Harness Engineering is the future… trust me.

David Ondrej interviews Magnus Müller, co-founder and CEO of Browser Use, about thin, self-modifiable browser harnesses and an emerging interaction model in which always-running agents propose actions against high-level goals while people retain approval and responsibility.

Key Points Covered

• The interface becomes the problem: Müller says reliable browser control does not by itself determine what people should ask increasingly capable agents to do. His experiment reverses the normal prompt flow by having the agent suggest work against a high-level goal [00:02:36]-[00:04:19].
• Proactive agents turn prompting into approval: His Telegram setup connects work services, checks for useful actions, and presents concise proposals that a person can approve, reject, or refine [00:05:21]-[00:08:06].
• Agent-originated work changes ownership: After an agent independently pursued a naming issue, Müller describes feeling less like the initiator and more like an employee; he then asks the system to explain each proposal's likely impact so he has a reason to care [00:08:58]-[00:11:47].
• A small harness lets the agent create missing tools: Müller presents Browser Harness as roughly 600 lines that an agent can inspect and extend for uploads, cross-origin frames, drawing interactions, dialogs, and other browser edge cases [00:29:17]-[00:32:52].
• Better coding models enable thinner abstractions: He argues that older models needed larger abstractions and carefully written tool prompts, whereas newer coding agents can combine low-level functions and modify the harness directly [00:32:52]-[00:33:55].
• Self-modification creates an update problem: When each running agent can alter its own source, local versions diverge from upstream. Müller proposes letting the agent choose how to reconcile changes and fix defects in the same harness it operates [00:25:29]-[00:27:22].
• Human approval is both control and bottleneck: The discussion distinguishes private autonomous work from externally visible actions such as emails or pull requests, where Müller still wants approval even though repeated swiping limits throughput [00:41:12]-[00:43:14].
• Engagement and agency remain unresolved: Müller worries that excessive suggestions become ignorable and that optimizing proposals for acceptance or addictiveness may increase productivity while reducing the person's sense of ownership [00:36:21]-[00:41:12].

Full video: https://www.youtube.com/watch?v=k8o_UgtrGyA(opens in a new tab)