ContentProjectionOptions

KIT · interface · Type contract

Candidate strategy for content projection.

Import

TypeScript

import type { ContentProjectionOptions } from '@jangts/agent-core/kits/projection';

JavaScript

/** @typedef {import('@jangts/agent-core/kits/projection').ContentProjectionOptions} ContentProjectionOptions */

Other public entry points:@jangts/agent-core/types, @jangts/agent-core/kits/projection, @jangts/agent-core/kits.

Definition

interface ContentProjectionOptions

Field structure

Field	Type	Required	Description
counts	readonly number[]	Required	Read-only. Maximum array items to keep, tried in order before moving to the next length.
lengths	readonly number[]	Required	Read-only. Maximum characters per string, tried in order inside each count candidate.
render	(excerpt: unknown) => string	Required	Read-only. Renders a shortened value; must be synchronous.
fallback	(limit: number) => string	Required	Read-only. Builds fallback text for a limit, used when no candidate fits; must be synchronous.

Member index

Member	Purpose
render	Renders a shortened value; must be synchronous.
fallback	Builds fallback text for a limit, used when no candidate fits; must be synchronous.

Member details

render

Renders a shortened value; must be synchronous.

ContentProjectionOptions.render(excerpt: unknown): string

Parameter	Type	Passing	Description
excerpt	unknown	Required	—

Returns: string.

fallback

Builds fallback text for a limit, used when no candidate fits; must be synchronous.

ContentProjectionOptions.fallback(limit: number): string

Parameter	Type	Passing	Description
limit	number	Required	—

Returns: string.

Examples

• Projection: project content under a budget: Shorten text first, then reduce entries; source data, projection result, and budget are explicitly separated by the App.

Prepare compact JSON for the same query result

Beginner · Node.js

TypeScript

import { Projection } from '@jangts/agent-core/kits/projection';
const projection = Projection.defineContentProjection({
  counts: [10, 3, 1], lengths: [200, 80, 20],
  render: value => JSON.stringify(value), fallback: () => '{}',
});
const result = projection.project({ value: { items: [{ title: '配置说明', body: '正文'.repeat(100) }] }, maxChars: 120 });
console.log(result.text, result.truncated);

JavaScript

import { Projection } from '@jangts/agent-core/kits/projection';
const projection = Projection.defineContentProjection({
    counts: [10, 3, 1], lengths: [200, 80, 20],
    render: value => JSON.stringify(value), fallback: () => '{}',
});
const result = projection.project({ value: { items: [{ title: '配置说明', body: '正文'.repeat(100) }] }, maxChars: 120 });
console.log(result.text, result.truncated);

Remove private fields from the same data, then project under budget

Configuration · Node.js

TypeScript

import { Projection } from '@jangts/agent-core/kits/projection';
const tree = Projection.defineTreeProjection({
  maxDepth: 4,
  visitRecord(record) { delete record.privateNote; },
});
const source = { items: [{ title: '配置说明', body: '正文'.repeat(100), privateNote: '不向模型提供' }] };
// 调用者明确选择副本所有权；visitor 不会碰原记录。
const publicData = tree.visit(structuredClone(source), undefined);
const compact = Projection.defineContentProjection({ counts: [10, 3, 1], lengths: [200, 80, 20], render: JSON.stringify, fallback: () => '{}' });
console.log(compact.project({ value: publicData, maxChars: 120 }));

JavaScript

import { Projection } from '@jangts/agent-core/kits/projection';
const tree = Projection.defineTreeProjection({
    maxDepth: 4,
    visitRecord(record) { delete record.privateNote; },
});
const source = { items: [{ title: '配置说明', body: '正文'.repeat(100), privateNote: '不向模型提供' }] };
// 调用者明确选择副本所有权；visitor 不会碰原记录。
const publicData = tree.visit(structuredClone(source), undefined);
const compact = Projection.defineContentProjection({ counts: [10, 3, 1], lengths: [200, 80, 20], render: JSON.stringify, fallback: () => '{}' });
console.log(compact.project({ value: publicData, maxChars: 120 }));

Related policy source

• Reduction order and tree traversal