fix: optimize request function call in withRetry and add integration test for POST body cache key update

Author: MattCCC

src/retry-handler.ts

@@ -140,7 +140,10 @@ export async function withRetry<
       }
     }
 
-    output = await requestFn(true, attempt); // isStaleRevalidation=false, isFirstAttempt=attempt===0
+    // Performance optimization: Call the request function with the current attempt number
+    // If this is the first attempt, we pass `isStaleRevalidation` as `false`,
+    // otherwise we pass `true` to indicate that this is a stale revalidation (no cache hit).
+    output = await requestFn(attempt > 0, attempt);
     const error = output.error;
 
     // Check if we should retry based on successful response

test/react/integration/post-body-cache-key.spec.tsx

@@ -0,0 +1,67 @@
+/**
+ * @jest-environment jsdom
+ */
+import { useState } from 'react';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { mockFetchResponse } from '../../utils/mockFetchResponse';
+import { useFetcher } from '../../../src/react/index';
+
+describe('POST body cache key update and refetch', () => {
+  it('uses new body on refetch, keeps static cache key, and updates UI state', async () => {
+    mockFetchResponse('/api/user', {
+      ok: true,
+      status: 200,
+      body: { echoed: { name: 'Alice' } },
+    });
+
+    function TestComponent() {
+      const [name, setName] = useState('Alice');
+      const { data, refetch, isLoading, isFetching, config } = useFetcher(
+        '/api/user',
+        {
+          method: 'POST',
+          body: { name },
+          cacheKey: '/api/user',
+          immediate: true,
+          retry: { retries: 5, delay: 1000, backoff: 2 },
+        },
+      );
+      return (
+        <div>
+          <div data-testid="result">{data?.echoed?.name}</div>
+          <div data-testid="config">{JSON.stringify(config)}</div>
+          <div data-testid="loading">{isLoading ? 'loading' : 'idle'}</div>
+          <div data-testid="fetching">{isFetching ? 'fetching' : 'idle'}</div>
+          <button onClick={() => setName('Bob')}>Change Name</button>
+          <button onClick={() => refetch()}>Refetch</button>
+        </div>
+      );
+    }
+
+    render(<TestComponent />);
+    await waitFor(() =>
+      expect(screen.getByTestId('result').textContent).toBe('Alice'),
+    );
+
+    mockFetchResponse('/api/user', {
+      ok: true,
+      status: 200,
+      body: { echoed: { name: 'Bob' } },
+    });
+    fireEvent.click(screen.getByText('Change Name'));
+    fireEvent.click(screen.getByText('Refetch'));
+    expect(screen.getByTestId('loading').textContent).toBe('loading');
+    expect(screen.getByTestId('fetching').textContent).toBe('fetching');
+    await waitFor(() =>
+      expect(screen.getByTestId('result').textContent).toBe('Bob'),
+    );
+    expect(screen.getByTestId('loading').textContent).toBe('idle');
+    expect(screen.getByTestId('fetching').textContent).toBe('idle');
+    expect(screen.getByTestId('config').textContent).toContain(
+      '"body":"{\\"name\\":\\"Bob\\"}"',
+    );
+    expect(screen.getByTestId('config').textContent).toContain(
+      '"cacheKey":"/api/user"',
+    );
+  });
+});