Most breakages fall into a handful of shapes. Find the symptom you are actually seeing, then take the matching first move before you send another prompt.
Symptom and first move
| Symptom | First move |
|---|---|
| Preview is blank or white | Something failed while rendering. Open the console and take the first error, not the last one — the rest are knock-on effects. |
| Build failed right after an edit | Almost always a broken import or typo in the file just changed. Revert that single change before trying anything else. |
| Works in preview, breaks once published | A difference in environment or data. Check anything depending on being logged in, or on a key or secret that isn't set in production. |
| Data doesn't appear | An empty result and a failed request look identical on screen. Ask the agent to show which one is actually happening before it changes anything. |
| My change didn't show up | Hard refresh first. If it's still missing, the agent probably edited a different component than the one you're looking at — point it at the right file with @. |
| Everything got slow | Usually one file doing too much. Ask for a refactor plan in Plan mode rather than a fix. |
| Looks broken only on mobile | Responsive behaviour was never specified. Re-prompt that one section with explicit desktop / tablet / mobile rules. |
| It fixed one thing and broke another | The prompt was too broad. Revert, then re-prompt naming exactly what to change and what to leave alone. |