[BUG] Session history missing from Desktop app UI after data reset (transcripts still on disk)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

After a data reset on my machine, the session history list in the Claude Code Desktop app no longer shows past sessions (~77 sessions, from 2026-07-15 to 2026-08-13), even though the original transcript files (.jsonl) for those sessions are still intact on disk at C:\Users\[user]\.claude\projects\.
I investigated and found that the app's visible session list is NOT read directly from .claude\projects. Instead it reads from a separate local state store at %APPDATA%\Claude\claude-code-sessions\<workspace-id>\<session-id>\local_*.json. After the reset, this store only contains 1 entry (the current session) — the other 77 sessions are missing from this index even though their raw .jsonl transcripts still exist untouched.
I'd like guidance on how to safely restore these sessions into the app's visible session list, since hand-writing the local_*.json metadata files myself seems risky (they contain large embedded config like full MCP tool schemas) and could corrupt the live session store.

What Should Happen?

After a data reset, the Desktop app's session list should still show all previously existing sessions, or at least allow re-importing/re-indexing the existing .jsonl transcript files already present in .claude\projects, since the underlying conversation data was never actually deleted.

Error Messages/Logs

No error dialog shown. The sessions simply do not appear in the session list — they are silently missing.

Steps to Reproduce

1. Use Claude Code Desktop app on a project folder that has accumulated many past sessions over time (in my case ~77 sessions from 2026-07-15 to 2026-08-13).
2. Perform a "data reset" on the machine (in my case, this coincided with the project folder's Git status/identity changing — the folder was no longer recognized as the same Git-tracked path as before).
3. Reopen the Claude Code Desktop app pointing at the same project folder.
4. Observe: the session history list in the UI only shows the current/newest session. All previous sessions are missing from the list.

Note: The underlying data is NOT actually lost —

• The raw .jsonl transcript files for all 77 old sessions still exist untouched on disk under C:\Users\[user]\.claude\projects\<old-project-folder>\.
• However, the app's own separate local session-state store at %APPDATA%\Claude\claude-code-sessions\<workspace-id>\<session-id>\local_*.json only contains 1 entry (the current session) after the reset — this appears to be the actual source the UI reads from, and it does not automatically re-index/discover the existing .jsonl transcripts in .claude\projects.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — worked normally before a local data reset on 2026-08-13

Claude Code Version

1.28929.0 (Claude Desktop app — could not run claude --version directly in this environment to get the exact CLI binary version)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

The 77 missing sessions span 2026-07-15 to 2026-08-13. Raw .jsonl transcripts have already been safely copied to C:\Users\Trivico\.claude\projects\D--AI-AGENT-BOSS\ as a precaution, but they still don't appear in the app's session list UI.