Add user-friendly error messages for API errors

- Detect credit/quota exhaustion and show helpful message
- Handle authentication errors gracefully
- Handle model not found errors
- Handle content policy violations
- Fall back to generic error for unknown issues

src/daemon_boyfriend/cogs/ai_chat.py

@@ -114,7 +114,56 @@ class AIChatCog(commands.Cog):
 
             except Exception as e:
                 logger.error(f"Mention response error: {e}", exc_info=True)
-                await message.reply("Sorry, I encountered an error. Please try again.")
+                error_message = self._get_error_message(e)
+                await message.reply(error_message)
+
+    def _get_error_message(self, error: Exception) -> str:
+        """Get a user-friendly error message based on the exception type.
+
+        Args:
+            error: The exception that occurred
+
+        Returns:
+            A user-friendly error message
+        """
+        error_str = str(error).lower()
+
+        # Check for credit/quota/billing errors
+        credit_keywords = [
+            "insufficient_quota",
+            "insufficient credits",
+            "quota exceeded",
+            "rate limit",
+            "billing",
+            "payment required",
+            "credit",
+            "exceeded your current quota",
+            "out of credits",
+            "no credits",
+            "balance",
+            "insufficient funds",
+        ]
+
+        if any(keyword in error_str for keyword in credit_keywords):
+            return "I'm currently out of API credits. Please try again later or contact the bot administrator."
+
+        # Check for authentication errors
+        auth_keywords = ["invalid api key", "unauthorized", "authentication", "invalid_api_key"]
+        if any(keyword in error_str for keyword in auth_keywords):
+            return (
+                "There's an issue with my API configuration. Please contact the bot administrator."
+            )
+
+        # Check for model errors
+        if "model" in error_str and ("not found" in error_str or "does not exist" in error_str):
+            return "The configured AI model is not available. Please contact the bot administrator."
+
+        # Check for content policy violations
+        if "content policy" in error_str or "safety" in error_str or "blocked" in error_str:
+            return "I can't respond to that request due to content policy restrictions."
+
+        # Default error message
+        return "Sorry, I encountered an error. Please try again."
 
     def _extract_message_content(self, message: discord.Message) -> str:
         """Extract the actual message content, removing bot mentions."""