Replace the writable+derived store pipeline in state.ts with a state.svelte.ts module: a deep $state inputState mutated only through the exported update functions, each of which persists the snapshot and re-validates it asynchronously into validatedState.current (with urls.current derived from it). Store subscriptions in components become $effect blocks, and the rough/grid toggles use function bindings. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>