Browser Mutation captures visual edits made in the Codex in-app browser and turns them into structured implementation intent for Codex.
It is intended for user-owned local development pages such as http://localhost:5174, http://127.0.0.1:3000, and similar loopback targets.
Browser Mutation is a community MIT project. It ships as:
- a standalone local collector/proxy
- a Codex skill
- a Codex plugin manifest
- an MCP server implementation
Browser Use can already highlight and annotate browser targets during automation. Browser Mutation is for a different step: turning a visual edit into implementation intent that Codex can apply to source code.
Use Browser Mutation when you need:
- before/after records for text, style, layout, icon, move, resize, reparent, reorder, and delete changes
- element identity, selector hints, neighboring layout context, and computed style snapshots
- optional React dev-mode source hints when available
- a captured edit payload after the user presses Send
- repeatable handoff from a human visual edit to a source-code patch
In short: Browser Use is useful for opening, inspecting, and interacting with browser pages. Browser Mutation captures what changed and why, so Codex can translate a visual edit into code.
In a new Codex thread, this should be enough:
Install this Codex skill/plugin:
https://github.com/JosPMSilva/Browser-mutation
Requirements: git, node, and Codex Desktop on Windows, macOS, or Linux.
Clone the repo into the standard local plugin location:
mkdir -p ~/plugins
git clone https://github.com/JosPMSilva/Browser-mutation.git ~/plugins/browser-mutation
cd ~/plugins/browser-mutation
node scripts/install-codex.mjs
node scripts/doctor.mjsRestart Codex Desktop. In Codex, open Plugins > Local Codex Tools > Browser Mutation, click Add to Codex or enable Browser Mutation, and make sure both Browser_mutation and Mutation toggles are enabled.
Start a fresh Codex thread after enabling so the skill list and MCP config are reloaded.
Then open a local app in the Codex in-app browser and ask:
Use Browser Mutation on this page.
node scripts/start-collector.mjs --target http://localhost:5174The local collector starts a browser proxy for the target page and records the edits sent from the Browser Mutation overlay. See the usage guide for the full workflow.
Run the MCP probe:
node scripts/doctor.mjsMIT