How should a permission-first AI workflow travel across Claude Code, Antigravity, and Codex?

AI coding agents are getting more capable, but my practical problem was keeping intent, approval, and verification consistent when switching between different hosts.

I built Full Stack HQ, an MIT-licensed open-source engineering workflow with:

One shared source of truth for agents, skills, workflows, and rules

Native adapters for Claude Code, Google Antigravity, and OpenAI Codex

Read-only environment diagnostics

Installer smoke tests

Windows and Ubuntu CI verification

The goal is not to create another AI coding host. It is to make the engineering workflow portable between the hosts people already use.

Repository:
https://github.com/sabahattink/antigravity-fullstack-hq

Release:
https://github.com/sabahattink/antigravity-fullstack-hq/releases/tag/v1.2.0

For people using multiple AI coding tools: what breaks most often in your workflow — shared rules, permissions, skills, or verification?