crate-seq-registry

crates.io read API, cargo publish subprocess, and exponential backoff retry loop.

CratesIoClient queries published versions and yanked state via the crates.io sparse index. All HTTP calls are blocking (reqwest); the sequential publish pipeline never needs concurrency.

backoff_publish retries on RateLimited outcomes with exponential backoff: base 1 s, cap 60 s, up to 5 retries, deterministic jitter per attempt. AlreadyPublished is treated as success. Any other failure stops the loop immediately.