diff --git a/api/controllers/inner_api/plugin/wraps.py b/api/controllers/inner_api/plugin/wraps.py
index 2f309262cb..ad369660d9 100644
--- a/api/controllers/inner_api/plugin/wraps.py
+++ b/api/controllers/inner_api/plugin/wraps.py
@@ -45,6 +45,15 @@ def get_user(tenant_id: str, user_id: str | None) -> EndUser:
                     .limit(1)
                 )
             else:
+                # Try id first (preserves the original "explicit end-user
+                # id → that specific user" semantics for callers that pass
+                # a known EndUser.id). Fall back to session_id so daemon-
+                # supplied session UUIDs dedup against the row created on
+                # the first Reverse Invocation call — without this, an
+                # id-only lookup never matched (create writes user_id to
+                # session_id, id is auto-generated) and a fresh EndUser
+                # was created per call, breaking multi-turn chat
+                # continuation (see #36736).
                 user_model = session.scalar(
                     select(EndUser)
                     .where(
@@ -53,6 +62,15 @@ def get_user(tenant_id: str, user_id: str | None) -> EndUser:
                     )
                     .limit(1)
                 )
+                if user_model is None:
+                    user_model = session.scalar(
+                        select(EndUser)
+                        .where(
+                            EndUser.session_id == user_id,
+                            EndUser.tenant_id == tenant_id,
+                        )
+                        .limit(1)
+                    )
 
             if not user_model:
                 user_model = EndUser(
diff --git a/api/tests/unit_tests/controllers/inner_api/plugin/test_plugin_wraps.py b/api/tests/unit_tests/controllers/inner_api/plugin/test_plugin_wraps.py
index 598677faff..cc581c0c75 100644
--- a/api/tests/unit_tests/controllers/inner_api/plugin/test_plugin_wraps.py
+++ b/api/tests/unit_tests/controllers/inner_api/plugin/test_plugin_wraps.py
@@ -94,9 +94,39 @@ class TestGetUser:
         # Assert
         assert result == mock_new_user
         mock_session.get.assert_not_called()
-        mock_session.scalar.assert_called_once()
+        # Non-anonymous miss now tries id, then session_id fallback (see
+        # #36736); both miss in this tenant → fall through to create.
+        assert mock_session.scalar.call_count == 2
         mock_session.add.assert_called_once_with(mock_new_user)
 
+    @patch("controllers.inner_api.plugin.wraps.select")
+    @patch("controllers.inner_api.plugin.wraps.EndUser")
+    @patch("controllers.inner_api.plugin.wraps.sessionmaker")
+    @patch("controllers.inner_api.plugin.wraps.db")
+    def test_should_return_existing_user_by_session_id_fallback_for_non_anonymous(
+        self, mock_db, mock_sessionmaker, mock_enduser_class, mock_select, app: Flask
+    ):
+        """Non-anonymous user_id misses on EndUser.id but hits on
+        EndUser.session_id — this is the plugin-daemon Reverse Invocation
+        case where the daemon sends a stable session-derived UUID that
+        was written into session_id on the first call. See #36736.
+        """
+        # Arrange
+        mock_user = MagicMock()
+        mock_session = MagicMock()
+        mock_sessionmaker.return_value.begin.return_value.__enter__.return_value = mock_session
+        # First scalar (id lookup) returns None, second (session_id fallback) hits.
+        mock_session.scalar.side_effect = [None, mock_user]
+
+        # Act
+        with app.app_context():
+            result = get_user("tenant123", "daemon-session-uuid")
+
+        # Assert
+        assert result == mock_user
+        assert mock_session.scalar.call_count == 2
+        mock_session.add.assert_not_called()
+
     @patch("controllers.inner_api.plugin.wraps.select")
     @patch("controllers.inner_api.plugin.wraps.EndUser")
     @patch("controllers.inner_api.plugin.wraps.sessionmaker")