updated `/stats` to use new slash command arch (#4146)

2 files changed, 141 insertions, 0 deletions

diff --git a/packages/cli/src/ui/commands/statsCommand.test.ts b/packages/cli/src/ui/commands/statsCommand.test.ts
new file mode 100644
index 00000000..485fcf69
--- /dev/null
+++ b/packages/cli/src/ui/commands/statsCommand.test.ts
@@ -0,0 +1,78 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { vi, describe, it, expect, beforeEach } from 'vitest';
+import { statsCommand } from './statsCommand.js';
+import { type CommandContext } from './types.js';
+import { createMockCommandContext } from '../../test-utils/mockCommandContext.js';
+import { MessageType } from '../types.js';
+import { formatDuration } from '../utils/formatters.js';
+
+describe('statsCommand', () => {
+  let mockContext: CommandContext;
+  const startTime = new Date('2025-07-14T10:00:00.000Z');
+  const endTime = new Date('2025-07-14T10:00:30.000Z');
+
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(endTime);
+
+    // 1. Create the mock context with all default values
+    mockContext = createMockCommandContext();
+
+    // 2. Directly set the property on the created mock context
+    mockContext.session.stats.sessionStartTime = startTime;
+  });
+
+  it('should display general session stats when run with no subcommand', () => {
+    if (!statsCommand.action) throw new Error('Command has no action');
+
+    statsCommand.action(mockContext, '');
+
+    const expectedDuration = formatDuration(
+      endTime.getTime() - startTime.getTime(),
+    );
+    expect(mockContext.ui.addItem).toHaveBeenCalledWith(
+      {
+        type: MessageType.STATS,
+        duration: expectedDuration,
+      },
+      expect.any(Number),
+    );
+  });
+
+  it('should display model stats when using the "model" subcommand', () => {
+    const modelSubCommand = statsCommand.subCommands?.find(
+      (sc) => sc.name === 'model',
+    );
+    if (!modelSubCommand?.action) throw new Error('Subcommand has no action');
+
+    modelSubCommand.action(mockContext, '');
+
+    expect(mockContext.ui.addItem).toHaveBeenCalledWith(
+      {
+        type: MessageType.MODEL_STATS,
+      },
+      expect.any(Number),
+    );
+  });
+
+  it('should display tool stats when using the "tools" subcommand', () => {
+    const toolsSubCommand = statsCommand.subCommands?.find(
+      (sc) => sc.name === 'tools',
+    );
+    if (!toolsSubCommand?.action) throw new Error('Subcommand has no action');
+
+    toolsSubCommand.action(mockContext, '');
+
+    expect(mockContext.ui.addItem).toHaveBeenCalledWith(
+      {
+        type: MessageType.TOOL_STATS,
+      },
+      expect.any(Number),
+    );
+  });
+});
diff --git a/packages/cli/src/ui/commands/statsCommand.ts b/packages/cli/src/ui/commands/statsCommand.ts
new file mode 100644
index 00000000..87e902d4
--- /dev/null
+++ b/packages/cli/src/ui/commands/statsCommand.ts
@@ -0,0 +1,63 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { MessageType, HistoryItemStats } from '../types.js';
+import { formatDuration } from '../utils/formatters.js';
+import { type CommandContext, type SlashCommand } from './types.js';
+
+export const statsCommand: SlashCommand = {
+  name: 'stats',
+  altName: 'usage',
+  description: 'check session stats. Usage: /stats [model|tools]',
+  action: (context: CommandContext) => {
+    const now = new Date();
+    const { sessionStartTime } = context.session.stats;
+    if (!sessionStartTime) {
+      context.ui.addItem(
+        {
+          type: MessageType.ERROR,
+          text: 'Session start time is unavailable, cannot calculate stats.',
+        },
+        Date.now(),
+      );
+      return;
+    }
+    const wallDuration = now.getTime() - sessionStartTime.getTime();
+
+    const statsItem: HistoryItemStats = {
+      type: MessageType.STATS,
+      duration: formatDuration(wallDuration),
+    };
+
+    context.ui.addItem(statsItem, Date.now());
+  },
+  subCommands: [
+    {
+      name: 'model',
+      description: 'Show model-specific usage statistics.',
+      action: (context: CommandContext) => {
+        context.ui.addItem(
+          {
+            type: MessageType.MODEL_STATS,
+          },
+          Date.now(),
+        );
+      },
+    },
+    {
+      name: 'tools',
+      description: 'Show tool-specific usage statistics.',
+      action: (context: CommandContext) => {
+        context.ui.addItem(
+          {
+            type: MessageType.TOOL_STATS,
+          },
+          Date.now(),
+        );
+      },
+    },
+  ],
+};