Desktop app session sidebar stays empty after reinstall, even though transcripts are fully intact

Summary

After reinstalling the Claude desktop app on Windows (to work around a persistent permission error), the left-hand session sidebar no longer shows any historical sessions for an existing project — even though the underlying transcript files on disk are fully intact and claude --resume from a terminal works perfectly.

Environment

• OS: Windows 11
• Claude desktop app, Code tab (Claude Code integration)
• App version seen in recent session metadata: 2.1.281 (older sessions in the same project were created with versions ranging from 2.1.258–2.1.280)

Steps to reproduce

1. Have an existing project with a large number of Claude Code sessions (190+ .jsonl transcripts under ~/.claude/projects/<project-hash>/).
2. Reinstall the Claude desktop app — in this case the app's own AppData\Roaming\Claude data folder got replaced/reset as part of troubleshooting (via a third-party AI assistant's guidance, not Anthropic's).
3. Reopen the app and point a session at the same project folder again.

Expected

The sidebar repopulates with the project's past sessions, since the transcript files themselves were never touched by the reinstall.

Actual

• The sidebar shows zero historical sessions for the project.
• The same emptiness reproduces via the session-management tool surface (list_sessions), which returns nothing for the project even after explicitly moving a session's working directory into it.
• The in-app session search can find text from old sessions (e.g. matching a ticket/branch name mentioned in one), but clicking a search result opens a generated artifact/file that session produced, not the conversation itself — so even search doesn't actually get you back into the session.

Confirmed NOT the problem

The raw transcript data is 100% intact and correctly structured. Running the standalone claude CLI binary (claude --resume) from a terminal in the project directory correctly lists and resumes every single historical session with full conversation history preserved. So this is specifically about whichever index backs the desktop app's sidebar / session-management surface — it's distinct from the transcript files and was not rebuilt or reconciled against them after the reinstall.

Things tried that did NOT fix it

• Switching an existing chat's working directory to the project folder (via the directory-change mechanism exposed to the agent).
• Starting a brand-new chat rooted in that same project folder.
• Resuming an old session via claude --resume from a terminal in that project, then checking the app's sidebar afterward (to see if activity would trigger re-indexing).
• Fully quitting the app (including checking for and killing lingering background/tray processes) and relaunching.

Impact

No data is actually lost — it's all recoverable via the CLI — but the desktop app itself currently offers no way to browse or resume pre-existing sessions after this kind of data-folder reset, which defeats the purpose of having a GUI session list at all.