Browser use in the agents window on remote agent hosts not working

Version: 1.139.0-insider
Commit: 4fa9fcf245ad90eb1f21fae5ed0511515e068b1d
Date: 2026-09-17T15:56:52Z
Electron: 43.6.0
ElectronBuildId: 15274685
Chromium: 150.0.7871.250
Node.js: 24.20.0
V8: 15.0.245.31-electron.0
@github/copilot: 1.0.84-5
@github/copilot-sdk: 1.0.13
OS: Darwin arm64 25.6.0

## What works
1. setup a ssh box (box1)
2. open a remote ssh window on an empty folder F on box1
3. ask copilot to create a html file and open it in the built-in browser
-> opening the file directly in the browser fails
-> the agent recovers by setting up a server; connecting to the server the browser works fine

## What doesn't work
1. in the Agents window, start a remote session in box1 in folder F
2. ask to agent to open the html file in the built-in browser
-> opening the file in the browser fails
-> opening the file served from a server fails