Context fragments: explicit source, trust, and budget

Core recognizes fragments and the assembly contract, validates source metadata and budgets, and has no built-in business compression algorithm.

A fragment contains id/sourceId/trust/lifetime/maxChars/role/value. trust describes source semantics and does not grant system permissions to data; external raw text is still data. Assembly outputs BuiltContext, containing messages, fragmentUsage, and character usage.

assembleFragments validates and assembles in the registered order and does not silently truncate over-limit fragments. assembleContextPlan audits the original fragments and the mutable range before assembling; it does not call a model selector or compressor. The recommended selection and compression algorithms are provided by ordinary Support nodes, and custom nodes can also implement the same contract.

ContextPlan is a candidate fragment and budget plan, not a model request that has already been sent. fragmentUsage is usage metadata after assembly and must not be treated as the original fragments.

Progressive examples for the same business case

Assemble one input from bare configuration

Beginner · Node.js

TypeScript

import { assembleFragments } from '@jangts/agent-core/context';
const input = assembleFragments([{ id: 'question', sourceId: 'request', trust: 'user',
  lifetime: 'turn', maxChars: 1000, role: 'user', value: '现在服务状态怎样？' }], 2000);
console.log(input.messages, input.fragmentUsage);

JavaScript

import { assembleFragments } from '@jangts/agent-core/context';
const input = assembleFragments([{ id: 'question', sourceId: 'request', trust: 'user',
        lifetime: 'turn', maxChars: 1000, role: 'user', value: '现在服务状态怎样？' }], 2000);
console.log(input.messages, input.fragmentUsage);

Add a candidate plan and final audit

Configuration · Node.js

An empty mutable fragment list means the original fragments may not be modified; no compression step is authorized automatically.

TypeScript

import { assembleContextPlan } from '@jangts/agent-core/context';
import type { ContextFragment } from '@jangts/agent-core/types';
const fragments: ContextFragment[] = [{ id: 'question', sourceId: 'request', trust: 'user',
  lifetime: 'turn', maxChars: 1000, role: 'user', value: '现在服务状态怎样？' }];
const input = assembleContextPlan({ fragments, originalFragments: fragments, mutableFragmentIds: [], maxInputChars: 2000 });
console.log(input.inputChars);

JavaScript

import { assembleContextPlan } from '@jangts/agent-core/context';
const fragments = [{ id: 'question', sourceId: 'request', trust: 'user',
        lifetime: 'turn', maxChars: 1000, role: 'user', value: '现在服务状态怎样？' }];
const input = assembleContextPlan({ fragments, originalFragments: fragments, mutableFragmentIds: [], maxInputChars: 2000 });
console.log(input.inputChars);

Policies & implementations

• Fragment validation and budget rejection