diff --git a/tests/unit/__init__.py b/tests/unit/__init__.py
index e69de29..da5784b 100644
--- a/tests/unit/__init__.py
+++ b/tests/unit/__init__.py
@@ -0,0 +1,37 @@
+"""Unit-test package init.
+
+Isolates ``HOME`` to a throwaway directory for the entire unit suite so
+no test ever reads or writes the real ``~/.bot-bottle`` (state, queue,
+and audit dirs all derive from ``supervise.bot_bottle_root()`` →
+``Path.home()``). Without this, a test that takes a ``flock`` on the
+real audit log can **block indefinitely** when a live bottle's supervise
+sidecar holds that lock — observed as a hung ``coverage run`` at 0% CPU —
+and unisolated tests otherwise pollute the developer's home dir.
+
+Individual tests that need their own ``HOME`` still override
+``os.environ['HOME']`` and restore it; they now restore to this isolated
+dir rather than the real one, so isolation holds either way. Tests that
+patch ``supervise.bot_bottle_root`` directly are unaffected.
+"""
+
+from __future__ import annotations
+
+import atexit
+import os
+import shutil
+import tempfile
+
+_real_home = os.environ.get("HOME")
+_tmp_home = tempfile.mkdtemp(prefix="bot-bottle-unit-home.")
+os.environ["HOME"] = _tmp_home
+
+
+def _restore_home() -> None:
+    if _real_home is None:
+        os.environ.pop("HOME", None)
+    else:
+        os.environ["HOME"] = _real_home
+    shutil.rmtree(_tmp_home, ignore_errors=True)
+
+
+atexit.register(_restore_home)