Browser Harness: 592-Line Self-Healing CDP Agent That Lets LLMs Write Missing Functions at Runtime — 12.7K Stars and 'The Bitter Lesson of Agent Harnesses' Blog Post
Browser-use released Browser Harness, a minimal (~592 lines of Python) self-healing browser automation framework that connects LLMs directly to Chrome via CDP with one WebSocket and nothing in between. The core design: when an agent encounters a missing capability (e.g., file upload), it edits helpers.py directly, adding the function it needs at runtime. Their blog post 'The Bitter Lesson of Agent Harnesses' argues that even tool abstractions should be deleted — give the LLM direct CDP access and the ability to edit its own harness, and it handles target reattachment, Chrome stalling, and page crashes itself. The JS variant provides 56 CDP domains with 652 typed wrappers. At 12.7K stars and trending, this is the thinnest-harness-wins philosophy taken to its logical conclusion.
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