createModelStrategy

SUPPORT · function · Runtime value

Compose runner options in precedence order: budget preset, selected model, declared reasoning, exact budget, then explicit Core fields.

The result is validated through the same Core binding rules but creates no runner and spends no calls.

Import

TypeScript

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

JavaScript

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

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

Definition

Type parameters

Type parameter	Constraint	Default type
Options	ModelStrategyOptions	—

Call

createModelStrategy<const Options extends ModelStrategyOptions>(options: Options): StrategyResult<Options>

Compose runner options in precedence order: budget preset, selected model, declared reasoning, exact budget, then explicit Core fields.

The result is validated through the same Core binding rules but creates no runner and spends no calls.

Type parameter	Constraint	Default type
Options	ModelStrategyOptions<readonly ModelTransportDefinition<unknown>[], ExecutionOptions>	—

Parameter	Type	Passing	Description
options	Options	Required	—

Returns: StrategyResult<Options>.

Return value structure

Field	Type	Required	Description
maxOutputTokens	number | undefined	Optional	Default output reservation; invoke can override it for one call.
maxCalls	number | undefined	Optional	Calls allowed for the whole request, including descendant runners' reservations.
callTimeoutMs	number | undefined	Optional	Deadline for one provider call, in milliseconds.
maxOutputChars	number | undefined	Optional	Cap on streamed output characters; exceeding it fails the call.
usage	boolean | undefined	Optional	Request and record provider usage for each call.
children	ModelChildPolicy | undefined	Optional	Read-only. See the type definition and usage context.
maxInputChars	number | undefined	Optional	Character budget for the assembled input.
maxSchemaChars	number | undefined	Optional	Character allowance for registered capability schemas.
tokenBudget	ModelTokenBudget | undefined	Optional	See the type definition and usage context.
provider	ChatProvider	Required	See the type definition and usage context.
transports	TransportsFrom<Options, TransportsFrom<SelectedReasoning<Options>, TransportsFrom<SelectedModel<Options>, readonly []>>> | undefined	Optional	See the type definition and usage context.
sink	{ output?: ModelRunnerPorts["onOutput"]; } | undefined	Optional	See the type definition and usage context.
errors	{ inputBudget?: ModelRunnerPorts["inputBudgetError"]; outputBudget?: ModelRunnerPorts["outputBudgetError"]; } | undefined	Optional	See the type definition and usage context.
execution	ExecutionFrom<Options, ExecutionFrom<SelectedReasoning<Options>, ExecutionFrom<SelectedModel<Options>, undefined>>> | undefined	Optional	See the type definition and usage context.

Examples

• 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.

Use a small budget for a short task and keep the same Core construction as needs grow

Beginner · Node.js

TypeScript

import { AgentCoreEngine, ModelRunner, Support } from '@jangts/agent-core';
const provider = { async *stream() { yield '服务在线。'; } };
const config = Support.createModelStrategy({ model: { provider }, budget: 'small' });
const model = new ModelRunner(config);
console.log((await model.invoke('服务状态？')).value);
const agent = new AgentCoreEngine({ model: config });
console.log(agent.branch.agentId);

JavaScript

import { AgentCoreEngine, ModelRunner, Support } from '@jangts/agent-core';
const provider = { async *stream() { yield '服务在线。'; } };
const config = Support.createModelStrategy({ model: { provider }, budget: 'small' });
const model = new ModelRunner(config);
console.log((await model.invoke('服务状态？')).value);
const agent = new AgentCoreEngine({ model: config });
console.log(agent.branch.agentId);

Refer to an existing model by ID and register the reasoning scheme explicitly

Configuration · Node.js

The example Providers are fully offline. Reasoning parameters for real providers are implemented through each Provider's explicit configuration.

TypeScript

import { ModelRunner, Support } from '@jangts/agent-core';
const fast = { async *stream() { yield '简短回答'; } };
const reasoned = { async *stream() { yield '经过复核的回答'; } };
const models = { fast: { provider: fast }, thorough: { provider: reasoned } };
const config = Support.createModelStrategy({ model: 'fast', models, budget: 'small',
  reasoning: 'high', reasoningOptions: { high: { provider: reasoned } },
  maxCalls: 1, maxOutputTokens: 1200,
});
console.log((await new ModelRunner(config).invoke('检查资料')).value);

JavaScript

import { ModelRunner, Support } from '@jangts/agent-core';
const fast = { async *stream() { yield '简短回答'; } };
const reasoned = { async *stream() { yield '经过复核的回答'; } };
const models = { fast: { provider: fast }, thorough: { provider: reasoned } };
const config = Support.createModelStrategy({ model: 'fast', models, budget: 'small',
    reasoning: 'high', reasoningOptions: { high: { provider: reasoned } },
    maxCalls: 1, maxOutputTokens: 1200,
});
console.log((await new ModelRunner(config).invoke('检查资料')).value);

Keep custom budgets and native Core ports effective

Extension · Node.js

The counter is for demonstration only. In production inject a counter that matches the actual model; do not use character estimates as real token counts.

TypeScript

import { ModelRunner, Support } from '@jangts/agent-core';
const provider = { async *stream() { yield 'done'; } };
const transport = Support.createTextTransport({ id: 'app:text' });
const config = Support.createModelStrategy({ model: { provider, transports: [transport] },
  budget: { maxCalls: 3, maxInputChars: 24000, callTimeoutMs: 20000 },
  tokenBudget: { counterId: 'app-counter', contextWindowTokens: 4000,
    countTokens({ messages }) { return messages.reduce((sum, message) => sum + message.content.length, 0); } },
});
const result = await new ModelRunner(config).invoke({ input: 'hello', transport });
console.log(result.value);

JavaScript

import { ModelRunner, Support } from '@jangts/agent-core';
const provider = { async *stream() { yield 'done'; } };
const transport = Support.createTextTransport({ id: 'app:text' });
const config = Support.createModelStrategy({ model: { provider, transports: [transport] },
    budget: { maxCalls: 3, maxInputChars: 24000, callTimeoutMs: 20000 },
    tokenBudget: { counterId: 'app-counter', contextWindowTokens: 4000,
        countTokens({ messages }) { return messages.reduce((sum, message) => sum + message.content.length, 0); } },
});
const result = await new ModelRunner(config).invoke({ input: 'hello', transport });
console.log(result.value);

Related policy source

• Recommended budgets, same-contract completion, and override order

Related definitions

• ModelRunnerOptions
• ModelRunnerSettings
• ModelStrategyOptions