Function stepTeammateSelection

src/hooks/useBackgroundTaskNavigation.ts:26–59

(
  delta: 1 | -1,
  setAppState: (updater: (prev: AppState) => AppState) => void,
)

// Step teammate selection by delta, wrapping across leader(-1)..teammates(0..n-1)..hide(n).
// First step from a collapsed tree expands it and parks on leader.
function stepTeammateSelection(
  delta: 1 | -1,
  setAppState: (updater: (prev: AppState) => AppState) => void,
): void {
  setAppState(prev => {
    const currentCount = getRunningTeammatesSorted(prev.tasks).length
    if (currentCount === 0) return prev

    if (prev.expandedView !== 'teammates') {
      return {
        ...prev,
        expandedView: 'teammates' as const,
        viewSelectionMode: 'selecting-agent',
        selectedIPAgentIndex: -1,
      }
    }

    const maxIdx = currentCount // hide row
    const cur = prev.selectedIPAgentIndex
    const next =
      delta === 1
        ? cur >= maxIdx
          ? -1
          : cur + 1
        : cur <= -1
          ? maxIdx
          : cur - 1
    return {
      ...prev,
      selectedIPAgentIndex: next,
      viewSelectionMode: 'selecting-agent',
    }
  })
}

/**
 * Custom hook that handles Shift+Up/Down keyboard navigation for background tasks.