> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sendykit.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent Payments

> How premium agent actions are paid for in SendyKit

## Current truth

The current implementation target is:

* **Stripe-native machine payments** for premium actions
* proof via `X-Stripe-Machine-Payment`

Not raw/direct x402 as the live public path.

## Header shape

```bash theme={null}
curl -H "X-API-Key: sk_..." \
  -H "X-Stripe-Machine-Payment: <payment-proof-or-intent-ref>" \
  https://your-server.com/sendykit/api/v2/ai/subject-lines
```

## When machine payments apply

Machine payments are for **premium actions**, not every request.

Examples:

* AI generation
* premium webhook trigger paths
* higher-cost automation work
* other policy-gated premium surfaces

## When they do not apply

Most normal operator automation should still use:

* `X-API-Key`
* JWT/session auth where appropriate

## Historical note

Older specs explored direct x402 flows.
That material is preserved as historical exploration, but it should not be treated as the live customer path unless explicitly revived later.