ContextReduction

SUPPORT · type · Type contract

One declared reduction step.

Import

TypeScript

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

JavaScript

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

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

Definition

Type: ContextReduction

Type expression

type ContextReduction = | {
      id: string;
      kind: 'trim';
      fragmentId: string;
      field: string;
      targetChars: number;
      grouping: ContextHistoryGrouping;
      keepGroups: number;
    }
  /** Rewrites one fragment through a registered compressor down to `targetChars`. */
  | ({
      id: string;
      kind: 'compress';
      fragmentId: string;
      targetChars: number;
      /** Recent history the compressor must preserve verbatim. */
      preserve?: ContextRecentHistory;
    } & ContextHandlerReference);

Union branch structure

Optional shapes of ContextReduction: choose one shape; required fields for each branch are listed separately.

Branch 1

Field	Type	Required	Description
id	string	Required	See the type definition and usage context.
kind	"trim"	Required	See the type definition and usage context.
fragmentId	string	Required	See the type definition and usage context.
field	string	Required	See the type definition and usage context.
targetChars	number	Required	See the type definition and usage context.
grouping	ContextHistoryGrouping	Required	See the type definition and usage context.
keepGroups	number	Required	See the type definition and usage context.

Branch 2

Field	Type	Required	Description
id	string	Required	See the type definition and usage context.
kind	"compress"	Required	See the type definition and usage context.
fragmentId	string	Required	See the type definition and usage context.
targetChars	number	Required	See the type definition and usage context.
preserve	ContextRecentHistory | undefined	Optional	Recent history the compressor must preserve verbatim.
handlerId	string	Required	Read-only. Registered handler id; an unknown id is rejected before execution.

Examples

• Context policy: validate, reduce, and audit: Support provides replaceable policy implementations while Core keeps the final input contract and budget checks.

Explicitly use a validation-only policy

Beginner · Node.js

TypeScript

import { Support } from '@jangts/agent-core';
import type { ContextPolicy } from '@jangts/agent-core/support/context';
const policy: ContextPolicy = { mode: 'validate' };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mode);

JavaScript

import { Support } from '@jangts/agent-core';
const policy = { mode: 'validate' };
Support.validateContextPolicy(policy, [], []);
console.log(policy.mode);

Configure reduction order from real business fragments

Configuration · Node.js

These numbers are explicit choices for the example business, not SDK recommendations for capacities that suit all models.

TypeScript

import { Support } from '@jangts/agent-core';
import type { ContextPolicy } from '@jangts/agent-core/support/context';
const policy: ContextPolicy = { mode: 'reduce', triggerChars: 1800, targetInputChars: 1500,
  selection: { mode: 'sequence' },
  steps: [{ id: 'recent-history', kind: 'trim', fragmentId: 'history', field: 'messages',
    grouping: { kind: 'user-turn' }, keepGroups: 2, targetChars: 1000 }],
};
Support.validateContextPolicy(policy, [], []);
console.log(policy.steps);

JavaScript

import { Support } from '@jangts/agent-core';
const policy = { mode: 'reduce', triggerChars: 1800, targetInputChars: 1500,
    selection: { mode: 'sequence' },
    steps: [{ id: 'recent-history', kind: 'trim', fragmentId: 'history', field: 'messages',
            grouping: { kind: 'user-turn' }, keepGroups: 2, targetChars: 1000 }],
};
Support.validateContextPolicy(policy, [], []);
console.log(policy.steps);

Related policy source

• Real scheduling catalog for policies and reduction operations

Related definitions

• ContextHandlerReference
• ContextHistoryGrouping
• ContextRecentHistory