feat(FN-669): add ntfy deep link support with dashboard hostname config

- Add ntfyDashboardHost setting to GlobalSettings for dashboard URL\n- Generate deep links in ntfy notifications with Click header\n- Handle ?task= query param in dashboard for direct task navigation\n- Add hostname configuration UI in Settings modal\n- Add comprehensive tests for deep link generation and handling

packages/dashboard/app/App.tsx

@@ -1,6 +1,6 @@
 import { useState, useCallback, useEffect } from "react";
 import type { TaskDetail, TaskCreateInput, Task, ThemeMode } from "@fusion/core";
-import { fetchConfig, fetchSettings, fetchAuthStatus, updateSettings, fetchModels } from "./api";
+import { fetchConfig, fetchSettings, fetchAuthStatus, updateSettings, fetchModels, fetchTaskDetail } from "./api";
 import type { ModelInfo } from "./api";
 import { Header } from "./components/Header";
 import { Board } from "./components/Board";
@@ -109,6 +109,27 @@ function AppInner() {
   }, []);
   const { toasts, addToast, removeToast } = useToast();
 
+  // Handle deep link to task on mount
+  useEffect(() => {
+    const params = new URLSearchParams(window.location.search);
+    const taskId = params.get("task");
+    if (!taskId) return;
+
+    // Clean URL immediately without reloading
+    const url = new URL(window.location.href);
+    url.searchParams.delete("task");
+    window.history.replaceState({}, "", url.toString());
+
+    // Load and open the task directly
+    fetchTaskDetail(taskId)
+      .then((task) => {
+        handleDetailOpen(task);
+      })
+      .catch(() => {
+        addToast(`Task ${taskId} not found`, "error");
+      });
+  }, []);
+
   // Persist view preference to localStorage
   useEffect(() => {
     localStorage.setItem("kb-dashboard-view", view);

packages/dashboard/app/components/SettingsModal.tsx

@@ -1378,6 +1378,37 @@ export function SettingsModal({
                 </button>
               </div>
             )}
+            {form.ntfyEnabled && (
+              <div className="form-group">
+                <label htmlFor="ntfyDashboardHost">Dashboard Hostname</label>
+                <input
+                  id="ntfyDashboardHost"
+                  type="text"
+                  placeholder="http://localhost:3000"
+                  value={form.ntfyDashboardHost || ""}
+                  onChange={(e) => {
+                    const val = e.target.value;
+                    setForm((f) => ({ ...f, ntfyDashboardHost: val || undefined }));
+                  }}
+                />
+                <small>
+                  Base URL for deep links in notifications. When set, clicking a notification
+                  will open the dashboard directly to the task. Example: http://localhost:3000
+                  or https://fusion.example.com
+                </small>
+                {form.ntfyDashboardHost && (
+                  !/^https?:\/\/.+/.test(form.ntfyDashboardHost) ? (
+                    <small className="field-error">
+                      Must be a valid URL starting with http:// or https://
+                    </small>
+                  ) : form.ntfyDashboardHost.includes("?") || form.ntfyDashboardHost.includes("#") ? (
+                    <small className="field-error">
+                      URL should not include query parameters or fragments
+                    </small>
+                  ) : null
+                )}
+              </div>
+            )}
           </>
         );
       case "authentication":

packages/dashboard/app/components/__tests__/App.test.tsx

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi, beforeEach } from "vitest";
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
 import { render, screen, fireEvent, waitFor, act } from "@testing-library/react";
 import { App } from "../../App";
 import type { Settings } from "@fusion/core";
@@ -35,6 +35,19 @@ vi.mock("../../api", async (importOriginal) => {
     logoutProvider: vi.fn(() => Promise.resolve({ success: true })),
     fetchModels: vi.fn(() => Promise.resolve([])),
     fetchGitRemotes: vi.fn(() => Promise.resolve([])),
+    fetchTaskDetail: vi.fn((id: string) => Promise.resolve({
+      id,
+      title: `Task ${id}`,
+      description: "Deep linked task",
+      column: "todo",
+      dependencies: [],
+      steps: [],
+      currentStep: 0,
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+      log: [],
+      prompt: "",
+    })),
   };
 });
 
@@ -49,12 +62,85 @@ vi.mock("../../hooks/useTasks", () => ({
   }),
 }));
 
-import { fetchAuthStatus, fetchSettings, updateSettings } from "../../api";
+import { fetchAuthStatus, fetchSettings, fetchTaskDetail, updateSettings } from "../../api";
 
 beforeEach(() => {
   vi.clearAllMocks();
 });
 
+describe("App deep link handling", () => {
+  const originalLocation = window.location;
+  const originalReplaceState = window.history.replaceState;
+
+  beforeEach(() => {
+    window.history.replaceState = vi.fn();
+    Object.defineProperty(window, "location", {
+      configurable: true,
+      value: new URL("http://localhost:3000/"),
+    });
+  });
+
+  afterEach(() => {
+    Object.defineProperty(window, "location", {
+      configurable: true,
+      value: originalLocation,
+    });
+    window.history.replaceState = originalReplaceState;
+  });
+
+  it("fetches and opens the task modal when task query param is present", async () => {
+    Object.defineProperty(window, "location", {
+      configurable: true,
+      value: new URL("http://localhost:3000/?task=FN-123"),
+    });
+
+    render(<App />);
+
+    await waitFor(() => {
+      expect(fetchTaskDetail).toHaveBeenCalledWith("FN-123");
+    });
+
+    await waitFor(() => {
+      expect(screen.getByText("Task FN-123")).toBeTruthy();
+    });
+
+    expect(window.history.replaceState).toHaveBeenCalledWith(
+      {},
+      "",
+      "http://localhost:3000/",
+    );
+  });
+
+  it("shows an error toast when the deep-linked task cannot be loaded", async () => {
+    Object.defineProperty(window, "location", {
+      configurable: true,
+      value: new URL("http://localhost:3000/?task=FN-404"),
+    });
+    (fetchTaskDetail as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error("Not found"));
+
+    render(<App />);
+
+    await waitFor(() => {
+      expect(fetchTaskDetail).toHaveBeenCalledWith("FN-404");
+    });
+
+    await waitFor(() => {
+      expect(screen.getByText("Task FN-404 not found")).toBeTruthy();
+    });
+  });
+
+  it("does nothing when no task query param is present", async () => {
+    render(<App />);
+
+    await waitFor(() => {
+      expect(fetchSettings).toHaveBeenCalled();
+    });
+
+    expect(fetchTaskDetail).not.toHaveBeenCalled();
+    expect(window.history.replaceState).not.toHaveBeenCalled();
+  });
+});
+
 describe("App auto-open Settings on unauthenticated", () => {
   it("auto-opens Settings to Authentication tab when all providers are unauthenticated", async () => {
     render(<App />);