diff --git a/tests/integrations/conftest.py b/tests/integrations/conftest.py
index 833e272b27..4671872356 100644
--- a/tests/integrations/conftest.py
+++ b/tests/integrations/conftest.py
@@ -1,8 +1,24 @@
 """Shared test helpers for integration tests."""
 
+import pytest
+
 from specify_cli.integrations.base import MarkdownIntegration
 
 
+@pytest.fixture(autouse=True)
+def _isolate_integration_home(monkeypatch: pytest.MonkeyPatch, tmp_path):
+    """Keep integration tests from reading or writing the real user home."""
+    home = tmp_path / "home"
+    for path in (home, home / ".cache", home / ".config", home / ".local" / "share"):
+        path.mkdir(parents=True, exist_ok=True)
+
+    monkeypatch.setenv("HOME", str(home))
+    monkeypatch.setenv("USERPROFILE", str(home))
+    monkeypatch.setenv("XDG_CACHE_HOME", str(home / ".cache"))
+    monkeypatch.setenv("XDG_CONFIG_HOME", str(home / ".config"))
+    monkeypatch.setenv("XDG_DATA_HOME", str(home / ".local" / "share"))
+
+
 class StubIntegration(MarkdownIntegration):
     """Minimal concrete integration for testing."""
 
diff --git a/tests/integrations/test_home_isolation.py b/tests/integrations/test_home_isolation.py
new file mode 100644
index 0000000000..e79ff5dff6
--- /dev/null
+++ b/tests/integrations/test_home_isolation.py
@@ -0,0 +1,21 @@
+"""Regression tests for integration-test environment isolation."""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+
+def test_integration_tests_use_tmp_home(tmp_path: Path) -> None:
+    home = tmp_path / "home"
+
+    assert Path(os.environ["HOME"]) == home
+    assert Path(os.environ["USERPROFILE"]) == home
+    assert Path(os.environ["XDG_CACHE_HOME"]) == home / ".cache"
+    assert Path(os.environ["XDG_CONFIG_HOME"]) == home / ".config"
+    assert Path(os.environ["XDG_DATA_HOME"]) == home / ".local" / "share"
+
+    assert home.is_dir()
+    assert (home / ".cache").is_dir()
+    assert (home / ".config").is_dir()
+    assert (home / ".local" / "share").is_dir()