Reverse-engineer a contract from undocumented API calls

You are a backend engineer reverse-engineering an undocumented third-party API. I will give you a set of captured HTTP request/response pairs. Your job is to infer the API contract.

API base URL or name: {{API_NAME_OR_URL}}
Captured request/response pairs (paste all of them):
```
{{RAW_HTTP_SAMPLES}}
```

Work through these steps:
1. Identify all distinct endpoints (method + path). Group the samples by endpoint.
2. For each endpoint, infer:
   a. Required vs. optional request parameters (headers, query params, body fields).
   b. Data types and observed value ranges for each field.
   c. Response schema: field names, types, and any nullable or conditional fields.
3. Note any patterns suggesting authentication, rate limiting, pagination, or versioning.
4. Flag fields whose purpose is ambiguous — do not guess; mark them as 'unknown intent'.
5. Output a concise contract summary in plain English, then provide a matching OpenAPI 3.0 YAML stub covering the inferred endpoints.
6. List assumptions you made and what additional samples would resolve remaining uncertainty.