improved a lot of things

packages/design-language/src/validator.ts

@@ -0,0 +1,89 @@
+import { DesignLanguageFileBodySchema, type DesignLanguageFileBody } from './schema.js';
+import type { ZodError } from 'zod';
+
+// ── Validation result ─────────────────────────────────────────────────────────
+
+export interface ValidationSuccess {
+  valid: true;
+  dlf: DesignLanguageFileBody;
+}
+
+export interface ValidationFailure {
+  valid: false;
+  errors: ValidationError[];
+}
+
+export interface ValidationError {
+  path: string;
+  message: string;
+}
+
+export type ValidationResult = ValidationSuccess | ValidationFailure;
+
+// ── Parse & validate ──────────────────────────────────────────────────────────
+
+export function validateDesignLanguageFile(input: unknown): ValidationResult {
+  const result = DesignLanguageFileBodySchema.safeParse(input);
+  if (result.success) {
+    return { valid: true, dlf: result.data };
+  }
+  return { valid: false, errors: formatZodErrors(result.error) };
+}
+
+function formatZodErrors(error: ZodError): ValidationError[] {
+  return error.errors.map(e => ({
+    path: e.path.join('.') || '(root)',
+    message: e.message,
+  }));
+}
+
+// ── Runtime constraint checks ─────────────────────────────────────────────────
+// These run during visual edits and AI completions to catch violations
+// against the active DLF before they're shown to the user.
+
+export interface ViolationCheck {
+  /** Name of the component being checked */
+  componentName: string;
+  /** Props being applied */
+  props: Record<string, unknown>;
+  /** The active DLF */
+  dlf: DesignLanguageFileBody;
+}
+
+export interface Violation {
+  prop: string;
+  value: unknown;
+  message: string;
+  severity: 'error' | 'warning';
+}
+
+export function checkComponentConstraints(check: ViolationCheck): Violation[] {
+  const { componentName, props, dlf } = check;
+  const violations: Violation[] = [];
+
+  const componentRule = dlf.components?.[componentName];
+  if (!componentRule) return violations;
+
+  const { props: propRules } = componentRule;
+  if (!propRules) return violations;
+
+  for (const [propKey, rule] of Object.entries(propRules)) {
+    const value = props[propKey];
+
+    // Use hasOwnProperty to distinguish "key absent" from "key set to undefined".
+    // Under exactOptionalPropertyTypes these are semantically different.
+    if (rule.required && !Object.prototype.hasOwnProperty.call(props, propKey)) {
+      violations.push({ prop: propKey, value, message: `"${propKey}" is required by design system rules`, severity: 'error' });
+    }
+
+    if (rule.forbidden && value !== undefined && rule.forbidden.includes(value)) {
+      violations.push({ prop: propKey, value, message: `"${propKey}=${String(value)}" is forbidden by design system rules`, severity: 'error' });
+    }
+
+    if (rule.allowed && value !== undefined && !rule.allowed.includes(value)) {
+      violations.push({ prop: propKey, value, message: `"${propKey}=${String(value)}" is not in the allowed values list`, severity: 'warning' });
+    }
+  }
+
+  return violations;
+}