恢复GE版本为0.18，生成SNIPPET后自动生成rag_text流程

app/services/table_snippet.py

@@ -459,6 +459,18 @@ def _stable_rag_item_id(table_id: int, version_ts: int, snippet_id: str) -> int:
     return int(digest[:16], 16) % 9_000_000_000_000_000_000
 
 
+def _to_serializable(value: Any) -> Any:
+    if value is None or isinstance(value, (str, int, float, bool)):
+        return value
+    if isinstance(value, datetime):
+        return value.isoformat()
+    if isinstance(value, dict):
+        return {k: _to_serializable(v) for k, v in value.items()}
+    if isinstance(value, list):
+        return [_to_serializable(v) for v in value]
+    return str(value)
+
+
 def _build_rag_text(snippet: Dict[str, Any]) -> str:
     # Deterministic text concatenation for embedding input.
     parts: List[str] = []
@@ -512,7 +524,8 @@ def _prepare_rag_payloads(
             continue
         rag_item_id = _stable_rag_item_id(table_id, version_ts, snippet_id)
         rag_text = _build_rag_text(snippet)
-        merged_json = json.dumps(snippet, ensure_ascii=False)
+        serializable_snippet = _to_serializable(snippet)
+        merged_json = json.dumps(serializable_snippet, ensure_ascii=False)
         updated_at_raw = snippet.get("updated_at_from_action") or now
         if isinstance(updated_at_raw, str):
             try: