fix(frontend): surface errors and keep dialog open on useConfirmedMutation action failure

frontend/src/app/hooks/useConfirmedMutation.test.tsx

@@ -0,0 +1,98 @@
+/**
+ * hooks/useConfirmedMutation.test.tsx
+ *
+ * Tests that useConfirmedMutation surfaces errors when the wrapped action rejects
+ * instead of silently closing the confirmation dialog and leaving an unhandled
+ * promise rejection.
+ */
+
+import { renderHook, act } from "@testing-library/react";
+import { useConfirmedMutation } from "./useConfirmedMutation";
+import { useToastStore } from "../stores/useToastStore";
+
+const createDeferred = (): {
+  promise: Promise<unknown>;
+  resolve: (value: unknown) => void;
+  reject: (reason: unknown) => void;
+} => {
+  let resolve!: (value: unknown) => void;
+  let reject!: (reason: unknown) => void;
+  const promise = new Promise<unknown>((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  return { promise, resolve, reject };
+};
+
+describe("useConfirmedMutation", () => {
+  beforeEach(() => {
+    useToastStore.getState().clearToasts();
+  });
+
+  it("keeps the dialog open and surfaces an error toast when the action rejects", async () => {
+    const deferred = createDeferred();
+    const action = jest.fn(() => deferred.promise);
+
+    const { result } = renderHook(() => useConfirmedMutation(action, { title: "Confirm" }));
+
+    act(() => {
+      result.current.trigger({ foo: "bar" } as never);
+    });
+
+    expect(result.current.dialogProps.isOpen).toBe(true);
+    expect(result.current.isLoading).toBe(false);
+
+    act(() => {
+      result.current.dialogProps.onConfirm();
+    });
+
+    expect(result.current.isLoading).toBe(true);
+
+    deferred.reject(new Error("boom"));
+
+    await act(async () => {
+      await deferred.promise.catch(() => {});
+    });
+
+    // Dialog stays open on failure
+    expect(result.current.dialogProps.isOpen).toBe(true);
+    // Loading is cleared
+    expect(result.current.isLoading).toBe(false);
+
+    // An error toast is surfaced
+    const errorToasts = useToastStore.getState().toasts.filter((t) => t.type === "error");
+    expect(errorToasts).toHaveLength(1);
+    expect(errorToasts[0].title).toBe("Transaction failed");
+    expect(errorToasts[0].description).toContain("boom");
+  });
+
+  it("closes the dialog and surfaces no error toast when the action resolves", async () => {
+    const deferred = createDeferred();
+    const action = jest.fn(() => deferred.promise);
+
+    const { result } = renderHook(() => useConfirmedMutation(action, { title: "Confirm" }));
+
+    act(() => {
+      result.current.trigger({ foo: "bar" } as never);
+    });
+
+    act(() => {
+      result.current.dialogProps.onConfirm();
+    });
+
+    expect(result.current.dialogProps.isOpen).toBe(true);
+    expect(result.current.isLoading).toBe(true);
+
+    deferred.resolve(undefined);
+
+    await act(async () => {
+      await deferred.promise;
+    });
+
+    expect(result.current.dialogProps.isOpen).toBe(false);
+    expect(result.current.isLoading).toBe(false);
+
+    const errorToasts = useToastStore.getState().toasts.filter((t) => t.type === "error");
+    expect(errorToasts).toHaveLength(0);
+  });
+});

frontend/src/app/hooks/useConfirmedMutation.ts

@@ -1,6 +1,7 @@
 "use client";
 
 import { useState, useCallback } from "react";
+import { useToastStore } from "../stores/useToastStore";
 import type { TransactionSummaryItem } from "../components/ui/ConfirmTransactionDialog";
 
 interface ConfirmedMutationOptions<TVariables> {
@@ -58,10 +59,20 @@ export function useConfirmedMutation<TVariables>(
     setIsLoading(true);
     try {
       await action(pendingVariables);
-    } finally {
       setIsLoading(false);
       setIsOpen(false);
       setPendingVariables(null);
+    } catch (error) {
+      setIsLoading(false);
+      const addToast = useToastStore.getState().addToast;
+      addToast({
+        type: "error",
+        title: "Transaction failed",
+        description:
+          error instanceof Error ? error.message : "An unexpected error occurred while confirming.",
+        duration: 10000,
+      });
+      // Keep the modal open so the user can retry or cancel
     }
   }, [action, pendingVariables]);