Is your feature request related to a problem? Please describe.

Refly's executable skills are free and open — any user or agent can pull and run any skill. There is no mechanism for a skill author to charge per-call: a skill that costs the author money to run (API calls, data acquisition, private model inference) has no way to recoup that cost inside the platform.

Users who want to share a paid data-retrieval skill (a domain lookup, a content extraction, a verified-check tool) currently have to set up their own x402 endpoint and manage payment outside Refly — or not offer the skill at all.

Describe the solution you'd like

Add an optional x402Payment field to a skill's metadata (in the skill declaration / skill.json or the refly-skills registry):

{
  "name": "domain-intel",
  "x402Payment": {
    "price_xno": 0.0001,
    "pay_to": "nano_1yo6c1t64ahfjdw1dxizmbbnpdmbrckwhw9phbg5pdkeubrizga4qhnjmnx7",
    "accepts": [
      {"chain": "nano", "network": "mainnet", "token": "XNO", "standard": "exact"}
    ]
  }
}

When a user or agent invokes a skill that declares x402Payment, the Refly runtime:

1. returns an x402 payment challenge (structured payment_required result / HTTP 402),
2. the client (Claude Code / Cursor / Codex / API) presents the challenge,
3. the caller authenticates a Nano payment and retries with the settlement proof,
4. the skill executes.

This is the same pattern as MCP x402 pay-per-call endpoints (spec: x402.org, x402Version 2).

Describe alternatives you've considered

• Keep all skills free. Works, but a skill author who pays for data/APIs has no way to recoup per-call cost inside Refly.
• Set up a separate paid endpoint outside Refly. Adds ops overhead and splits the skill from its payment.

Additional context

A working reference. Vend API Merchant MCP (extract.paypercall.dev/mcp) already implements this pattern: pay-per-call tools (web extract, link checker, geoip, domain intelligence, web search, youtube transcript) — each call ~0.0001 XNO, no signup, no API keys.

• MCP manifest: https://extract.paypercall.dev/.well-known/mcp
• x402 settlement manifest: https://extract.paypercall.dev/.well-known/x402
• A bare probe returns 402 with the full challenge: curl -i https://extract.paypercall.dev/api/v1/extract?url=https://example.com

Why this is additive

• Not a change to how free skills work — just an optional metadata field.
• Lets skill authors recover API costs per-call without building a separate payment system.
• Brings Refly's executable skills to the x402 agent-payment ecosystem for free.
• The payer infrastructure (x402 client wallet, Nano settlement) already exists and is framework-agnostic.

Security

• The x402 payment is settled peer-to-peer (no escrow, no platform trust).
• The Refly runtime only relays the x402 challenge and checks the settlement proof on retry — it never holds or touches funds.
• A skill without x402Payment works exactly as before.