/goal and Codex will keep on looping until it evaluates that the goal has been completed... or the configured token budget has been exhausted.
It looks like the feature is mainly implemented though the goals/continuation.md and goals/budget_limit.md prompts, which are automatically injected at the end of a turn.
Tags: ai, openai, prompt-engineering, generative-ai, llms, coding-agents, system-prompts, codex-cli, agentic-engineering