405 lines
16 KiB
TypeScript
405 lines
16 KiB
TypeScript
/**
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* Enforced JSON Schema subset shared by tool outputs, generated Code Mode
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* types, subagents, and workflows. The subset accepts any JSON root, an
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* annotation-only schema for unconstrained JSON, one scalar `type`, object
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* `properties`/`required`/boolean `additionalProperties`, array `items`,
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* type-correct scalar `enum`/`const`, and exact-one `oneOf`.
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*
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* Unsupported or misplaced keywords reject rather than being accepted without
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* enforcement. Consumers that require an object root apply
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* {@link assertObjectJsonSchema} at their own boundary.
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* @module dsh-tools/json-schema
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*/
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import { assertNever, HarnessError } from '@deepseek-ai/dsh-llm'
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import { isJsonValue, type JsonValue } from '@deepseek-ai/dsh-session'
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/** Scalar JSON values supported by `enum` and `const`. */
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export type JsonSchemaScalar = string | number | boolean | null
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/** Single-type keywords accepted by the enforced subset. */
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export type JsonSchemaType = 'object' | 'array' | 'string' | 'number' | 'integer' | 'boolean' | 'null'
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/** Scalar-only schema types accepted by literal constraints. */
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type JsonSchemaScalarType = Exclude<JsonSchemaType, 'object' | 'array'>
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/**
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* One raw JSON Schema node in the enforced subset. The optional fields express
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* the external wire shape; {@link assertSupportedJsonSchema} rejects invalid
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* combinations before a caller treats the node as trusted.
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*/
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export interface JsonSchemaNode {
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/** Omit with no constraints for any JSON value, or use `oneOf`. */
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type?: JsonSchemaType
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/** Exactly one branch must validate; at least two branches are required. */
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oneOf?: JsonSchemaNode[]
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/** Nested property schemas (`type: 'object'` only). */
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properties?: Record<string, JsonSchemaNode>
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/** Required property names; each must appear in `properties`. */
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required?: string[]
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/** `false` rejects undeclared keys; absent/`true` follows JSON Schema's open default. */
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additionalProperties?: boolean
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/** Item schema (`type: 'array'` only); absent accepts any JSON item. */
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items?: JsonSchemaNode
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/** Allowed values for a scalar node. */
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enum?: JsonSchemaScalar[]
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/** The single allowed value for a scalar node. */
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const?: JsonSchemaScalar
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/** Annotation, ignored for validation. */
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description?: string
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/** Annotation, ignored for validation. */
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title?: string
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/** Annotation, ignored for validation but required to be lossless JSON. */
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default?: JsonValue
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/** Annotation, ignored for validation but required to be lossless JSON. */
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examples?: JsonValue
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}
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/** A consumer-constrained object-rooted schema. */
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export type ObjectJsonSchema = JsonSchemaNode & { type: 'object' }
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/**
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* Thrown when a raw schema falls outside the enforced subset. `violations`
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* lists every offending path instead of stopping at the first author error.
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*/
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export class JsonSchemaError extends HarnessError {
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/** Individual schema violations in walk order. */
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readonly violations: string[]
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constructor(violations: string[]) {
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super(`unsupported JSON schema: ${violations.join('; ')}`, 'UNSUPPORTED_SCHEMA')
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this.name = 'JsonSchemaError'
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this.violations = violations
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}
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}
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const CONSTRAINT_KEYWORDS = new Set([
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'type',
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'oneOf',
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'properties',
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'required',
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'additionalProperties',
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'items',
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'enum',
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'const',
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])
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const ANNOTATION_KEYWORDS = new Set(['description', 'title', 'default', 'examples'])
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const SCHEMA_TYPES: readonly JsonSchemaType[] = ['object', 'array', 'string', 'number', 'integer', 'boolean', 'null']
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/**
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* Test for a realm-agnostic plain JSON record without accepting arrays or
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* exotic objects.
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* @param value - candidate record from any JavaScript realm.
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* @returns Whether the value has a plain-object prototype chain.
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*/
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export function isPlainJsonRecord(value: unknown): value is Record<string, unknown> {
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if (typeof value !== 'object' || value === null || Array.isArray(value)) return false
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const proto: unknown = Object.getPrototypeOf(value)
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return proto === null || Object.getPrototypeOf(proto) === null
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}
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/** Lossless finite JSON number, excluding negative zero. */
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function isJsonNumber(value: unknown): value is number {
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return typeof value === 'number' && Number.isFinite(value) && !Object.is(value, -0)
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}
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/** Whether a scalar is valid for one declared schema type. */
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function scalarMatches(type: JsonSchemaScalarType, value: unknown): value is JsonSchemaScalar {
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switch (type) {
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case 'string': return typeof value === 'string'
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case 'number': return isJsonNumber(value)
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case 'integer': return isJsonNumber(value) && Number.isInteger(value)
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case 'boolean': return typeof value === 'boolean'
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case 'null': return value === null
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/* v8 ignore next -- JsonSchemaScalarType is closed; this retains compile-time exhaustiveness. */
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default: return assertNever(type, 'JsonSchemaType')
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}
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}
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/** Collect every violation for one raw schema node. */
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function checkSchemaNode(node: unknown, path: string, violations: string[], seen: Set<object>): void {
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if (!isPlainJsonRecord(node)) {
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violations.push(`${path} must be a schema object`)
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return
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}
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if (seen.has(node)) {
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violations.push(`${path} is circular`)
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return
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}
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seen.add(node)
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try {
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for (const key of Object.keys(node)) {
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if (CONSTRAINT_KEYWORDS.has(key)) continue
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if (ANNOTATION_KEYWORDS.has(key)) {
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try {
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if (!isJsonValue(node[key])) violations.push(`${path}.${key} annotation must be lossless JSON data`)
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} catch {
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violations.push(`${path}.${key} annotation must be lossless JSON data`)
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}
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continue
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}
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violations.push(`${path}.${key} is not a supported keyword (subset: type/oneOf/properties/required/additionalProperties/items/enum/const + annotations)`)
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}
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if (node.description !== undefined && typeof node.description !== 'string') {
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violations.push(`${path}.description must be a string`)
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}
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if (node.title !== undefined && typeof node.title !== 'string') {
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violations.push(`${path}.title must be a string`)
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}
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const hasType = Object.hasOwn(node, 'type')
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const hasOneOf = Object.hasOwn(node, 'oneOf')
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if (hasType && hasOneOf) {
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violations.push(`${path} cannot declare both type and oneOf`)
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return
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}
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if (!hasType && !hasOneOf) {
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for (const key of ['properties', 'required', 'additionalProperties', 'items', 'enum', 'const']) {
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if (Object.hasOwn(node, key)) violations.push(`${path}.${key} requires type or oneOf`)
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}
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return
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}
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if (hasOneOf) {
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const oneOf = node.oneOf
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if (!Array.isArray(oneOf) || oneOf.length < 2) {
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violations.push(`${path}.oneOf must be an array of at least two schemas`)
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} else {
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for (let index = 0; index < oneOf.length; index++) {
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checkSchemaNode(oneOf[index], `${path}.oneOf[${index}]`, violations, seen)
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}
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}
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for (const key of ['properties', 'required', 'additionalProperties', 'items', 'enum', 'const']) {
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if (Object.hasOwn(node, key)) violations.push(`${path}.${key} is not supported beside oneOf`)
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}
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return
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}
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const type = node.type
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if (typeof type !== 'string' || !(SCHEMA_TYPES as readonly unknown[]).includes(type)) {
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violations.push(Array.isArray(type)
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? `${path}.type must be a single type string (type arrays are not supported)`
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: `${path}.type must be one of ${SCHEMA_TYPES.join('/')}`)
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return
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}
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const schemaType = type as JsonSchemaType
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const allowedFor: Record<string, JsonSchemaType[]> = {
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properties: ['object'],
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required: ['object'],
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additionalProperties: ['object'],
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items: ['array'],
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enum: ['string', 'number', 'integer', 'boolean', 'null'],
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const: ['string', 'number', 'integer', 'boolean', 'null'],
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}
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for (const [key, types] of Object.entries(allowedFor)) {
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if (Object.hasOwn(node, key) && !types.includes(schemaType)) {
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violations.push(`${path}.${key} is not supported on type "${schemaType}"`)
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}
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}
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switch (schemaType) {
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case 'object': {
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const properties = node.properties
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if (Object.hasOwn(node, 'properties')) {
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if (!isPlainJsonRecord(properties)) {
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violations.push(`${path}.properties must be an object of schemas`)
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} else {
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for (const [key, child] of Object.entries(properties)) {
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checkSchemaNode(child, `${path}.properties.${key}`, violations, seen)
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}
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}
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}
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const required = node.required
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if (Object.hasOwn(node, 'required')) {
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if (!Array.isArray(required) || required.some(entry => typeof entry !== 'string')) {
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violations.push(`${path}.required must be an array of strings`)
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} else {
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const declared = isPlainJsonRecord(properties) ? properties : {}
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for (const key of required as string[]) {
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if (!Object.hasOwn(declared, key)) violations.push(`${path}.required names "${key}" which is not in properties`)
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}
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}
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}
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if (Object.hasOwn(node, 'additionalProperties') && typeof node.additionalProperties !== 'boolean') {
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violations.push(`${path}.additionalProperties must be a boolean`)
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}
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break
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}
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case 'array': {
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if (Object.hasOwn(node, 'items')) checkSchemaNode(node.items, `${path}.items`, violations, seen)
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break
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}
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case 'string':
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case 'number':
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case 'integer':
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case 'boolean':
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case 'null': {
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const allowed = node.enum
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const enumValid = Array.isArray(allowed)
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&& allowed.length > 0
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&& allowed.every(entry => scalarMatches(schemaType, entry))
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if (Object.hasOwn(node, 'enum')) {
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if (!enumValid) {
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violations.push(`${path}.enum must be a non-empty array of ${schemaType} values`)
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}
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}
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const constValid = scalarMatches(schemaType, node.const)
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if (Object.hasOwn(node, 'const')) {
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if (!constValid) {
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violations.push(`${path}.const must be a ${schemaType} value`)
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} else if (enumValid && !allowed.includes(node.const as JsonSchemaScalar)) {
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violations.push(`${path}.const must be one of ${path}.enum when both are declared`)
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}
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}
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break
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}
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/* v8 ignore next -- schemaType was narrowed from the closed SCHEMA_TYPES table above. */
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default: assertNever(schemaType, 'JsonSchemaType')
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}
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} finally {
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seen.delete(node)
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}
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}
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/**
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* Assert that an arbitrary raw schema uses only the enforced subset.
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* Annotation-only schemas are accepted as the standard unconstrained-JSON
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* form; callers that require an object root use {@link assertObjectJsonSchema}.
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* @param schema - untrusted raw JSON Schema.
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* @returns Assertion that the schema belongs to the supported subset.
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*/
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export function assertSupportedJsonSchema(schema: unknown): asserts schema is JsonSchemaNode {
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const violations: string[] = []
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checkSchemaNode(schema, 'schema', violations, new Set())
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if (violations.length > 0) throw new JsonSchemaError(violations)
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}
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/**
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* Assert the enforced subset plus the object-root constraint retained by
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* subagent and workflow structured outputs.
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* @param schema - untrusted caller-supplied schema.
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* @returns Assertion that the schema belongs to the supported subset and has an object root.
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*/
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export function assertObjectJsonSchema(schema: unknown): asserts schema is ObjectJsonSchema {
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const violations: string[] = []
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checkSchemaNode(schema, 'schema', violations, new Set())
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if (violations.length === 0 && (schema as JsonSchemaNode).type !== 'object') {
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violations.push('schema.type must be "object" (structured output is object-rooted)')
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}
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if (violations.length > 0) throw new JsonSchemaError(violations)
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}
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/** Safely test the lossless JSON boundary when a getter may throw. */
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function safelyIsJsonValue(value: unknown): boolean {
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try {
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return isJsonValue(value)
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} catch {
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return false
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}
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}
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/** Root-aware diagnostic path for the parameter validator's empty sentinel. */
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function diagnosticPath(path: string): string {
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return path === '' ? 'arguments' : path
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}
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/** Append one object property without a leading dot at an implicit root. */
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function propertyPath(path: string, key: string): string {
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return path === '' ? key : `${path}.${key}`
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}
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/** Contain hostile getters/proxies so validation remains total for arbitrary values. */
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function checkValue(node: JsonSchemaNode, value: unknown, path: string): string[] {
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if (node.type !== undefined && !(SCHEMA_TYPES as readonly unknown[]).includes(node.type)) {
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return checkValueUnchecked(node, value, path)
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}
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try {
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return checkValueUnchecked(node, value, path)
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} catch {
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return [`"${diagnosticPath(path)}" must be a lossless JSON value`]
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}
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}
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/** Collect value violations for one trusted schema node after the exception boundary. */
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function checkValueUnchecked(node: JsonSchemaNode, value: unknown, path: string): string[] {
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if (node.oneOf !== undefined) {
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const matches = node.oneOf.filter(branch => checkValue(branch, value, path).length === 0).length
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return matches === 1 ? [] : [`"${diagnosticPath(path)}" must match exactly one oneOf branch (matched ${matches})`]
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}
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if (node.type === undefined) {
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return safelyIsJsonValue(value) ? [] : [`"${diagnosticPath(path)}" must be a lossless JSON value`]
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}
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switch (node.type) {
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case 'object': {
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if (!isPlainJsonRecord(value)) return [`"${diagnosticPath(path)}" must be an object`]
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const violations: string[] = []
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const properties = node.properties ?? {}
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for (const key of node.required ?? []) {
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if (!Object.hasOwn(value, key) || value[key] === undefined) violations.push(`missing required property "${propertyPath(path, key)}"`)
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}
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for (const [key, child] of Object.entries(properties)) {
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if (!Object.hasOwn(value, key) || value[key] === undefined) continue
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violations.push(...checkValue(child, value[key], propertyPath(path, key)))
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}
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if (node.additionalProperties === false) {
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for (const key of Object.keys(value)) {
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if (!Object.hasOwn(properties, key)) violations.push(`"${propertyPath(path, key)}" is not a declared property (additionalProperties: false)`)
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}
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}
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if (violations.length > 0) return violations
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return safelyIsJsonValue(value) ? [] : [`"${diagnosticPath(path)}" must be a lossless JSON object`]
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}
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case 'array': {
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if (!Array.isArray(value) || Object.getPrototypeOf(value) !== Array.prototype) return [`"${diagnosticPath(path)}" must be an array`]
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const items = node.items
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const violations = items === undefined
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? []
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: value.flatMap((entry, index) => checkValue(items, entry, `${path}[${index}]`))
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if (violations.length > 0) return violations
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return safelyIsJsonValue(value) ? [] : [`"${diagnosticPath(path)}" must be a dense lossless JSON array`]
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}
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case 'string': {
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if (typeof value !== 'string') return [`"${diagnosticPath(path)}" must be a string`]
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break
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}
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case 'number': {
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if (typeof value !== 'number') return [`"${diagnosticPath(path)}" must be a number`]
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if (!isJsonNumber(value)) return [`"${diagnosticPath(path)}" must be a finite JSON number`]
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break
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}
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case 'integer': {
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if (!isJsonNumber(value) || !Number.isInteger(value)) return [`"${diagnosticPath(path)}" must be an integer`]
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break
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}
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case 'boolean': {
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if (typeof value !== 'boolean') return [`"${diagnosticPath(path)}" must be a boolean`]
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break
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}
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case 'null': {
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if (value !== null) return [`"${diagnosticPath(path)}" must be null`]
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break
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}
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default: return assertNever(node.type, 'JsonSchemaType')
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}
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if (node.enum !== undefined && !node.enum.includes(value)) {
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return [`"${diagnosticPath(path)}" must be one of ${JSON.stringify(node.enum)}`]
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}
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if (Object.hasOwn(node, 'const') && value !== node.const) {
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return [`"${diagnosticPath(path)}" must be ${JSON.stringify(node.const)}`]
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}
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return []
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}
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/**
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* Validate a candidate value against an asserted raw schema. The function is
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* total for arbitrary values and returns path-qualified violations.
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* @param schema - a schema accepted by {@link assertSupportedJsonSchema}.
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* @param value - the candidate JSON value.
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* @param path - root label used in diagnostics.
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* @returns All violations in walk order; empty means valid.
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*/
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export function validateJsonSchemaValue(schema: JsonSchemaNode, value: unknown, path = 'value'): string[] {
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return checkValue(schema, value, path)
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}
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