// Phase 107: real-app derived fixture from apps/libs/json_cur.hako:find_balanced_array_end
// Expect numeric output lines: 1 then 3

static box Main {
  find_balanced_array_end(s, idx) {
    local n = s.length()
    if s.substring(idx, idx+1) != "[" { return -1 }
    local depth = 0
    local i = idx
    loop (i < n) {
      local ch = s.substring(i, i+1)
      if ch == "[" { depth = depth + 1 }
      if ch == "]" { depth = depth - 1  if depth == 0 { return i } }
      i = i + 1
    }
    return -1
  }

  main() {
    print(find_balanced_array_end("[]", 0))
    print(find_balanced_array_end("[[]]", 0))
    return "OK"
  }
}