[Windows] Re-added local projects lose historical sessions after project-state/index recovery

Bug

On Windows, Codex Desktop can lose the local project registry after a startup state/index failure. Re-adding the project folders with Ctrl+O restores only empty project shells; historical local sessions are not re-associated with the restored projects. The underlying session data may still exist locally, including image-heavy sessions.

Environment

• Product: Codex Desktop
• Platform: Windows
• Scope: local projects and local sessions
• Exact app version: [please fill from About Codex]

Observed sequence

1. Use several local projects and create multiple sessions, including sessions with image/visual content.
2. Restart Codex Desktop.
3. The sidebar shows no local projects.
4. The startup log reports a failure to parse the global state (an unexpected NUL character in JSON).
5. Re-add the project folders with Ctrl+O.
6. The folders appear as projects again, but the older sessions are missing from the project history/sidebar. The project contains only the folder/project shell.

Expected behavior

When the local project registry or index is damaged, Codex Desktop should rebuild it from persisted local metadata and re-associate existing sessions with the matching project by canonical path/project identity. Re-adding a folder should not create a new empty project identity that hides the old history. Image-containing sessions should remain discoverable and openable.

Actual behavior

The project folders can be restored manually, but historical sessions are not shown under them. This makes the UI look as if the conversations were deleted, even when the local session files remain on disk.

Requested fix

• Detect and recover from invalid/corrupt global project state instead of silently starting with an empty project registry.
• Reconcile existing sessions with re-added projects by canonical path and/or stable project identity.
• Provide a local “rebuild/reindex projects and sessions” recovery action.
• Preserve a backup of local metadata before migration.
• Make image-heavy sessions searchable/openable after recovery.
• Show a clear diagnostic when project metadata is unavailable.

Privacy

No private session transcript, local absolute path, account identifier, token, or screenshot is included here.

Start by reproducing the Windows startup failure and inspect how the global project state, local session metadata, and Ctrl+O project re-add flow are handled. Done means corrupt metadata produces a clear diagnostic and safe backup, existing sessions are re-associated with matching projects, and image-containing sessions remain searchable and openable.