Tag: harness
All the articles with the tag "harness".
How Coding Agents Work: Claude Code and Cursor, from Their Documentation
Updated:Coding agents are the most demanding agent harnesses in production: large codebases, many tools, real side effects, and a definition of done that can actually be executed. How Claude Code and Cursor work, using only what their documentation and engineering posts state: the gather-act-verify loop, searching a codebase with grep and with an embedding index (and why Cursor dropped the index), verification, project memory, context management, permissions and checkpoints, subagents and hooks (with a working hook), and Cursor's tab and apply models.
LangChain and LangGraph, from the Inside: What the Frameworks Compile Down To
Updated:Agent frameworks are an opinion about state and control flow. LangChain's runnables composed with a pipe turn out to be function composition with a shared interface; LangGraph's state graph is a loop with typed state, reducers and a checkpoint after every step. The same agent written by hand and with LangGraph (LangGraph 1.2, langchain-core 1.6): the same 10 lines with LangGraph's prebuilt pieces, under half a millisecond of overhead per run, and what that buys: pausing for a person's approval, editing a pending tool call, resuming, and replaying from any saved step.
Engineering Around the Model: Harnesses, Loops, Graphs and the Definition of Done
Updated:The model sets the ceiling; the harness around it decides how close an agent gets. The parts of a harness; loop design (stopping conditions, retries, budgets); graphs and when they beat a loop; and the definition of done as a check the harness runs instead of a claim the model makes. Measured on a small agent: a verifier that checks only where the answer came from, against the same agent without it, with success at each step budget; and what Anthropic's long-running harnesses do about agents that declare victory early.