fix(auth): clear stale password errors on the reset password page (#13035)

#### Description

- Submitting a weak password on the reset page returned the backend
`invalid_password` error, and the pane stayed up after the password was
fixed, replaying its shake while typing.
- The mismatch flag was imperative state set on blur, so it went stale
when a field was cleared; toggling it remounted the API error pane.
- Validation is now derived from watched form values, the same way
SignUp does it, and the mutation is reset on edit so the API error
clears as soon as either field changes.
- Added tests for both cases.

#### Issues closed by this PR

Closes SigNoz/keystone-pod#144

#### Screenshots / Screen Recordings



https://github.com/user-attachments/assets/48dcfa17-9fbc-47bc-83c5-75b0bb46ced0

frontend/src/container/ResetPassword/__tests__/ResetPassword.test.tsx

@@ -155,6 +155,39 @@ describe('ResetPassword Component', () => {
 				{ timeout: 200 },
 			);
 		});
+
+		it('clears password mismatch error when confirm password is emptied', async () => {
+			const user = userEvent.setup({ pointerEventsCheck: 0 });
+
+			render(<ResetPassword version="1.0.0" />, undefined, {
+				initialRoute: '/password-reset?token=reset-token-123',
+			});
+
+			const passwordInput = screen.getByPlaceholderText(/enter new password/i);
+			const confirmPasswordInput = screen.getByPlaceholderText(
+				/confirm your new password/i,
+			);
+			const submitButton = screen.getByRole('button', {
+				name: /reset password/i,
+			});
+
+			await user.type(passwordInput, 'password123');
+			await user.type(confirmPasswordInput, 'password456');
+			await user.tab();
+
+			await waitFor(() => {
+				expect(screen.getByText(/passwords don't match/i)).toBeInTheDocument();
+			});
+
+			await user.clear(confirmPasswordInput);
+
+			await waitFor(() => {
+				expect(
+					screen.queryByText(/passwords don't match/i),
+				).not.toBeInTheDocument();
+				expect(submitButton).toBeDisabled();
+			});
+		});
 	});
 
 	describe('Successful Password Reset', () => {
@@ -288,6 +321,65 @@ describe('ResetPassword Component', () => {
 				expect(screen.queryByText(/invalid token/i)).not.toBeInTheDocument();
 			});
 		});
+
+		it('clears API error when the user edits the password', async () => {
+			const user = userEvent.setup({ pointerEventsCheck: 0 });
+
+			server.use(
+				rest.post(RESET_PASSWORD_ENDPOINT, (_req, res, ctx) =>
+					res(
+						ctx.status(400),
+						ctx.json({
+							error: {
+								code: 'invalid_password',
+								message: 'password must be at least 8 characters long',
+							},
+						}),
+					),
+				),
+			);
+
+			render(<ResetPassword version="1.0.0" />, undefined, {
+				initialRoute: '/password-reset?token=reset-token-123',
+			});
+
+			const passwordInput = screen.getByPlaceholderText(/enter new password/i);
+			const confirmPasswordInput = screen.getByPlaceholderText(
+				/confirm your new password/i,
+			);
+			const submitButton = screen.getByRole('button', {
+				name: /reset password/i,
+			});
+
+			await user.type(passwordInput, 'weak');
+			await user.type(confirmPasswordInput, 'weak');
+
+			await waitFor(() => {
+				expect(submitButton).not.toBeDisabled();
+			});
+
+			await user.click(submitButton);
+
+			await waitFor(() => {
+				expect(
+					screen.getByText(/password must be at least 8 characters long/i),
+				).toBeInTheDocument();
+			});
+
+			await user.type(passwordInput, 'Er1!');
+
+			await waitFor(() => {
+				expect(
+					screen.queryByText(/password must be at least 8 characters long/i),
+				).not.toBeInTheDocument();
+			});
+
+			await user.type(confirmPasswordInput, 'Er1!');
+
+			await waitFor(() => {
+				expect(submitButton).not.toBeDisabled();
+			});
+		});
 	});
 
 	describe('Loading States', () => {

frontend/src/container/ResetPassword/index.tsx

@@ -10,7 +10,6 @@ import { useResetPassword } from 'api/generated/services/users';
 import AuthError from 'components/AuthError/AuthError';
 import AuthPageContainer from 'components/AuthPageContainer';
 import ROUTES from 'constants/routes';
-import useDebouncedFn from 'hooks/useDebouncedFunction';
 import { useNotifications } from 'hooks/useNotifications';
 import history from 'lib/history';
 import { ArrowRight, CircleAlert, KeyRound } from '@signozhq/icons';
@@ -23,10 +22,7 @@ import './ResetPassword.styles.scss';
 type FormValues = { password: string; confirmPassword: string };
 
 function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
-	const [confirmPasswordError, setConfirmPasswordError] =
-		useState<boolean>(false);
-
-	const [isValidPassword, setIsValidPassword] = useState(false);
+	const [confirmPasswordTouched, setConfirmPasswordTouched] = useState(false);
 	const { t } = useTranslation(['common']);
 	const { search } = useLocation();
 	const params = new URLSearchParams(search);
@@ -37,6 +33,7 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 		mutate: resetPassword,
 		isLoading,
 		error: mutationError,
+		reset: resetMutation,
 	} = useResetPassword();
 
 	const errorMessage = useMemo(
@@ -45,11 +42,30 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 	);
 
 	const [form] = Form.useForm<FormValues>();
-	const handleFormSubmit = (): void => {
-		const { password } = form.getFieldsValue();
+	const password = Form.useWatch('password', form);
+	const confirmPassword = Form.useWatch('confirmPassword', form);
+
+	const isPasswordMismatch =
+		Boolean(confirmPassword) && password !== confirmPassword;
+	const showPasswordMismatchError = confirmPasswordTouched && isPasswordMismatch;
+	const isValidPassword =
+		Boolean(password?.trim()) &&
+		Boolean(confirmPassword?.trim()) &&
+		password === confirmPassword;
+
+	const handleValuesChange = (): void => {
+		if (mutationError) {
+			resetMutation();
+		}
+	};
+
+	const handleSubmit = (): void => {
+		if (!token) {
+			return;
+		}
 
 		resetPassword(
-			{ data: { password, token: token || '' } },
+			{ data: { password: form.getFieldValue('password'), token } },
 			{
 				onSuccess: (): void => {
 					notifications.success({
@@ -63,80 +79,6 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 		);
 	};
 
-	const validatePassword = (): boolean => {
-		const { password, confirmPassword } = form.getFieldsValue();
-
-		if (
-			password &&
-			confirmPassword &&
-			password.trim() &&
-			confirmPassword.trim() &&
-			password.length > 0 &&
-			confirmPassword.length > 0
-		) {
-			return password === confirmPassword;
-		}
-
-		return false;
-	};
-
-	const handleValuesChange = useDebouncedFn((): void => {
-		const { password, confirmPassword } = form.getFieldsValue();
-
-		if (!password || !confirmPassword) {
-			setIsValidPassword(false);
-		}
-
-		// Only clear error if passwords match while typing (but don't set error until blur)
-		if (
-			password &&
-			confirmPassword &&
-			password.trim() &&
-			confirmPassword.trim()
-		) {
-			const isValid = validatePassword();
-			setIsValidPassword(isValid);
-
-			// Only clear error if passwords match, don't set error on mismatch
-			if (isValid) {
-				setConfirmPasswordError(false);
-			}
-		}
-	}, 100);
-
-	const handlePasswordBlur = (): void => {
-		const { confirmPassword } = form.getFieldsValue();
-		// Only validate if confirm password has a value
-		if (confirmPassword && confirmPassword.trim()) {
-			const isValid = validatePassword();
-			setIsValidPassword(isValid);
-			setConfirmPasswordError(!isValid);
-		}
-	};
-
-	const handleConfirmPasswordBlur = (): void => {
-		const { password, confirmPassword } = form.getFieldsValue();
-		if (
-			password &&
-			password.trim() &&
-			confirmPassword &&
-			confirmPassword.trim()
-		) {
-			const isValid = validatePassword();
-			setIsValidPassword(isValid);
-			setConfirmPasswordError(!isValid);
-		}
-	};
-
-	const handleSubmit = (): void => {
-		const isValid = validatePassword();
-		setIsValidPassword(isValid);
-
-		if (token) {
-			handleFormSubmit();
-		}
-	};
-
 	return (
 		<AuthPageContainer>
 			<div className="reset-password-card">
@@ -158,6 +100,7 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 				<FormContainer
 					form={form}
 					onFinish={handleSubmit}
+					onValuesChange={handleValuesChange}
 					className="reset-password-form"
 				>
 					<div className="reset-password-form-container">
@@ -171,8 +114,6 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 								>
 									<AntdInput.Password
 										tabIndex={0}
-										onChange={handleValuesChange}
-										onBlur={handlePasswordBlur}
 										id="password"
 										data-testid="password"
 										placeholder="Enter new password"
@@ -189,8 +130,7 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 									rules={[{ required: true, message: 'Please enter confirm password!' }]}
 								>
 									<AntdInput.Password
-										onChange={handleValuesChange}
-										onBlur={handleConfirmPasswordBlur}
+										onBlur={(): void => setConfirmPasswordTouched(true)}
 										id="confirmPassword"
 										data-testid="confirmPassword"
 										placeholder="Confirm your new password"
@@ -201,7 +141,7 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 						</div>
 					</div>
 
-					{confirmPasswordError && (
+					{showPasswordMismatchError && (
 						<Callout
 							type="error"
 							size="small"
@@ -213,7 +153,7 @@ function ResetPassword({ version }: ResetPasswordProps): JSX.Element {
 						</Callout>
 					)}
 
-					{errorMessage && !confirmPasswordError && (
+					{errorMessage && !showPasswordMismatchError && (
 						<AuthError error={errorMessage} />
 					)}