Registration fails with "Missing input schema" — what format does parseResponse expect?

[8randonpickart5]

My 8 endpoints at alderpost.co/api/* are registered and working on x402scan, but re-registration fails with parseResponse: Missing input schema.
My 402 response returns a base64-encoded PAYMENT-REQUIRED header. I've tried putting inputSchema in:

accepts[0].inputSchema
accepts[0].config.inputSchema
Top-level inputSchema alongside accepts

All return "Missing input schema."
Could you share what field path parseResponse looks for? Or point me to the source file so I can match the exact format?
Example endpoint: https://www.alderpost.co/api/domain-shield

[craigbidenbot]

How inputSchema resolution works

The discovery library (@agentcash/discovery) tries two sources for inputSchema, in order:

1. The 402 response body (probe)

Since you're using x402 v2 (base64 header), the library decodes the header, parses the JSON, and looks for the schema at this exact path:

extensions.bazaar.schema.properties.input.properties.body

Or, if no body key:

extensions.bazaar.schema.properties.input.properties.queryParams

So your 402 payload (before base64 encoding) needs to look like:

{
  "x402Version": 2,
  "accepts": [ ... ],
  "extensions": {
    "bazaar": {
      "schema": {
        "properties": {
          "input": {
            "properties": {
              "body": {
                "type": "object",
                "properties": {
                  "domain": { "type": "string", "description": "Domain to check" }
                },
                "required": ["domain"]
              }
            }
          }
        }
      }
    }
  }
}

The key insight: it's not at accepts[0].inputSchema or top-level inputSchema — it's nested under extensions.bazaar.schema.properties.input.properties.body.

2. OpenAPI spec fallback

If the 402 body doesn't have an inputSchema, the library falls back to your OpenAPI spec (if you serve one at /.well-known/openapi.json or /openapi.json). It extracts inputSchema from the operation's requestBody or parameters. If you already have an OpenAPI spec with proper request schemas defined, that would also work.

Relevant source

The parsing logic lives in @agentcash/discovery — specifically the extractSchemas2() function for x402 v2 payloads. The code is in the npm package at dist/index.js if you want to trace it yourself.