// EmitterBox — thin wrapper to emit JSON v0 (extracted)
box EmitterBox {
  emit_program(json, usings_json) {
    if json == null { return json }
    // Normalize usings payload to at least an empty array so meta.usings is always present
    local payload = usings_json
    if payload == null { payload = "[]" }
    if payload.length() == 0 { payload = "[]" }
    // Inject meta.usings before closing brace of top-level object
    local n = json.lastIndexOf("}")
    if n < 0 { return json }
    local head = json.substring(0, n)
    local tail = json.substring(n, json.length())
    local needs_comma = 1
    if head.length() == 0 { needs_comma = 0 } else {
      local last = head.substring(head.length() - 1, head.length())
      if last == "{" || last == "," { needs_comma = 0 }
    }
    if needs_comma == 1 { head = head + "," }
    return head + "\"meta\":{\"usings\":" + payload + "}" + tail
  }
}

static box EmitterStub {
  main(args) { return 0 }
}