Retry Helper With Jitter and a Budget

Write a small retry helper for calling someone else's API. Retry the failures that are transient. Do not retry a 400. CONTEXT Call: [HTTP JSON API] Idempotent: [YES | NO — if no, retries are off by default] Max attempts: [3] Budget: [2 SECONDS TOTAL] Respect Retry-After: [YES] DELIVER 1) The function signature: the operation, a classifier, and options. The classifier returns retry or throw for status codes and network errors. 2) Backoff: exponential plus full jitter, capped so the sum stays inside the budget. Show the numbers for the default. 3) Retry-After honored when present, still inside the budget. 4) Attempt count logged, no retry on abort. 5) Tests: a 500 then a 200, a 400 that does not retry, a Retry-After that delays, an operation that is not idempotent and therefore does not retry unless the caller opts in. 6) A note on where this must not wrap a non-idempotent charge unless the charge itself has an idempotency key. Keep it dependency-free unless I asked for a library.