Check a caption against the project's brand guardrails (banned words/topics, tone, link policy, posting cap) WITHOUT creating a post. Fix the draft before create_post instead of burning a rejection.

Read rules_checked before treating a pass as a pass: empty means the project has no guardrails configured, so allowed: true means nothing objected rather than that the caption was checked. rules_skipped lists rules that were asked and could not answer — the topic and tone classifiers fail open by design.