feat(desktop): Electron shell M2 — embedded server, desktop login, instance lock (#173)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/desktop/test/util.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import {
+  appOriginFor,
+  desktopLoginUrl,
+  isAppUrl,
+  parsePortFile,
+  restartDelayMs,
+} from "../src/util.js";
+
+describe("parsePortFile", () => {
+  it("accepts a port with surrounding whitespace", () => {
+    expect(parsePortFile("17365\n")).toBe(17365);
+    expect(parsePortFile("  80  ")).toBe(80);
+  });
+  it("rejects garbage, empty, zero, and out-of-range values", () => {
+    expect(parsePortFile("")).toBeNull();
+    expect(parsePortFile("abc")).toBeNull();
+    expect(parsePortFile("0")).toBeNull();
+    expect(parsePortFile("65536")).toBeNull();
+    expect(parsePortFile("12 34")).toBeNull();
+  });
+});
+
+describe("app origin and login URL", () => {
+  it("builds the localhost origin and the one-shot login URL", () => {
+    expect(appOriginFor(7364)).toBe("http://localhost:7364");
+    expect(desktopLoginUrl("http://localhost:7364", "a b/c")).toBe(
+      "http://localhost:7364/api/auth/desktop-login?token=a%20b%2Fc",
+    );
+  });
+});
+
+describe("isAppUrl", () => {
+  const origin = "http://localhost:7364";
+  it("accepts only the app origin", () => {
+    expect(isAppUrl("http://localhost:7364/chat", origin)).toBe(true);
+    expect(isAppUrl("http://localhost:7365/", origin)).toBe(false);
+    expect(isAppUrl("http://127.0.0.1:7364/preview/x", origin)).toBe(false);
+    expect(isAppUrl("https://example.com", origin)).toBe(false);
+    expect(isAppUrl("not a url", origin)).toBe(false);
+    expect(isAppUrl("http://localhost:7364/", null)).toBe(false);
+  });
+});
+
+describe("restartDelayMs", () => {
+  it("doubles from 1s and caps at 8s", () => {
+    expect([0, 1, 2, 3, 4].map(restartDelayMs)).toEqual([1000, 2000, 4000, 8000, 8000]);
+  });
+});