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Duplicate Guard & Retry Budget

Idempotency enforcement, per-merchant retry quotas, and exact-once delivery proof

🚫 Duplicates Blocked

0

⏸ Merchants Paused

0

✓ Confirmed Deliveries

3

🔑 Unique Keys Issued

3

🧪 Live Demo Controls

"Send Duplicate Payment" fires 2 webhooks with the same idempotency key — the second is instantly blocked. "Trigger Retry Storm" fires 6 failing webhooks in quick succession to exceed the budget and auto-pause the merchant.

Every payment listed below was delivered exactly once. Idempotency keys ensure no shop is charged twice.

Idempotency Key	Gateway	Amount	Delivered At	Verification
idem_ghi9012	Stripe	USD 320	6:10:08 AM	✓ VERIFIED UNIQUE
idem_abc1234	SSLCommerz	BDT 145	6:08:38 AM	✓ VERIFIED UNIQUE
idem_jkl3456	bKash	BDT 25	6:06:38 AM	✓ VERIFIED UNIQUE

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How Duplicate Guard Works

Every payment is assigned a unique idempotency_key (UUID) before entering the system. The key is checked against a Redis/PostgreSQL ledger before any delivery attempt. If the key already exists, the webhook is instantly rejected with status: duplicate_blocked — ensuring the shop is never charged or shipped twice, even during retry storms. The Retry Budget layer sits above this — tracking per-merchant retry counts within a sliding time window and automatically pausing merchants that show pathological failure patterns, preventing cascade overload.