fix: make timeline activation durable and visible

tests/browser/management-ui.test.tsx

@@ -120,6 +120,16 @@ const PLAYBACK_DETAIL = {
   snapshot: GROUP.playback,
 };
 
+const TIMELINE = {
+  description: null,
+  eligibleFrom: null,
+  eligibleUntil: null,
+  id: "timeline-1",
+  name: "Sunday morning",
+  revision: 3,
+  updatedAt: "2026-08-30T15:00:00.000Z",
+};
+
 beforeEach(() => {
   container = document.createElement("div");
   document.body.append(container);
@@ -194,6 +204,78 @@ describe("Signage dashboard", () => {
     expect(container.querySelector("[data-testid='signage-controls']")).toBeNull();
   });
 
+  it("shows which timeline remains active after the dashboard data is reloaded", async () => {
+    const host = createFakeHost({
+      permissions: ["signage.view", "signage.playback.control"],
+      routes: [
+        { method: "GET", path: "settings", respond: () => jsonResponse(FAKE_SETTINGS) },
+        { method: "GET", path: "channel-groups", respond: () => jsonResponse({ groups: [GROUP] }) },
+        {
+          method: "GET",
+          path: "timelines",
+          respond: () => jsonResponse({ timelines: [TIMELINE] }),
+        },
+        { method: "GET", path: "playback/group-1", respond: () => jsonResponse(PLAYBACK_DETAIL) },
+        { method: "GET", path: "providers", respond: () => jsonResponse({ providers: [] }) },
+      ],
+    });
+
+    await render(<SignageDashboard context={host.context} />);
+    expect(container.textContent).toContain("Active: Sunday morning");
+    await click(
+      [...container.querySelectorAll("[role='tab']")].find(
+        (candidate) => candidate.textContent === "Timelines",
+      ),
+    );
+
+    expect(container.textContent).toContain("Active in Main");
+    expect(buttonNamed("Active")?.disabled).toBe(true);
+  });
+
+  it("keeps a failed activation visible instead of pretending it succeeded", async () => {
+    const inactiveGroup = {
+      ...GROUP,
+      playback: { ...GROUP.playback, activeTimelineId: null, currentSelectionId: null },
+    };
+    const host = createFakeHost({
+      permissions: ["signage.view", "signage.playback.control"],
+      routes: [
+        { method: "GET", path: "settings", respond: () => jsonResponse(FAKE_SETTINGS) },
+        {
+          method: "GET",
+          path: "channel-groups",
+          respond: () => jsonResponse({ groups: [inactiveGroup] }),
+        },
+        {
+          method: "GET",
+          path: "timelines",
+          respond: () => jsonResponse({ timelines: [TIMELINE] }),
+        },
+        { method: "GET", path: "playback/group-1", respond: () => jsonResponse(PLAYBACK_DETAIL) },
+        { method: "GET", path: "providers", respond: () => jsonResponse({ providers: [] }) },
+        {
+          method: "POST",
+          path: "playback/group-1/activate",
+          respond: () =>
+            errorResponse("SIGNAGE_CONFLICT", "The request conflicts with the current state.", 409),
+        },
+      ],
+    });
+
+    await render(<SignageDashboard context={host.context} />);
+    await click(
+      [...container.querySelectorAll("[role='tab']")].find(
+        (candidate) => candidate.textContent === "Timelines",
+      ),
+    );
+    await click(buttonNamed("Activate"));
+
+    expect(container.textContent).toContain("Sunday morning");
+    expect(container.querySelector("[role='alert']")?.textContent).toContain(
+      "The request conflicts with the current state.",
+    );
+  });
+
   it("shows Signage's own sanitized reason when a save is refused", async () => {
     const host = createFakeHost({
       permissions: ["signage.view", "signage.timelines.manage"],

tests/playback.test.ts

@@ -589,6 +589,30 @@ describe("authoritative playback", () => {
     expect(announcements.resolveRequests.length).toBe(callsBefore);
   });
 
+  it("keeps the active timeline through a complete playback-service restart", async () => {
+    const group = await seedGroup();
+    const timeline = await seedPattern();
+    await service.activate(group.group.id, timeline.timeline.id, "now");
+    const before = await service.snapshot(group.group.id);
+
+    service.stop();
+    clock += 2000;
+    service = createPlaybackService({
+      newId,
+      now: () => clock,
+      registry,
+      setTimer: () => undefined,
+      settings: { ...SIGNAGE_DEFAULT_SETTINGS, playbackHistoryLimit: 20 },
+      store,
+    });
+    await service.start();
+
+    const after = await service.snapshot(group.group.id);
+    expect(after.activeTimelineId).toBe(timeline.timeline.id);
+    expect(after.currentSelectionId).toBe(before.currentSelectionId);
+    expect(after.deadlineAtMs).toBe(before.deadlineAtMs);
+  });
+
   it("publishes a compact snapshot, with no payload or timeline in it", async () => {
     const group = await seedGroup();
     const timeline = await seedPattern();