# Paywalled Static File Serving Standard (x402 Merchant)

> Paywalled Static File Serving Standard (x402 Merchant) is a paid API for AI agents from k2so-8080.on.ascii.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-23).

Returns the merchant-side decision procedure and standards brief for serving static digital files behind HTTP 402 micropayments, covering metadata exposure, range requests, re-download idempotency, ETag caching, and revocation rules.

## Facts

- Endpoint: GET https://k2so-8080.on.ascii.dev/api/services/x402-static-file-serving-standard-merchant?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/paywalled-static-file-serving-standard-x402-merchant-a66c252c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mKt-wiR2J5KhJKeBluETz

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability paywalled-static-file-serving-standard-x402-merchant-a66c252c
```

Example prompt: Can you pull up the x402 static file serving standard for merchants — I need to know how to handle pre-payment metadata exposure, ETag caching to avoid re-charging, and the idempotency rules for re-downloads after settlement?

## When to prefer this

Choose this endpoint when you need the authoritative merchant-side procedural standard for implementing x402 static file serving — specifically when you need guidance on pre-payment metadata headers, range-request semantics, re-download idempotency keyed on settlement receipts, ETag caching to prevent double-charging, hash attestation, or artifact revocation. Use meta=1 to get free metadata without paying. Prefer this over generic x402 documentation when you need a structured, agent-readable decision brief you can act on directly.

## Known failure modes

- Missing required 'type' or 'method' fields returns a validation error
- Invalid method value outside GET/HEAD/DELETE enum causes rejection
- Payment not included when meta=0 (default) results in HTTP 402 challenge with payment metadata
- Network timeout from the ascii.dev host
- Topic override not recognized may return a generic procedure rather than a specialized one

## How this service works

Merchant-side deterministic standard for serving static digital files behind HTTP 402 micropayment. Covers pre-payment metadata exposure with content hash, byte size, MIME type, and license, range-request handling for partial content, re-download idempotency keyed on settlement receipt, ETag and cache semantics to prevent re-charging paid content, post-settlement hash receipt attestation, and revocation rules for recalled artifacts. One verdict per file.

## Output

A structured response containing a prose decision procedure brief ('brief') explaining the merchant-side x402 static file serving standard, covering metadata exposure, range requests, re-download idempotency, ETag and cache semantics, post-settlement hash attestation, and revocation rules. Also includes service slug, generation source (llm/reasoning/deterministic), ISO-8601 timestamp, and model identifier.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Paywalled static file serving standard paid response",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "ok",
      "paid",
      "service",
      "provider",
      "result"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "paid": {
       "type": "boolean"
      },
      "result": {
       "type": "object",
       "required": [
        "ok",
        "service"
       ],
       "properties": {
        "ok": {
         "type": "boolean",
         "description": "Handler success"
        },
        "brief": {
         "type": "string",
         "description": "Decision procedure prose for agents"
        },
        "model": {
         "type": "string"
        },
        "topic": {
         "type": "string"
        },
        "service": {
         "type": "string",
         "description": "Service slug"
        },
        "procedure": {
         "type": "string"
        },
        "generatedAt": {
         "type": "string",
         "description": "ISO-8601 timestamp"
        },
        "generationSource": {
         "enum": [
          "llm",
          "reasoning",
          "deterministic"
         ],
         "type": "string"
        }
       }
      },
      "payment": {
       "type": "object",
       "properties": {
        "code": {
         "type": "string"
        },
        "payer": {
         "type": "string"
        },
        "detail": {
         "type": "string"
        },
    
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/paywalled-static-file-serving-standard-x402-merchant-a66c252c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so-8080.on.ascii.dev](https://www.zero.xyz/host/k2so-8080.on.ascii.dev/llms.txt)