Loop Engineering is a free, no-signup toolkit for designing the system around an AI agent — not just the prompt. Describe a task and it generates copyable /goal prompts for Claude Code & Codex, a runnable continuous-claude command, and a safe GitHub Actions skeleton. It also has a token-cost calculator, a loop readiness score, AGENTS.md/SKILL.md generators, templates, and a failure-case library. Everything runs in your browser — nothing uploaded or executed.