test(app): reproduce cursor separation on unequal restore sizes

Replay a 41-row shell restore into both 41-row and 35-row native emulators. The smaller replay leaves the cursor six rows below the prompt after the viewport grows. This intentionally failing reproduction preserves the unresolved restore sizing defect for investigation.

packages/app/src/terminal/native-renderer/headless-terminal-output-drain.test.ts

@@ -107,7 +107,7 @@ function createScreenRestorer(
 
   return {
     async restore(snapshot: Awaited<ReturnType<typeof benchmarkSnapshot>>) {
-      drain.restoreSnapshot(snapshot);
+      drain.restoreText(renderTerminalSnapshotToAnsi(snapshot));
       await drain.flush();
       frameRecorder.frames[0]?.();
       return screen;
@@ -116,6 +116,38 @@ function createScreenRestorer(
 }
 
 describe("native terminal output drain", () => {
+  test.each([41, 35])(
+    "keeps a restored shell cursor beside its prompt after replay at %i rows",
+    async (rows) => {
+      const source = createNativeHeadlessTerminal({ rows: 41, cols: 49 });
+      await source.write(Array.from({ length: 16 }, (_, i) => `probe ${i}\r\n`).join("") + "$ ");
+      const snapshot = source.getState();
+      const terminal = createNativeHeadlessTerminal({ rows, cols: 49 });
+      const frameRecorder = createFrameRecorder();
+      const drain = createNativeTerminalOutputDrain({
+        write: (chunk) => terminal.write(chunk),
+        reset: () => terminal.reset(),
+        getViewportState: () => terminal.getViewportState(),
+        onPaint: () => {},
+        scheduleFrame: frameRecorder.scheduleFrame,
+        cancelFrame: frameRecorder.cancelFrame,
+      });
+      try {
+        drain.restoreText(renderTerminalSnapshotToAnsi(snapshot));
+        await drain.flush();
+        terminal.resize({ rows: 41, cols: 49 });
+        const restored = terminal.getState();
+        const promptRow = restored.grid.findIndex((row) => rowText(row) === "$ ".trimEnd());
+        expect(promptRow).toBeGreaterThanOrEqual(0);
+        expect(restored.cursor).toEqual({ row: promptRow, col: 2 });
+      } finally {
+        drain.dispose();
+        terminal.dispose();
+        source.dispose();
+      }
+    },
+  );
+
   test("drains large bursts without waiting one frame per 2KB parse slice", async () => {
     const writes: string[] = [];
     const parseSamples: Array<{ parsedChars: number; queuedChars: number }> = [];