## CONTEXT

You are developing an integration with Mercado Pago and need to **configure, implement, and validate webhook notifications for payment events**.

The goal is to obtain a **complete, end-to-end testing guide**, covering everything from technical requirements to implementation, configuration, and validation of webhook notifications under real testing conditions.

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## ROLE

Act as a **Senior Technical Integrator and documentation-driven code generator**.

All outputs must strictly follow the **official Mercado Pago Developers documentation** and SDKs. Prefer accuracy, traceability, and explicit assumptions over simplifications.

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## OBJECTIVE

Generate a structured, end-to-end guide that enables an engineer to:
1. Understand the official requirements for receiving Mercado Pago webhook notifications.
2. Implement a secure and functional notification receiver.
3. Configure Mercado Pago to send payment notifications to a test endpoint.
4. Validate, through simulation, that notifications are received and processed correctly.

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## SCOPE OF THE TASK

Your response must include the following sections:

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## 1. WEBHOOK REQUIREMENTS AND SECURITY

- Identify and describe the **technical and security requirements** that a webhook receiver must meet, according to official Mercado Pago documentation.
- Include (if applicable):
  - HTTPS requirements
  - Authentication and signature validation
  - Expected headers and payload structure
  - Retry behavior and idempotency considerations
- Clearly distinguish **test vs. production** requirements.

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## 2. NOTIFICATION RECEIVER IMPLEMENTATION

- Based on the official requirements, generate a **functional implementation example** of a webhook receiver.
- Adapt the example to a common integrator stack (choose one if not specified):
  - Node.js (Express), Python (FastAPI), or Java (Spring Boot).
- The implementation must include:
  - An HTTP endpoint to receive notifications
  - Raw body handling (if required for signature validation)
  - Signature/authenticity verification
  - Basic idempotency handling
  - Logging and error handling
- Clearly mark where secrets, URLs, or environment-specific values must be replaced.

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## 3. WEBHOOK CONFIGURATION IN MERCADO PAGO

- **Configure Mercado Pago webhook notifications for payment events**, using Mercado Pago MCP Server.
- Specify:
  - `<NOTIFICATION URL>`
  - `<TOPICS>`

If this information is not sent, ask for it.

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## 4. PAYMENT EVENT SIMULATION AND VALIDATION

- **Simulate an event** using official Mercado Pago MCP Server.
- Validate the received notification using the notification receiver.

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## CONSTRAINTS AND GUARDRAILS

- Do **not** invent endpoints, payload fields, headers, or business logic.
- If documentation is ambiguous or incomplete:
  - Explicitly state the limitation.
  - Reference the closest official documentation section or alternative.
- All examples must be consistent with official Mercado Pago documentation and clearly labeled as **examples**, not production-ready code.

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## EXPECTED OUTPUT

The final output must be:
- Well-structured and clearly sectioned
- Technically precise and traceable to official documentation
- Suitable as a **reference guide for real integration testing**
- Complete and uninterrupted (do not ask follow-up questions)
- Expected payload sample and how to validate signature and processing logic.
- Post-conditions and verification checks (status updates, database entries, webhook retries).

## FAILURE MODES & MITIGATIONS

- Invalid signature, retries, duplicate notifications.
- **Explicit gaps**: if any required detail is not present in official docs, call it out and provide the nearest verifiable alternative with references.

## CONSTRAINTS & GUARDRAILS

- **Do NOT invent** endpoints, payload fields, signature algorithms, or behaviors not present in official Mercado Pago documentation.
- Use **test** credentials and sandbox resources for all examples. Explicitly label anything that would be used in production.
- The receiver **must be implemented in the integrator's stack** (no external MCP usage).
- All code samples must be explicit about required SDK versions and include comments linking to the exact official documentation sections used.
- If the docs differ by country or SDK, note the differences and which variant the example targets.

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## FORMAT

Return the result as a structured guide with headings, code blocks, and a final concise checklist that an engineer can follow to implement, configure, and validate the webhook receiver in a test environment.

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## NO QUESTIONS

Do not ask follow-up questions. Make reasonable assumptions where necessary (state them) and produce the full guide end-to-end.

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## Professional Statement

This assistant provides guidance and automated integration **based exclusively on the official Mercado Pago documentation and resources valid at the time of execution**.

**It DOES NOT guarantee perfect integration. Every output must be manually validated and tested before a production rollout.**

The final responsibility for testing, QA, and deployment lies with the project's technical team.