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Why Did We Process the Same Message Twice?
Why acknowledgement boundaries make duplicate delivery normal—and how idempotent consumers make it safe.
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ResilienceWhy Did Our Retry Make the Incident Worse?
Uncoordinated retries multiply load exactly when a dependency has the least capacity.
MessagingWhy Can't We Just Publish the Event After SaveChanges()?A crash between a database commit and message publication creates a durable inconsistency.
Distributed SystemsWhy Isn't Exactly-Once Actually Exactly Once?Exactly-once guarantees have boundaries; external side effects usually live beyond them.
Distributed SystemsWhy Did We Process the Same Message Twice?Why acknowledgement boundaries make duplicate delivery normal—and how idempotent consumers make it safe.
API DesignWhy Did the User Get Charged Twice After Clicking Once?A timeout can hide a successful request, causing a well-meaning retry to repeat the charge.