Runnable seven-case receiver proof

Webhook Idempotency Acceptance Fixture

A dependency-free Node.js fixture that demonstrates how a webhook receiver can reserve an event before a side effect, acknowledge an identical retry and fail closed when delivery state is uncertain.

The engineering problem

Why this tool exists

TradingView can retry webhook delivery, networks can time out after a receiver starts work and concurrent copies can arrive before the first request finishes. Without a stable event identity and atomic reservation, one logical signal can create multiple downstream actions.

Published capabilities

Stable event-ID reservation before the downstream side effect
Successful duplicate acknowledgement for an identical payload
Conflict response when an event ID is reused with changed content
Concurrent-retry suppression while the first receipt is in flight
Fail-closed handling for uncertain downstream completion
Seven deterministic tests runnable with the built-in Node test runner

Engineering evidence

Original dependency-free fixture and test source published on GitHub
Seven deterministic cases pass without credentials, network calls or live trading
Synthetic timeline report exposes the first duplicated side-effect boundary
Public source states the production-persistence and crash-recovery limitations explicitly

What this case study does not claim

The in-memory store is an acceptance fixture, not production persistence or distributed locking.
The proof does not claim exchange acceptance, endpoint uptime, crash recovery or live-trading safety.
A production implementation still needs a durable atomic reservation and reconciliation policy in the buyer-owned infrastructure.

Need related custom work?

Pine/Webhook Reconciliation — Written decision after contact

Review scope and boundaries

Trading risk disclosure

Futures and forex trading contains substantial risk and is not for every investor. An investor could potentially lose all or more than the initial investment. Risk capital is money that can be lost without jeopardizing one's financial security or lifestyle. Only risk capital should be used for trading, and only those with sufficient risk capital should consider trading. Past performance is not necessarily indicative of future results.

Hypothetical performance disclosure

Hypothetical performance results have many inherent limitations. No representation is being made that any account will or is likely to achieve profits or losses similar to those shown. There are frequently sharp differences between hypothetical performance results and the actual results subsequently achieved by any particular trading program. Hypothetical results are generally prepared with the benefit of hindsight, do not involve financial risk, and cannot completely account for the impact of financial risk in actual trading. Market conditions, the ability to withstand losses, and adherence to a trading program can all materially affect actual results.

NinjaTrader trademark disclosure

NinjaTrader® is a registered trademark of NinjaTrader Group, LLC. No NinjaTrader company has any affiliation with the owner, developer, or provider of the products or services described herein, or any interest, ownership or otherwise, in any such product or service, or endorses, recommends or approves any such product or service.