Each vault's tile layout and tabs now survive an app restart, along with the selected vault and (pre-existing) workspace kind. - tilingPersistence: serializeLayout / buildInitialTileTabs / maxIdSuffix (pure + tested) and load/save to localStorage under textile.tiling.<vaultId>. Persists the split tree, active tile, and each tile's documents + active index; not handles or load state. - useTilingDocumentSlots: accept initialTiles, seed the tab map with loading tabs, and re-open the documents in a mount-only effect (cancelled on unmount). Exposes tileTabs for serialization. - TilingWorkspace: lazy-init tree/activeTile/id-counter from the persisted layout (keyed by instanceKey = vault provider id) and write on change (skipping no-op rewrites). - App: persist + restore selectedProviderId (textile.selectedVault); the registry loads vaults synchronously so the restored vault survives the auto-select effects. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>