diff --git a/custom_agent.py b/custom_agent.py
index 3786074..16a5728 100644
--- a/custom_agent.py
+++ b/custom_agent.py
@@ -6,6 +6,7 @@ from pathlib import Path
 
 from dotenv import load_dotenv
 from memory import MemoryRecallClient
+from tts import BlackboxTTS
 
 from asr import BlackboxSTT
 from livekit.agents import (
@@ -27,9 +28,9 @@ from livekit.agents import (
     room_io,
     stt,
 )
+from livekit.agents.voice.generation import update_instructions as update_chat_instructions
 from livekit.plugins import openai, silero
 from livekit.plugins.turn_detector.multilingual import MultilingualModel
-from tts import BlackboxTTS
 
 logger = logging.getLogger("custom-agent")
 
@@ -47,9 +48,19 @@ ROOM_LOCATOR_INSTRUCTIONS = """
 如果用户的问题与房间物品定位无关，则正常回答用户问题。
 """.strip()
 
+GENERAL_INSTRUCTIONS = """
+你是一个智能语音助手。
+正常回答用户问题。
+回答自然、简洁、准确。
+""".strip()
+
+ROOM_LOCATOR_MODE = "room_locator"
+GENERAL_MODE = "general"
+
+
 class CustomAgent(Agent):
     def __init__(self, *, memory_client: MemoryRecallClient | None = None) -> None:
-        super().__init__(instructions=ROOM_LOCATOR_INSTRUCTIONS)
+        super().__init__(instructions=GENERAL_INSTRUCTIONS)
         self._memory_client = memory_client
 
     async def on_enter(self) -> None:
@@ -63,9 +74,24 @@ class CustomAgent(Agent):
         model_settings: ModelSettings,
     ) -> AsyncIterable[llm.ChatChunk | str | FlushSentinel]:
         llm_node_started_at = time.perf_counter()
-        memory_context = await self._recall_room_memory(chat_ctx)
-        if memory_context:
-            chat_ctx = _with_memory_as_latest_user_message(chat_ctx, memory_context)
+
+        user_query = _latest_user_text(chat_ctx)
+        mode = _select_mode(user_query)
+        logger.info("Selected agent mode: %s", mode)
+
+        chat_ctx = chat_ctx.copy()
+        update_chat_instructions(
+            chat_ctx,
+            instructions=ROOM_LOCATOR_INSTRUCTIONS
+            if mode == ROOM_LOCATOR_MODE
+            else GENERAL_INSTRUCTIONS,
+            add_if_missing=True,
+        )
+
+        if mode == ROOM_LOCATOR_MODE:
+            memory_context = await self._recall_room_memory(chat_ctx)
+            if memory_context:
+                chat_ctx = _with_memory_as_latest_user_message(chat_ctx, memory_context)
 
         llm_result = Agent.default.llm_node(self, chat_ctx, tools, model_settings)
         if not hasattr(llm_result, "__aiter__"):
@@ -124,6 +150,104 @@ class CustomAgent(Agent):
             return ""
 
 
+def _select_mode(user_query: str) -> str:
+    normalized = _normalize_text(user_query)
+    if not normalized:
+        return GENERAL_MODE
+
+    if _is_room_locator_query(normalized):
+        return ROOM_LOCATOR_MODE
+
+    return GENERAL_MODE
+
+
+def _is_room_locator_query(normalized_text: str) -> bool:
+    room_context_hints = (
+        "房间",
+        "屋里",
+        "屋子",
+        "室内",
+        "客厅",
+        "卧室",
+        "书房",
+        "厨房",
+        "餐厅",
+        "沙发",
+        "桌",
+        "椅",
+        "床",
+        "门",
+        "窗",
+        "柜",
+        "电视",
+        "空调",
+        "书架",
+        "灯",
+        "冰箱",
+        "茶几",
+        "电脑",
+        "包",
+        "瓶",
+        "相机",
+        "植物",
+    )
+    spatial_hints = (
+        "在哪里",
+        "在哪",
+        "位置",
+        "方位",
+        "旁边",
+        "左边",
+        "右边",
+        "前面",
+        "后面",
+        "上面",
+        "下面",
+        "附近",
+        "对面",
+        "靠近",
+        "挨着",
+        "隔着",
+    )
+    software_hints = (
+        "python",
+        "代码",
+        "函数",
+        "class",
+        "bug",
+        "日志",
+        "logging",
+        "api",
+        "server",
+        "agent",
+        "prompt",
+        "模型",
+        "数据库",
+        "git",
+        "uv",
+        "ruff",
+        "mypy",
+    )
+
+    if any(hint in normalized_text for hint in software_hints):
+        return False
+
+    has_spatial_hint = any(hint in normalized_text for hint in spatial_hints)
+    has_room_context_hint = any(hint in normalized_text for hint in room_context_hints)
+
+    if has_spatial_hint and has_room_context_hint:
+        return True
+
+    if has_spatial_hint and len(normalized_text) <= 12:
+        return True
+
+    return False
+
+
+def _normalize_text(text: str) -> str:
+    return "".join(text.split()).lower()
+
+
 def _latest_user_text(chat_ctx: ChatContext) -> str:
     for item in reversed(chat_ctx.items):
         if isinstance(item, ChatMessage) and item.role == "user":
@@ -175,7 +299,7 @@ async def entrypoint(ctx: JobContext) -> None:
         raise RuntimeError(f"CUSTOM_LLM_API_KEY is not set in {CUSTOM_ENV_PATH}")
 
     TTS_URL = os.getenv("CUSTOM_TTS_URL") or os.getenv(
-        "VOXCPM_TTS_URL", "http://localhost:5050/tts-blackbox"
+        "VOXCPM_TTS_URL", "http://localhost:5000/tts-blackbox"
     )
     TTS_MODEL = os.getenv("CUSTOM_TTS_MODEL") or os.getenv("VOXCPM_TTS_MODEL", "voxcpmtts")
     TTS_SAMPLE_RATE = _env_int("CUSTOM_TTS_SAMPLE_RATE", 16000)