@@ -20,7 +20,7 @@
 
 import asyncio
 import copy
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from airflow import settings
 from airflow.models.taskinstance import TaskInstance
@@ -146,23 +146,17 @@ def run_task_instance(
     from airflow.sdk.definitions.dag import _run_task
 
     # Session handling is a mess in tests; use a fresh ti to run the task.
-    if AIRFLOW_V_3_4_PLUS:
-        new_ti = TaskInstance.get_task_instance(
-            dag_id=ti.dag_id,
-            run_id=ti.run_id,
-            task_id=ti.task_id,
-            map_index=ti.region_index,
-            region_id=ti.region_id,
-            **session_kwargs,
-        )
-    else:
-        new_ti = TaskInstance.get_task_instance(
-            dag_id=ti.dag_id,
-            run_id=ti.run_id,
-            task_id=ti.task_id,
-            map_index=ti.map_index,
-            **session_kwargs,
-        )
+    # Without a region, get_task_instance applies public_region_filter, which excludes loop regions, so
+    # a loop pass would not be found and the caller's ti would run instead of this pass's row.
+    region_kwargs: dict[str, Any] = {"region_id": ti.region_id} if AIRFLOW_V_3_4_PLUS else {}
+    new_ti = TaskInstance.get_task_instance(
+        dag_id=ti.dag_id,
+        run_id=ti.run_id,
+        task_id=ti.task_id,
+        map_index=ti.map_index,
+        **region_kwargs,
+        **session_kwargs,
+    )
     # Some tests don't even save the ti at all, in which case new_ti is None.
     taskrun_result = _run_task(ti=new_ti or ti, task=task)
     _dispose_in_process_async_connections()
 
@@ -164,6 +164,10 @@ The plugin exposes a FastAPI app at ``/hitl-review``. Base URL:
 - ``run_id``: Dag run ID.
 - ``task_id``: Task ID.
 - ``map_index``: Map index for mapped tasks. Use ``-1`` for non-mapped tasks or index for dynamic mapping.
+- ``region_id`` and ``region_index``: Select one pass of a loop. Send them together; ``region_index``
+  without ``region_id`` is rejected. Only supported on Airflow 3.4 or later; earlier hosts return 400 when
+  either is sent. A task inside a loop addressed without them returns 400, and a selection that matches
+  more than one task instance returns 409.
 
 Endpoints
 ^^^^^^^^^
 
@@ -91,6 +91,7 @@ def _get_bundle_url() -> str:
     if AIRFLOW_V_3_4_PLUS:
         from airflow.api_fastapi.core_api.services.public.task_coordinates import resolve_task_scope
         from airflow.models.dagbag import DBDagBag
+        from airflow.models.task_coordinates import TaskCoordinateResolver
 
     def _get_session():
         with create_session(scoped=False) as session:
@@ -105,11 +106,11 @@ def _read_xcom(
         run_id: str,
         task_id: str,
         map_index: int = -1,
-        region_id: UUID | None = None,
+        region_id: UUID | None,
         key: str,
     ):
         """Read a single XCom value from the database."""
-        scope = {"region_id": region_id} if AIRFLOW_V_3_4_PLUS else {}
+        scope = {"region_id": region_id, "include_node_regions": False} if AIRFLOW_V_3_4_PLUS else {}
         read = XComModel.get_many(
             run_id=run_id,
             key=key,
@@ -131,7 +132,7 @@ def _read_xcom_by_prefix(
         run_id: str,
         task_id: str,
         map_index: int = -1,
-        region_id: UUID | None = None,
+        region_id: UUID | None,
         prefix: str,
     ) -> dict[int, Any]:
         """Read all iteration-keyed XCom entries matching *prefix* (e.g. ``airflow_hitl_review_agent_output_``)."""
@@ -142,6 +143,7 @@ def _read_xcom_by_prefix(
                 task_ids=task_id,
                 map_indexes=map_index,
                 region_id=region_id,
+                include_node_regions=False,
             )
             entity = read.column_descriptions[0]["entity"]
             query = read.with_only_columns(entity.key, entity.value).where(entity.key.like(f"{prefix}%"))
@@ -167,7 +169,7 @@ def _write_xcom(
         run_id: str,
         task_id: str,
         map_index: int = -1,
-        region_id: UUID | None = None,
+        region_id: UUID | None,
         key: str,
         value,
     ):
@@ -180,7 +182,7 @@ def _write_xcom(
                     TI.run_id == run_id,
                     TI.task_id == task_id,
                     TI.region_index == map_index,
-                    TI.region_id == (region_id or UUID(int=0)),
+                    TI.region_id == region_id,
                 )
             )
             if owner is None:
@@ -237,7 +239,7 @@ def _is_task_completed(
         run_id: str,
         task_id: str,
         map_index: int = -1,
-        region_id: UUID | None = None,
+        region_id: UUID | None,
     ) -> bool:
         """Return True if the task instance is no longer running."""
         query = select(TI.state).where(
@@ -249,7 +251,7 @@ def _is_task_completed(
             query = query.where(
                 TI.working_set.is_(True),
                 TI.region_index == map_index,
-                TI.region_id == (region_id or UUID(int=0)),
+                TI.region_id == region_id,
             )
         else:
             query = query.where(TI.map_index == map_index)
@@ -265,7 +267,7 @@ def _build_session_response(
         run_id: str,
         task_id: str,
         map_index: int = -1,
-        region_id: UUID | None = None,
+        region_id: UUID | None,
     ) -> HITLReviewResponse | None:
         """Build `HITLReviewResponse` from XCom entries."""
         raw = _read_xcom(
@@ -339,8 +341,7 @@ def _get_task_scope(
                 dag_id=dag_id,
                 run_id=run_id,
                 task_id=task_id,
-                session=db,
-                dag_bag=DBDagBag(),
+                resolver=TaskCoordinateResolver(DBDagBag(), db),
                 map_index=map_index,
                 region_id=region_id,
                 region_index=region_index,
 
@@ -59,10 +59,28 @@ const PluginComponent: FC<PluginComponentProps> = (props) => {
     ? { region_id: taskInstance.region_id, region_index: taskInstance.region_index }
     : undefined;
 
-  return <ChatPage
-    key={`${dagId}/${runId}/${taskId}/${mapIndex}/${taskInstance?.id ?? ""}/${region?.region_id ?? ""}/${region?.region_index ?? ""}`}
-    dagId={dagId} runId={runId} taskId={taskId} mapIndex={mapIndex} region={region}
-  />;
+  // Remounts ChatPage on any selection change: useSession keeps its first createApi(...) in a ref,
+  // so without a new key it would keep sending the previous pass's region.
+  const sessionKey = [
+    dagId,
+    runId,
+    taskId,
+    mapIndex,
+    taskInstance?.id ?? "",
+    region?.region_id ?? "",
+    region?.region_index ?? "",
+  ].join("/");
+
+  return (
+    <ChatPage
+      key={sessionKey}
+      dagId={dagId}
+      runId={runId}
+      taskId={taskId}
+      mapIndex={mapIndex}
+      region={region}
+    />
+  );
 };
 
 /**