feat: persist sidebar layout + open/closed state between refreshes

Sidebar panel layout (which views are open and their order) and the
sidebar open/closed toggle are now persisted to localStorage. Default
layout is just the Model view at the top.

- ViewSidebar accepts an onChange callback that reports panel kinds
- App.svelte creates two createLocalStore instances (dispatch.sidebar.views
  + dispatch.sidebar.open) using the store's storage adapter
- AppStore exposes its storage instance so the shell persists via the
  same adapter (test-injectable, not globalThis.localStorage)
- Tests pre-populate fake storage with ["extensions"] for the 4 tests
  that need the Extensions view visible

686 tests green. 0 svelte-check warnings (2 pre-existing errors from
missing transport-contract exports, unchanged).

4 files changed, 51 insertions, 20 deletions

diff --git a/src/app/App.svelte b/src/app/App.svelte
index 41e68ef..57fe16f 100644
--- a/src/app/App.svelte
+++ b/src/app/App.svelte
@@ -45,6 +45,8 @@
 		manifest as workspaceManifest,
 	} from "../features/workspace";
 	import type { AppStore } from "./store.svelte";
+	import { createLocalStore } from "../adapters/local-storage";
+	import { untrack } from "svelte";
 
 	let { store }: { store: AppStore } = $props();
 
@@ -72,16 +74,16 @@
 		{ id: "settings", label: "Settings" },
 	] as const;
 
-	// Default sidebar layout: Model, Language Servers, Extensions, Cache Warming, Tasks, Compaction, Settings.
-	const initialViews = [
-		"model",
-		"lsp",
-		"extensions",
-		"cache-warming",
-		"tasks",
-		"compaction",
-		"settings",
-	] as const;
+	// Default sidebar layout: just the Model view.
+	const DEFAULT_VIEWS: readonly string[] = ["model"];
+	const sidebarStore = createLocalStore<readonly string[]>("dispatch.sidebar.views", {
+		storage: untrack(() => store.storage),
+	});
+	const sidebarPanels = sidebarStore.load() ?? DEFAULT_VIEWS;
+
+	function handleSidebarChange(kinds: readonly (string | null)[]): void {
+		sidebarStore.save(kinds.filter((k): k is string => k !== null));
+	}
 
 	// Frontend module list for the "Loaded Modules" view, AGGREGATED from each
 	// feature's public `manifest` export so it can't drift from what's actually
@@ -177,11 +179,18 @@
 		smartScroll.reset();
 	});
 
-	// Right sidebar: open by default on wide screens (pushes the chat aside),
-	// closed by default on narrow screens (overlays the chat). Initial state is
-	// derived from the viewport width once; the hamburger toggles it thereafter.
+	// Right sidebar: persisted open/closed state. Defaults to open on wide
+	// screens (first visit), then remembers the user's toggle thereafter.
 	const WIDE_BREAKPOINT = 1024; // Tailwind `lg`
-	let sidebarOpen = $state(typeof window !== "undefined" ? window.innerWidth >= WIDE_BREAKPOINT : true);
+	const sidebarOpenStore = createLocalStore<boolean>("dispatch.sidebar.open", {
+		storage: untrack(() => store.storage),
+	});
+	const storedSidebarOpen = sidebarOpenStore.load();
+	let sidebarOpen = $state(storedSidebarOpen ?? (typeof window !== "undefined" ? window.innerWidth >= WIDE_BREAKPOINT : true));
+
+	$effect(() => {
+		sidebarOpenStore.save(sidebarOpen);
+	});
 
 	function handleInvoke(msg: InvokeMessage) {
 		store.invoke(msg.surfaceId, msg.actionId, msg.payload);
@@ -404,7 +413,7 @@
 			class="flex h-full w-80 flex-col gap-2 overflow-y-auto border-l border-base-300 bg-base-100 p-3 transition-transform duration-300 ease-out"
 			style="transform: translateX({sidebarOpen ? '0' : '100%'})"
 		>
-			<ViewSidebar kinds={viewKinds} initial={initialViews} content={viewContent} />
+			<ViewSidebar kinds={viewKinds} initial={sidebarPanels} onChange={handleSidebarChange} content={viewContent} />
 		</div>
 	</aside>
 
diff --git a/src/app/App.test.ts b/src/app/App.test.ts
index d22f84b..6a39296 100644
--- a/src/app/App.test.ts
+++ b/src/app/App.test.ts
@@ -98,6 +98,12 @@ function createFakeStorage(): Storage {
 	};
 }
 
+function createFakeStorageWithViews(views: readonly string[] = ["extensions"]): Storage {
+	const storage = createFakeStorage();
+	storage.setItem("dispatch.sidebar.views", JSON.stringify(views));
+	return storage;
+}
+
 function sentMessages(ws: FakeSocket) {
 	return ws.sent.map((s) => JSON.parse(s));
 }
@@ -161,7 +167,7 @@ describe("App component interaction tests", () => {
 		const store = createAppStore({
 			socketFactory: () => ws,
 			fetchImpl: fakeFetchImpl(),
-			localStorage: createFakeStorage(),
+			localStorage: createFakeStorageWithViews(),
 		});
 		ws.resolveOpen();
 
@@ -225,7 +231,7 @@ describe("App component interaction tests", () => {
 		const store = createAppStore({
 			socketFactory: () => ws,
 			fetchImpl: fakeFetchImpl(),
-			localStorage: createFakeStorage(),
+			localStorage: createFakeStorageWithViews(),
 		});
 		ws.resolveOpen();
 
@@ -345,7 +351,7 @@ describe("App component interaction tests", () => {
 		const store = createAppStore({
 			socketFactory: () => ws,
 			fetchImpl: fakeFetchImpl(),
-			localStorage: createFakeStorage(),
+			localStorage: createFakeStorageWithViews(),
 		});
 		ws.resolveOpen();
 
@@ -388,13 +394,13 @@ describe("App component interaction tests", () => {
 		const store = createAppStore({
 			socketFactory: () => ws,
 			fetchImpl: fakeFetchImpl(),
-			localStorage: createFakeStorage(),
+			localStorage: createFakeStorageWithViews(),
 		});
 		ws.resolveOpen();
 
 		render(App, { props: { store } });
 
-		// Extensions is the default view, so the modules table renders immediately.
+		// Extensions view is pre-populated in the fake storage, so the modules table renders immediately.
 		expect(screen.getByRole("columnheader", { name: "Module" })).toBeInTheDocument();
 		for (const name of [
 			"chat",
diff --git a/src/app/store.svelte.ts b/src/app/store.svelte.ts
index f212920..bb08585 100644
--- a/src/app/store.svelte.ts
+++ b/src/app/store.svelte.ts
@@ -93,6 +93,9 @@ export interface AppStore {
 	/** Every received surface spec, in catalog order — all auto-subscribed + expanded. */
 	readonly surfaces: readonly SurfaceSpec[];
 	readonly lastError: ProtocolState["lastError"];
+	/** The localStorage instance the store uses for persistence (tabs, chatLimit).
+	 *  Exposed so the shell can persist sidebar layout via the same adapter. */
+	readonly storage: Storage | undefined;
 	/** The current spec for one surface by id (discovery-by-id), or null if absent. */
 	surface(surfaceId: string): SurfaceSpec | null;
 	send(text: string): void;
@@ -747,6 +750,9 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 		get lastError() {
 			return protocol.lastError;
 		},
+		get storage() {
+			return localStorageOpt;
+		},
 		get cwd(): string | null {
 			return cwd;
 		},
diff --git a/src/features/views/ui/ViewSidebar.svelte b/src/features/views/ui/ViewSidebar.svelte
index c4b466f..e4a3ee6 100644
--- a/src/features/views/ui/ViewSidebar.svelte
+++ b/src/features/views/ui/ViewSidebar.svelte
@@ -17,6 +17,7 @@
 		kinds,
 		content,
 		initial,
+		onChange,
 	}: {
 		/** The view kinds offered in every panel's dropdown. */
 		kinds: readonly ViewKind[];
@@ -24,6 +25,8 @@
 		content: Snippet<[string]>;
 		/** Optional seed of panel kinds; defaults to one panel of the first kind. */
 		initial?: readonly (string | null)[];
+		/** Called whenever the panel layout changes (add/remove/select). */
+		onChange?: (kinds: readonly (string | null)[]) => void;
 	} = $props();
 
 	// Local UI composition state, owned by this unit and folded through the pure
@@ -32,6 +35,10 @@
 	let state = $state<PanelsState>(
 		untrack(() => initialPanels(initial ?? [kinds[0]?.id ?? null])),
 	);
+
+	function notify(): void {
+		onChange?.(state.panels.map((p) => p.kind));
+	}
 </script>
 
 <div class="flex min-h-0 flex-col gap-2">
@@ -45,6 +52,7 @@
 					onchange={(e) => {
 						const v = e.currentTarget.value;
 						state = selectKind(state, panel.id, v === "" ? null : v);
+						notify();
 					}}
 				>
 					<option value="" disabled>Select a view</option>
@@ -59,6 +67,7 @@
 						aria-label="Remove view"
 						onclick={() => {
 							state = removePanel(state, panel.id);
+							notify();
 						}}
 					>
 						✕
@@ -80,6 +89,7 @@
 		aria-label="Add view"
 		onclick={() => {
 			state = addPanel(state);
+			notify();
 		}}
 	>
 		+