feat(cli): add /btw command architecture and types

packages/cli/src/services/BuiltinCommandLoader.ts

@@ -21,6 +21,7 @@ import {
 import { aboutCommand } from '../ui/commands/aboutCommand.js';
 import { agentsCommand } from '../ui/commands/agentsCommand.js';
 import { authCommand } from '../ui/commands/authCommand.js';
+import { btwCommand } from '../ui/commands/btwCommand.js';
 import { bugCommand } from '../ui/commands/bugCommand.js';
 import { chatCommand, debugCommand } from '../ui/commands/chatCommand.js';
 import { clearCommand } from '../ui/commands/clearCommand.js';
@@ -120,6 +121,7 @@ export class BuiltinCommandLoader implements ICommandLoader {
       aboutCommand,
       ...(this.config?.isAgentsEnabled() ? [agentsCommand] : []),
       authCommand,
+      btwCommand,
       bugCommand,
       {
         ...chatCommand,

packages/cli/src/ui/commands/btwCommand.ts

@@ -0,0 +1,33 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { CommandKind, type SlashCommand } from './types.js';
+
+export const btwCommand: SlashCommand = {
+  name: 'btw',
+  description: 'Ask a side question without affecting history (ephemeral)',
+  kind: CommandKind.BUILT_IN,
+  autoExecute: true,
+  isSafeConcurrent: true,
+  action: (context, args) => {
+    const query = args.trim();
+    if (!query) {
+      return {
+        type: 'command_output',
+        value: [
+          {
+            text: 'Please provide a question, e.g. /btw what is this regex doing?',
+          },
+        ],
+      };
+    }
+
+    return {
+      type: 'btw',
+      query,
+    };
+  },
+};

packages/cli/src/ui/commands/types.ts

@@ -166,6 +166,11 @@ export interface LogoutActionReturn {
   type: 'logout';
 }
 
+export interface BtwActionReturn {
+  type: 'btw';
+  query: string;
+}
+
 export type SlashCommandActionReturn =
   | CommandActionReturn<HistoryItemWithoutId[]>
   | QuitActionReturn
@@ -173,7 +178,8 @@ export type SlashCommandActionReturn =
   | ConfirmShellCommandsActionReturn
   | ConfirmActionReturn
   | OpenCustomDialogActionReturn
-  | LogoutActionReturn;
+  | LogoutActionReturn
+  | BtwActionReturn;
 
 export enum CommandKind {
   BUILT_IN = 'built-in',