ContextFragment

CORE · interface · Type contract

One piece of model-visible input before assembly.

Import

TypeScript

import type { ContextFragment } from '@jangts/agent-core/context';

JavaScript

/** @typedef {import('@jangts/agent-core/context').ContextFragment} ContextFragment */

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

Definition

interface ContextFragment

Field structure

Field	Type	Required	Description
id	string	Required	Unique, stable id matching ^[a-z][a-zA-Z0-9:._-]*$; duplicates are rejected.
sourceId	string	Required	Owning source (module or registration) used to explain where the content came from.
trust	ContextTrust	Required	Producer trust level. user and tool content cannot become a system message.
lifetime	ContextLifetime	Required	Declared validity window of this content.
maxChars	number	Required	Hard upper bound in JSON characters; must be a positive safe integer.
role	"system" | "user"	Required	Message slot the fragment occupies when assembled.
value	string | Record<string, unknown>	Required	Rendered content. A system message accepts a string only, never a record.

Examples

• 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.

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);

Related policy source

• Fragment validation and budget rejection

Related definitions

• ContextLifetime
• ContextTrust