ContextCompressor

SUPPORT · interface · Type contract

Registered compressor handler.

Import

TypeScript

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

JavaScript

/** @typedef {import('@jangts/agent-core/support').ContextCompressor} ContextCompressor */

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

Definition

interface ContextCompressor

Field structure

Field	Type	Required	Description
id	string	Required	See the type definition and usage context.
maxCalls	number | undefined	Optional	Maximum model calls through callModel, default 1; declare 0 for local compression.
compress	(call: ContextCompressionCall, context: ExecutionContext) => Promise<ContextFragment["value"]>	Required	Produces a replacement value no larger than the requested target where possible.

Member index

Member	Purpose
compress	Produces a replacement value no larger than the requested target where possible.

Member details

compress

Produces a replacement value no larger than the requested target where possible.

ContextCompressor.compress(call: ContextCompressionCall, context: ExecutionContext): Promise<ContextFragment["value"]>

Produces a replacement value no larger than the requested target where possible.

Parameter	Type	Passing	Description
call	ContextCompressionCall	Required	—
context	ExecutionContext	Required	—

Fields of call

Field	Type	Required	Description
stageId	string	Required	Read-only. See the type definition and usage context.
fragment	ContextFragment	Required	Fragment to compress; its targetChars bound is enforced by the engine.
targetChars	number	Required	See the type definition and usage context.
callModel	ContextModelCall	Required	Same runner's budget, timeout, transports and diagnostics. No recursive processing.

Fields of context

Field	Type	Required	Description
logger	SubFlowLog | undefined	Optional	Read-only. Explicit optional recorder for this operation; never inferred from diagnostics.
signal	AbortSignal	Required	Read-only. Non-optional cancellation signal; never undefined once execution has started.
diagnostics	DiagnosticContext | undefined	Optional	Read-only. Diagnostic scope of the enclosing call, when recording is enabled.

Returns: Promise<string \| Record<string, unknown>>.

Awaited value: string \| Record<string, unknown>.

Examples

• Compressors and selectors: recommended implementations and custom algorithms: Bind prompts, output parsing, and algorithms as handlers; model I/O goes through callModel of the same request.

Bind a text compression handler

Beginner · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
const compressor = Support.createContextCompressor({
  id: 'history-summary', instruction: '保留事实、时间和未完成事项，精简重复表达。',
  transport: 'core:plain-text', maxOutputTokens: 500,
  parse(value: unknown) { if (typeof value !== 'string' || !value.trim()) throw new TypeError('需要非空摘要'); return value; },
});
console.log(compressor.id);

JavaScript

import { Support } from '@jangts/agent-core';
const compressor = Support.createContextCompressor({
    id: 'history-summary', instruction: '保留事实、时间和未完成事项，精简重复表达。',
    transport: 'core:plain-text', maxOutputTokens: 500,
    parse(value) { if (typeof value !== 'string' || !value.trim())
        throw new TypeError('需要非空摘要'); return value; },
});
console.log(compressor.id);

A selector explicitly controls the visible excerpt range

Configuration · Node.js

selector-json must be registered by the App and return value={stepIds:string[]}; an ordinary text transport must not be treated as already parsed JSON. This example only shows handler assembly and sends no request.

TypeScript

import { Support } from '@jangts/agent-core';
const selector = Support.createContextSelector({ id: 'select-reduction',
  transport: 'selector-json', maxOutputTokens: 200, maxExcerptChars: 1000,
});
console.log(selector.id);

JavaScript

import { Support } from '@jangts/agent-core';
const selector = Support.createContextSelector({ id: 'select-reduction',
    transport: 'selector-json', maxOutputTokens: 200, maxExcerptChars: 1000,
});
console.log(selector.id);

Related policy source

• Default selection instruction and excerpt range
• Compression request and the real callModel contract

Related definitions

• ContextCompressionCall
• ContextFragment
• ExecutionContext