#Idempotency
2 articles
Workflow
Always Claim the State Before Sending Anything Out
A "read the state, then send" guard looks safe until a worker gets killed after sending but before writing to the database, and a retry sends the same thing to the customer twice. This article covers the full set of duplicate prevention measures I use, from atomic claims to retry_after and failed() handlers that must never overwrite a successful state.
Factory to Cloud Behind NAT: Push Snapshots and a Command Queue
The production machine sits in a LAN behind NAT with no public IP, but the owner wants to view data on a cloud website and make edits from a phone that reach the internal machine — possible without opening ports or setting up a VPN, using push snapshots + an edit command queue + idempotent acks