Two months ago I started building voice agents for small service businesses. dental clinics and HVAC companies that lose real money every time a call goes to voicemail. I'm doing it solo, alongside a day job, which means every wrong turn costs me a weekend I don't get back. Here's what actually went wrong, what I'd tell myself on day one, and the parts of the stack that held up. The stack, briefly Vapi for the voice layer (speech-to-text, the LLM turn, text-to-speech) n8n self-hosted on a cheap