LangChain Deleted Its Agent's System Prompt and Todo List. The Evals Didn't Notice.
LangChain's Deep Agents v0.7 cut base input tokens 65 percent, from 5,395 to 1,895 a turn, by deleting its own system prompt, trimming tool descriptions that duplicated the schemas, and demoting the write_todos planning tool to opt-in after evals showed it was not earning its keep. The lean harness was not cheaper on every model, which is the part worth measuring before you copy it.
The Agent Loop Is Moving Out of Your Codebase
In the week of July 16, AWS AgentCore went GA, Microsoft shipped its Agent Harness at BUILD, and the OpenAI, Anthropic, and Google SDKs made declarative loops first-class. The plan-act-observe loop you hand-wrote is turning into a managed runtime feature. The loop was never the hard part, and knowing what you give up when the runtime owns it is the part worth thinking about.
Migrate to uv and Ruff Before OpenAI Ships Its Own
OpenAI is acquiring Astral. Get ahead of the inevitable change in defaults with this practical migration guide.