上下文装配：稳定元数据配置一次
Support 提前绑定片段元数据、格式化和顺序，请求只提供变化的业务输入。
defineContextFragments 适合已经拥有完整片段声明的清单；defineContextAssembly 复用另一份元数据目录及贡献插槽，避免每处重复配置来源和预算。二者都返回同一个 ContextBuilder 合同，fragments、plan、build 仅表示不同准备阶段。
maxInputChars 可绑定固定值或按本次 input 计算，单次请求仍可显式覆盖。没有任何预算来源时拒绝，不能将“没有设置”解释为无限容量。format/transform 同步，固定原接收者；动态 App 服务内容仍在本次输入中读取。
transformContextText 统一转换字符串与对象中嵌套字符串，转换后再测量；它不负责翻译正确性或把数据升级为指令。
由简到繁的同业务示例
一次配置，以后只给问题和历史
入门 · Node.js
ts
import { Support } from '@jangts/agent-core';
type Input = { question: string; history: readonly { role: string; content: string }[] };
const builder = Support.defineContextFragments<Input>([
{ id: 'question', sourceId: 'request', trust: 'user', lifetime: 'turn', maxChars: 1000,
role: 'user', format: input => input.question },
{ id: 'history', sourceId: 'conversation', trust: 'user', lifetime: 'turn', maxChars: 10000,
role: 'user', format: input => ({ messages: input.history }) },
], { maxInputChars: 1200 });
const context = builder.build({ input: { question: '服务状态？', history: [] } });
console.log(context.messages);js
import { Support } from '@jangts/agent-core';
const builder = Support.defineContextFragments([
{ id: 'question', sourceId: 'request', trust: 'user', lifetime: 'turn', maxChars: 1000,
role: 'user', format: input => input.question },
{ id: 'history', sourceId: 'conversation', trust: 'user', lifetime: 'turn', maxChars: 10000,
role: 'user', format: input => ({ messages: input.history }) },
], { maxInputChars: 1200 });
const context = builder.build({ input: { question: '服务状态？', history: [] } });
console.log(context.messages);同一个 builder 提前给出计划
配置 · Node.js
ts
import { Support } from '@jangts/agent-core';
type Input = { question: string; history: readonly { role: string; content: string }[] };
const builder = Support.defineContextFragments<Input>([
{ id: 'question', sourceId: 'request', trust: 'user', lifetime: 'turn', maxChars: 1000,
role: 'user', format: input => input.question },
{ id: 'history', sourceId: 'conversation', trust: 'user', lifetime: 'turn', maxChars: 10000,
role: 'user', format: input => ({ messages: input.history }) },
], { maxInputChars: 1200 });
const input = { question: '服务状态？', history: [] };
const plan = builder.plan({ input });
const expanded = builder.fragments(input);
console.log(plan.maxInputChars, expanded.map(fragment => fragment.id));
const largerRequest = builder.build({ input, maxInputChars: 2000 });
console.log(largerRequest.maxInputChars);js
import { Support } from '@jangts/agent-core';
const builder = Support.defineContextFragments([
{ id: 'question', sourceId: 'request', trust: 'user', lifetime: 'turn', maxChars: 1000,
role: 'user', format: input => input.question },
{ id: 'history', sourceId: 'conversation', trust: 'user', lifetime: 'turn', maxChars: 10000,
role: 'user', format: input => ({ messages: input.history }) },
], { maxInputChars: 1200 });
const input = { question: '服务状态？', history: [] };
const plan = builder.plan({ input });
const expanded = builder.fragments(input);
console.log(plan.maxInputChars, expanded.map(fragment => fragment.id));
const largerRequest = builder.build({ input, maxInputChars: 2000 });
console.log(largerRequest.maxInputChars);复用元数据目录与请求贡献插槽
扩展 · Node.js
ts
import { Support } from '@jangts/agent-core';
import type { ContextFragment } from '@jangts/agent-core/types';
type Input = { question: string; evidence: string };
const builder = Support.defineContextAssembly<Input, 'question', 'evidence'>([
{ kind: 'fragment', id: 'question', format: input => input.question },
{ kind: 'contributions', placement: 'evidence' },
], {
maxInputChars: 2000,
fragment(id, value): ContextFragment { return { id, sourceId: 'request', trust: 'user', lifetime: 'turn', role: 'user', maxChars: 1000, value }; },
contributions: { evidence(input) { return [{ id: 'evidence', sourceId: 'service', trust: 'server', lifetime: 'turn', role: 'user', maxChars: 1000, value: input.evidence }]; } },
});
console.log(builder.build({ input: { question: '状态？', evidence: '最近检查：正常' } }).messages);js
import { Support } from '@jangts/agent-core';
const builder = Support.defineContextAssembly([
{ kind: 'fragment', id: 'question', format: input => input.question },
{ kind: 'contributions', placement: 'evidence' },
], {
maxInputChars: 2000,
fragment(id, value) { return { id, sourceId: 'request', trust: 'user', lifetime: 'turn', role: 'user', maxChars: 1000, value }; },
contributions: { evidence(input) { return [{ id: 'evidence', sourceId: 'service', trust: 'server', lifetime: 'turn', role: 'user', maxChars: 1000, value: input.evidence }]; } },
});
console.log(builder.build({ input: { question: '状态？', evidence: '最近检查：正常' } }).messages);