feat: add GET route to get he breakdown of an agent's context window

letta/schemas/memory.py

@@ -10,6 +10,15 @@
 from letta.schemas.block import Block
 
 
+class ContextWindowOverview(BaseModel):
+    """
+    Overview of the context window, including the number of messages and tokens.
+    """
+
+    num_messages: int = Field(..., description="The number of messages in the context window.")
+    num_tokens: int = Field(..., description="The number of tokens in the context window.")
+
+
 class Memory(BaseModel, validate_assignment=True):
     """
 

letta/server/rest_api/routers/v1/agents.py

@@ -19,6 +19,7 @@
 from letta.schemas.memory import (
     ArchivalMemorySummary,
     BasicBlockMemory,
+    ContextWindowOverview,
     CreateArchivalMemory,
     Memory,
     RecallMemorySummary,
@@ -51,6 +52,20 @@ def list_agents(
     return server.list_agents(user_id=actor.id)
 
 
+@router.get("/{agent_id}/context", response_model=ContextWindowOverview, operation_id="get_agent_context_window")
+def get_agent_context_window(
+    agent_id: str,
+    server: "SyncServer" = Depends(get_letta_server),
+    user_id: Optional[str] = Header(None, alias="user_id"),  # Extract user_id from header, default to None if not present
+):
+    """
+    Retrieve the context window of a specific agent.
+    """
+    actor = server.get_user_or_default(user_id=user_id)
+
+    return server.get_agent_context_window(user_id=actor.id, agent_id=agent_id)
+
+
 @router.post("/", response_model=AgentState, operation_id="create_agent")
 def create_agent(
     agent: CreateAgent = Body(...),

letta/server/server.py

@@ -72,7 +72,12 @@
 from letta.schemas.job import Job
 from letta.schemas.letta_message import LettaMessage
 from letta.schemas.llm_config import LLMConfig
-from letta.schemas.memory import ArchivalMemorySummary, Memory, RecallMemorySummary
+from letta.schemas.memory import (
+    ArchivalMemorySummary,
+    ContextWindowOverview,
+    Memory,
+    RecallMemorySummary,
+)
 from letta.schemas.message import Message, MessageCreate, MessageRole, UpdateMessage
 from letta.schemas.openai.chat_completion_response import UsageStatistics
 from letta.schemas.organization import Organization, OrganizationCreate
@@ -2087,3 +2092,10 @@ def add_llm_model(self, request: LLMConfig) -> LLMConfig:
 
     def add_embedding_model(self, request: EmbeddingConfig) -> EmbeddingConfig:
         """Add a new embedding model"""
+
+    def get_agent_context_window(
+        self,
+        user_id: str,
+        agent_id: str,
+    ) -> ContextWindowOverview:
+        raise NotImplementedError