--- title: "#idempotency articles | Hashnode" description: "Explore 42 articles tagged #idempotency on Hashnode. Tutorials, guides, and how-tos from the community." url: "https://hashnode.com/tag/idempotency" --- Tag # #idempotency 42 posts · 1 followers [Dmytro Nasyrov](https://hashnode.com/@dmytro-nasyrov) · [3d ago](https://hashnode.com/posts/casino-wallet-recovery-session-round-ledger-state/6af425dd27d0807c65d18a8e) ### [Casino Wallet Recovery: Keep Session, Round and Ledger State Separate](https://pharos-production.hashnode.dev/casino-wallet-recovery-session-round-ledger-state?utm_source=hashnode&utm_medium=feed) A three-domain ownership map and fictional late-event sequence for assigning recovery evidence. 17 min read · [pharos-production.hashnode.dev](https://pharos-production.hashnode.dev/casino-wallet-recovery-session-round-ledger-state?utm_source=hashnode&utm_medium=feed) [Parminder singh](https://hashnode.com/@param007) · [4d ago](https://hashnode.com/posts/payment-failed-money-deducted-idempotency/6af2d4383c36fe3908d4fd5a) ### [Payment failed but money deducted: how idempotency keys stop double charges](https://systemdesignwithparam.hashnode.dev/payment-failed-money-deducted-idempotency?utm_source=hashnode&utm_medium=feed) The app says "Payment failed". A second later your phone gets an SMS: ₹2,000 debited. You tap Pay again. Now ₹4,000 is gone, and you still have no order. https://www.youtube.com/watch?v=A6hrGCQidgM 7 min read · [systemdesignwithparam.hashnode.dev](https://systemdesignwithparam.hashnode.dev/payment-failed-money-deducted-idempotency?utm_source=hashnode&utm_medium=feed) [2](https://hashnode.com/posts/payment-failed-money-deducted-idempotency/6af2d4383c36fe3908d4fd5a) [Gautam Patel](https://hashnode.com/@iamgautam03) · [Nov 2](https://hashnode.com/posts/what-happens-when-the-same-event-is-processed-twice-ensuring-effects-happen-only-once/6ae8731628c4c10a1e7a51d2) ### [What Happens When the Same Event Is Processed Twice? Ensuring Effects Happen Only Once](https://iamgautam.hashnode.dev/what-happens-when-the-same-event-is-processed-twice-ensuring-effects-happen-only-once?utm_source=hashnode&utm_medium=feed) Learn how idempotency keys, database transactions, and concurrency control prevent duplicate operations when processed multiple times. 13 min read · [iamgautam.hashnode.dev](https://iamgautam.hashnode.dev/what-happens-when-the-same-event-is-processed-twice-ensuring-effects-happen-only-once?utm_source=hashnode&utm_medium=feed) [Cruxtab Technologies Pvt. Ltd.](https://hashnode.com/@cruxtab) · [Oct 30](https://hashnode.com/posts/building-idempotent-shopify-webhook-processing-with-database-constraints/6ae49426c59e715aaf52a4fc) ### [Building Idempotent Shopify Webhook Processing with Database Constraints](https://cruxtab-technologies.hashnode.dev/building-idempotent-shopify-webhook-processing-with-database-constraints?utm_source=hashnode&utm_medium=feed) Learn how Shopify applications can prevent duplicate webhook processing using database uniqueness, shop-scoped deduplication keys, and safe event handling. 3 min read · [cruxtab-technologies.hashnode.dev](https://cruxtab-technologies.hashnode.dev/building-idempotent-shopify-webhook-processing-with-database-constraints?utm_source=hashnode&utm_medium=feed) [Powerduck](https://hashnode.com/@powerduck) · [Oct 28](https://hashnode.com/posts/agent-stored-consumer-offset-in-config-replayed-backlog/6ae25b14bfe5a9dca77a1a56) ### [The agent stored the consumer offset in config, and a redeploy replayed the whole backlog](https://blogs.powerduck.com/agent-stored-consumer-offset-in-config-replayed-backlog?utm_source=hashnode&utm_medium=feed) The agent tracked the last processed event in an environment constant, ran green locally, and reset on the first redeploy; the consumer re-read the whole queue and resent every welcome email to existing users. 3 min read · [blogs.powerduck.com](https://blogs.powerduck.com/agent-stored-consumer-offset-in-config-replayed-backlog?utm_source=hashnode&utm_medium=feed) [Powerduck](https://hashnode.com/@powerduck) · [Oct 24](https://hashnode.com/posts/agent-retries-whole-task-duplicates-side-effects/6add22c65e86b31bcc799356) ### [The agent retried the whole task after one failed tool call and duplicated the side effects](https://blogs.powerduck.com/agent-retries-whole-task-duplicates-side-effects?utm_source=hashnode&utm_medium=feed) The agent wrapped the whole order job in a retry loop; on a payment timeout it restarted from the top, charged again, and sent a second receipt. Replaying finished steps turns a timeout into duplicate side effects. Retry the failed step, not the task, and make the call idempotent. 4 min read · [blogs.powerduck.com](https://blogs.powerduck.com/agent-retries-whole-task-duplicates-side-effects?utm_source=hashnode&utm_medium=feed) [Meghsham Kapure](https://hashnode.com/@meghsham) · [Oct 19](https://hashnode.com/posts/rest-api-design/6ad595024ca9adfb2633dc37) ### [REST API DESIGN](https://meghsham.hashnode.dev/rest-api-design?utm_source=hashnode&utm_medium=feed) From Roy Fielding's constraints to everyday practice: how to design consistent, predictable REST APIs with the right URLs, methods, pagination, and status codes. 8 min read · [meghsham.hashnode.dev](https://meghsham.hashnode.dev/rest-api-design?utm_source=hashnode&utm_medium=feed) [Kant Claude](https://hashnode.com/@kantclaude) · [Oct 17](https://hashnode.com/posts/make-your-retries-safe-idempotency-in-plain-terms/6ad303226a3d2cb824adb092) ### [Make Your Retries Safe: Idempotency in Plain Terms](https://kantclaude.hashnode.dev/make-your-retries-safe-idempotency-in-plain-terms?utm_source=hashnode&utm_medium=feed) Retries are everywhere: HTTP clients, job queues, webhook senders, that one engineer who double-clicks every button. If your operation isn't safe to run twice, a retry can turn one payment into two. A 2 min read · [kantclaude.hashnode.dev](https://kantclaude.hashnode.dev/make-your-retries-safe-idempotency-in-plain-terms?utm_source=hashnode&utm_medium=feed) [1](https://hashnode.com/posts/make-your-retries-safe-idempotency-in-plain-terms/6ad303226a3d2cb824adb092) [Adrian Studio](https://hashnode.com/@adrianstudio3) · [Oct 4](https://hashnode.com/posts/after-the-idempotency-window-a-late-retry-decision/6ac21a75a3c95a8e8b8cb0c2) ### [After the idempotency window: a late retry decision](https://adrianstudio3.hashnode.dev/after-the-idempotency-window-a-late-retry-decision?utm_source=hashnode&utm_medium=feed) A queued retry can still carry the original key after the provider has stopped remembering it. The key in your database and the provider's deduplication record have different lifetimes. A recovery pro 5 min read · [adrianstudio3.hashnode.dev](https://adrianstudio3.hashnode.dev/after-the-idempotency-window-a-late-retry-decision?utm_source=hashnode&utm_medium=feed) [Mihai\_LeanZero](https://hashnode.com/@mihaileanzero) · [Oct 3](https://hashnode.com/posts/skip-the-migration-writes-that-change-nothing-without-skipping-the-ones-that-matter/6ac1909a3a3a83cc36483737) ### [Skip the migration writes that change nothing, without skipping the ones that matter](https://leanzero.hashnode.dev/skip-the-migration-writes-that-change-nothing-without-skipping-the-ones-that-matter?utm_source=hashnode&utm_medium=feed) A semantic hash lets a re-run skip writes that change nothing — and can erase the identity you meant to compare. The pattern, and the tests that catch it. 12 min read · [leanzero.hashnode.dev](https://leanzero.hashnode.dev/skip-the-migration-writes-that-change-nothing-without-skipping-the-ones-that-matter?utm_source=hashnode&utm_medium=feed)