browser-use / jev-ultrafast

# Jev Ultrafast ⚡
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**A browser agent with a dynamic, indexed action space.**
Give it one goal. TypeSafe's Jev picks an operation and an element. A small LLM writes text only when the operation is `TYPE_TEXT`.
**Zürich → London on Google Flights in 7.1 seconds.** One natural-language goal, actual text generation, and loading waits included.
Watch the MP4 · Measurements · Read the loop
## The action space
Every observation produces a new element table:
 [code] 
The operations are `CLICK`, `TYPE_TEXT`, `SELECT`, `SCROLL_UP`, `SCROLL_DOWN`, `WAIT`, `DONE`, and `BLOCKED`. Only supported operations and targets are offered.
 [code] 
Target questions are speculative. If the operation is `CLICK`, only `click_target` can execute. Two decisions, **one network round trip**. Each target head contains only compatible elements. Native dropdown choices carry an observed element/option index.
There are no site-specific action scripts or prepared field strings in the policy. The Flights example supplies a goal and independently verifies the outcome. The screenshot renderer adds labels afterward; it does not drive the browser.
## Try it
 [code] 
Open **http://127.0.0.1:8766** and click **Start demo → Run automatically**. The inspector shows numbered elements, operation probabilities, target probabilities, and executed actions. **Choose next** pauses before execution.
Chrome connects through Browser Harness, installed by `uv sync`. Run `uv run browser-harness --doctor` if it needs connecting. Allow remote debugging in Chrome when prompted.
`TEXT_MODEL_API_KEY` is an OpenRouter key in the example configuration. The current demo uses `inception/mercury-2.5` with reasoning disabled. Gemini, GLM, and DeepSeek can also use the OpenAI-compatible text helper; configure the appropriate model, endpoint, and reasoning setting.
## Use the library
 [code] 
Run with `uv run --env-file .env python your_script.py`. The same policy can run a different task:
 [code] 
`uv run --env-file .env python examples/flights.py --keep-open` performs the flight search, checks the actual route/date/results, and saves its trace. It does not select or book a flight.
## Why it moves
- **One request per decision cycle.** Operation and target heads share the same observed state.
- **No screenshots in the default agent loop.** Jev consumes structured state. The inspector opts into screenshots; the video uses a separate continuous screencast.
- **One browser call per snapshot.** Read visible controls, their names, values, and text atomically. Keep references to the actual DOM nodes.
- **Validate the selected target.** Clicks check the document, form values, target, and nearby context. Animation alone does not force another prediction. Resolve current geometry and reject covered controls before input.
- **Wait for useful state.** After typing into a combobox, w