createJsonTransport

SUPPORT · function · Runtime value

Create a typed JSON transport without a capability-selection envelope.

The transport embeds the JSON Schema in the instruction and requires the response to be one complete JSON value. The returned response parser rejects native call events and invalid JSON, then validates the value through the supplied schema.

Import

TypeScript

import { createJsonTransport } from '@jangts/agent-core/support';

JavaScript

import { createJsonTransport } from '@jangts/agent-core/support';

Other public entry points:@jangts/agent-core, @jangts/agent-core/types, @jangts/agent-core/support, @jangts/agent-core/support/model.

Definition

Type parameters

Type parameter	Constraint	Default type
Output	—	—
Id	string	string

Call

createJsonTransport<Output, const Id extends string = string>(definition: { readonly id: Id; readonly outputSchema: import("../../structs/common.js").SchemaAdapter<Output>; readonly options?: Pick<ModelOptions, "temperature" | "json">; }): ModelTransportDefinition<Output> & { readonly id: Id; }

Create a typed JSON transport without a capability-selection envelope.

The transport embeds the JSON Schema in the instruction and requires the response to be one complete JSON value. The returned response parser rejects native call events and invalid JSON, then validates the value through the supplied schema.

Type parameter	Constraint	Default type
Output	—	—
Id	string	string

Parameter	Type	Passing	Description
definition	{ readonly id: Id; readonly outputSchema: import("../../structs/common.js").SchemaAdapter<Output>; readonly options?: Pick<ModelOptions, "temperature" | "json">; }	Required	—

Fields of definition

Field	Type	Required	Description
id	Id	Required	Read-only. See the type definition and usage context.
outputSchema	SchemaAdapter<Output>	Required	Read-only. See the type definition and usage context.
options	Pick<ModelOptions, "json" | "temperature"> | undefined	Optional	Read-only. See the type definition and usage context.

Returns: ModelTransportDefinition<Output> & { readonly id: Id; }.

Return value structure

Field	Type	Required	Description
id	Id	Required	Read-only. Transport id used by call requests and reported in diagnostics.
prepare	(stageId: string) => PreparedModelTransport<Output>	Required	Builds the prepared transport for stageId; must not spend a call by itself.

Examples

• JSON value transport: validate structured results directly: Generate JSON collection and parsing from an output Schema without adding a tool-selection envelope, and return a unified model result.

Minimal JSON summary: bind Schema and parser in one step

Beginner · Node.js

TypeScript

import { ModelRunner, Support } from '@jangts/agent-core';
const summary = Support.createJsonTransport({ id: 'summary', outputSchema: {
  jsonSchema: { type: 'object', properties: { text: { type: 'string' } }, required: ['text'], additionalProperties: false },
  parse(value: unknown) {
    if (!value || typeof value !== 'object' || !('text' in value) || typeof value.text !== 'string') throw new TypeError('需要摘要正文');
    return { text: value.text };
  },
} });
const provider = { async *stream() { yield '{"text":"服务运行正常。"}'; } };
const model = new ModelRunner({ provider, transports: [summary] });
const result = await model.invoke({ input: '概括服务状态', transport: summary });
console.log(result.value.text, result.invocation);

JavaScript

import { ModelRunner, Support } from '@jangts/agent-core';
const summary = Support.createJsonTransport({ id: 'summary', outputSchema: {
        jsonSchema: { type: 'object', properties: { text: { type: 'string' } }, required: ['text'], additionalProperties: false },
        parse(value) {
            if (!value || typeof value !== 'object' || !('text' in value) || typeof value.text !== 'string')
                throw new TypeError('需要摘要正文');
            return { text: value.text };
        },
    } });
const provider = { async *stream() { yield '{"text":"服务运行正常。"}'; } };
const model = new ModelRunner({ provider, transports: [summary] });
const result = await model.invoke({ input: '概括服务状态', transport: summary });
console.log(result.value.text, result.invocation);

Add temperature, budget, and a custom parser to the same summary contract

Extension · Node.js

Both examples use offline Providers. When switching providers, the same transport and call contract continue to apply.

TypeScript

import { ModelRunner, Support } from '@jangts/agent-core';
class SummarySchema {
  readonly jsonSchema = { type: 'object', properties: { text: { type: 'string' } }, required: ['text'], additionalProperties: false };
  #maxChars = 100;
  parse(value: unknown) {
    if (!value || typeof value !== 'object' || !('text' in value) || typeof value.text !== 'string'
      || !value.text.trim() || value.text.length > this.#maxChars) throw new TypeError('需要简短摘要');
    return { text: value.text };
  }
}
const summary = Support.createJsonTransport({ id: 'summary', outputSchema: new SummarySchema(), options: { temperature: 0.2 } });
const model = new ModelRunner({ provider: { async *stream() { yield '{"text":"服务运行正常。"}'; } },
  transports: [summary], maxCalls: 2, maxOutputTokens: 256,
});
console.log((await model.invoke({ input: '概括服务状态', transport: 'summary' })).value.text);

JavaScript

import { ModelRunner, Support } from '@jangts/agent-core';
class SummarySchema {
    jsonSchema = { type: 'object', properties: { text: { type: 'string' } }, required: ['text'], additionalProperties: false };
    #maxChars = 100;
    parse(value) {
        if (!value || typeof value !== 'object' || !('text' in value) || typeof value.text !== 'string'
            || !value.text.trim() || value.text.length > this.#maxChars)
            throw new TypeError('需要简短摘要');
        return { text: value.text };
    }
}
const summary = Support.createJsonTransport({ id: 'summary', outputSchema: new SummarySchema(), options: { temperature: 0.2 } });
const model = new ModelRunner({ provider: { async *stream() { yield '{"text":"服务运行正常。"}'; } },
    transports: [summary], maxCalls: 2, maxOutputTokens: 256,
});
console.log((await model.invoke({ input: '概括服务状态', transport: 'summary' })).value.text);

Related policy source

• JSON collection, decoding, and output Schema validation

Related definitions

• ModelOptions
• ModelTransportDefinition