Yes, "guardrails" is a squishy term. But it gets clearer if you ask what transition is being guarded.

Some of this is inside the model, like topic refusals. Forge sits at the tool call level.

My personal workflow uses guardrails at the SDLC level: I have a standard pipeline (plan, design, code, build, test). I use gates between each stage, and the right composition leads to a much higher quality in the final product.

Also worth mentioning that gate failures are given to the agent that produced the artifact, so it has a chance to fix it. That means that I don't have to review obviously wrong output.