[BUG] VS Code extension: deleting a session is instant and permanent - no confirmation, no undo, transcript unlinked

Preflight Checklist

• [x] I have searched existing issues and this bug hasn't been reported yet (closest is #81064, which is about the desktop app, where a confirmation modal does exist — see "Additional context")
• [x] This is a single bug report (not multiple issues)

What's Wrong?

In the VS Code extension, clicking delete on a session in the session list deletes it immediately, with no confirmation prompt. One mis-click permanently destroys the session.

It is also unrecoverable. The delete unlinks ~/.claude/projects/<project-slug>/<session-id>.jsonl outright:

• The file does not go to the Recycle Bin (on Windows), so there is no OS-level undo.
• There is no in-app undo, no archive, and no "recently deleted" view.
• ~/.claude/backups/ holds only .claude.json copies, not transcripts.
• ~/.claude/file-history/<session-id>/ (edit snapshots) is not a fallback — it only exists for sessions that made file edits, and holds no conversation.
• Nothing usable remains in ~/.claude/debug/, ~/.claude/cache/, or ~/.claude/sessions/ — the pid record in sessions/*.json keeps the session id, but the transcript it points at is gone.

So the only remaining recovery paths are VSS "Previous Versions" (if System Protection happens to be enabled) or a raw disk undelete tool. For a long session that represents hours of work, a single unconfirmed click is a lot to lose.

What Should Happen?

At minimum, deleting a session should require a confirmation step.

Better: make the delete recoverable instead of irreversible — delete immediately with an Undo toast, and move deleted sessions to a "Recently deleted" list with explicit permanent removal and/or expiry after N days. That way accidental deletes cost nothing and there is no per-delete modal tax when pruning several sessions.

If neither is in scope soon, moving the transcript to the OS trash/Recycle Bin instead of unlinking it would at least make recovery possible.

Error Messages/Logs

None — the deletion succeeds silently. There is no log entry recording which session was deleted, which also makes it impossible to identify afterwards what was lost.

Steps to Reproduce

1. Open the Claude Code VS Code extension in a project with existing sessions.
2. Open the session/resume list.
3. Click the delete action on a session.
4. The session disappears at once, with no confirmation dialog.
5. Check ~/.claude/projects/<project-slug>/ — the corresponding <session-id>.jsonl is gone, and it is not in the Recycle Bin.

Claude Code Version

2.1.251

Platform

VS Code extension (entrypoint: claude-vscode)

Operating System

Windows 11 Pro (10.0.26200)

Additional context

Related: #81064 asks for the desktop app's delete-session confirmation modal to be replaced with an undoable delete plus a "Recently deleted" view. The two are complementary — the desktop app has a confirmation and wants recoverability instead, while the VS Code extension currently has neither. A shared "delete is instantly undoable, transcript retained for N days" behaviour across surfaces would resolve both.