diff --git a/apps/api/src/services/config/config_profile_resolver.py b/apps/api/src/services/config/config_profile_resolver.py
index e1f24d3..a717de5 100644
--- a/apps/api/src/services/config/config_profile_resolver.py
+++ b/apps/api/src/services/config/config_profile_resolver.py
@@ -569,7 +569,7 @@ def apply_resolved_profile(
         expanded_target = os.path.normpath(expand_container_path(mount.target, home_dir))
         mount_dir = mounts_dir / expanded_target.lstrip("/").replace("/", "_")
         for file_path, content in mount.files.items():
-            write_canonical_file(mount_dir, file_path, content)
+            write_canonical_file(mount_dir, file_path, content, preserve_inode=True)
 
         volume_mounts.append(
             {
diff --git a/apps/api/tests/unit/test_config_profile_resolver.py b/apps/api/tests/unit/test_config_profile_resolver.py
index b0e94a6..f3b70e5 100644
--- a/apps/api/tests/unit/test_config_profile_resolver.py
+++ b/apps/api/tests/unit/test_config_profile_resolver.py
@@ -584,6 +584,37 @@ class TestApplyResolvedProfile:
         assert canonical_file.stat().st_ino == original_inode
         assert canonical_file.read_text() == "value = 2"
 
+    def test_mounted_file_update_preserves_bind_mount_inode(self, tmp_path) -> None:
+        """A file inside a profile directory mount must update in place."""
+        profile_id = uuid.uuid4()
+        instance_root = tmp_path / "instances"
+        resolved = ResolvedProfile(
+            profile_id=profile_id,
+            profile_name="test",
+            mounts={
+                "/etc/tool": ResolvedMount(
+                    target="/etc/tool", mode="rw", files={"settings.toml": "value = 1"}
+                )
+            },
+        )
+
+        apply_resolved_profile(str(instance_root / "instance-a"), resolved)
+        canonical_file = (
+            instance_root
+            / "config-profiles"
+            / str(profile_id)
+            / "mounts"
+            / "etc_tool"
+            / "settings.toml"
+        )
+        original_inode = canonical_file.stat().st_ino
+
+        resolved.mounts["/etc/tool"].files["settings.toml"] = "value = 2"
+        apply_resolved_profile(str(instance_root / "instance-a"), resolved)
+
+        assert canonical_file.stat().st_ino == original_inode
+        assert canonical_file.read_text() == "value = 2"
+
     def test_instances_share_profile_scoped_mount_sources(self, tmp_path) -> None:
         """Different instance paths resolve a profile to one canonical source."""
         profile_id = uuid.uuid4()