fix: asyncio.Lock on channel create + PROJECT_NAME in .env.example

.env.example

@@ -10,5 +10,8 @@ BRAIN_PATH=C:\Users\Certes\.gemini\antigravity\brain
 # 세션 활성 판단: 마지막 파일 변경으로부터 이 시간(초) 이내면 활성
 ACTIVE_TIMEOUT_SECONDS=300
 
+# Project name (used for Discord channel: AG-{PROJECT_NAME})
+PROJECT_NAME=gravity_control
+
 # Watcher Settings
 DEBOUNCE_SECONDS=2

bot.py

@@ -97,6 +97,7 @@ class GravityBot(commands.Bot):
         self.session_status_messages: dict[str, int] = {}  # conv_id → msg_id
         self._sent_approval_ids: set[str] = set()
         self._ready_event = asyncio.Event()
+        self._channel_lock = asyncio.Lock()  # Prevents double-create race
         self.bridge = BridgeProtocol()
         self.session_category: discord.CategoryChannel | None = None
         self.guild: discord.Guild | None = None
@@ -187,12 +188,17 @@ class GravityBot(commands.Bot):
     async def _get_project_channel(self) -> discord.TextChannel:
         """Get the project channel. Create if it doesn't exist yet.
 
-        Thread-safe: only ONE channel will ever be created because
-        self.project_channel acts as a singleton guard.
+        Uses asyncio.Lock to prevent race between event processor
+        and approval scanner both creating channels simultaneously.
         """
         if self.project_channel:
             return self.project_channel
 
+        async with self._channel_lock:
+            # Double-check after acquiring lock
+            if self.project_channel:
+                return self.project_channel
+
             # Create the channel
             try:
                 self.project_channel = await self.guild.create_text_channel(