diff --git a/pyproject.toml b/pyproject.toml
index 3acb548..3426741 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -100,7 +100,6 @@ omit = [
     "*/tests/*",
     "*/__pycache__/*",
     # Integration-heavy modules that require running servers/processes
-    "*/local_server.py",
     "*/app_session.py",
     "*/terminal_session.py",
     "*/exit_poller.py",
@@ -116,5 +115,5 @@ exclude_lines = [
     "if __name__ == .__main__.:",
     "assert ",
 ]
-# Unit test coverage target - integration tests would add ~20% more
+# Unit test coverage target
 fail_under = 80
diff --git a/src/textual_webterm/local_server.py b/src/textual_webterm/local_server.py
index 26d588d..ca0550b 100644
--- a/src/textual_webterm/local_server.py
+++ b/src/textual_webterm/local_server.py
@@ -8,7 +8,6 @@ import hashlib
 import io
 import json
 import logging
-import re
 import signal
 from pathlib import Path
 from typing import TYPE_CHECKING
@@ -38,12 +37,6 @@ SCREENSHOT_MAX_BYTES = 65536
 SCREENSHOT_CACHE_SECONDS = 1.0
 SCREENSHOT_MAX_CACHE_SECONDS = 60.0
 
-SVG_MONO_FONT_STACK = (
-    'ui-monospace, "SFMono-Regular", "FiraCode Nerd Font", "FiraMono Nerd Font", '
-    '"Fira Code", "Roboto Mono", Menlo, Monaco, Consolas, "Liberation Mono", '
-    '"DejaVu Sans Mono", "Courier New", monospace'
-)
-
 WEBTERM_STATIC_PATH = Path(__file__).parent / "static"
 
 
@@ -91,22 +84,6 @@ class LocalClientConnector(SessionConnector):
         await self.server.handle_session_close(self.session_id, self.route_key)
 
 
-def _rewrite_svg_fonts(svg: str) -> str:
-    """Make Rich SVG output self-contained and aligned with our monospace styling."""
-
-    # Rich export_svg embeds @font-face rules that reference external CDNs.
-    svg = re.sub(r"@font-face\s*\{.*?\}\s*", "", svg, flags=re.DOTALL)
-
-    # Force our local monospace stack even if Rich sets font-family to Fira Code.
-    override = f"\ntext {{ font-family: {SVG_MONO_FONT_STACK} !important; }}\n"
-    if "</style>" in svg:
-        svg = svg.replace("</style>", override + "</style>", 1)
-    else:
-        svg = svg.replace("<svg ", f"<svg><style>{override}</style> ", 1)
-
-    return svg
-
-
 def _apply_carriage_returns(text: str) -> list[str]:
     """Interpret \r as 'return to start of line' (overwrite), not a newline.
 
@@ -133,22 +110,6 @@ class LocalServer:
     def mark_route_activity(self, route_key: str) -> None:
         self._route_last_activity[route_key] = asyncio.get_event_loop().time()
 
-    def _get_cached_screenshot_response(
-        self, request: web.Request, route_key: str
-    ) -> web.Response | None:
-        cached = self._screenshot_cache.get(route_key)
-        if cached is None:
-            return None
-
-        etag = self._screenshot_cache_etag.get(route_key)
-        if etag and request.headers.get("If-None-Match") == etag:
-            raise web.HTTPNotModified(headers={"ETag": etag, "Cache-Control": "no-cache"})
-
-        headers = {"Cache-Control": "no-cache"}
-        if etag:
-            headers["ETag"] = etag
-        return web.Response(text=cached[1], content_type="image/svg+xml", headers=headers)
-
     def _get_screenshot_cache_ttl(self, route_key: str, now: float) -> float:
         last_activity = self._route_last_activity.get(route_key, 0.0)
         idle_for = max(0.0, now - last_activity)
@@ -196,7 +157,6 @@ class LocalServer:
         self._screenshot_cache_etag: dict[str, str] = {}
         self._screenshot_locks: dict[str, asyncio.Lock] = {}
         self._route_last_activity: dict[str, float] = {}
-        self._screenshot_last_rendered_activity: dict[str, float] = {}
 
     @property
     def app_count(self) -> int:
@@ -328,14 +288,12 @@ class LocalServer:
         msg_type = envelope[0]
 
         if msg_type == "stdin":
-            self.mark_route_activity(route_key)
             data = envelope[1] if len(envelope) > 1 else ""
             session_process = self.session_manager.get_session_by_route_key(RouteKey(route_key))
             if session_process:
                 await session_process.send_bytes(data.encode("utf-8"))
 
         elif msg_type == "resize":
-            self.mark_route_activity(route_key)
             size_data = envelope[1] if len(envelope) > 1 else {}
             width = max(1, min(500, int(size_data.get("width", 80))))
             height = max(1, min(500, int(size_data.get("height", 24))))
@@ -464,15 +422,6 @@ class LocalServer:
         if session_process is None or not hasattr(session_process, "get_replay_buffer"):
             raise web.HTTPNotFound(text="Session not found")
 
-        # If nothing has changed since the last render, serve cached screenshot without
-        # touching the session replay buffer.
-        last_activity = self._route_last_activity.get(route_key, 0.0)
-        last_rendered_activity = self._screenshot_last_rendered_activity.get(route_key, -1.0)
-        if last_activity <= last_rendered_activity:
-            cached_response = self._get_cached_screenshot_response(request, route_key)
-            if cached_response is not None:
-                return cached_response
-
         replay_data = await session_process.get_replay_buffer()  # type: ignore[func-returns-value]
         if len(replay_data) > SCREENSHOT_MAX_BYTES:
             replay_data = replay_data[-SCREENSHOT_MAX_BYTES:]
@@ -498,17 +447,16 @@ class LocalServer:
         ttl = self._get_screenshot_cache_ttl(route_key, now)
         cached = self._screenshot_cache.get(route_key)
 
-        # If we have a cached screenshot and the session is idle, keep serving it until
-        # new activity occurs (no periodic re-render).
-        if cached is not None and self._route_last_activity.get(route_key, 0.0) == 0.0:
-            cached_response = self._get_cached_screenshot_response(request, route_key)
-            if cached_response is not None:
-                return cached_response
+        if cached is not None:
+            etag = self._screenshot_cache_etag.get(route_key)
+            if etag and request.headers.get("If-None-Match") == etag:
+                raise web.HTTPNotModified(headers={"ETag": etag, "Cache-Control": "no-cache"})
 
-        if cached is not None and (now - cached[0]) < ttl:
-            cached_response = self._get_cached_screenshot_response(request, route_key)
-            if cached_response is not None:
-                return cached_response
+            if (now - cached[0]) < ttl:
+                headers = {"Cache-Control": "no-cache"}
+                if etag:
+                    headers["ETag"] = etag
+                return web.Response(text=cached[1], content_type="image/svg+xml", headers=headers)
 
         lock = self._screenshot_locks.get(route_key)
         if lock is None:
@@ -519,10 +467,15 @@ class LocalServer:
             # Another request may have refreshed the cache while we waited.
             ttl = self._get_screenshot_cache_ttl(route_key, now)
             cached = self._screenshot_cache.get(route_key)
-            if cached is not None and (now - cached[0]) < ttl:
-                cached_response = self._get_cached_screenshot_response(request, route_key)
-                if cached_response is not None:
-                    return cached_response
+            etag = self._screenshot_cache_etag.get(route_key)
+            if cached is not None:
+                if etag and request.headers.get("If-None-Match") == etag:
+                    raise web.HTTPNotModified(headers={"ETag": etag, "Cache-Control": "no-cache"})
+                if (now - cached[0]) < ttl:
+                    headers = {"Cache-Control": "no-cache"}
+                    if etag:
+                        headers["ETag"] = etag
+                    return web.Response(text=cached[1], content_type="image/svg+xml", headers=headers)
 
             def _render_svg() -> str:
                 console = Console(record=True, width=width, height=height, file=io.StringIO())
@@ -552,13 +505,9 @@ class LocalServer:
                 )
 
             svg = await asyncio.to_thread(_render_svg)
-            svg = _rewrite_svg_fonts(svg)
             etag = hashlib.sha1(svg.encode("utf-8"), usedforsecurity=False).hexdigest()
             self._screenshot_cache[route_key] = (asyncio.get_event_loop().time(), svg)
             self._screenshot_cache_etag[route_key] = etag
-            self._screenshot_last_rendered_activity[route_key] = self._route_last_activity.get(
-                route_key, 0.0
-            )
             headers = {"Cache-Control": "no-cache", "ETag": etag}
             return web.Response(text=svg, content_type="image/svg+xml", headers=headers)
 
diff --git a/tests/test_local_server_unit.py b/tests/test_local_server_unit.py
index 17e32a6..a04157a 100644
--- a/tests/test_local_server_unit.py
+++ b/tests/test_local_server_unit.py
@@ -6,7 +6,12 @@ import pytest
 from aiohttp import web
 
 from textual_webterm.config import App, Config
-from textual_webterm.local_server import LocalServer, _apply_carriage_returns
+from textual_webterm.local_server import (
+    LocalClientConnector,
+    LocalServer,
+    _apply_carriage_returns,
+    _rewrite_svg_fonts,
+)
 
 
 class TestGetStaticPath:
@@ -369,3 +374,251 @@ class TestWebSocketProtocol:
         assert ping[0] == "ping"
         assert pong[0] == "pong"
         assert ping[1] == pong[1]
+
+
+class TestLocalServerMoreCoverage:
+    @pytest.fixture
+    def server_with_no_apps(self, tmp_path):
+        config = Config(apps=[])
+        config_file = tmp_path / "config.toml"
+        config_file.write_text("")
+        return LocalServer(config_path=str(config_file), config=config, host="localhost", port=8080)
+
+    @pytest.mark.asyncio
+    async def test_handle_health_check(self, server_with_no_apps):
+        resp = await server_with_no_apps._handle_health_check(MagicMock())
+        assert resp.text == "Local server is running"
+
+    def test_select_app_for_route_picks_default(self, server_with_no_apps, monkeypatch):
+        default_app = App(name="D", slug="d", path=".", command="echo d", terminal=True)
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_default_app", lambda: default_app)
+        assert server_with_no_apps._select_app_for_route("missing") == default_app
+
+    @pytest.mark.asyncio
+    async def test_handle_session_data_no_ws_noop(self, server_with_no_apps):
+        await server_with_no_apps.handle_session_data("rk", b"data")
+
+    @pytest.mark.asyncio
+    async def test_handle_session_data_sends_bytes(self, server_with_no_apps):
+        ws = MagicMock()
+        ws.send_bytes = AsyncMock()
+        server_with_no_apps._websocket_connections["rk"] = ws
+        await server_with_no_apps.handle_session_data("rk", b"data")
+        ws.send_bytes.assert_awaited_once_with(b"data")
+
+    @pytest.mark.asyncio
+    async def test_handle_binary_message_sends_bytes(self, server_with_no_apps):
+        ws = MagicMock()
+        ws.send_bytes = AsyncMock()
+        server_with_no_apps._websocket_connections["rk"] = ws
+        await server_with_no_apps.handle_binary_message("rk", b"bin")
+        ws.send_bytes.assert_awaited_once_with(b"bin")
+
+    @pytest.mark.asyncio
+    async def test_handle_session_close_ends_session_and_closes_ws(self, server_with_no_apps, monkeypatch):
+        ws = MagicMock()
+        ws.close = AsyncMock()
+        server_with_no_apps._websocket_connections["rk"] = ws
+        monkeypatch.setattr(server_with_no_apps.session_manager, "on_session_end", MagicMock())
+        await server_with_no_apps.handle_session_close("sid", "rk")
+        server_with_no_apps.session_manager.on_session_end.assert_called_once_with("sid")
+        ws.close.assert_awaited_once()
+
+    def test_force_exit_sets_event(self, server_with_no_apps):
+        assert not server_with_no_apps.exit_event.is_set()
+        server_with_no_apps.force_exit()
+        assert server_with_no_apps.exit_event.is_set()
+
+    def test_get_static_path_import_error_returns_none(self, monkeypatch):
+        import builtins
+
+        from textual_webterm.local_server import _get_static_path
+
+        real_import = builtins.__import__
+
+        def fake_import(name, globals=None, locals=None, fromlist=(), level=0):
+            if name == "textual_serve":
+                raise ImportError("nope")
+            return real_import(name, globals, locals, fromlist, level)
+
+        monkeypatch.setattr(builtins, "__import__", fake_import)
+        assert _get_static_path() is None
+
+    def test_add_terminal_windows_noop(self, server_with_no_apps, monkeypatch):
+        from textual_webterm import constants as constants_mod
+
+        monkeypatch.setattr(constants_mod, "WINDOWS", True)
+        server_with_no_apps.add_terminal("T", "cmd", "slug")
+        assert "slug" not in server_with_no_apps.session_manager.apps_by_slug
+
+    @pytest.mark.asyncio
+    async def test_handle_screenshot_404_when_no_running_session(self, server_with_no_apps, monkeypatch):
+        request = MagicMock()
+        request.query = {}
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_first_running_session", lambda: None)
+        with pytest.raises(web.HTTPNotFound):
+            await server_with_no_apps._handle_screenshot(request)
+
+    @pytest.mark.asyncio
+    async def test_handle_screenshot_404_when_session_missing_buffer(self, server_with_no_apps, monkeypatch):
+        request = MagicMock()
+        request.query = {"route_key": "rk"}
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_session_by_route_key", lambda _rk: object())
+        with pytest.raises(web.HTTPNotFound):
+            await server_with_no_apps._handle_screenshot(request)
+
+    @pytest.mark.asyncio
+    async def test_get_ws_url_falls_back_when_no_host_header(self, server_with_no_apps):
+        request = MagicMock()
+        request.headers = {}
+        request.secure = False
+        url = server_with_no_apps._get_ws_url_from_request(request, "rk")
+        assert url.startswith("ws://")
+
+    @pytest.mark.asyncio
+    async def test_root_terminal_page_includes_assets_and_dataset(self, server_with_no_apps, monkeypatch):
+        server_with_no_apps.session_manager.apps_by_slug["rk"] = App(
+            name="Known",
+            slug="rk",
+            path=".",
+            command="echo",
+            terminal=True,
+        )
+        request = MagicMock()
+        request.query = {"route_key": "rk"}
+        request.headers = {"Host": "localhost:8080"}
+        request.secure = False
+
+        resp = await server_with_no_apps._handle_root(request)
+        assert "/static/css/xterm.css" in resp.text
+        assert "/static-webterm/monospace.css" in resp.text
+        assert "data-session-websocket-url" in resp.text
+        assert "data-font-size" in resp.text
+
+    def test_rewrite_svg_fonts_removes_font_face_and_forces_stack(self):
+        svg = (
+            '<svg xmlns="http://www.w3.org/2000/svg">'
+            '<style>@font-face{src:url(https://cdnjs.cloudflare.com/x);} text{font-family:Fira Code;}</style>'
+            '<text>hi</text>'
+            '</svg>'
+        )
+        out = _rewrite_svg_fonts(svg)
+        assert "@font-face" not in out
+        assert "cdnjs.cloudflare.com" not in out
+        assert "ui-monospace" in out
+
+    def test_rewrite_svg_fonts_injects_style_if_missing(self):
+        svg = '<svg xmlns="http://www.w3.org/2000/svg"><text>hi</text></svg>'
+        out = _rewrite_svg_fonts(svg)
+        assert "ui-monospace" in out
+
+    @pytest.mark.asyncio
+    async def test_cached_screenshot_etag_returns_304(self, server_with_no_apps):
+        request = MagicMock()
+        request.headers = {"If-None-Match": "abc"}
+        server_with_no_apps._screenshot_cache["rk"] = (0.0, "<svg></svg>")
+        server_with_no_apps._screenshot_cache_etag["rk"] = "abc"
+
+        with pytest.raises(web.HTTPNotModified):
+            server_with_no_apps._get_cached_screenshot_response(request, "rk")
+
+    @pytest.mark.asyncio
+    async def test_cached_screenshot_etag_sets_headers(self, server_with_no_apps):
+        request = MagicMock()
+        request.headers = {}
+        server_with_no_apps._screenshot_cache["rk"] = (0.0, "<svg></svg>")
+        server_with_no_apps._screenshot_cache_etag["rk"] = "abc"
+
+        resp = server_with_no_apps._get_cached_screenshot_response(request, "rk")
+        assert resp is not None
+        assert resp.headers.get("ETag") == "abc"
+
+    def test_screenshot_cache_ttl_backs_off(self, server_with_no_apps, monkeypatch):
+        # Drive each tier by controlling now and last_activity.
+        server_with_no_apps._route_last_activity["rk"] = 99.0
+        assert server_with_no_apps._get_screenshot_cache_ttl("rk", now=100.0) == 1.0
+        assert server_with_no_apps._get_screenshot_cache_ttl("rk", now=110.0) == 5.0
+        assert server_with_no_apps._get_screenshot_cache_ttl("rk", now=200.0) == 15.0
+        assert server_with_no_apps._get_screenshot_cache_ttl("rk", now=1000.0) == 60.0
+
+    @pytest.mark.asyncio
+    async def test_handle_screenshot_uses_cache_when_no_new_activity(self, server_with_no_apps, monkeypatch):
+        request = MagicMock()
+        request.query = {"route_key": "rk"}
+        request.headers = {}
+
+        session = MagicMock()
+        session.get_replay_buffer = AsyncMock(return_value=b"SHOULD_NOT_BE_READ")
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_session_by_route_key", lambda _rk: session)
+
+        server_with_no_apps._screenshot_cache["rk"] = (0.0, "<svg>cached</svg>")
+        server_with_no_apps._screenshot_cache_etag["rk"] = "etag"
+        server_with_no_apps._route_last_activity["rk"] = 5.0
+        server_with_no_apps._screenshot_last_rendered_activity["rk"] = 5.0
+
+        resp = await server_with_no_apps._handle_screenshot(request)
+        assert "cached" in resp.text
+        session.get_replay_buffer.assert_not_awaited()
+
+    @pytest.mark.asyncio
+    async def test_handle_screenshot_invalid_width_height_defaults(self, server_with_no_apps, monkeypatch):
+        request = MagicMock()
+        request.query = {"route_key": "rk", "width": "nope", "height": "nope"}
+        request.headers = {}
+
+        session = MagicMock()
+        session.get_replay_buffer = AsyncMock(return_value=b"hello\n")
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_session_by_route_key", lambda _rk: session)
+
+        resp = await server_with_no_apps._handle_screenshot(request)
+        assert resp.content_type == "image/svg+xml"
+        assert "<svg" in resp.text
+
+    @pytest.mark.asyncio
+    async def test_handle_root_no_apps_available(self, server_with_no_apps):
+        request = MagicMock()
+        request.query = {}
+        resp = await server_with_no_apps._handle_root(request)
+        assert "No Apps Available" in resp.text
+
+    @pytest.mark.asyncio
+    async def test_dispatch_ws_message_ping_sends_pong(self, server_with_no_apps):
+        ws = MagicMock()
+        ws.send_json = AsyncMock()
+        created = await server_with_no_apps._dispatch_ws_message(["ping", "x"], "rk", ws, False)
+        assert created is False
+        ws.send_json.assert_awaited_once_with(["pong", "x"])
+
+    @pytest.mark.asyncio
+    async def test_dispatch_ws_message_stdin_sends_bytes_to_session(self, server_with_no_apps, monkeypatch):
+        session = MagicMock()
+        session.send_bytes = AsyncMock()
+        monkeypatch.setattr(server_with_no_apps.session_manager, "get_session_by_route_key", lambda _rk: session)
+
+        ws = MagicMock()
+        created = await server_with_no_apps._dispatch_ws_message(["stdin", "hi"], "rk", ws, False)
+        assert created is False
+        session.send_bytes.assert_awaited_once_with(b"hi")
+
+    @pytest.mark.asyncio
+    async def test_connector_methods_forward_to_server(self):
+        server = MagicMock()
+        server.mark_route_activity = MagicMock()
+        server.handle_session_data = AsyncMock()
+        server.handle_binary_message = AsyncMock()
+        server.handle_session_close = AsyncMock()
+
+        connector = LocalClientConnector(server, "sid", "rk")
+        await connector.on_data(b"data")
+        server.mark_route_activity.assert_called_once_with("rk")
+        server.handle_session_data.assert_awaited_once_with("rk", b"data")
+
+        await connector.on_meta({"type": "open_url", "url": "https://example.com"})
+        await connector.on_meta({"type": "deliver_file_start", "path": "/tmp/x"})
+        await connector.on_meta({"type": "unknown"})
+
+        await connector.on_binary_encoded_message(b"bin")
+        server.handle_binary_message.assert_awaited_once_with("rk", b"bin")
+
+        await connector.on_close()
+        server.handle_session_close.assert_awaited_once_with("sid", "rk")
diff --git a/tests/test_local_server_websocket_integration.py b/tests/test_local_server_websocket_integration.py
new file mode 100644
index 0000000..4286bd7
--- /dev/null
+++ b/tests/test_local_server_websocket_integration.py
@@ -0,0 +1,84 @@
+from __future__ import annotations
+
+import json
+
+import pytest
+from aiohttp import WSMsgType, web
+from aiohttp.test_utils import TestClient, TestServer
+
+from textual_webterm.config import App, Config
+from textual_webterm.local_server import LocalServer
+
+
+async def _make_client(server: LocalServer) -> TestClient:
+    app = web.Application()
+    app.add_routes(server._build_routes())
+    test_server = TestServer(app)
+    client = TestClient(test_server)
+    await client.start_server()
+    return client
+
+
+@pytest.mark.asyncio
+async def test_websocket_creates_session_on_resize(tmp_path):
+    config = Config(apps=[App(name="Test", slug="test", path=".", command="echo test", terminal=True)])
+    config_file = tmp_path / "config.toml"
+    config_file.write_text("")
+    server = LocalServer(config_path=str(config_file), config=config)
+
+    # Avoid spawning any real processes.
+    created = {"args": None}
+
+    async def fake_create(route_key: str, width: int, height: int) -> None:
+        created["args"] = (route_key, width, height)
+
+    server._create_terminal_session = fake_create  # type: ignore[method-assign]
+
+    client = await _make_client(server)
+    try:
+        ws = await client.ws_connect("/ws/test")
+        await ws.send_str(json.dumps(["resize", {"width": 90, "height": 25}]))
+        await ws.close()
+    finally:
+        await client.close()
+
+    assert created["args"] == ("test", 90, 25)
+
+
+@pytest.mark.asyncio
+async def test_websocket_ping_pong(tmp_path):
+    config = Config(apps=[App(name="Test", slug="test", path=".", command="echo test", terminal=True)])
+    config_file = tmp_path / "config.toml"
+    config_file.write_text("")
+    server = LocalServer(config_path=str(config_file), config=config)
+
+    client = await _make_client(server)
+    try:
+        ws = await client.ws_connect("/ws/test")
+        await ws.send_str(json.dumps(["ping", "123"]))
+
+        msg = await ws.receive(timeout=1)
+        assert msg.type == WSMsgType.TEXT
+        assert json.loads(msg.data) == ["pong", "123"]
+
+        await ws.close()
+    finally:
+        await client.close()
+
+
+@pytest.mark.asyncio
+async def test_websocket_ignores_invalid_envelopes(tmp_path):
+    config = Config(apps=[App(name="Test", slug="test", path=".", command="echo test", terminal=True)])
+    config_file = tmp_path / "config.toml"
+    config_file.write_text("")
+    server = LocalServer(config_path=str(config_file), config=config)
+
+    client = await _make_client(server)
+    try:
+        ws = await client.ws_connect("/ws/test")
+        await ws.send_str("not json")
+        await ws.send_str(json.dumps({"not": "a list"}))
+        await ws.send_str(json.dumps([]))
+        await ws.close()
+    finally:
+        await client.close()