DiagnosticContext

CORE · interface · Type contract

Recording scope bound to one execution identity.

A child scope inherits the sink and observer of its parent; only identity changes.

Import

TypeScript

import type { DiagnosticContext } from '@jangts/agent-core/diagnostics';

JavaScript

/** @typedef {import('@jangts/agent-core/diagnostics').DiagnosticContext} DiagnosticContext */

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

Definition

interface DiagnosticContext

Field structure

Field	Type	Required	Description
identity	Readonly<DiagnosticIdentity> | undefined	Optional	Read-only. Identity of the current scope, when the scope is bound to an execution.
enabled	(event: CoreEventName, content?: "metadata" | "content") => boolean	Required	Cheap pre-check so callers can skip building expensive payloads.
emit	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], debug?: DebugStepsOutput) => void	Required	Records one fact.
deliver	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], sink: (event: Extract<CoreEvent, { type: K; }>) => void | Promise<void>) => Promise<void>	Required	Ordered content delivery uses the same fact, while consumer failures propagate.
child	(spanId: string, fields?: Readonly<DiagnosticSpanFields>) => DiagnosticContext	Required	Derives a child span; fields fills values the child knows but the parent does not.
withObserver	(observer: import("./execution/events.js").ExecutionObserver) => DiagnosticContext	Required	Bind live observation without changing the log destination or request identity.

Member index

Member	Purpose
enabled	Cheap pre-check so callers can skip building expensive payloads.
emit	Records one fact.
deliver	Ordered content delivery uses the same fact, while consumer failures propagate.
child	Derives a child span; fields fills values the child knows but the parent does not.
withObserver	Bind live observation without changing the log destination or request identity.

Member details

enabled

Cheap pre-check so callers can skip building expensive payloads.

DiagnosticContext.enabled(event: CoreEventName, content?: "metadata" | "content"): boolean

Cheap pre-check so callers can skip building expensive payloads.

Parameter	Type	Passing	Description
event	keyof CoreEventPayloads	Required	—
content	"metadata" | "content" | undefined	Optional	—

Returns: boolean.

emit

Records one fact.

DiagnosticContext.emit<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], debug?: DebugStepsOutput): void

Records one fact.

Type parameter	Constraint	Default type
K	keyof CoreEventPayloads	—

Parameter	Type	Passing	Description
event	K	Required	—
payload	() => CoreEventPayloads[K]	Required	—
debug	DebugStepsOutput | undefined	Optional	—

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

Branch 1

undefined

Branch 2

Field	Type	Required	Description
usedModel	boolean | undefined	Optional	Read-only. Model use reported by this handler; omitted when unknown.
recordedSubSteps	readonly Readonly<RecordedSubStep>[] | undefined	Optional	Read-only. Runtime-owned immutable snapshot, committed when a logger writes or fixes a step.

Returns: void.

deliver

Ordered content delivery uses the same fact, while consumer failures propagate.

DiagnosticContext.deliver<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], sink: (event: Extract<CoreEvent, { type: K; }>) => void | Promise<void>): Promise<void>

Ordered content delivery uses the same fact, while consumer failures propagate.

Type parameter	Constraint	Default type
K	keyof CoreEventPayloads	—

Parameter	Type	Passing	Description
event	K	Required	—
payload	() => CoreEventPayloads[K]	Required	—
sink	(event: Extract<CoreEvent, { type: K; }>) => void | Promise<void>	Required	—

Returns: Promise<void>.

Awaited value: void.

child

Derives a child span; fields fills values the child knows but the parent does not.

DiagnosticContext.child(spanId: string, fields?: Readonly<DiagnosticSpanFields>): DiagnosticContext

Derives a child span; fields fills values the child knows but the parent does not.

Parameter	Type	Passing	Description
spanId	string	Required	—
fields	Readonly<DiagnosticSpanFields> | undefined	Optional	—

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

Branch 1

undefined

Branch 2

Field	Type	Required	Description
parentInvocationId	string | undefined	Optional	Read-only. Enclosing invocation, when one invocation triggers another.
invocationId	string | undefined	Optional	Read-only. Invocation that produced the fact, when the fact belongs to one.
nodeRole	"invocation" | "workflow-node" | "workflow-boundary" | "loop-step" | undefined	Optional	Read-only. Role the emitting span plays in the execution graph.
agentId	string | undefined	Optional	Read-only. App-owned agent identity.
branchId	string | undefined	Optional	Read-only. App-owned branch identity.
agentVersionId	string | undefined	Optional	Read-only. App-owned immutable version identity of the agent definition.
parentBranchId	string | undefined	Optional	Read-only. Branch this branch was forked from, when applicable.
parentAgentVersionId	string | undefined	Optional	Read-only. Version of the parent branch at the fork point.
forkPointId	string | undefined	Optional	Read-only. App-owned fork marker shared by the forked branch and its origin.
workflowInvocationId	string | undefined	Optional	Read-only. Workflow invocation the fact belongs to.
workflowNodeId	string | undefined	Optional	Read-only. Workflow node invocation the fact belongs to.
definitionKind	string | undefined	Optional	Read-only. Kind of the workflow/agent definition that dispatched the node.
definitionId	string | undefined	Optional	Read-only. Id of that definition.
definitionRevision	string | undefined	Optional	Read-only. Revision of that definition; distinguishes executions of different definition states.
nodeId	string | undefined	Optional	Read-only. Node id inside the workflow.
nodeName	string | undefined	Optional	Read-only. Human-readable node name.
nodeKind	string | undefined	Optional	Read-only. Node kind as declared by the App.
nodeDescription	string | undefined	Optional	Read-only. Optional node description for diagnostics display.
stageId	string | undefined	Optional	Read-only. Model stage that produced the fact.
modelId	string | undefined	Optional	Read-only. Model binding used, when the fact concerns a model call.

Returns: DiagnosticContext.

Return value structure

Field	Type	Required	Description
identity	Readonly<DiagnosticIdentity> | undefined	Optional	Read-only. Identity of the current scope, when the scope is bound to an execution.
enabled	(event: CoreEventName, content?: "metadata" | "content") => boolean	Required	Cheap pre-check so callers can skip building expensive payloads.
emit	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], debug?: DebugStepsOutput) => void	Required	Records one fact.
deliver	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], sink: (event: Extract<CoreEvent, { type: K; }>) => void | Promise<void>) => Promise<void>	Required	Ordered content delivery uses the same fact, while consumer failures propagate.
child	(spanId: string, fields?: Readonly<DiagnosticSpanFields>) => DiagnosticContext	Required	Derives a child span; fields fills values the child knows but the parent does not.
withObserver	(observer: import("./execution/events.js").ExecutionObserver) => DiagnosticContext	Required	Bind live observation without changing the log destination or request identity.

withObserver

Bind live observation without changing the log destination or request identity.

DiagnosticContext.withObserver(observer: import("./execution/events.js").ExecutionObserver): DiagnosticContext

Bind live observation without changing the log destination or request identity.

Parameter	Type	Passing	Description
observer	ExecutionObserver	Required	—

Fields of observer

Field	Type	Required	Description
accepts	((descriptor: Readonly<ExecutionEventDescriptor>) => boolean) | undefined	Optional	Metadata-only by default. Content requires an explicit accepts decision.
event	(event: Readonly<CoreEvent>) => void | Promise<void>	Required	Handles one fact; a rejected promise propagates to the emitting call.

Returns: DiagnosticContext.

Return value structure

Field	Type	Required	Description
identity	Readonly<DiagnosticIdentity> | undefined	Optional	Read-only. Identity of the current scope, when the scope is bound to an execution.
enabled	(event: CoreEventName, content?: "metadata" | "content") => boolean	Required	Cheap pre-check so callers can skip building expensive payloads.
emit	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], debug?: DebugStepsOutput) => void	Required	Records one fact.
deliver	<K extends CoreEventName>(event: K, payload: () => CoreEventPayloads[K], sink: (event: Extract<CoreEvent, { type: K; }>) => void | Promise<void>) => Promise<void>	Required	Ordered content delivery uses the same fact, while consumer failures propagate.
child	(spanId: string, fields?: Readonly<DiagnosticSpanFields>) => DiagnosticContext	Required	Derives a child span; fields fills values the child knows but the parent does not.
withObserver	(observer: import("./execution/events.js").ExecutionObserver) => DiagnosticContext	Required	Bind live observation without changing the log destination or request identity.

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.

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

Related definitions

• CoreEvent
• CoreEventName
• CoreEventPayloads
• DebugStepsOutput
• DiagnosticIdentity
• DiagnosticSpanFields
• ExecutionObserver