Fix dataset collection tag duplication when copying a history

HistoryDatasetCollectionAssociation.copy() was internally calling
copy_tags_from(), but both callers (History.copy() and
DatasetCollectionManager.copy()) also called copy_tags_from() on the
returned HDCA, resulting in every tag being duplicated.

Move the tag-copying responsibility entirely into HDCA.copy() via a new
target_user parameter (falling back to source history user), and remove
the redundant copy_tags_from() calls from both callers. This is safer
than the reverse approach since any future caller of HDCA.copy() will
get correct tag copying automatically.

Fixes https://github.com/galaxyproject/galaxy/issues/21872

lib/galaxy/managers/collections.py

@@ -508,8 +508,8 @@ class DatasetCollectionManager:
             flush=False,
             element_destination=element_destination,
             dataset_instance_attributes=dataset_instance_attributes,
+            target_user=trans.get_user(),
         )
-        new_hdca.copy_tags_from(target_user=trans.get_user(), source=source_hdca)
         if not copy_elements:
             parent.add_dataset_collection(new_hdca)
         trans.sa_session.commit()

lib/galaxy/model/__init__.py

@@ -3747,13 +3747,18 @@ class History(Base, HasTags, Dictifiable, UsesAnnotations, HasName, Serializable
         else:
             hdcas = self.active_dataset_collections
         for hdca in hdcas:
-            new_hdca = hdca.copy(flush=False, element_destination=new_history, set_hid=False, minimize_copies=True)
+            new_hdca = hdca.copy(
+                flush=False,
+                element_destination=new_history,
+                set_hid=False,
+                minimize_copies=True,
+                target_user=target_user,
+            )
             new_history.add_dataset_collection(new_hdca, set_hid=False)
             db_session.add(new_hdca)
 
             if target_user:
                 new_hdca.copy_item_annotation(db_session, self.user, hdca, target_user, new_hdca)
-                new_hdca.copy_tags_from(target_user, hdca)
 
         new_history.hid_counter = self.hid_counter
         db_session.commit()
@@ -7850,6 +7855,7 @@ class HistoryDatasetCollectionAssociation(
         flush: bool = True,
         set_hid: bool = True,
         minimize_copies: bool = False,
+        target_user: Optional[User] = None,
     ):
         """
         Create a copy of this history dataset collection association. Copy
@@ -7878,8 +7884,9 @@ class HistoryDatasetCollectionAssociation(
         hdca.collection = collection_copy
         session = required_object_session(self)
         session.add(hdca)
-        if self.history and self.history.user:
-            hdca.copy_tags_from(self.history.user, self)
+        copy_user = target_user or (self.history.user if self.history else None)
+        if copy_user:
+            hdca.copy_tags_from(copy_user, self)
         if element_destination and set_hid:
             element_destination.stage_addition(hdca)
             element_destination.add_pending_items()

lib/galaxy_test/api/test_histories.py

@@ -522,6 +522,46 @@ class TestHistoriesApi(ApiTestCase, BaseHistories):
         new_update_time = history["update_time"]
         assert original_update_time == new_update_time
 
+    def test_copy_history_does_not_duplicate_tags(self):
+        history_id = self.dataset_populator.new_history()
+        # Create a standalone dataset and tag it
+        new_hda = self.dataset_populator.new_dataset(history_id, content="tagged dataset")
+        hda_id = new_hda["id"]
+        self.dataset_populator.tag_dataset(history_id, hda_id, tags=["hda_tag"])
+        # Create a collection and tag it
+        fetch_response = self.dataset_collection_populator.create_list_in_history(
+            history_id, contents=["Hello", "World"], direct_upload=True
+        )
+        collection = self.dataset_collection_populator.wait_for_fetched_collection(fetch_response.json())
+        hdca_id = collection["id"]
+        self._put(
+            f"histories/{history_id}/contents/{hdca_id}", data={"tags": ["hdca_tag"]}, json=True
+        ).raise_for_status()
+        # Also tag a dataset within the collection
+        element_hda_id = collection["elements"][0]["object"]["id"]
+        self.dataset_populator.tag_dataset(history_id, element_hda_id, tags=["element_tag"])
+
+        # Copy the history
+        copied_history_response = self.dataset_populator.copy_history(history_id)
+        copied_history_response.raise_for_status()
+        copied_history = copied_history_response.json()
+        copied_history_id = copied_history["id"]
+
+        # Verify standalone HDA tags are not duplicated
+        copied_contents = self._get(f"histories/{copied_history_id}/contents").json()
+        copied_hdas = [c for c in copied_contents if c["history_content_type"] == "dataset" and c["visible"]]
+        assert len(copied_hdas) == 1
+        copied_hda_details = self.dataset_populator.get_history_dataset_details(
+            history_id=copied_history_id, dataset_id=copied_hdas[0]["id"]
+        )
+        assert copied_hda_details["tags"] == ["hda_tag"], f"Expected ['hda_tag'] but got {copied_hda_details['tags']}"
+
+        # Verify HDCA tags are not duplicated
+        copied_collection = self.dataset_populator.get_history_collection_details(
+            history_id=copied_history_id, history_content_type="dataset_collection"
+        )
+        assert copied_collection["tags"] == ["hdca_tag"], f"Expected ['hdca_tag'] but got {copied_collection['tags']}"
+
     # TODO: (CE) test_create_from_copy
     def test_import_from_model_store_dict(self):
         response = self.dataset_populator.create_from_store(store_dict=history_model_store_dict())