Integrated browser should tell the agent when the website is already open in one of the tabs.

[digitarald]

Testing #297103

• While agent develops a prototype, already have the preview open
• 🐛 Agent prompts to open a new integrated browser, now I have 2 open
• After a few dev cycles I now have 5 browsers open

Expected: Agent sees I have a browser open with the dev site and just starts testing

[jruales]

@kycutler shouldn't this have been fixed with your PR: #297163

[kycutler]

@digitarald can you try this again with latest Insiders + chat extension, and using a non-Anthropic model?

This seems to be caused by confusion over which "open browser" tool to use and should be fixed by #297552 + microsoft/vscode-copilot-chat#3984. Anthropic models also have some issue finding the right open tool -- that should be fixed soon by #297724.

Regarding the feedback that the agent should be able to request access to an existing page, that is tracked by #297372.

Thanks!