chore: fix tracing for text chat mode

api/tests/test_text_chat_session_service.py

@@ -0,0 +1,45 @@
+import pytest
+
+from api.services.workflow.text_chat_session_service import (
+    TextChatTurnNotFoundError,
+    build_pending_text_chat_turn,
+    truncate_text_chat_future_turns,
+    validate_text_chat_turn_cursor,
+)
+
+
+def test_build_pending_text_chat_turn_sets_pending_shape():
+    turn = build_pending_text_chat_turn(user_text="Hello")
+
+    assert turn["id"].startswith("turn_")
+    assert turn["status"] == "pending"
+    assert turn["user_message"]["text"] == "Hello"
+    assert turn["assistant_message"] is None
+    assert turn["events"] == []
+    assert turn["usage"] == {}
+
+
+def test_truncate_text_chat_future_turns_moves_rewound_branch_to_discarded_future():
+    session_data = {
+        "cursor_turn_id": "turn-2",
+        "turns": [
+            {"id": "turn-1"},
+            {"id": "turn-2"},
+            {"id": "turn-3"},
+        ],
+        "discarded_future": [],
+    }
+
+    active_turns, discarded_future = truncate_text_chat_future_turns(session_data)
+
+    assert active_turns == [{"id": "turn-1"}, {"id": "turn-2"}]
+    assert discarded_future[0]["rewound_from_turn_id"] == "turn-2"
+    assert discarded_future[0]["turns"] == [{"id": "turn-3"}]
+
+
+def test_validate_text_chat_turn_cursor_raises_for_missing_turn():
+    with pytest.raises(TextChatTurnNotFoundError):
+        validate_text_chat_turn_cursor(
+            {"turns": [{"id": "turn-1"}]},
+            "turn-404",
+        )