Zukko Blog
Guides to Claude Code, Cursor, Codex and the Claude and GPT APIs: setup, token savings and troubleshooting.
Idempotency-Key: retrying requests without paying twice
4 min · · API
A client-side timeout doesn't mean the request never ran on the server. The Idempotency-Key header solves that without manually checking usage history.
503 errors — the model provider is unavailable
2 min · · errors
A 503 says the problem is not yours. How to survive it without losing work, and why streamed errors arrive with a 200.
429 Too Many Requests — what to do
2 min · · errors
A 429 is not a failure, it is a request to wait. How to retry properly and why agent workloads hit it soonest.
The model's answer stops mid-sentence — why
2 min · · errors
The answer cuts off mid-word. There are four causes, and one field in the API response tells them apart.