chat: deleting last user tool set should remove .toolsets.jsonc

[jamesmontemagno]

Problem

When deleting user-defined tool sets, removing the final remaining tool set leaves .toolsets.jsonc on disk (often as an empty or effectively empty file).

Expected behavior

If the last user tool set is deleted, the extension should delete .toolsets.jsonc entirely instead of leaving an empty config file behind.

Why this matters

• Keeps workspace config clean and intention-revealing.
• Matches user expectation that no tool sets means no tool-set file.
• Avoids edge cases in file watchers/parsers around empty config artifacts.

Repro

1. Create .toolsets.jsonc with one user tool set.
2. Delete that tool set via the UI/action.
3. Observe file remains instead of being removed.

Suggested fix

• On delete, if no user tool sets remain, remove .toolsets.jsonc.
• Respect FS trash capability checks and provide actionable error messages if removal fails.

[vs-code-engineering]

This feature request is now a candidate for our backlog. The community has 60 days to upvote the issue. If it receives 20 upvotes we will move it to our backlog. If not, we will close it. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[jamesmontemagno]

Fixed in : #320486

[jamesmontemagno]

@aeschli can be close when ready now that merged