diff --git a/backend/tests/_host_path_helpers.py b/backend/tests/_host_path_helpers.py
new file mode 100644
index 000000000..ed3648636
--- /dev/null
+++ b/backend/tests/_host_path_helpers.py
@@ -0,0 +1,14 @@
+"""Helpers for asserting on paths the codebase spells in host-native style.
+
+The provisioner's ``join_host_path`` deliberately preserves the host
+filesystem style (explicit ``PureWindowsPath`` branch), and
+``os.path.normpath`` re-spells POSIX inputs with backslashes on Windows, so
+hostPath volume strings, docker ``--mount`` args and ``PYTHONPATH`` entries
+carry ``\\`` on a Windows host where POSIX CI sees ``/``. Tests that match
+segments inside such strings normalize with :func:`posix_path` instead of
+hard-coding one separator; the replace is a no-op on POSIX inputs.
+"""
+
+
+def posix_path(path: str) -> str:
+    return path.replace("\\", "/")
diff --git a/backend/tests/test_provisioner_pvc_volumes.py b/backend/tests/test_provisioner_pvc_volumes.py
index ae7c1b7ca..bbc2f7732 100644
--- a/backend/tests/test_provisioner_pvc_volumes.py
+++ b/backend/tests/test_provisioner_pvc_volumes.py
@@ -1,6 +1,7 @@
 """Regression tests for provisioner three-way skills + PVC volume support."""
 
 import pytest
+from _host_path_helpers import posix_path
 
 
 def _thread_skill_mounts(
@@ -39,7 +40,7 @@ class TestBuildVolumes:
         pub = volumes[0]
         assert pub.name == "skills-public"
         assert pub.host_path is not None
-        assert pub.host_path.path.endswith("/skills_view/public")
+        assert posix_path(pub.host_path.path).endswith("/skills_view/public")
         assert pub.host_path.type == "Directory"
         assert pub.persistent_volume_claim is None
 
@@ -50,7 +51,7 @@ class TestBuildVolumes:
         custom = volumes[1]
         assert custom.name == "skills-custom"
         assert custom.host_path is not None
-        assert "users/user-7/skills_view/custom" in custom.host_path.path
+        assert "users/user-7/skills_view/custom" in posix_path(custom.host_path.path)
         assert custom.host_path.type == "Directory"
 
     def test_hostpath_skills_legacy_volume(self, provisioner_module):
@@ -63,7 +64,7 @@ class TestBuildVolumes:
         legacy = volumes[2]
         assert legacy.name == "skills-legacy"
         assert legacy.host_path is not None
-        assert "users/default/skills_view/legacy" in legacy.host_path.path
+        assert "users/default/skills_view/legacy" in posix_path(legacy.host_path.path)
         assert legacy.host_path.type == "Directory"
 
     def test_hostpath_without_legacy_flag_still_has_empty_capable_mount(self, provisioner_module):
@@ -82,7 +83,7 @@ class TestBuildVolumes:
         provisioner_module.USERDATA_PVC_NAME = ""
         volumes = provisioner_module._build_volumes("my-thread-42")
         userdata_vol = volumes[-1]
-        path = userdata_vol.host_path.path
+        path = posix_path(userdata_vol.host_path.path)
         assert "my-thread-42" in path
         assert path.endswith("user-data")
         assert userdata_vol.host_path.type == "DirectoryOrCreate"
@@ -149,7 +150,7 @@ class TestBuildVolumes:
         assert len(volumes) == 5
         extra_vol = volumes[-1]
         assert extra_vol.name == "extra-0"
-        assert extra_vol.host_path.path == "/state/users/alice/integrations/lark-cli/config"
+        assert posix_path(extra_vol.host_path.path) == "/state/users/alice/integrations/lark-cli/config"
         assert extra_vol.host_path.type == "DirectoryOrCreate"
 
     def test_extra_mount_uses_userdata_pvc_when_configured(self, provisioner_module):
diff --git a/backend/tests/test_review_changed_public_skills.py b/backend/tests/test_review_changed_public_skills.py
index d9f89c39a..148d2ea30 100644
--- a/backend/tests/test_review_changed_public_skills.py
+++ b/backend/tests/test_review_changed_public_skills.py
@@ -5,6 +5,7 @@ from pathlib import Path, PurePosixPath
 
 import pytest
 import review_changed_public_skills as runner
+from _host_path_helpers import posix_path
 from skill_review_waivers import EMPTY_MANIFEST, WaiverManifest
 
 
@@ -302,7 +303,7 @@ def test_main_exits_nonzero_when_review_cli_reports_error(tmp_path: Path, monkey
             "never",
         ]
         assert kwargs["cwd"] == tmp_path
-        assert "backend/packages/harness" in kwargs["env"]["PYTHONPATH"]
+        assert "backend/packages/harness" in posix_path(kwargs["env"]["PYTHONPATH"])
         assert kwargs["capture_output"] is True
         assert kwargs["text"] is True
         assert kwargs["check"] is False
diff --git a/backend/tests/test_three_way_skills_mount_e2e.py b/backend/tests/test_three_way_skills_mount_e2e.py
index 091fc4001..8c32fe4e2 100644
--- a/backend/tests/test_three_way_skills_mount_e2e.py
+++ b/backend/tests/test_three_way_skills_mount_e2e.py
@@ -15,6 +15,7 @@ from types import SimpleNamespace
 from unittest.mock import patch
 
 import pytest
+from _host_path_helpers import posix_path
 
 from deerflow.config.extensions_config import ExtensionsConfig, SkillStateConfig
 from deerflow.config.paths import Paths
@@ -602,11 +603,11 @@ class TestThreeWayMountEndToEnd:
 
         assert "/mnt/skills/custom" in mount_entries
         assert "dst=/mnt/skills/custom" in mount_entries["/mnt/skills/custom"]
-        assert "users/noob/skills_view/custom" in mount_entries["/mnt/skills/custom"]
+        assert "users/noob/skills_view/custom" in posix_path(mount_entries["/mnt/skills/custom"])
 
         assert "/mnt/skills/integrations" in mount_entries
         assert "dst=/mnt/skills/integrations" in mount_entries["/mnt/skills/integrations"]
-        assert "users/noob/skills_view/integrations" in mount_entries["/mnt/skills/integrations"]
+        assert "users/noob/skills_view/integrations" in posix_path(mount_entries["/mnt/skills/integrations"])
 
         # noob has no per-user custom → legacy is mounted
         assert "/mnt/skills/legacy" in mount_entries