// Mini-VM scanning and numeric helpers
static box MiniVmScan {
  // helper: find needle from position pos
  index_of_from(hay, needle, pos) {
    // Guard position; clamp to valid range to avoid negative substring
    if pos < 0 { pos = 0 }
    local n = hay.length()
    if pos >= n { return -1 }
    local m = needle.length()
    if m <= 0 { return pos }
    local i = pos
    local limit = n - m
    loop (i <= limit) {
      local seg = hay.substring(i, i + m)
      if seg == needle { return i }
      i = i + 1
    }
    return -1
  }

  // helper: find balanced bracket range [ ... ] starting at idx (points to '[')
  find_balanced_array_end(json, idx) {
    @n = json.length()
    if json.substring(idx, idx+1) != "[" { return -1 }
    @depth = 0
    @i = idx
    @in_str = 0
    @guard = 0
    loop (i < n) {
      guard = guard + 1
      if guard > 50000 { return -1 }
      @ch = json.substring(i, i+1)
      if in_str == 1 {
        if ch == "\\" { i = i + 2  continue }
        if ch == "\"" { in_str = 0  i = i + 1  continue }
        i = i + 1
        continue
      }
      if ch == "\"" { in_str = 1  i = i + 1  continue }
      if ch == "[" { depth = depth + 1 }
      if ch == "]" {
        depth = depth - 1
        if depth == 0 { return i }
      }
      i = i + 1
    }
    return -1
  }

  // helper: find balanced object range { ... } starting at idx (points to '{')
  find_balanced_object_end(json, idx) {
    @n = json.length()
    if json.substring(idx, idx+1) != "{" { return -1 }
    @depth = 0
    @i = idx
    @in_str = 0
    @guard = 0
    loop (i < n) {
      guard = guard + 1
      if guard > 50000 { return -1 }
      @ch = json.substring(i, i+1)
      if in_str == 1 {
        if ch == "\\" { i = i + 2  continue }
        if ch == "\"" { in_str = 0  i = i + 1  continue }
        i = i + 1
        continue
      }
      if ch == "\"" { in_str = 1  i = i + 1  continue }
      if ch == "{" { depth = depth + 1 }
      if ch == "}" {
        depth = depth - 1
        if depth == 0 { return i }
      }
      i = i + 1
    }
    return -1
  }

  _str_to_int(s) {
    @i = 0
    @n = s.length()
    @acc = 0
    loop (i < n) {
      @ch = s.substring(i, i+1)
      if ch == "0" { acc = acc * 10 + 0  i = i + 1  continue }
      if ch == "1" { acc = acc * 10 + 1  i = i + 1  continue }
      if ch == "2" { acc = acc * 10 + 2  i = i + 1  continue }
      if ch == "3" { acc = acc * 10 + 3  i = i + 1  continue }
      if ch == "4" { acc = acc * 10 + 4  i = i + 1  continue }
      if ch == "5" { acc = acc * 10 + 5  i = i + 1  continue }
      if ch == "6" { acc = acc * 10 + 6  i = i + 1  continue }
      if ch == "7" { acc = acc * 10 + 7  i = i + 1  continue }
      if ch == "8" { acc = acc * 10 + 8  i = i + 1  continue }
      if ch == "9" { acc = acc * 10 + 9  i = i + 1  continue }
      break
    }
    return acc
  }
  _digit_char(d) {
    if d == 0 { return "0" }
    if d == 1 { return "1" }
    if d == 2 { return "2" }
    if d == 3 { return "3" }
    if d == 4 { return "4" }
    if d == 5 { return "5" }
    if d == 6 { return "6" }
    if d == 7 { return "7" }
    if d == 8 { return "8" }
    if d == 9 { return "9" }
    return "0"
  }
  _int_to_str(n) {
    if n == 0 { return "0" }
    @v = n
    @out = ""
    loop (v > 0) {
      @d = v % 10
      @ch = _digit_char(d)
      out = ch + out
      v = v / 10
    }
    return out
  }

  // Read digit runs starting at pos
  read_digits(json, pos) {
    @out = ""
    loop (true) {
      @s = json.substring(pos, pos+1)
      if s == "" { break }
      if s == "0" { out = out + s  pos = pos + 1  continue }
      if s == "1" { out = out + s  pos = pos + 1  continue }
      if s == "2" { out = out + s  pos = pos + 1  continue }
      if s == "3" { out = out + s  pos = pos + 1  continue }
      if s == "4" { out = out + s  pos = pos + 1  continue }
      if s == "5" { out = out + s  pos = pos + 1  continue }
      if s == "6" { out = out + s  pos = pos + 1  continue }
      if s == "7" { out = out + s  pos = pos + 1  continue }
      if s == "8" { out = out + s  pos = pos + 1  continue }
      if s == "9" { out = out + s  pos = pos + 1  continue }
      break
    }
    return out
  }

  // Linear pass: sum all numbers outside of quotes
  sum_numbers_no_quotes(json) {
    @i = 0
    @n = json.length()
    @total = 0
    loop (i < n) {
      @ch = json.substring(i, i+1)
      if ch == "\"" {
        @j = index_of_from(json, "\"", i+1)
        if j < 0 { break }
        i = j + 1
        continue
      }
      @d = read_digits(json, i)
      if d { total = total + _str_to_int(d)  i = i + d.length()  continue }
      i = i + 1
    }
    return _int_to_str(total)
  }

  // Naive: sum all digit runs anywhere
  sum_all_digits_naive(json) {
    @i = 0
    @n = json.length()
    @total = 0
    loop (i < n) {
      @d = read_digits(json, i)
      if d { total = total + _str_to_int(d)  i = i + d.length()  continue }
      i = i + 1
    }
    return _int_to_str(total)
  }

  // Sum first two integers outside quotes; returns string or empty
  sum_first_two_numbers(json) {
    @i = 0
    @n = json.length()
    @total = 0
    local found = 0
    loop (i < n) {
      @ch = json.substring(i, i+1)
      if ch == "\"" {
        @j = index_of_from(json, "\"", i+1)
        if j < 0 { break }
        i = j + 1
        continue
      }
      @d = read_digits(json, i)
      if d {
        total = total + _str_to_int(d)
        found = found + 1
        i = i + d.length()
        if found >= 2 { return _int_to_str(total) }
        continue
      }
      i = i + 1
    }
    return ""
  }
}