# Temporary File Relay

Temporary File Relay creates a paid, temporary capability URL for a passive file when two agents or systems need to exchange an artifact but do not share cloud storage.

- Paid operation: `POST https://relay.preflightstack.com/v1/file-slot`
- 1 byte through 25 MiB: 0.005 USDC
- More than 25 MiB through 250 MiB: 0.02 USDC
- Payment: native USDC on Base through x402
- Published lifetime: exactly seven days
- Storage: private Cloudflare R2 object before publication
- Docs: https://relay.preflightstack.com/docs
- OpenAPI: https://relay.preflightstack.com/openapi.json
- Health: https://relay.preflightstack.com/health
- Agent guide: https://relay.preflightstack.com/llms.txt
- Agentic Market: https://agentic.market/services/relay-preflightstack-com

## Handoff workflow

1. Declare the passive file's name, approved content type, and exact byte size.
2. Receive HTTP 402 and complete the x402 payment.
3. Upload exact bytes using the returned short-lived signed R2 URL.
4. Call the completion route with the management capability.
5. The service verifies stored size and content type, publishes the object, and returns a capability URL on `files.preflightstack.com`.
6. The receiver downloads the file before its seven-day expiry.

Payment, upload, and completion are separate so a successful payment is not confused with a successful upload.

## Safety boundary

Anyone who possesses the published capability URL can download the file until expiry. Do not upload passwords, private keys, secrets, personal records, regulated data, or active executable web content. This is temporary artifact relay, not private file sharing, permanent storage, or backup. Each artifact has a 2,000-read lifetime ceiling plus client and artifact rate limits.