Validation

A misspelled op does not throw – it renders nothing. Content in the wrong slot of a composite renders placeholders. The validator turns those silent failures into a report an agent can act on.

import { validateNodes, describeOps } from "nodality/validate";

const report = validateNodes([{ op: "dithr", target: ["hero"] }], elements);

{ "ok": false,
  "errors": [
    { "code": "UNKNOWN_OP", "path": "nodes[0].op", "got": "dithr",
      "suggestions": ["dither"], "valid": ["hexalize", "offset", "flow", "…"] } ],
  "warnings": [] }

Each error carries a code, the path that failed, what it got, did-you-mean suggestions and the valid vocabulary for that position. Pass elements too and every target is checked against real ids, and the elements themselves are validated.

Common codes:

Code	Means
UNKNOWN_OP	No op by that name
UNKNOWN_PARAM	The op has no such parameter
UNKNOWN_TARGET	A target id that no element has
UNKNOWN_ELEMENT_TYPE	An element type that names nothing
WRONG_CONTENT_SLOT	Content in items where the type reads children, or the reverse
MISSING_FIELD	A required field, such as an element's type, is absent

Checking the rendered page

Valid input can still produce a wrong page. checkPage drives a real browser at a phone and a desktop width and reports in the same shape:

import { checkPage } from "nodality/check"; // needs Playwright in your project

const report = await checkPage(html);

Both are also MCP tools.