I Built an AI Agent That Negotiates My Bills For Me, Here's Everything That Went Wrong

This post showcases my journey of the All Things Agentic Hackathon.

I'm a second semester software engineering student, and a few weeks ago I had an idea I couldn't stop thinking about, what if an AI agent could actually haggle on my behalf, the way I never have the nerve to on a retention call?

That idea became Haggle, an agent that researches real competitor pricing, then negotiates round by round against a second AI playing a subscription service's retention department, until it lands a deal or walks away. Built on Gemini 3.5 Flash, Google ADK 2.0, and the A2A (Agent-to-Agent) protocol, for the All Things Agentic Hackathon's Taskmaster track.

The idea took an afternoon. Getting it actually working took a lot longer, and almost none of the hard parts were about AI. Here's what actually happened.

Here's the architecture in brief:

I Built an AI Agent That Negotiates My Bills For Me, Here's Everything That Went Wrong

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