diff --git a/apps/loopover-ui/src/lib/api/request-notify-retry.test.ts b/apps/loopover-ui/src/lib/api/request-notify-retry.test.ts
new file mode 100644
index 0000000000..75143cf046
--- /dev/null
+++ b/apps/loopover-ui/src/lib/api/request-notify-retry.test.ts
@@ -0,0 +1,61 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+// #8676: notifyApiFailure shows a sonner toast whose "Retry" action drives runRetryWithProgress' in-flight
+// re-entrancy guard. Mock sonner to capture each toast.error's action.onClick, and stub ./status so
+// pingHealth/getApiStatus don't touch the network.
+const { toast } = vi.hoisted(() => ({
+  toast: Object.assign(vi.fn(), {
+    error: vi.fn(),
+    loading: vi.fn(),
+    success: vi.fn(),
+    dismiss: vi.fn(),
+  }),
+}));
+vi.mock("sonner", () => ({ toast }));
+vi.mock("./status", () => ({
+  beginRequest: vi.fn(),
+  endRequest: vi.fn(),
+  reportApiFailure: vi.fn(),
+  reportApiOk: vi.fn(),
+  describeApiStatus: () => "",
+  getApiStatus: () => ({ status: "ok" }),
+  pingHealth: vi.fn(),
+}));
+
+import { notifyApiFailure } from "./request";
+
+function lastRetryAction(): () => void {
+  const calls = (toast.error as ReturnType<typeof vi.fn>).mock.calls;
+  const opts = calls.at(-1)?.[1] as { action?: { onClick: () => void } } | undefined;
+  return opts?.action?.onClick as () => void;
+}
+
+describe("notifyApiFailure re-entrancy guard (#8676)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("preserves an in-flight retrying flag so a mid-retry notifyApiFailure can't double-fire the retry", async () => {
+    // A retry that never settles keeps `retrying` true for the whole test (the .finally that clears it never runs).
+    const retry = vi.fn(() => new Promise<void>(() => {}));
+    notifyApiFailure({ label: "widget", kind: "http", status: 500, retry });
+    lastRetryAction()(); // click Retry -> runRetryWithProgress sets retrying:true, calls retry() (next microtask)
+    await Promise.resolve(); // flush the `Promise.resolve().then(() => retry())` hop
+    expect(retry).toHaveBeenCalledTimes(1);
+
+    // A second failure notification for the SAME label lands while the first retry is still in flight. Before
+    // #8676 this full-object-replaced the entry, resetting retrying:false and defeating the guard.
+    notifyApiFailure({ label: "widget", kind: "http", status: 500, retry });
+    lastRetryAction()(); // click Retry again -> must be blocked by the still-true retrying guard
+    await Promise.resolve();
+    expect(retry).toHaveBeenCalledTimes(1); // still once, not a concurrent second run
+  });
+
+  it("still updates repeatCount on repeat failures when no retry is in flight (regression)", () => {
+    const retry = vi.fn();
+    notifyApiFailure({ label: "poll", kind: "network", retry });
+    notifyApiFailure({ label: "poll", kind: "network", retry }); // same kind within 5s -> repeatCount 2
+    const opts = (toast.error as ReturnType<typeof vi.fn>).mock.calls.at(-1)?.[1] as { description?: unknown };
+    expect(String(opts?.description)).toContain("2× in a row");
+  });
+});
diff --git a/apps/loopover-ui/src/lib/api/request.ts b/apps/loopover-ui/src/lib/api/request.ts
index beab6500ba..422f3c3194 100644
--- a/apps/loopover-ui/src/lib/api/request.ts
+++ b/apps/loopover-ui/src/lib/api/request.ts
@@ -125,7 +125,11 @@ export function notifyApiFailure(args: {
   const recent = prev && now - prev.lastNotifiedAt < 5000;
   const repeatCount = sameKind && recent ? prev.repeatCount + 1 : 1;
 
-  notifierState.set(id, { kind, status, lastNotifiedAt: now, repeatCount, retrying: false });
+  // #8676: MERGE, don't replace -- a full-object replacement here reset `retrying` to false on the shared
+  // entry even while runRetryWithProgress had a retry in flight, silently defeating its `if (entry.retrying)
+  // return` re-entrancy guard and allowing a concurrent second retry. Preserve an in-flight `true`; all other
+  // fields still update as before.
+  notifierState.set(id, { kind, status, lastNotifiedAt: now, repeatCount, retrying: prev?.retrying === true });
 
   const statusLabel =
     apiStatus !== "ok" && apiStatus !== "idle" ? describeApiStatus(apiStatus) : null;