fix(webui): persist large sidebar ordering state

webui/src/tests/app-layout.test.tsx

@@ -13,6 +13,7 @@ const getSessionAutomationsSpy = vi.fn<(key: string) => Promise<SessionAutomatio
 const toggleThemeSpy = vi.fn();
 const updateUrlSpy = vi.fn();
 const attachSpy = vi.fn();
+const setSidebarStateSpy = vi.fn();
 const runStatusHandlers = new Set<(chatId: string, startedAt: number | null) => void>();
 const sessionUpdateHandlers = new Set<(chatId: string, scope?: string) => void>();
 let mockSessions: ChatSummary[] = [];
@@ -218,6 +219,7 @@ vi.mock("@/lib/nanobot-client", () => {
     sendMessage = vi.fn();
     newChat = vi.fn();
     attach = attachSpy;
+    setSidebarState = setSidebarStateSpy;
     close = vi.fn();
     updateUrl = updateUrlSpy;
     updateMaxFrameBytes = vi.fn();
@@ -245,6 +247,7 @@ describe("App layout", () => {
     getSessionAutomationsSpy.mockReset().mockResolvedValue([]);
     toggleThemeSpy.mockReset();
     attachSpy.mockReset();
+    setSidebarStateSpy.mockReset();
     runStatusHandlers.clear();
     sessionUpdateHandlers.clear();
     window.history.replaceState(null, "", "/");
@@ -1403,13 +1406,6 @@ describe("App layout", () => {
         if (href === "/api/webui/sidebar-state") {
           return { ok: true, json: async () => initialState };
         }
-        if (href.startsWith("/api/webui/sidebar-state/update?")) {
-          const encoded = new URLSearchParams(href.split("?", 2)[1]).get("state");
-          return {
-            ok: true,
-            json: async () => JSON.parse(encoded ?? "{}"),
-          };
-        }
         return { ok: false, status: 404 };
       }),
     );
@@ -1429,12 +1425,11 @@ describe("App layout", () => {
       expect(within(sidebar).getByText("Archived")).toBeInTheDocument(),
     );
     expect(within(sidebar).getByRole("button", { name: /^First chat$/ })).toBeInTheDocument();
-    const updateUrl = vi.mocked(fetch).mock.calls
-      .map(([url]) => String(url))
-      .find((url) => url.startsWith("/api/webui/sidebar-state/update?"));
-    expect(updateUrl).toBeTruthy();
-    const encoded = new URLSearchParams(updateUrl?.split("?", 2)[1]).get("state");
-    expect(JSON.parse(encoded ?? "{}").view.show_archived).toBe(true);
+    expect(setSidebarStateSpy).toHaveBeenCalledWith(
+      expect.objectContaining({
+        view: expect.objectContaining({ show_archived: true }),
+      }),
+    );
 
     expect(within(sidebar).queryByRole("button", { name: "View" })).not.toBeInTheDocument();
   });

webui/src/tests/nanobot-client.test.ts

@@ -1,6 +1,7 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 import { NanobotClient } from "@/lib/nanobot-client";
+import type { SidebarStatePayload } from "@/lib/types";
 
 /**
  * Minimal fake WebSocket implementing the subset NanobotClient touches.
@@ -935,6 +936,44 @@ describe("NanobotClient", () => {
     expect(client.hasUnsettledRun("chat-scope-control")).toBe(true);
   });
 
+  it("sends large sidebar ordering state outside the HTTP request line", () => {
+    const client = new NanobotClient({
+      url: "ws://test",
+      reconnect: false,
+      socketFactory: (url) => new FakeSocket(url) as unknown as WebSocket,
+    });
+    const sessionOrder = Array.from(
+      { length: 160 },
+      (_, index) => `websocket:${index.toString().padStart(4, "0")}-${"x".repeat(48)}`,
+    );
+    const state: SidebarStatePayload = {
+      schema_version: 1,
+      pinned_keys: [],
+      archived_keys: [],
+      session_order: sessionOrder,
+      title_overrides: {},
+      project_name_overrides: {},
+      tags_by_key: {},
+      collapsed_groups: {},
+      view: {
+        density: "comfortable",
+        show_previews: false,
+        show_timestamps: false,
+        show_archived: false,
+        sort: "manual",
+      },
+      updated_at: null,
+    };
+
+    client.connect();
+    lastSocket().fakeOpen();
+    client.setSidebarState(state);
+
+    const [serialized] = lastSocket().sent;
+    expect(new TextEncoder().encode(serialized).byteLength).toBeGreaterThan(8_192);
+    expect(JSON.parse(serialized)).toEqual({ type: "set_sidebar_state", state });
+  });
+
   it("does not correlate a new-chat scope rejection to an unrelated sent turn", async () => {
     const client = new NanobotClient({
       url: "ws://test",