Revert "perf: optimize prefix caching by skipping system prompt rebuild on every step" (#9380)
Revert "perf: optimize prefix caching by skipping system prompt rebuild on ev…" This reverts commit eafa4144c2577a45b7007a177b701863b98d1dfa.
This commit is contained in:
Sarah Wooders
committed by
Caren Thomas
Caren Thomas
parent
9dbe28e8f1
commit
526da4c49b
@@ -1,178 +0,0 @@
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"""
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Integration tests for system prompt prefix caching optimization.
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These tests verify that the system prompt is NOT rebuilt on every step,
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only after compaction or message reset. This helps preserve prefix caching
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for LLM providers.
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"""
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import pytest
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from letta_client import Letta
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@pytest.fixture(scope="module")
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def client(server_url: str) -> Letta:
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"""Creates and returns a synchronous Letta REST client for testing."""
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return Letta(base_url=server_url)
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@pytest.fixture(scope="function")
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def agent(client: Letta):
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"""Create a test agent and clean up after test."""
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agent_state = client.agents.create(
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name="test-prefix-cache-agent",
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include_base_tools=True,
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model="openai/gpt-4o-mini",
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embedding="openai/text-embedding-ada-002",
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)
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yield agent_state
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# Cleanup
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try:
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client.agents.delete(agent_state.id)
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except Exception:
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pass
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class TestSystemPromptPrefixCaching:
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"""Test that system prompt stays stable during normal agent execution."""
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def test_system_prompt_stable_after_memory_tool_and_messages(self, client: Letta, agent):
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"""
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Test workflow:
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1. Get initial system prompt and human block value
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2. Tell agent to update its memory block using the memory tool
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3. Verify block was modified but system prompt hasn't changed
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4. Send another message to the agent
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5. Verify system prompt still hasn't changed
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6. Manually update a block via API
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7. Send another message and verify system prompt still hasn't changed
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(memory block changes are deferred to compaction)
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"""
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# Step 1: Get initial context window, system prompt, and human block value
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initial_context = client.agents.context.retrieve(agent.id)
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initial_system_prompt = initial_context.system_prompt
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assert initial_system_prompt, "Initial system prompt should not be empty"
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# Get initial human block value
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human_block = None
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for block in agent.memory.blocks:
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if block.label == "human":
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human_block = block
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break
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assert human_block, "Agent should have a 'human' memory block"
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initial_block_value = human_block.value
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# Step 2: Tell the agent to update its memory using the memory tool
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response = client.agents.messages.create(
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agent_id=agent.id,
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messages=[
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{
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"role": "user",
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"content": "Please use the core_memory_append tool to add the following to your 'human' block: 'User likes pizza.'",
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}
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],
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)
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assert response.messages, "Agent should respond with messages"
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# Step 3: Verify block was modified but system prompt hasn't changed
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# Check that the block was actually modified
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updated_block = client.blocks.retrieve(human_block.id)
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assert updated_block.value != initial_block_value, "Memory block should have been modified by the agent"
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assert "pizza" in updated_block.value.lower(), "Memory block should contain the new content about pizza"
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# Verify system prompt hasn't changed
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context_after_memory_update = client.agents.context.retrieve(agent.id)
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system_prompt_after_memory = context_after_memory_update.system_prompt
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assert system_prompt_after_memory == initial_system_prompt, (
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"System prompt should NOT change after agent uses memory tool (deferred to compaction)"
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)
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# Step 4: Send another message to the agent
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response2 = client.agents.messages.create(
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agent_id=agent.id,
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messages=[
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{
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"role": "user",
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"content": "What is my favorite food?",
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}
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],
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)
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assert response2.messages, "Agent should respond with messages"
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# Step 5: Verify system prompt still hasn't changed
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context_after_second_message = client.agents.context.retrieve(agent.id)
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system_prompt_after_second = context_after_second_message.system_prompt
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assert system_prompt_after_second == initial_system_prompt, "System prompt should remain stable after multiple messages"
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# Step 6: Manually update a block via the API
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# Find the human block
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human_block = None
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for block in agent.memory.blocks:
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if block.label == "human":
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human_block = block
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break
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assert human_block, "Agent should have a 'human' memory block"
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# Update the block directly via API
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client.blocks.modify(
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block_id=human_block.id,
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value=human_block.value + "\nUser also likes sushi.",
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)
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# Step 7: Send another message and verify system prompt still hasn't changed
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response3 = client.agents.messages.create(
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agent_id=agent.id,
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messages=[
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{
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"role": "user",
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"content": "What foods do I like?",
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}
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],
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)
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assert response3.messages, "Agent should respond with messages"
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# Verify system prompt STILL hasn't changed (deferred to compaction/reset)
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context_after_manual_update = client.agents.context.retrieve(agent.id)
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system_prompt_after_manual = context_after_manual_update.system_prompt
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assert system_prompt_after_manual == initial_system_prompt, (
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"System prompt should NOT change after manual block update (deferred to compaction)"
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)
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def test_system_prompt_updates_after_reset(self, client: Letta, agent):
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"""
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Test that system prompt IS updated after message reset.
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1. Get initial system prompt
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2. Manually update a memory block
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3. Reset messages
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4. Verify system prompt HAS changed to include the new memory
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"""
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# Step 1: Get initial system prompt
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initial_context = client.agents.context.retrieve(agent.id)
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initial_system_prompt = initial_context.system_prompt
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# Step 2: Manually update a block via the API
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human_block = None
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for block in agent.memory.blocks:
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if block.label == "human":
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human_block = block
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break
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assert human_block, "Agent should have a 'human' memory block"
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# Add distinctive text that we can verify in the system prompt
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new_memory_content = "UNIQUE_TEST_MARKER_12345: User loves ice cream."
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client.blocks.modify(
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block_id=human_block.id,
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value=human_block.value + f"\n{new_memory_content}",
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)
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# Step 3: Reset messages (this should trigger system prompt rebuild)
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client.agents.messages.reset(agent.id)
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# Step 4: Verify system prompt HAS changed and includes the new memory
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context_after_reset = client.agents.context.retrieve(agent.id)
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system_prompt_after_reset = context_after_reset.system_prompt
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assert system_prompt_after_reset != initial_system_prompt, "System prompt SHOULD change after message reset"
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assert "UNIQUE_TEST_MARKER_12345" in system_prompt_after_reset, (
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"System prompt should include the updated memory block content after reset"
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)
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