// Mini-VM JSON cursor helpers (extracted)
// One static box per file per using/include policy
static box MiniJsonCur {
  _is_digit(ch) { if ch == "0" { return 1 } if ch == "1" { return 1 } if ch == "2" { return 1 } if ch == "3" { return 1 } if ch == "4" { return 1 } if ch == "5" { return 1 } if ch == "6" { return 1 } if ch == "7" { return 1 } if ch == "8" { return 1 } if ch == "9" { return 1 } return 0 }
  // Skip whitespace from pos; return first non-ws index or -1
  next_non_ws(s, pos) {
    local i = pos
    local n = s.length()
    loop (i < n) {
      local ch = s.substring(i, i+1)
      if ch != " " && ch != "\n" && ch != "\r" && ch != "\t" { return i }
      i = i + 1
    }
    return -1
  }
  // Read a quoted string starting at pos '"'; returns decoded string (no state)
  read_quoted_from(s, pos) {
    local i = pos
    if s.substring(i, i+1) != "\"" { return "" }
    i = i + 1
    local out = ""
    local n = s.length()
    loop (i < n) {
      local ch = s.substring(i, i+1)
      if ch == "\"" { break }
      if ch == "\\" {
        i = i + 1
        ch = s.substring(i, i+1)
      }
      out = out + ch
      i = i + 1
    }
    return out
  }
  // Read consecutive digits from pos
  read_digits_from(s, pos) {
    local out = ""
    local i = pos
    // guard against invalid position (null/negative)
    if i == null { return out }
    if i < 0 { return out }
    loop (true) {
      local ch = s.substring(i, i+1)
      if ch == "" { break }
      // inline digit check to avoid same-box method dispatch
      if ch == "0" { out = out + ch  i = i + 1  continue }
      if ch == "1" { out = out + ch  i = i + 1  continue }
      if ch == "2" { out = out + ch  i = i + 1  continue }
      if ch == "3" { out = out + ch  i = i + 1  continue }
      if ch == "4" { out = out + ch  i = i + 1  continue }
      if ch == "5" { out = out + ch  i = i + 1  continue }
      if ch == "6" { out = out + ch  i = i + 1  continue }
      if ch == "7" { out = out + ch  i = i + 1  continue }
      if ch == "8" { out = out + ch  i = i + 1  continue }
      if ch == "9" { out = out + ch  i = i + 1  continue }
      break
    }
    return out
  }
}