feat: add new RateLimitExceededError (#2277)

Co-authored-by: Caren Thomas <caren@caren-mac.local>

letta/errors.py

@@ -1,4 +1,5 @@
 import json
+from enum import Enum
 from typing import TYPE_CHECKING, List, Optional, Union
 
 # Avoid circular imports
@@ -6,9 +7,31 @@ if TYPE_CHECKING:
     from letta.schemas.message import Message
 
 
+class ErrorCode(Enum):
+    """Enum for error codes used by client."""
+
+    INTERNAL_SERVER_ERROR = "INTERNAL_SERVER_ERROR"
+    CONTEXT_WINDOW_EXCEEDED = "CONTEXT_WINDOW_EXCEEDED"
+    RATE_LIMIT_EXCEEDED = "RATE_LIMIT_EXCEEDED"
+
+
 class LettaError(Exception):
     """Base class for all Letta related errors."""
 
+    def __init__(self, message: str, code: Optional[ErrorCode] = None, details: dict = {}):
+        self.message = message
+        self.code = code
+        self.details = details
+        super().__init__(message)
+
+    def __str__(self) -> str:
+        if self.code:
+            return f"{self.code.value}: {self.message}"
+        return self.message
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}(message='{self.message}', code='{self.code}', details={self.details})"
+
 
 class LettaToolCreateError(LettaError):
     """Error raised when a tool cannot be created."""
@@ -16,10 +39,7 @@ class LettaToolCreateError(LettaError):
     default_error_message = "Error creating tool."
 
     def __init__(self, message=None):
-        if message is None:
-            message = self.default_error_message
-        self.message = message
-        super().__init__(self.message)
+        super().__init__(message=message or self.default_error_message)
 
 
 class LettaConfigurationError(LettaError):
@@ -27,23 +47,17 @@ class LettaConfigurationError(LettaError):
 
     def __init__(self, message: str, missing_fields: Optional[List[str]] = None):
         self.missing_fields = missing_fields or []
-        super().__init__(message)
+        super().__init__(message=message, details={"missing_fields": self.missing_fields})
 
 
 class LettaAgentNotFoundError(LettaError):
     """Error raised when an agent is not found."""
-
-    def __init__(self, message: str):
-        self.message = message
-        super().__init__(self.message)
+    pass
 
 
 class LettaUserNotFoundError(LettaError):
     """Error raised when a user is not found."""
-
-    def __init__(self, message: str):
-        self.message = message
-        super().__init__(self.message)
+    pass
 
 
 class LLMError(LettaError):
@@ -54,24 +68,45 @@ class LLMJSONParsingError(LettaError):
     """Exception raised for errors in the JSON parsing process."""
 
     def __init__(self, message="Error parsing JSON generated by LLM"):
-        self.message = message
-        super().__init__(self.message)
+        super().__init__(message=message)
 
 
 class LocalLLMError(LettaError):
     """Generic catch-all error for local LLM problems"""
 
     def __init__(self, message="Encountered an error while running local LLM"):
-        self.message = message
-        super().__init__(self.message)
+        super().__init__(message=message)
 
 
 class LocalLLMConnectionError(LettaError):
     """Error for when local LLM cannot be reached with provided IP/port"""
 
     def __init__(self, message="Could not connect to local LLM"):
-        self.message = message
-        super().__init__(self.message)
+        super().__init__(message=message)
+
+
+class ContextWindowExceededError(LettaError):
+    """Error raised when the context window is exceeded but further summarization fails."""
+
+    def __init__(self, message: str, details: dict = {}):
+        error_message = f"{message} ({details})"
+        super().__init__(
+            message=error_message,
+            code=ErrorCode.CONTEXT_WINDOW_EXCEEDED,
+            details=details,
+        )
+
+
+class RateLimitExceededError(LettaError):
+    """Error raised when the llm rate limiter throttles api requests."""
+
+    def __init__(self, message: str, max_retries: int):
+        error_message = f"{message} ({max_retries})"
+        super().__init__(
+            message=error_message,
+            code=ErrorCode.RATE_LIMIT_EXCEEDED,
+            details={"max_retries": max_retries},
+        )
 
 
 class LettaMessageError(LettaError):