Part 2 of a two-part case study on building an ERC-20 rewards service in Go. This one covers stdlib signing, the event loop shape that runs the async pipelines, and replay protection at the consumer end. TL;DR Signing an on-chain transaction is two library calls. crypto/ecdsa plus go-ethereum/types land it in five lines. Event pipelines are one for { select } over three channels. The same shape runs the deposit monitor and the reconciler. Reach for Zerohash, Fireblocks, or Circle first. Write this code only when self-custody is part of the product. Go does not give you ABI (Application Binary Interface) encoding, reorg handling, gas estimation, or HSM (Hardware Security Module) integration. Those are domain problems, not language problems.…