Retries make your event pipeline deliver duplicates. Which effects can you make exactly once, and where does that guarantee stop?

Trace a retry through the broker, database and external provider. The guarantee changes at each boundary, and a recorded intent does not prove a payment or email completed.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.