Replace repeated project-by-session directory matching across sidebar hooks with a shared ownership index that resolves each unique directory once and exposes direct project and folder-scope buckets.
Gate destructive folder reconciliation on authoritative session data and topology readiness, preserve last-known worktrees after discovery failures, and retain nested-project, VS Code, active/archive dedupe, and Windows drive-root semantics.
Narrow cross-directory subscriptions to session and status slices so streaming deltas no longer trigger global aggregation. Reuse a cached session ID index for permission lineage checks instead of rebuilding it on every session switch.
On the reported 15-project, 67-worktree, 14,561-session shape, ownership indexing averages 3.81 ms versus roughly 450 ms for the cache-only hotfix.
Validation: 28 targeted tests, UI type-check, UI lint, and dead-code analysis.
Bohdan Triapitsyn