feat(cli): implement startup team selection dialog and UI integration

- Add TeamSelectionDialog component for team discovery UX
- Intercept startup flow in AppContainer to show team selection if needed
- Update DialogManager to orchestrate team selection UI
- Add handleTeamSelect and isTeamSelectionActive to UI contexts
- Fix pre-existing StyledLine compilation error in TableRenderer
- Refactor promptProvider-teams.test.ts to resolve type errors
- Add unit tests for TeamSelectionDialog
- Fix ESLint warnings for exhaustive-deps in AppContainer
- Resolve syntax corruptions in AppContainer.tsx and DialogManager.tsx

packages/cli/src/ui/components/DialogManager.tsx

@@ -25,6 +25,7 @@ import { relaunchApp } from '../../utils/processUtils.js';
 import { SessionBrowser } from './SessionBrowser.js';
 import { PermissionsModifyTrustDialog } from './PermissionsModifyTrustDialog.js';
 import { ModelDialog } from './ModelDialog.js';
+import { TeamSelectionDialog } from './TeamSelectionDialog.js';
 import { theme } from '../semantic-colors.js';
 import { useUIState } from '../contexts/UIStateContext.js';
 import { useUIActions } from '../contexts/UIActionsContext.js';
@@ -60,6 +61,14 @@ export const DialogManager = ({
     terminalWidth: uiTerminalWidth,
   } = uiState;
 
+  if (uiState.isTeamSelectionActive) {
+    return (
+      <TeamSelectionDialog
+        teams={config.getTeamRegistry().getAllTeams()}
+        onSelect={uiActions.handleTeamSelect}
+      />
+    );
+  }
   if (uiState.adminSettingsChanged) {
     return <AdminSettingsChangedDialog />;
   }

packages/cli/src/ui/components/TeamSelectionDialog.test.tsx

@@ -0,0 +1,115 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { act } from 'react';
+import { TeamSelectionDialog } from './TeamSelectionDialog.js';
+import { renderWithProviders } from '../../test-utils/render.js';
+import { waitFor } from '../../test-utils/async.js';
+import { type TeamDefinition } from '@google/gemini-cli-core';
+
+describe('<TeamSelectionDialog />', () => {
+  const mockTeams: TeamDefinition[] = [
+    {
+      name: 'team-1',
+      displayName: 'Team One',
+      description: 'First team description',
+      instructions: 'Instructions 1',
+      agents: [],
+    },
+    {
+      name: 'team-2',
+      displayName: 'Team Two',
+      description: 'Second team description',
+      instructions: 'Instructions 2',
+      agents: [],
+    },
+  ];
+
+  const mockOnSelect = vi.fn();
+
+  beforeEach(() => {
+    mockOnSelect.mockReset();
+  });
+
+  const renderComponent = async () => renderWithProviders(
+      <TeamSelectionDialog teams={mockTeams} onSelect={mockOnSelect} />,
+    );
+
+  it('renders all options correctly', async () => {
+    const { lastFrame, unmount } = await renderComponent();
+    const output = lastFrame();
+
+    expect(output).toContain('Select an Agent Team');
+    expect(output).toContain('Team One');
+    expect(output).toContain('First team description');
+    expect(output).toContain('Team Two');
+    expect(output).toContain('Second team description');
+    expect(output).toContain('No Team');
+    expect(output).toContain('Browse Marketplace (Coming Soon)');
+    expect(output).toContain('Create Team (Coming Soon)');
+    unmount();
+  });
+
+  it('calls onSelect with team name when a team is selected', async () => {
+    const { stdin, waitUntilReady, unmount } = await renderComponent();
+
+    // Default selection is index 0 (Team One)
+    await act(async () => {
+      stdin.write('\r'); // Enter
+    });
+    await waitUntilReady();
+
+    await waitFor(() => {
+      expect(mockOnSelect).toHaveBeenCalledWith('team-1');
+    });
+    unmount();
+  });
+
+  it('calls onSelect with undefined when "No Team" is selected', async () => {
+    const { stdin, waitUntilReady, unmount } = await renderComponent();
+
+    // Navigate to "No Team" (index 2)
+    await act(async () => {
+      stdin.write('\u001B[B'); // Down
+    });
+    await waitUntilReady();
+    await act(async () => {
+      stdin.write('\u001B[B'); // Down
+    });
+    await waitUntilReady();
+
+    await act(async () => {
+      stdin.write('\r'); // Enter
+    });
+    await waitUntilReady();
+
+    await waitFor(() => {
+      expect(mockOnSelect).toHaveBeenCalledWith(undefined);
+    });
+    unmount();
+  });
+
+  it('does not call onSelect for placeholder options', async () => {
+    const { stdin, waitUntilReady, unmount } = await renderComponent();
+
+    // Navigate to "Browse Marketplace" (index 3)
+    for (let i = 0; i < 3; i++) {
+      await act(async () => {
+        stdin.write('\u001B[B'); // Down
+      });
+      await waitUntilReady();
+    }
+
+    await act(async () => {
+      stdin.write('\r'); // Enter
+    });
+    await waitUntilReady();
+
+    expect(mockOnSelect).not.toHaveBeenCalled();
+    unmount();
+  });
+});

packages/cli/src/ui/components/TeamSelectionDialog.tsx

@@ -0,0 +1,100 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type React from 'react';
+import { useCallback, useMemo } from 'react';
+import { Box, Text } from 'ink';
+import { type TeamDefinition } from '@google/gemini-cli-core';
+import { theme } from '../semantic-colors.js';
+import { DescriptiveRadioButtonSelect } from './shared/DescriptiveRadioButtonSelect.js';
+
+interface TeamSelectionDialogProps {
+  teams: TeamDefinition[];
+  onSelect: (teamName: string | undefined) => void;
+}
+
+export function TeamSelectionDialog({
+  teams,
+  onSelect,
+}: TeamSelectionDialogProps): React.JSX.Element {
+  const options = useMemo(() => {
+    const list = teams.map((team) => ({
+      value: team.name,
+      title: team.displayName,
+      description: team.description,
+      key: team.name,
+    }));
+
+    list.push({
+      value: 'none',
+      title: 'No Team',
+      description: 'Continue with standard Gemini CLI experience',
+      key: 'none',
+    });
+
+    list.push({
+      value: 'marketplace',
+      title: 'Browse Marketplace (Coming Soon)',
+      description: 'Discover and install teams from the community',
+      key: 'marketplace',
+    });
+
+    list.push({
+      value: 'create',
+      title: 'Create Team (Coming Soon)',
+      description: 'Define your own agent team and orchestration instructions',
+      key: 'create',
+    });
+
+    return list;
+  }, [teams]);
+
+  const handleSelect = useCallback(
+    (value: string) => {
+      if (value === 'none') {
+        onSelect(undefined);
+      } else if (value === 'marketplace' || value === 'create') {
+        // No-op for coming soon features
+        return;
+      } else {
+        onSelect(value);
+      }
+    },
+    [onSelect],
+  );
+
+  return (
+    <Box
+      borderStyle="round"
+      borderColor={theme.border.default}
+      flexDirection="column"
+      padding={1}
+      width="100%"
+    >
+      <Text bold color={theme.text.primary}>
+        Select an Agent Team
+      </Text>
+      <Text color={theme.text.secondary}>
+        Choose a specialized team to orchestrate your tasks.
+      </Text>
+
+      <Box marginTop={1}>
+        <DescriptiveRadioButtonSelect
+          items={options}
+          onSelect={handleSelect}
+          showNumbers={true}
+          maxItemsToShow={10}
+        />
+      </Box>
+
+      <Box marginTop={1}>
+        <Text color={theme.text.secondary}>
+          (Use arrow keys to navigate, Enter to select)
+        </Text>
+      </Box>
+    </Box>
+  );
+}