Function formatCommandsWithinBudget

src/tools/SkillTool/prompt.ts:70–171

(
  commands: Command[],
  contextWindowTokens?: number,
)

const MIN_DESC_LENGTH = 20

export function formatCommandsWithinBudget(
  commands: Command[],
  contextWindowTokens?: number,
): string {
  if (commands.length === 0) return ''

  const budget = getCharBudget(contextWindowTokens)

  // Try full descriptions first
  const fullEntries = commands.map(cmd => ({
    cmd,
    full: formatCommandDescription(cmd),
  }))
  // join('\n') produces N-1 newlines for N entries
  const fullTotal =
    fullEntries.reduce((sum, e) => sum + stringWidth(e.full), 0) +
    (fullEntries.length - 1)

  if (fullTotal <= budget) {
    return fullEntries.map(e => e.full).join('\n')
  }

  // Partition into bundled (never truncated) and rest
  const bundledIndices = new Set<number>()
  const restCommands: Command[] = []
  for (let i = 0; i < commands.length; i++) {
    const cmd = commands[i]!
    if (cmd.type === 'prompt' && cmd.source === 'bundled') {
      bundledIndices.add(i)
    } else {
      restCommands.push(cmd)
    }
  }

  // Compute space used by bundled skills (full descriptions, always preserved)
  const bundledChars = fullEntries.reduce(
    (sum, e, i) =>
      bundledIndices.has(i) ? sum + stringWidth(e.full) + 1 : sum,
    0,
  )
  const remainingBudget = budget - bundledChars

  // Calculate max description length for non-bundled commands
  if (restCommands.length === 0) {
    return fullEntries.map(e => e.full).join('\n')
  }

  const restNameOverhead =
    restCommands.reduce((sum, cmd) => sum + stringWidth(cmd.name) + 4, 0) +
    (restCommands.length - 1)
  const availableForDescs = remainingBudget - restNameOverhead
  const maxDescLen = Math.floor(availableForDescs / restCommands.length)

  if (maxDescLen < MIN_DESC_LENGTH) {
    // Extreme case: non-bundled go names-only, bundled keep descriptions
    if (process.env.USER_TYPE === 'ant') {
      logEvent('tengu_skill_descriptions_truncated', {
        skill_count: commands.length,