Preview & debug

Preview (dry-run) in the editor evaluates the rule against your real data and lists every change it would make — item, field, before → after, and the note() reason — without writing anything to Amazon. It is the same evaluation a real run performs, so what you see is what you would get.

Reading a preview

• Each proposed change shows the entity (with its campaign/ad group context), the exact value change, and the reason.
• The run log reports how many items were evaluated and how many matched — a preview that says “0 items evaluated” usually means the window or entity is wrong, not that the rule is broken.
• Previews respect the same change cap as real runs, and tell you when they were truncated by it.

Debug traces

When a condition doesn't behave the way you expect, run a debug preview: it records, per item, the values each part of your condition evaluated to — e.g. that keyword.acos read 0.62 while your threshold was 0.45 — so you can see exactly why an item matched or didn't. This is the fastest way to answer “why did/didn't the rule touch this keyword?”

A safe development loop

1. Write the rule (or paste one from the cookbook) with the schedule on Manual.
2. Preview, and read the proposed changes — are the right items matched, are amounts sane?
3. Save in Review mode with a real schedule; approve its queued runs for a week or two.
4. Switch to Auto-apply once its judgment has earned it.