App update disconnects session registry from existing ~/.claude/projects transcripts (sessions become unlisted/unresumable, data intact)

Description

After the desktop app auto-updated (two version folders present under %APPDATA%\Claude\claude-code\, installed minutes apart — e.g. 2.1.258 → 2.1.280), the app's session list/search no longer shows any historical sessions for a project directory that has 40+ prior sessions. The underlying transcript data is untouched; only the app's session registry appears affected.

Evidence gathered via the in-app tools

• ~/.claude/projects/<project-hash>/*.jsonl still contains all prior transcripts intact — verified file count (43), total size (~233 MB), and mtimes (most recent transcript written the same day as the update, so the transcript store itself is unaffected).
• The app's own session-management tools return nothing for this history:
• Listing sessions (include_archived: true) returns none besides the current session.
• Full-text search across session transcripts for a term that appears in nearly every prior transcript for this project returns zero hits.
• A direct lookup by a known session UUID (taken straight from an existing .jsonl filename in ~/.claude/projects/...) returns "Session <id> not found."
• This points to the app's session registry/index being disconnected from (or not backfilled from) the raw ~/.claude/projects transcript store after the update — an indexing regression, not data loss.

Impact

Users cannot resume, browse, or full-text-search prior sessions through the app after this update, even though the underlying .jsonl transcripts for those sessions are fully intact on disk at their original path.

Environment

• OS: Windows 11 Pro (10.0.26200)
• App updated same-day between two adjacent versions, installed ~7 minutes apart (folders retained under %APPDATA%\Claude\claude-code\)
• Affected project had 40+ prior sessions, none of which now resolve via session listing, search, or direct ID lookup

Expected behavior

Prior sessions should remain listed, searchable, and resumable after an app update, since the underlying transcript files were not modified, moved, or deleted by the update.