API Request Error Handling And Checkpoint System

The prompt behind this diagram

Create a flowchart showing API request error handling with a checkpoint and retry system. Include steps: Client Sends Request, API Gateway Receives Request, Validate Request Schema, decision for validation failure returning a 400 error, Save Checkpoint Before Processing, Call Downstream Service, decision checking if the call succeeded, a retry loop with exponential backoff up to three attempts, a fallback to cached response if retries exhausted, Log Error to Monitoring System, and Return Response to Client.

Paste your own description (or Terraform / docker-compose / SQL schema) into draft1 and get a diagram like this for your exact system.