refactor(desktop): harden workspace shell foundation

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/desktop/src/lib/demo-workspace.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from "vitest";
+import {
+  buildDemoStringPreview,
+  formatDemoDurationFromMillis,
+  parseDemoTtlToSeconds,
+  persistDemoKeyTtl,
+  updateDemoKeyTtl,
+  updateDemoStringValue,
+  type DemoWorkspaceKey,
+} from "./demo-workspace";
+
+const demoKeys: DemoWorkspaceKey[] = [
+  {
+    id: "cache:homepage",
+    name: "cache:homepage",
+    type: "string",
+    ttl: "48s",
+    preview: "serialized landing payload",
+    editable: true,
+    value: "{\"hero\":\"Redis GUI\"}",
+    summary: "String keys are editable in V1.",
+  },
+];
+
+describe("demo workspace helpers", () => {
+  it("updates string values and refreshes the visible preview", () => {
+    expect(
+      updateDemoStringValue(demoKeys, "cache:homepage", "next value"),
+    ).toEqual([
+      {
+        ...demoKeys[0],
+        value: "next value",
+        preview: "next value",
+      },
+    ]);
+  });
+
+  it("updates TTL state for session-local demo flows", () => {
+    expect(updateDemoKeyTtl(demoKeys, "cache:homepage", 90_000)[0]?.ttl).toBe("1m");
+    expect(persistDemoKeyTtl(demoKeys, "cache:homepage")[0]?.ttl).toBe("persistent");
+  });
+
+  it("formats preview text and durations consistently", () => {
+    expect(buildDemoStringPreview("alpha beta gamma delta epsilon zeta eta theta", 16)).toBe(
+      "alpha beta gamm…",
+    );
+    expect(formatDemoDurationFromMillis(750)).toBe("750ms");
+    expect(formatDemoDurationFromMillis(5_000)).toBe("5s");
+    expect(formatDemoDurationFromMillis(7_200_000)).toBe("2h");
+    expect(parseDemoTtlToSeconds("750ms")).toBe(0);
+    expect(parseDemoTtlToSeconds("5s")).toBe(5);
+    expect(parseDemoTtlToSeconds("2h")).toBe(7200);
+    expect(parseDemoTtlToSeconds("persistent")).toBe(-1);
+  });
+});