feat: allow empty /btw command

.changeset/open-empty-btw-panel.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": minor
+---
+
+Allow `/btw` to open the side-channel panel before entering a question.

apps/kimi-code/src/tui/commands/btw.ts

@@ -4,11 +4,6 @@ import type { SlashCommandHost } from './dispatch';
 
 export async function handleBtwCommand(host: SlashCommandHost, args: string): Promise<void> {
   const prompt = args.trim();
-  if (prompt.length === 0) {
-    host.showError('Usage: /btw <question>');
-    return;
-  }
-
   const session = host.session;
   if (host.state.appState.model.trim().length === 0 || session === undefined) {
     host.showError(LLM_NOT_SET_MESSAGE);

apps/kimi-code/src/tui/components/panes/btw-panel.ts

@@ -233,6 +233,10 @@ export class BtwPanelComponent implements Component {
     return this.currentTurn()?.phase === 'running';
   }
 
+  isEmpty(): boolean {
+    return this.turns.length === 0;
+  }
+
   scroll(direction: 'up' | 'down'): boolean {
     if (this.maxScrollTop <= 0) return false;
     const current = this.followTail ? this.maxScrollTop : this.scrollTop;

apps/kimi-code/src/tui/controllers/btw-panel.ts

@@ -52,7 +52,7 @@ export class BtwPanelController {
 
   clear(): void {
     const active = this.active;
-    if (active?.panel.isRunning()) {
+    if (active !== undefined && this.shouldCancelOnUnmount(active.panel)) {
       void this.cancelAgent(active.agentId);
     }
     this.active = undefined;
@@ -64,9 +64,9 @@ export class BtwPanelController {
   closeOrCancel(): boolean {
     const active = this.active;
     if (active === undefined) return false;
-    const wasRunning = active.panel.isRunning();
+    const shouldCancel = this.shouldCancelOnUnmount(active.panel);
     this.close(active.panel);
-    if (wasRunning) {
+    if (shouldCancel) {
       void this.cancelAgent(active.agentId);
     }
     return true;
@@ -213,6 +213,10 @@ export class BtwPanelController {
     });
   }
 
+  private shouldCancelOnUnmount(panel: BtwPanelComponent): boolean {
+    return panel.isRunning() || panel.isEmpty();
+  }
+
   private withInteractiveAgent<T>(agentId: string, fn: () => Promise<T>): Promise<T> {
     const previousAgentId = this.host.harness.interactiveAgentId;
     this.host.harness.interactiveAgentId = agentId;

apps/kimi-code/test/tui/commands/resolve.test.ts

@@ -36,6 +36,11 @@ describe('resolveSlashCommandInput', () => {
       args: 'New title',
     });
     expect(resolve('/init')).toMatchObject({ kind: 'builtin', name: 'init', args: '' });
+    expect(resolve('/btw')).toMatchObject({
+      kind: 'builtin',
+      name: 'btw',
+      args: '',
+    });
     expect(resolve('/btw what are you doing?')).toMatchObject({
       kind: 'builtin',
       name: 'btw',

apps/kimi-code/test/tui/kimi-tui-message-flow.test.ts

@@ -1100,15 +1100,15 @@ describe('KimiTUI message flow', () => {
           coalescedCount: 1,
           stale: false,
         },
-        prompt: '提醒用户：这是每分钟提醒',
+        prompt: 'Remind the user: this is a once-per-minute reminder',
       } as Event,
       vi.fn(),
     );
 
     const entry = driver.state.transcriptEntries.at(-1);
     expect(entry).toMatchObject({
       kind: 'cron',
-      content: '提醒用户：这是每分钟提醒',
+      content: 'Remind the user: this is a once-per-minute reminder',
       cronData: {
         jobId: 'deadbeef',
         cron: '* * * * *',
@@ -1120,7 +1120,7 @@ describe('KimiTUI message flow', () => {
     const transcript = stripSgr(driver.state.transcriptContainer.render(120).join('\n'));
     expect(transcript).toContain('Scheduled reminder fired');
     expect(transcript).toContain('* * * * *');
-    expect(transcript).toContain('提醒用户：这是每分钟提醒');
+    expect(transcript).toContain('Remind the user: this is a once-per-minute reminder');
     expect(transcript).not.toContain('<cron-fire');
   });
 
@@ -1352,32 +1352,68 @@ describe('KimiTUI message flow', () => {
     driver.state.appState.streamingPhase = 'composing';
     driver.state.livePane.mode = 'thinking';
 
-    driver.handleUserInput('/btw 你现在在做啥？');
+    driver.handleUserInput('/btw What are you working on right now?');
 
     await vi.waitFor(() => {
       expect(session.startBtw).toHaveBeenCalledWith();
     });
     await vi.waitFor(() => {
-      expect(session.prompt).toHaveBeenCalledWith('你现在在做啥？');
+      expect(session.prompt).toHaveBeenCalledWith('What are you working on right now?');
     });
     expect(session.steer).not.toHaveBeenCalled();
     expect(driver.state.appState.streamingPhase).toBe('composing');
     expect(driver.state.livePane.mode).toBe('thinking');
     expect(harness.track).toHaveBeenCalledWith('input_command', { command: 'btw' });
   });
 
+  it('opens /btw without a question and sends the first panel input to a side agent', async () => {
+    const session = makeSession();
+    const { driver } = await makeDriver(session);
+
+    driver.handleUserInput('/btw');
+
+    await vi.waitFor(() => {
+      expect(session.startBtw).toHaveBeenCalledWith();
+    });
+    expect(session.prompt).not.toHaveBeenCalled();
+    expect(stripSgr(renderBtwPanel(driver))).toContain('Ready for a side question...');
+
+    driver.handleUserInput('What are you working on right now?');
+
+    await vi.waitFor(() => {
+      expect(session.prompt).toHaveBeenCalledWith('What are you working on right now?');
+    });
+    expect(session.steer).not.toHaveBeenCalled();
+    expect(stripSgr(renderBtwPanel(driver))).toContain('Q: What are you working on right now?');
+  });
+
+  it('cancels an unused /btw side agent when closing an empty panel', async () => {
+    const session = makeSession();
+    const { driver } = await makeDriver(session);
+
+    driver.handleUserInput('/btw');
+
+    await vi.waitFor(() => {
+      expect(session.startBtw).toHaveBeenCalledWith();
+    });
+    driver.state.editor.onEscape?.();
+
+    expect(session.cancel).toHaveBeenCalledOnce();
+    expect(driver.state.btwPanelContainer.children).toHaveLength(0);
+  });
+
   it('renders /btw output in a dedicated panel instead of an Agent tool card', async () => {
     const session = makeSession();
     const { driver } = await makeDriver(session);
-    await openBtwPanel(driver, session, '你现在在做啥？');
+    await openBtwPanel(driver, session, 'What are you working on right now?');
 
     driver.sessionEventHandler.handleEvent(
       {
         type: 'assistant.delta',
         agentId: 'agent-btw',
         sessionId: 'ses-1',
         turnId: 0,
-        delta: '正在实现 /btw 的独立面板。',
+        delta: 'I am implementing the dedicated /btw panel.',
       } as Event,
       () => {},
     );
@@ -1414,12 +1450,12 @@ describe('KimiTUI message flow', () => {
     expect(panel).not.toContain('BTW failed');
     expect(panel).not.toContain('Ask:');
     expect(panel).not.toContain('Type follow-up');
-    expect(panel).toContain('Q: 你现在在做啥？');
-    expect(panel).toContain('正在实现 /btw 的独立面板。');
+    expect(panel).toContain('Q: What are you working on right now?');
+    expect(panel).toContain('I am implementing the dedicated /btw panel.');
     expect(panel).not.toContain('Agent');
     expect(transcript).not.toContain('BTW');
     expect(transcript).not.toContain('Esc close');
-    expect(transcript).not.toContain('正在实现 /btw 的独立面板。');
+    expect(transcript).not.toContain('I am implementing the dedicated /btw panel.');
   });
 
   it('keeps the /btw panel closest to the input after later transcript output', async () => {
@@ -1921,15 +1957,16 @@ describe('KimiTUI message flow', () => {
     expect(renderedPanel).toContain('answer from new side agent');
   });
 
-  it('does not run /btw without a question or selected model', async () => {
+  it('does not run /btw without a selected model', async () => {
     const { driver, session } = await makeDriver();
 
+    driver.state.appState.model = '';
     driver.handleUserInput('/btw');
     expect(session.startBtw).not.toHaveBeenCalled();
-    expect(stripSgr(renderTranscript(driver))).toContain('Usage: /btw <question>');
+    expect(driver.state.btwPanelContainer.children).toHaveLength(0);
+    expect(stripSgr(renderTranscript(driver))).toContain('LLM not set');
 
-    driver.state.appState.model = '';
-    driver.handleUserInput('/btw 现在在做什么？');
+    driver.handleUserInput('/btw What are you doing now?');
 
     expect(session.startBtw).not.toHaveBeenCalled();
     expect(stripSgr(renderTranscript(driver))).toContain('LLM not set');

docs/en/reference/slash-commands.md

@@ -108,7 +108,7 @@ Prompt mode exits with code `0` when the goal completes, `3` when it blocks, and
 | Command | Alias | Description | Always available |
 | --- | --- | --- | --- |
 | `/help` | `/h`, `/?` | Show keyboard shortcuts and all available commands. | Yes |
-| `/btw <question>` | — | Open a side-channel conversation in a forked subagent without steering the current main agent turn. | Yes |
+| `/btw [question]` | — | Open a side-channel conversation in a forked subagent without steering the current main agent turn. Without a question, it opens the panel and waits for input. | Yes |
 | `/usage` | — | Show token usage, context consumption, and quota information. | Yes |
 | `/status` | — | Show the current session runtime status, including version, model, working directory, and permission mode. | Yes |
 | `/mcp` | — | List the MCP servers in the current session and their connection status. | Yes |

docs/zh/reference/slash-commands.md

@@ -108,7 +108,7 @@ Prompt 模式在 goal 完成时以退出码 `0` 退出，在 blocked 时以 `3`
 | 命令 | 别名 | 说明 | 随时可用 |
 | --- | --- | --- | --- |
 | `/help` | `/h`、`/?` | 显示快捷键和所有可用命令。 | 是 |
-| `/btw <问题>` | — | 在 fork 出的子 Agent 中打开旁路对话，不改变当前主 Agent 轮次。 | 是 |
+| `/btw [问题]` | — | 在 fork 出的子 Agent 中打开旁路对话，不改变当前主 Agent 轮次；不带问题时会先打开面板并等待输入。 | 是 |
 | `/usage` | — | 显示 token 用量、上下文占用以及配额信息。 | 是 |
 | `/status` | — | 显示当前会话运行时状态，包括版本、模型、工作目录和权限模式等。 | 是 |
 | `/mcp` | — | 列出当前会话中的 MCP server 及其连接状态。 | 是 |