[FEATURE] Desktop app: move existing sessions to a renamed project folder in place (Choose folder forks and archives instead)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

In the desktop app (Code tab, sidebar grouped by project), there is no way to move existing sessions to a project folder that has been renamed on disk.

I renamed a project folder (.../kiosks → .../gcvm kiosks). The two sessions started there stayed under a sidebar heading named "kiosks", and neither the heading nor the sessions' working folder can be changed.

Opening either session shows "Working folder no longer exists. Choose a different folder to continue." with Choose folder and Archive. Choosing the renamed folder does not move the session. Instead it:

1. archives the original session, whose record still points at the old folder;
2. creates a new session titled "<original title> (fork)" in the new folder, with the transcript copied;
3. recreates ~/.claude/projects/<old-encoded-path>/ with byte-identical copies of the original transcripts, alongside the copies already at the new encoded path.

Nothing is lost, but every rename leaves a forked duplicate, an archived original, a duplicate transcript directory, and a "(fork)" suffix to clean up by hand, one session at a time.

Proposed Solution

A way to change an existing session's working folder in place: same session, no fork, no archive. Any of these would do it:

• A "Move to folder…" action on a session, or on a whole project group in the sidebar, which would cover every session in it at once.
• Make Choose folder on the "Working folder no longer exists" banner relocate the session rather than fork it, or offer both.
• Detect a renamed folder (the session's transcripts already present under the new encoded path in ~/.claude/projects) and offer to re-home every affected session at once.

Alternative Solutions

• Choose folder works but forks and archives, as described above.
• Archiving old sessions removes them from the sidebar, but sidebar titles under a project heading are a useful at-a-glance history of past work, so archiving loses something.
• Custom sidebar groups render as separate sections above the project list, so they can't stand in for a renamed project heading.
• Editing the session records in ~/Library/Application Support/Claude/claude-code-sessions/ is unsupported.

Priority

Medium - Would be very helpful

Feature Category

Other

Use Case Example

When a website rebuild launches, the old project folder is renamed with a date suffix (example.com → example.com-old-2027-01-15) and the rebuild folder takes the plain domain name (example.com Rebuild 2026 → example.com). Every session in both folders is stranded at each launch. With a move-in-place action, those sessions would simply follow their folders.

Additional Context

Claude desktop app 2.26454.0 (Claude Code 2.1.278), macOS 26.6.2.

Related: #33636 (sessions lost when a project directory is moved or renamed, VS Code extension), #92965 (folder picker unresponsive after a working folder moved), #71837 (no UI to change root directory when the working directory no longer exists).