# Release metadata for v0.6.0
version: "0.6.0"
date: "2026-09-03"
author: "qualiow"
status: active

notes: >
  Asynchronous money movement. Everything up to v0.5.0 assumes a request and a response: you ask
  the system something and judge the answer. A payment rail does not work that way — the platform
  asks a provider to move money, the provider answers minutes later over a channel it will not
  retry, a sweeper closes whatever never arrived, and the thing that has to be right is a balance
  nobody returned in any of those responses. Exactly-Once Verification is the ledger half: read
  the balance before and after every case and assert the delta, then attack the flow with the five
  cases that actually break it — an identity collision between two records created at the same
  instant, the same event redelivered simultaneously rather than in a loop, a contradicting event,
  an event arriving after a timeout already closed the record, and a settlement amount that does
  not match what was requested. Asynchronous Callback Contracts is the receiving half: whether the
  endpoint is authenticated at all, which field it really deduplicates on as opposed to which one
  the documentation claims, what it does with an event matching no record, and whether its
  response lets the caller tell applied from duplicate from discarded. Both carry the same warning,
  learned the hard way: a system correct on every sequential path and wrong on every concurrent one
  passes ordinary testing, and when its identity defect starts corrupting your own parallel test
  run, the answer is to serialise and say so — never to make the assertions tolerant, and never to
  retry until it goes green.

entry_count: 2

entries:
  - technique-exactly-once-verification
  - technique-async-callback-contracts