ModelTokenBudget

CORE · interface · Type contract

Provider-injected token accounting.

Core never guesses a character-to-token conversion, so token budgets exist only when a host supplies a real counter.

Import

TypeScript

import type { ModelTokenBudget } from '@jangts/agent-core/model';

JavaScript

/** @typedef {import('@jangts/agent-core/model').ModelTokenBudget} ModelTokenBudget */

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

Definition

interface ModelTokenBudget

Field structure

Field	Type	Required	Description
counterId	string	Required	Identifies the tokenizer and its version; recorded in every measurement.
contextWindowTokens	number	Required	Total context window of the model, in tokens.
safetyMarginTokens	number | undefined	Optional	Additional reserve subtracted together with the output reservation.
countTokens	(input: { messages: readonly ModelMessage[]; functions?: ModelOptions["functions"]; json?: boolean; }) => number	Required	Counts input tokens for the exact request shape that will be sent.

Member index

Member	Purpose
countTokens	Counts input tokens for the exact request shape that will be sent.

Member details

countTokens

Counts input tokens for the exact request shape that will be sent.

ModelTokenBudget.countTokens(input: { messages: readonly ModelMessage[]; functions?: ModelOptions["functions"]; json?: boolean; }): number

Counts input tokens for the exact request shape that will be sent.

Parameter	Type	Passing	Description
input	{ messages: readonly ModelMessage[]; functions?: ModelOptions["functions"]; json?: boolean; }	Required	—

Fields of input

Field	Type	Required	Description
messages	readonly ModelMessage[]	Required	See the type definition and usage context.
functions	readonly ModelFunction[] | undefined	Optional	See the type definition and usage context.
json	boolean | undefined	Optional	See the type definition and usage context.

Returns: number.

Examples

• ModelRunner: input can be shortened while the output contract stays the same: Execute one model interaction through the real Provider port and return a value plus the invocation for this call.
• Bind once, multiple models per run, and switching across runs: Provide stable model configuration at construction; requests select by configuration ID instead of injecting a Provider repeatedly.
• Model strategy: explicit selection and recommended budgets: Select from registered models and reasoning configurations, complete Core settings with local budget tiers, and keep per-field exact overrides.
• Decorators: complete handlers and existing host methods: Classes construct definitions automatically; methods bind the real host. Outputs still use original define, constructor and bind contracts.

Two inputs for the same output

Beginner · Node.js

TypeScript

import { ModelRunner } from '@jangts/agent-core/model';
const provider = {
  async *stream(messages: readonly { content: string }[]) {
    yield '收到：' + messages.at(-1)!.content;
  },
};
const runner = new ModelRunner({ provider });
const first = await runner.invoke('你好');
const second = await runner.invoke({ input: '你好' });
console.log(first.value, second.value);
console.log(first.invocation.invocationId);

JavaScript

import { ModelRunner } from '@jangts/agent-core/model';
const provider = {
    async *stream(messages) {
        yield '收到：' + messages.at(-1).content;
    },
};
const runner = new ModelRunner({ provider });
const first = await runner.invoke('你好');
const second = await runner.invoke({ input: '你好' });
console.log(first.value, second.value);
console.log(first.invocation.invocationId);

Add budget and request cancellation

Configuration · Node.js

TypeScript

import { ModelRunner } from '@jangts/agent-core/model';
const provider = {
  async *stream(messages: readonly { content: string }[]) {
    yield '收到：' + messages.at(-1)!.content;
  },
};
const runner = new ModelRunner({ provider, maxCalls: 2, maxInputChars: 4000,
  maxOutputChars: 2000, callTimeoutMs: 15000,
  execution: { signal: AbortSignal.timeout(20000) },
});
const result = await runner.invoke({ input: '你好', stageId: 'reply', maxOutputTokens: 600 });
console.log(result.value, runner.remainingCalls);

JavaScript

import { ModelRunner } from '@jangts/agent-core/model';
const provider = {
    async *stream(messages) {
        yield '收到：' + messages.at(-1).content;
    },
};
const runner = new ModelRunner({ provider, maxCalls: 2, maxInputChars: 4000,
    maxOutputChars: 2000, callTimeoutMs: 15000,
    execution: { signal: AbortSignal.timeout(20000) },
});
const result = await runner.invoke({ input: '你好', stageId: 'reply', maxOutputTokens: 600 });
console.log(result.value, runner.remainingCalls);

Related policy source

• Core default budget values
• Recommended budgets, same-contract completion, and override order

Related definitions

• ModelMessage
• ModelOptions