(init.body, JSON.stringify({ platform: "macos" }));
+    assert.deepEqual(init.headers, {
+      "Content-Type": "text/plain;charset=UTF-8",
+    });
+    assert.equal(init.body, JSON.stringify({ platform: "windows" }));
   });
 });

src/lib/trackDownload.ts

@@ -1,6 +1,7 @@
 import type { PlatformId } from "../data/siteContent";
 
 export const DEFAULT_LICENSE_TRACKING_BASE = "https://license.ttrpgplayer.ru/";
+const TRACK_DOWNLOAD_CONTENT_TYPE = "text/plain;charset=UTF-8";
 
 function normalizeBaseUrl(base: string): string {
   return base.endsWith("/") ? base : `${base}/`;
@@ -21,13 +22,28 @@ export function resolveTrackDownloadUrl(base?: string): string {
   return `${normalizeBaseUrl(base ?? resolveLicenseTrackingBase())}v1/track/download`;
 }
 
+export function buildTrackDownloadPayload(platform: PlatformId): string {
+  return JSON.stringify({ platform });
+}
+
 export function trackDownload(platform: PlatformId): void {
+  const url = resolveTrackDownloadUrl();
+  const body = buildTrackDownloadPayload(platform);
+
+  if (
+    typeof navigator !== "undefined" &&
+    typeof navigator.sendBeacon === "function"
+  ) {
+    const blob = new Blob([body], { type: TRACK_DOWNLOAD_CONTENT_TYPE });
+    if (navigator.sendBeacon(url, blob)) return;
+  }
+
   if (typeof fetch === "undefined") return;
 
-  void fetch(resolveTrackDownloadUrl(), {
+  void fetch(url, {
     method: "POST",
-    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ platform }),
+    headers: { "Content-Type": TRACK_DOWNLOAD_CONTENT_TYPE },
+    body,
     keepalive: true,
   }).catch(() => {
     // fire-and-forget: ignore network errors