diff --git a/mcp_server.py b/mcp_server.py
index f5109ac..16cf42a 100644
--- a/mcp_server.py
+++ b/mcp_server.py
@@ -14,6 +14,7 @@ Configuration (mcp_config.json):
     }
 """
 import os
+import re
 import sys
 import functools
 import contextlib
@@ -48,9 +49,6 @@ mcp = FastMCP("gitea-tools", instructions=(
 ))
 
 
-
-import re
-
 def extract_linked_issue_numbers(text: str | None, branch_name: str | None = None) -> list[int]:
     issues = set()
     if text:
diff --git a/tests/test_mcp_server.py b/tests/test_mcp_server.py
index 4e457ac..371b09e 100644
--- a/tests/test_mcp_server.py
+++ b/tests/test_mcp_server.py
@@ -1377,8 +1377,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}, {"name": "bug", "id": 2}]
             if method == "GET" and "issues/1" in url:
                 return {"labels": [{"name": "status:in-progress"}, {"name": "bug"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/1/labels/1"):
                 return {}
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             return {}
         self.mock_api.side_effect = api_side_effect
 
@@ -1395,8 +1397,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}, {"name": "bug", "id": 2}]
             if method == "GET" and "issues/1" in url:
                 return {"labels": [{"name": "bug"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and "labels" in url:
                 self.fail("Should not DELETE labels")
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             return {}
         self.mock_api.side_effect = api_side_effect
 
@@ -1425,8 +1429,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}, {"name": "bug", "id": 2}]
             if method == "GET" and "issues/123" in url:
                 return {"labels": [{"name": "status:in-progress"}, {"name": "bug"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/123/labels/1"):
                 return {}
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             return {}
         self.mock_api.side_effect = api_side_effect
 
@@ -1455,8 +1461,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}, {"name": "bug", "id": 2}]
             if method == "GET" and "issues/123" in url:
                 return {"labels": [{"name": "status:in-progress"}, {"name": "bug"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/123/labels/1"):
                 return {}
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             return {}
         self.mock_api.side_effect = api_side_effect
 
@@ -1479,8 +1487,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}]
             if method == "GET" and "issues/123" in url:
                 return {"labels": [{"name": "status:in-progress"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/123/labels/1"):
                 return {}
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             if method == "POST" and "comments" in url:
                 return {}
             return {}
@@ -1509,8 +1519,12 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return {"labels": [{"name": "status:in-progress"}]}
             if method == "GET" and "issues/125" in url:
                 return {"labels": []}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/123/labels/1"):
                 return {}
+            if method == "DELETE" and url.endswith("/issues/124/labels/1"):
+                return {}
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             if method == "POST" and "comments" in url:
                 return {}
             return {}
@@ -1548,8 +1562,10 @@ class TestTrackerHygieneCleanup(unittest.TestCase):
                 return [{"name": "status:in-progress", "id": 1}]
             if method == "GET" and "issues/1" in url:
                 return {"labels": [{"name": "status:in-progress"}]}
-            if method == "DELETE" and "labels/1" in url:
+            if method == "DELETE" and url.endswith("/issues/1/labels/1"):
                 raise RuntimeError("API failure")
+            if method == "PUT" and "labels" in url:
+                self.fail("Should not replace the issue label set")
             return {}
         self.mock_api.side_effect = api_side_effect