fix: source binded bug

backend/main.py

@@ -108,10 +108,12 @@ def _looks_like_sql_intent(message: str) -> bool:
         if re.search(pattern, text, re.IGNORECASE):
             return False
     positive_patterns = [
-        r"\b(select|from|where|group by|order by|having|join|union|limit)\b",
+        r"\b(select|from|where|group by|order by|having|join|union|limit|count|sum|avg|max|min)\b",
         r"(统计|汇总|分组|排序|筛选|过滤|环比|同比|趋势|top\s*\d+|前\d+|占比|均值|平均|最大|最小|总数|总量|明细)",
-        r"(多少|几条|多少条|有多少|查询|检索|按.*(天|周|月|年))",
-        r"(chart|plot|visuali[sz]e|dashboard)",
+        r"(多少|几条|多少条|有多少|查询|检索|列出|列表|清单|显示|展示|查看|分析|对比|情况|数据|信息|记录)",
+        r"(chart|plot|visuali[sz]e|dashboard|画图|图表|可视化)",
+        r"\b(list|show|get|find|search|analyze|compare)\b",
+        r"\b(how many|what|which|who|when|where)\b",
     ]
     for pattern in positive_patterns:
         if re.search(pattern, text, re.IGNORECASE):
@@ -119,24 +121,37 @@ def _looks_like_sql_intent(message: str) -> bool:
     return False
 
 
-def _should_use_nl2sql(request: ChatRequest) -> Tuple[bool, str]:
+def _should_use_nl2sql(request: ChatRequest) -> Tuple[bool, str, str]:
+    # Determine the effective data source from session context or request
+    session_ctx = _session_context_for_routing(request.session_id)
+    session_source = (session_ctx.get("selected_data_source") or "").strip().lower()
+    request_source = (request.source or "").strip().lower()
+    
+    # Priority: Session bound source > Request source > "postgres"
+    effective_source = request_source
+    if session_source.startswith("ds:") or session_source == "upload":
+        effective_source = session_source
+
     if request.route_mode == "sql":
-        return True, "route_mode=sql"
+        return True, "route_mode=sql", effective_source
     if request.route_mode == "chat":
-        return False, "route_mode=chat"
+        return False, "route_mode=chat", effective_source
     if request.prefer_sql_chart:
-        return True, "prefer_sql_chart=true"
+        return True, "prefer_sql_chart=true", effective_source
+        
     has_sql_intent = _looks_like_sql_intent(request.message)
     if not has_sql_intent:
-        return False, "message_non_sql_intent"
-    session_ctx = _session_context_for_routing(request.session_id)
-    selected_data_source = (session_ctx.get("selected_data_source") or "").strip().lower()
-    if selected_data_source.startswith("ds:") or selected_data_source == "upload":
-        return True, "message_sql_intent_with_session_datasource"
-    source = (request.source or "").strip().lower()
-    if source == "upload" or source.startswith("ds:"):
-        return True, "message_sql_intent_with_request_datasource"
-    return True, "message_sql_intent"
+        return False, "message_non_sql_intent", effective_source
+        
+    # If we have intent, check if we have a valid source context
+    if effective_source.startswith("ds:") or effective_source == "upload":
+        return True, "message_sql_intent_with_datasource", effective_source
+    
+    # Even if just "postgres" (default), if intent is strong, we might allow it?
+    # But usually we want a bound source. 
+    # Let's keep existing logic: if intent is strong, return True.
+    # But effectively, if source is "postgres", it might fail later if no tables are there.
+    return True, "message_sql_intent", effective_source
 
 
 class SessionAliasUpdateRequest(BaseModel):
@@ -193,10 +208,10 @@ def _persist_session_turn(
 @app.post("/nanobot/chat")
 async def nanobot_chat(request: ChatRequest):
     try:
-        use_nl2sql, route_reason = _should_use_nl2sql(request)
+        use_nl2sql, route_reason, resolved_source = _should_use_nl2sql(request)
         if use_nl2sql:
             nl2sql_result = await process_nl2sql(
-                NL2SQLRequest(query=request.message, source=request.source, file_url=request.file_url)
+                NL2SQLRequest(query=request.message, source=resolved_source, file_url=request.file_url)
             )
             text = _build_sql_chart_text(nl2sql_result)
             viz_payload = _build_sql_chart_viz(nl2sql_result)
@@ -220,11 +235,11 @@ async def nanobot_chat(request: ChatRequest):
 async def nanobot_chat_stream(request: ChatRequest):
     async def event_generator():
         try:
-            use_nl2sql, route_reason = _should_use_nl2sql(request)
+            use_nl2sql, route_reason, resolved_source = _should_use_nl2sql(request)
             yield f"data: {json.dumps({'type': 'routing', 'selected': 'sql' if use_nl2sql else 'chat', 'reason': route_reason}, ensure_ascii=False)}\n\n"
             if use_nl2sql:
                 nl2sql_result = await process_nl2sql(
-                    NL2SQLRequest(query=request.message, source=request.source, file_url=request.file_url)
+                    NL2SQLRequest(query=request.message, source=resolved_source, file_url=request.file_url)
                 )
                 persisted_viz_payload = _build_sql_chart_viz(nl2sql_result)
                 viz_payload = {