fix: redo #2085 (#2087)

letta/client/client.py

@@ -1600,6 +1600,18 @@ def remove_agent_memory_block(self, agent_id: str, block_label: str) -> Memory:
             raise ValueError(f"Failed to remove agent memory block: {response.text}")
         return Memory(**response.json())
 
+    def update_agent_memory_limit(self, agent_id: str, block_label: str, limit: int) -> Memory:
+
+        # @router.patch("/{agent_id}/memory/limit", response_model=Memory, operation_id="update_agent_memory_limit")
+        response = requests.patch(
+            f"{self.base_url}/{self.api_prefix}/agents/{agent_id}/memory/limit",
+            headers=self.headers,
+            json={"label": block_label, "limit": limit},
+        )
+        if response.status_code != 200:
+            raise ValueError(f"Failed to update agent memory limit: {response.text}")
+        return Memory(**response.json())
+
 
 class LocalClient(AbstractClient):
     """
@@ -2823,3 +2835,6 @@ def add_agent_memory_block(self, agent_id: str, create_block: BlockCreate) -> Me
 
     def remove_agent_memory_block(self, agent_id: str, block_label: str) -> Memory:
         return self.server.unlink_block_from_agent_memory(user_id=self.user_id, agent_id=agent_id, block_label=block_label)
+
+    def update_agent_memory_limit(self, agent_id: str, block_label: str, limit: int) -> Memory:
+        return self.server.update_agent_memory_limit(user_id=self.user_id, agent_id=agent_id, block_label=block_label, limit=limit)

letta/schemas/block.py

@@ -124,6 +124,13 @@ class Config:
         extra = "ignore"  # Ignores extra fields
 
 
+class BlockLimitUpdate(BaseModel):
+    """Update the limit of a block"""
+
+    label: str = Field(..., description="Label of the block.")
+    limit: int = Field(..., description="New limit of the block.")
+
+
 class UpdatePersona(BlockUpdate):
     """Update a persona block"""
 

letta/schemas/memory.py

@@ -187,6 +187,19 @@ def update_block_label(self, current_label: str, new_label: str):
         # Then swap the block to the new label
         self.memory[new_label] = self.memory.pop(current_label)
 
+    def update_block_limit(self, label: str, limit: int):
+        """Update the limit of a block"""
+        if label not in self.memory:
+            raise ValueError(f"Block with label {label} does not exist")
+        if not isinstance(limit, int):
+            raise ValueError(f"Provided limit must be an integer")
+
+        # Check to make sure the new limit is greater than the current length of the block
+        if len(self.memory[label].value) > limit:
+            raise ValueError(f"New limit {limit} is less than the current length of the block {len(self.memory[label].value)}")
+
+        self.memory[label].limit = limit
+
 
 # TODO: ideally this is refactored into ChatMemory and the subclasses are given more specific names.
 class BasicBlockMemory(Memory):

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

@@ -7,7 +7,7 @@
 
 from letta.constants import DEFAULT_MESSAGE_TOOL, DEFAULT_MESSAGE_TOOL_KWARG
 from letta.schemas.agent import AgentState, CreateAgent, UpdateAgentState
-from letta.schemas.block import Block, BlockCreate, BlockLabelUpdate
+from letta.schemas.block import Block, BlockCreate, BlockLabelUpdate, BlockLimitUpdate
 from letta.schemas.enums import MessageStreamStatus
 from letta.schemas.letta_message import (
     LegacyLettaMessage,
@@ -218,6 +218,7 @@ def update_agent_memory(
 ):
     """
     Update the core memory of a specific agent.
+        This endpoint accepts new memory contents (labels as keys, and values as values) and updates the core memory of the agent identified by the user ID and agent ID.
     This endpoint accepts new memory contents to update the core memory of the agent.
     This endpoint only supports modifying existing blocks; it does not support deleting/unlinking or creating/linking blocks.
     """
@@ -287,6 +288,27 @@ def remove_agent_memory_block(
     return updated_memory
 
 
+@router.patch("/{agent_id}/memory/limit", response_model=Memory, operation_id="update_agent_memory_limit")
+def update_agent_memory_limit(
+    agent_id: str,
+    update_label: BlockLimitUpdate = Body(...),
+    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
+):
+    """
+    Update the limit of a block in an agent's memory.
+    """
+    actor = server.get_user_or_default(user_id=user_id)
+
+    memory = server.update_agent_memory_limit(
+        user_id=actor.id,
+        agent_id=agent_id,
+        block_label=update_label.label,
+        limit=update_label.limit,
+    )
+    return memory
+
+
 @router.get("/{agent_id}/memory/recall", response_model=RecallMemorySummary, operation_id="get_agent_recall_memory_summary")
 def get_agent_recall_memory_summary(
     agent_id: str,

letta/server/server.py

@@ -1929,3 +1929,33 @@ def unlink_block_from_agent_memory(self, user_id: str, agent_id: str, block_labe
             raise ValueError(f"Agent with id {agent_id} not found after linking block")
         assert unlinked_block.label not in updated_agent.memory.list_block_labels()
         return updated_agent.memory
+
+    def update_agent_memory_limit(self, user_id: str, agent_id: str, block_label: str, limit: int) -> Memory:
+        """Update the limit of a block in an agent's memory"""
+
+        # Get the user
+        user = self.user_manager.get_user_by_id(user_id=user_id)
+
+        # Link a block to an agent's memory
+        letta_agent = self._get_or_load_agent(agent_id=agent_id)
+        letta_agent.memory.update_block_limit(label=block_label, limit=limit)
+        assert block_label in letta_agent.memory.list_block_labels()
+
+        # write out the update the database
+        self.block_manager.create_or_update_block(block=letta_agent.memory.get_block(block_label), actor=user)
+
+        # check that the block was updated
+        updated_block = self.block_manager.get_block_by_id(block_id=letta_agent.memory.get_block(block_label).id, actor=user)
+        assert updated_block and updated_block.limit == limit
+
+        # Recompile the agent memory
+        letta_agent.rebuild_memory(force=True, ms=self.ms)
+
+        # save agent
+        save_agent(letta_agent, self.ms)
+
+        updated_agent = self.ms.get_agent(agent_id=agent_id)
+        if updated_agent is None:
+            raise ValueError(f"Agent with id {agent_id} not found after linking block")
+        assert updated_agent.memory.get_block(label=block_label).limit == limit
+        return updated_agent.memory

tests/test_client.py

@@ -810,3 +810,34 @@ def test_add_remove_agent_memory_block(client: Union[LocalClient, RESTClient], a
 
 #     finally:
 #         client.delete_agent(new_agent.id)
+
+
+def test_update_agent_memory_limit(client: Union[LocalClient, RESTClient], agent: AgentState):
+    """Test that we can update the limit of a block in an agent's memory"""
+
+    agent = client.create_agent(name=create_random_username())
+
+    try:
+        current_labels = agent.memory.list_block_labels()
+        example_label = current_labels[0]
+        example_new_limit = 1
+        current_block = agent.memory.get_block(label=example_label)
+        current_block_length = len(current_block.value)
+
+        assert example_new_limit != agent.memory.get_block(label=example_label).limit
+        assert example_new_limit < current_block_length
+
+        # We expect this to throw a value error
+        with pytest.raises(ValueError):
+            client.update_agent_memory_limit(agent_id=agent.id, block_label=example_label, limit=example_new_limit)
+
+        # Now try the same thing with a higher limit
+        example_new_limit = current_block_length + 10000
+        assert example_new_limit > current_block_length
+        client.update_agent_memory_limit(agent_id=agent.id, block_label=example_label, limit=example_new_limit)
+
+        updated_agent = client.get_agent(agent_id=agent.id)
+        assert example_new_limit == updated_agent.memory.get_block(label=example_label).limit
+
+    finally:
+        client.delete_agent(agent.id)

tests/test_memory.py

@@ -140,3 +140,16 @@ def test_update_block_label(sample_memory: Memory):
     sample_memory.update_block_label(current_label=test_old_label, new_label=test_new_label)
     assert test_new_label in sample_memory.list_block_labels()
     assert test_old_label not in sample_memory.list_block_labels()
+
+
+def test_update_block_limit(sample_memory: Memory):
+    """Test updating the limit of a block"""
+
+    test_new_limit = 1000
+    current_labels = sample_memory.list_block_labels()
+    test_old_label = current_labels[0]
+
+    assert sample_memory.get_block(label=test_old_label).limit != test_new_limit
+
+    sample_memory.update_block_limit(label=test_old_label, limit=test_new_limit)
+    assert sample_memory.get_block(label=test_old_label).limit == test_new_limit