fasthands

fasthands is an open-source computer-use engine that observes a page once and then sends only what changed. Every click is hash-checked at the moment it fires, so a page that shifts under the agent aborts the batch instead of hitting the wrong button. It runs with Claude, GPT, or a small model on your own laptop.

How it works

1. 01

   The engine takes one compact tree of the interactive page, gives each element a stable ref and content hash, and afterwards sends only diffs.

2. 02

   The model returns a JSON batch of actions; the executor re-hashes every ref before firing and aborts with a drift note if the page changed.

3. 03

   xray adds the page's own validation rules to the observation, so the agent fixes forms before submitting instead of after a failed submit.

What it does

• Observes the page as a compact tree once, then sends diffs with stable element refs
• Guarded action batches: every ref is re-hashed before it fires and the batch aborts on drift
• xray reads the HTML contract (required, pattern, min/max) and blocks a submit the browser says will fail
• Reads canvas draw commands and WebGL scene graphs, and draws with guarded pointer strokes
• Works with Anthropic, OpenAI or any OpenAI-compatible endpoint such as Ollama, with no SDK dependencies