feat(FN-4332): complete Step 4 — add notification failure controls

Fusion-Task-Id: FN-4332
Fusion-Task-Lineage: c920ac71-906b-458d-b496-1b60540b58f3

packages/dashboard/app/components/SettingsModal.tsx

@@ -404,6 +404,8 @@ export function SettingsModal({
     ntfyEnabled: false,
     ntfyTopic: undefined,
     ntfyAccessToken: undefined,
+    failureNotificationMode: "sticky-only",
+    failureNotificationDelayMs: 30000,
     webhookEnabled: false,
     webhookUrl: undefined,
     webhookFormat: "generic",
@@ -5022,6 +5024,47 @@ export function SettingsModal({
             {renderScopeBanner()}
             <h4 className="settings-section-heading">Notifications</h4>
 
+            <div className="notification-provider-card">
+              <div className="form-group">
+                <label htmlFor="failureNotificationMode">Failure notification mode</label>
+                <select
+                  id="failureNotificationMode"
+                  value={form.failureNotificationMode ?? "sticky-only"}
+                  onChange={(e) => {
+                    const value = e.target.value as "sticky-only" | "all";
+                    setForm((f) => ({ ...f, failureNotificationMode: value }));
+                  }}
+                >
+                  <option value="sticky-only">Sticky failures only (default)</option>
+                  <option value="all">All failures (legacy)</option>
+                </select>
+                <small>
+                  Sticky-only suppresses notifications for transient failures that the engine auto-recovers. Choose &quot;All failures&quot; for the legacy immediate-notification behavior.
+                </small>
+              </div>
+              <div className="form-group">
+                <label htmlFor="failureNotificationDelayMs">Failure notification delay (ms)</label>
+                <input
+                  id="failureNotificationDelayMs"
+                  type="number"
+                  min={0}
+                  step={1000}
+                  disabled={(form.failureNotificationMode ?? "sticky-only") === "all"}
+                  value={form.failureNotificationDelayMs ?? 30000}
+                  onChange={(e) => {
+                    const parsed = Number(e.target.value);
+                    setForm((f) => ({
+                      ...f,
+                      failureNotificationDelayMs: Number.isFinite(parsed) && parsed >= 0 ? parsed : 0,
+                    }));
+                  }}
+                />
+                <small>
+                  How long a failure must persist before a push notification is sent. 0 = notify immediately.
+                </small>
+              </div>
+            </div>
+
             <div className="notification-provider-card">
               <div className="notification-provider-header">
                 <strong>ntfy</strong>

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

@@ -3245,6 +3245,34 @@ describe("SettingsModal", () => {
       expect(screen.getByText("Webhook")).toBeInTheDocument();
     });
 
+    it("renders failure mode controls and persists updated values", async () => {
+      renderModal();
+      await waitForSettingsModalReady();
+      await openNotificationsSection();
+
+      const modeSelect = screen.getByLabelText("Failure notification mode") as HTMLSelectElement;
+      const delayInput = screen.getByLabelText("Failure notification delay (ms)") as HTMLInputElement;
+
+      expect(modeSelect.value).toBe("sticky-only");
+      expect(delayInput.value).toBe("30000");
+
+      await userEvent.selectOptions(modeSelect, "all");
+      expect(delayInput).toBeDisabled();
+      await userEvent.selectOptions(modeSelect, "sticky-only");
+      await userEvent.clear(delayInput);
+      await userEvent.type(delayInput, "45000");
+      await userEvent.click(screen.getByRole("button", { name: "Save" }));
+
+      await waitFor(() => {
+        expect(mockUpdateGlobalSettings).toHaveBeenCalledWith(
+          expect.objectContaining({
+            failureNotificationMode: "sticky-only",
+            failureNotificationDelayMs: 45000,
+          }),
+        );
+      });
+    });
+
     it("shows ntfy fields when ntfy provider is enabled", async () => {
       mockFetchSettings.mockResolvedValueOnce({ ...defaultSettings, ntfyEnabled: true, ntfyTopic: "test-topic" });
       renderModal();