diff --git a/meshchatx.rsm b/meshchatx.rsm
index 5b0847f0..6d932af4 100644
Binary files a/meshchatx.rsm and b/meshchatx.rsm differ
diff --git a/pyproject.toml b/pyproject.toml
index f1e0835b..69863c4e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -129,9 +129,31 @@ parallel = true
 
 [tool.mutmut]
 paths_to_mutate = ["meshchatx/src/backend/"]
+# mutmut copies only paths_to_mutate into mutants/, then pytest runs from that
+# directory. meshchatx/ then shadows the installed package as a namespace
+# package, so these non-backend modules must be copied too.
+also_copy = [
+    "meshchatx/__init__.py",
+    "meshchatx/android_codec2.py",
+    "meshchatx/android_push_bridge.py",
+    "meshchatx/meshchat.py",
+    "meshchatx/pycodec2_ctypes.py",
+    "meshchatx/repository_http_standalone.py",
+    "meshchatx/src/__init__.py",
+    "meshchatx/src/build_meta.py",
+    "meshchatx/src/env_utils.py",
+    "meshchatx/src/path_utils.py",
+    "meshchatx/src/ssl_self_signed.py",
+    "meshchatx/src/version.py",
+]
+pytest_add_cli_args = [
+    "-m",
+    "not integration and not long_running and not eect and not lxst_real and not live_validation",
+]
 pytest_add_cli_args_test_selection = [
     "tests/backend/",
     "--ignore=tests/backend/test_performance_hotpaths.py",
     "--ignore=tests/backend/test_memory_profiling.py",
     "--ignore=tests/backend/test_performance_bottlenecks.py",
+    "--ignore=tests/backend/eect",
 ]
diff --git a/tests/backend/test_mutmut_also_copy.py b/tests/backend/test_mutmut_also_copy.py
new file mode 100644
index 00000000..270fc54a
--- /dev/null
+++ b/tests/backend/test_mutmut_also_copy.py
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: 0BSD
+
+"""mutmut mutants/ must include meshchatx modules outside src/backend."""
+
+from __future__ import annotations
+
+import tomllib
+from pathlib import Path
+
+
+def _root() -> Path:
+    return Path(__file__).resolve().parents[2]
+
+
+def _mutmut_config() -> dict:
+    data = tomllib.loads((_root() / "pyproject.toml").read_text(encoding="utf-8"))
+    return data["tool"]["mutmut"]
+
+
+def _also_copy_covers(rel: Path, also_copy: list[str]) -> bool:
+    rel_s = rel.as_posix()
+    for item in also_copy:
+        normalized = item.rstrip("/")
+        if rel_s == item or rel_s == normalized:
+            return True
+        if rel_s.startswith(normalized + "/"):
+            return True
+    return False
+
+
+def test_mutmut_also_copy_covers_package_modules_outside_backend():
+    also_copy = list(_mutmut_config().get("also_copy", []))
+    root = _root()
+    required = sorted(
+        path
+        for path in (
+            list((root / "meshchatx").glob("*.py"))
+            + list((root / "meshchatx" / "src").glob("*.py"))
+        )
+        if path.name != "_build_meta_baked.py"
+    )
+    missing = [
+        path.relative_to(root).as_posix()
+        for path in required
+        if not _also_copy_covers(path.relative_to(root), also_copy)
+    ]
+    assert missing == []