# Papermill
> Turn markdown or JSON into real Office documents (.docx, .xlsx, .pptx),
> returned as bytes. Pay per call with USDC via x402 — no accounts, no API
> keys, nothing stored.

## Endpoints
- POST /v1/docx — $0.005 — body: markdown (Content-Type: text/markdown)
  or JSON {"markdown": "..."}. Returns .docx bytes.
- POST /v1/xlsx — $0.005 — body: JSON {"sheets": [{"name", "rows",
  "header", "columns", "autofilter"}]} (or top-level "rows" for one sheet).
  Cell strings starting with "=" become live formulas. Returns .xlsx bytes.
- POST /v1/pptx — $0.01 — body: JSON {"slides": [{"layout":
  "title|content|section|blank", "title", "subtitle", "bullets", "notes",
  "images"}]}. Returns .pptx bytes.
- POST /v1/validate — FREE — body: {"format": "docx|xlsx|pptx", "input": ...}.
  Returns {"valid": bool, "errors": [{"path", "message"}]}. Integrate here
  before paying.

## Behavior
- Send "Accept: application/json" to get {"filename", "content_base64"}
  instead of raw bytes.
- Payment: x402 v2, scheme "exact", USDC. An unpaid POST returns 402 with
  the exact payment requirements (amount, payTo, network) — sign and retry
  with the X-PAYMENT header. Invalid input returns 422 and is never charged.
- Deterministic output: the same input always produces byte-identical files
  (safe to cache/verify).
- Caps: 1 MB request; 200 markdown pages / 50,000 cells / 60 slides; images
  base64-embedded only (max 5 MB decoded); remote image URLs are rejected.
- 15 s generation timeout. Nothing is stored; request content is never logged.

## Machine-readable
- OpenAPI: /openapi.json