Show HN: Chr2 – consensus for side effects (exactly-once is a lie)

Source: Hacker News

Issue

Most consensus libraries (Raft, Paxos) treat the state machine as a pure black box. This is fine until your state machine needs to actually do something, like charge a credit card, fire a webhook, or send an email.
If a leader crashes after the side effect but before committing it, you get duplicate…