ModelCallTrace

CORE · interface · Type contract

Accumulated facts of one model call, reported on success and on failure.

Import

TypeScript

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

JavaScript

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

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

Definition

interface ModelCallTrace

Extends or implements: InvocationMetadata.

Field structure

Field	Type	Required	Description
callSequence	number	Required	One-based position of the call within its runner's lifetime.
stageId	string	Required	See the type definition and usage context.
modelId	string | undefined	Optional	Model binding used for the call, when one was configured.
inputChars	number	Required	Counted input characters (messages, instruction and schemas).
inputTokens	number | undefined	Optional	Measured input tokens; present only with an explicit token counter.
inputTokenLimit	number | undefined	Optional	Token ceiling the measurement was compared against.
outputChars	number	Required	Characters received from the provider.
firstOutputMs	number | null | undefined	Optional	Time to first streamed part in milliseconds; null until a part arrived.
outputDurationMs	number | undefined	Optional	Milliseconds from the first part to the end of the stream.
status	InvocationStatus	Required	See the type definition and usage context.
codes	string[]	Required	Error or protocol codes observed during the call, in occurrence order.
usage	ModelUsage | undefined	Optional	See the type definition and usage context.
functionCall	{ id: string; name: string; argumentChars: number; } | undefined	Optional	Selected function call, when the response produced one.
calls	readonly { id: string; name: string; argumentChars: number; toolId?: string; }[] | undefined	Optional	All calls produced by a session response; omitted for single-selection transports.
context	{ fragmentUsage: ContextFragmentUsage[]; stablePrefixChars: number; } | undefined	Optional	Context accounting: per-fragment usage and characters shared with the previous call.
runId	string | undefined	Optional	Read-only. Root run this invocation belongs to, when the host runs inside a diagnostics scope.
spanId	string | undefined	Optional	Read-only. Diagnostics span of this invocation.
parentSpanId	string | undefined	Optional	Read-only. Span that caused this invocation; absent for a root invocation.
parentInvocationId	string | undefined	Optional	Read-only. Enclosing invocation when one call triggers another.
invocationId	string	Required	Read-only. Opaque per-invocation id shared by receipt, events and diagnostic records.
startedAtMs	number	Required	Read-only. Start instant in epoch milliseconds.
durationMs	number	Required	Read-only. Elapsed milliseconds from start to completion.

Examples

• Process observation and node reports: The App subscribes to Core execution facts; nodes report their own usedModel and use an instance sub-logger to record intent first and then results, while the Loop owns identity and logging.
• 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.
• Actual request measurement and same-call preparation snapshot: Use prepare only when context must be handled ahead of time; multiple measurements and the final send reuse the same transport preparation.
• Child execution: isolated records, shared ancestor quota: A child Runner does not inherit conversation or the output receiver, but cannot bypass parent budget, cancellation, or deadlines.

Observe the nodes and model events a task passes through

Beginner · Node.js

TypeScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';

type State = { name: string; answer?: string };
const workflow = defineWorkflow<State, string>({
  id: 'greeting',
  nodes: [{
    id: 'greet', description: '根据本次姓名生成问候', startsRound: true,
    run: state => ({ answer: '你好，' + state.name }),
    routes: [route.deliver('answer')],
  }],
});
const agent = new AgentCoreEngine({ workflow, execution: {
  observe: { event(event) { console.log(event.type, event.eventId); } },
} });
console.log(await agent.run({ name: 'Ivan' }));

JavaScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
const workflow = defineWorkflow({
    id: 'greeting',
    nodes: [{
            id: 'greet', description: '根据本次姓名生成问候', startsRound: true,
            run: state => ({ answer: '你好，' + state.name }),
            routes: [route.deliver('answer')],
        }],
});
const agent = new AgentCoreEngine({ workflow, execution: {
        observe: { event(event) { console.log(event.type, event.eventId); } },
    } });
console.log(await agent.run({ name: 'Ivan' }));

Report a business stage while the node executes

Configuration · Node.js

The node only reports facts it knows; Core owns node identity and execution association.

TypeScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
type State = { name: string; answer?: string };
const workflow = defineWorkflow<State, string>({ id: 'greeting', nodes: [{
  id: 'greet', description: '生成问候', startsRound: true,
  run(state, context) {
    context.report({ payload: { phase: 'formatting' } });
    return { answer: '你好，' + state.name };
  }, routes: [route.deliver('answer')],
}] });
const agent = new AgentCoreEngine({ workflow, execution: {
  observe: { event(event) { console.log(event.type); } },
} });
console.log(await agent.run({ name: 'Ivan' }));

JavaScript

import { AgentCoreEngine, defineWorkflow, route } from '@jangts/agent-core/engine';
const workflow = defineWorkflow({ id: 'greeting', nodes: [{
            id: 'greet', description: '生成问候', startsRound: true,
            run(state, context) {
                context.report({ payload: { phase: 'formatting' } });
                return { answer: '你好，' + state.name };
            }, routes: [route.deliver('answer')],
        }] });
const agent = new AgentCoreEngine({ workflow, execution: {
        observe: { event(event) { console.log(event.type); } },
    } });
console.log(await agent.run({ name: 'Ivan' }));

Related policy source

• Shared execution fact source and consumption isolation
• Sub-step statuses and their progression
• Core default budget values
• Same-call preparation and real input measurement

Related definitions

• ContextFragmentUsage
• InvocationMetadata
• InvocationStatus
• ModelUsage