Windows: sidebar sessions render empty when session cwd is a git repo/worktree; non-git sessions fine; backend store intact

Environment: Claude for Windows 1.26832.0 (056ee2), Windows 11 Home 10.0.26200.

Symptom: After a recent app update, most sessions in the desktop sidebar render only their title — opening them shows an empty conversation. Persists across a full quit (tray → right-click → Quit) and relaunch.

Key correlation: whether a session renders appears to track whether its working directory is a git checkout:

• Sessions whose cwd is a plain folder (no git repo) render fine — e.g. several personal content-creation sessions in ordinary Downloads/OneDrive folders all open normally.
• Sessions whose cwd is a git repo or git worktree render empty — including many whose working directories still exist on disk with intact checkouts (only a minority are legitimately-reaped worktrees).

This suggests the renderer fails while resolving git/worktree metadata for the session, rather than failing to locate the conversation content.

Verified NOT data loss:

• CLI transcripts under ~/.claude/projects/ are intact (1,249 .jsonl files).
• The app's own session-management API returns full conversations for sessions that render empty — e.g. list_events returns a complete 913-message transcript for one such session.
• Sidebar session IDs (local_<uuid>) match no transcript filename — the index→content mapping is app-internal and appears broken at the renderer layer for git-associated sessions.

Secondary regression — recency sort: the sidebar now groups sessions by folder, with the folder groups ordered alphabetically; "sort by recency" only applies within each folder group. With many repos/worktrees, globally-recent sessions are effectively unfindable by recency (previously a flat recency-ordered list).

Possibly related but a different failure mode than #72438: there the sidebar index itself is lost (macOS, sidebar shows no sessions at all); here the index/list is intact and the failure is at conversation render, correlated with git-associated sessions.

Happy to provide diagnostics.