Hacker News readers describe varied AI agent stacks, mixing paid plans like Claude Ultra, Google Ultra, and Z.ai with free OpenRouter models, DeepSeek credits, and local open-weight models. Many build custom orchestrators and subagent frameworks, often wired into Slack or CLI tools, while others rely on GitHub Copilot CLI and Docker/microVM sandboxing for safety. Cost control, token efficiency, transparency, and isolation emerge as key concerns.