Domain Buy Failure Modes

Status	Meaning	Correct response
400	Invalid domain format	Ask for a normal hostname like myapp.com.
402	Not enough Cloud credits	Tell the user to top up in billing before buying.
404	App missing or wrong organization	Re-check appId; do not charge or retry blindly.
409	Domain unavailable or attached elsewhere	Suggest alternatives from /domains/search.
502	Cloudflare registration failed	The API refunds the debit; report the error and retry only if the user wants.

Never auto-buy a paid domain. The user must explicitly confirm the exact domain after seeing the price.

If the same user asks to retry the same domain after a partial success, call the same /domains/buy route once. It can recover local metadata for a domain that Cloudflare already registered and returns alreadyRegistered instead of charging again.