This is a submission for the Gemma 4 Challenge: Build with Gemma 4 What I Built gemma-coder — a single-file Python CLI that turns Gemma 4 into an agentic coding assistant. It reads your CLAUDE.md or AGENTS.md rulebook, uses a model-agnostic XML tool protocol, and ships the 12-rule claude-code-pro-pack baseline as the default behavior file. The interesting part isn't the loop — it's that the whole thing works against Gemma 4 E2B (2 billion effective parameters) running locally. The same file runs against 31B on cloud for the power users, E4B on a phone, E2B on a Raspberry Pi 5. Same protocol, same rulebook, different scale. Why Gemma 4 E2B specifically The obvious submission path is to reach for 31B and flex. I went the other way. Three reasons: 1. E2B is the one that demonstrates the Gemma 4 story. Running server-grade models in the cloud is boring — OpenAI and Anthropic do that better.…