diff --git a/src/textual_webterm/local_server.py b/src/textual_webterm/local_server.py
index fba0305..b4a0bb7 100644
--- a/src/textual_webterm/local_server.py
+++ b/src/textual_webterm/local_server.py
@@ -366,11 +366,13 @@ class LocalServer:
         self._websocket_connections[route_key] = ws
 
         session_id = self.session_manager.routes.get(RouteKey(route_key))
+        session = None
         if session_id is not None:
             session = self.session_manager.get_session(session_id)
             if session is None or not session.is_running():
                 self.session_manager.on_session_end(session_id)
                 session_id = None
+                session = None
             else:
                 # Force terminal redraw on reconnect to avoid blank screen
                 if hasattr(session, 'force_redraw'):
@@ -378,8 +380,14 @@ class LocalServer:
                 if hasattr(session, 'send_bytes'):
                     await session.send_bytes(CLEAR_AND_REDRAW_SEQ.encode('utf-8'))
 
+
         session_created = session_id is not None
 
+        if session_created and session is not None and hasattr(session, 'get_replay_buffer'):
+            replay = await session.get_replay_buffer()
+            if replay:
+                await ws.send_bytes(replay)
+
         try:
             async for msg in ws:
                 if msg.type == WSMsgType.TEXT:
@@ -853,12 +861,14 @@ class LocalServer:
         return web.Response(text=html_content, content_type="text/html")
 
     async def handle_session_data(self, route_key: RouteKey, data: bytes) -> None:
+        self.mark_route_activity(str(route_key))
         ws = self._websocket_connections.get(route_key)
         if ws is None:
             return
         await ws.send_bytes(data)
 
     async def handle_binary_message(self, route_key: RouteKey, payload: bytes) -> None:
+        self.mark_route_activity(str(route_key))
         ws = self._websocket_connections.get(route_key)
         if ws is None:
             return
diff --git a/tests/test_local_server_unit.py b/tests/test_local_server_unit.py
index adc1af0..1bd64e8 100644
--- a/tests/test_local_server_unit.py
+++ b/tests/test_local_server_unit.py
@@ -694,7 +694,17 @@ class TestLocalServerMoreCoverage:
         assert queue.get_nowait() == "existing"
 
     @pytest.mark.asyncio
-    async def test_mark_route_activity_triggers_notification(self, server_with_no_apps):
+    async def test_handle_session_data_marks_activity(self, server_with_no_apps, monkeypatch):
+        ws = MagicMock()
+        ws.send_bytes = AsyncMock()
+        server_with_no_apps._websocket_connections["rk"] = ws
+        server_with_no_apps._route_last_activity["rk"] = 0.0
+
+        await server_with_no_apps.handle_session_data("rk", b"data")
+        assert server_with_no_apps._route_last_activity["rk"] > 0.0
+        ws.send_bytes.assert_awaited_once_with(b"data")
+
+    def test_mark_route_activity_triggers_notification(self, server_with_no_apps):
         """Test that mark_route_activity triggers SSE notification."""
         import asyncio
 
diff --git a/tests/test_local_server_websocket_integration.py b/tests/test_local_server_websocket_integration.py
index 53a9ef4..d574941 100644
--- a/tests/test_local_server_websocket_integration.py
+++ b/tests/test_local_server_websocket_integration.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import json
+from unittest.mock import AsyncMock
 
 import pytest
 from aiohttp import WSMsgType, web
@@ -59,9 +60,16 @@ async def test_websocket_creates_session_on_resize(tmp_path):
     server.session_manager.routes["test"] = "sid"
     server.session_manager.sessions["sid"] = DummySession()
 
+    # Replay buffer should be sent on reconnect
+    replay_session = server.session_manager.sessions["sid"]
+    replay_session.get_replay_buffer = AsyncMock(return_value=b"replay")
+
     client = await _make_client(server)
     try:
         ws = await client.ws_connect("/ws/test")
+        msg = await ws.receive(timeout=1)
+        assert msg.type == WSMsgType.BINARY
+        assert msg.data == b"replay"
         await ws.close()
     finally:
         await client.close()