feat: accept wide chat layout setting in updates

Sanitizes wideChatLayoutEnabled when it is a boolean
Rejects non-boolean values for the setting
Covers the new behavior with tests

packages/web/server/lib/opencode/settings-helpers.js

@@ -558,6 +558,9 @@ export const createSettingsHelpers = (dependencies) => {
     if (typeof candidate.expandedEditorToolbar === 'boolean') {
       result.expandedEditorToolbar = candidate.expandedEditorToolbar;
     }
+    if (typeof candidate.wideChatLayoutEnabled === 'boolean') {
+      result.wideChatLayoutEnabled = candidate.wideChatLayoutEnabled;
+    }
     if (typeof candidate.showSplitAssistantMessageActions === 'boolean') {
       result.showSplitAssistantMessageActions = candidate.showSplitAssistantMessageActions;
     }

packages/web/server/lib/opencode/settings-helpers.test.js

@@ -66,6 +66,14 @@ describe('settings helpers', () => {
     expect(helpers.sanitizeSettingsUpdate({ draftStartersVisible: 'false' })).toEqual({});
   });
 
+  it('accepts only booleans for wide chat layout', () => {
+    const helpers = createTestHelpers();
+
+    expect(helpers.sanitizeSettingsUpdate({ wideChatLayoutEnabled: true })).toEqual({ wideChatLayoutEnabled: true });
+    expect(helpers.sanitizeSettingsUpdate({ wideChatLayoutEnabled: false })).toEqual({ wideChatLayoutEnabled: false });
+    expect(helpers.sanitizeSettingsUpdate({ wideChatLayoutEnabled: 'true' })).toEqual({});
+  });
+
   it('accepts messageStreamTransport as a persisted shared setting', () => {
     const helpers = createTestHelpers();