@mastra/core/dist/docs/references/reference-observability-tracing-spans.md

Mastra is a framework for building AI-powered applications and agents with a modern TypeScript stack.

# Spans

## `BaseSpan`

Base interface for all span types.

```typescript
interface BaseSpan<TType extends SpanType> {
  /** Unique span identifier */
  id: string

  /** OpenTelemetry-compatible trace ID (32 hex chars) */
  traceId: string

  /** Name of the span */
  name: string

  /** Type of the span */
  type: TType

  /** When span started */
  startTime: Date

  /** When span ended */
  endTime?: Date

  /** Type-specific attributes */
  attributes?: SpanTypeMap[TType]

  /** User-defined metadata */
  metadata?: Record<string, any>

  /** Input passed at the start of the span */
  input?: any

  /** Output generated at the end of the span */
  output?: any

  /** Error information if span failed */
  errorInfo?: {
    message: string
    id?: string
    domain?: string
    category?: string
    details?: Record<string, any>
  }

  /** Snapshot of the RequestContext */
  requestContext?: Record<string, any>
  /** Is an event span? (occurs at startTime, has no endTime) */
  isEvent: boolean
}
```

## Span

Span interface, used internally for tracing. Extends BaseSpan with lifecycle methods and properties.

```typescript
interface Span<TType extends SpanType> extends BaseSpan<TType> {
  /** Is an internal span? (spans internal to the operation of mastra) */
  isInternal: boolean

  /** Parent span reference (undefined for root spans) */
  parent?: AnySpan

  /** Pointer to the ObservabilityInstance instance */
  observabilityInstance: ObservabilityInstance
}
```

### Properties

```typescript
/** Returns TRUE if the span is the root span of a trace */
get isRootSpan(): boolean

/** Returns TRUE if the span is a valid span (not a NO-OP Span) */
get isValid(): boolean

/** Get the closest parent spanId that isn't an internal span */
getParentSpanId(includeInternalSpans?: boolean): string | undefined

/** Returns a lightweight span ready for export */
exportSpan(includeInternalSpans?: boolean): ExportedSpan<TType> | undefined
```

### Methods

#### end

```typescript
end(options?: EndSpanOptions<TType>): void
```

Ends the span and triggers export to configured exporters. Sets the `endTime` and optionally updates `output`, `metadata`, and `attributes`.

#### error

```typescript
error(options: ErrorSpanOptions<TType>): void
```

Records an error on the span. Sets the `errorInfo` field and can optionally end the span.

#### update

```typescript
update(options: UpdateSpanOptions<TType>): void
```

Updates span data while it's still active. Can modify `input`, `output`, `metadata`, and `attributes`.

#### `createChildSpan`

```typescript
createChildSpan<TChildType extends SpanType>(
  options: ChildSpanOptions<TChildType>
): Span<TChildType>
```

Creates a child span under this span. Child spans track sub-operations and inherit the trace context.

#### `createEventSpan`

```typescript
createEventSpan<TChildType extends SpanType>(
  options: ChildEventOptions<TChildType>
): Span<TChildType>
```

Creates an event span under this span. Event spans represent point-in-time occurrences with no duration.

## `ExportedSpan`

Exported Span interface, used for tracing exporters. A lightweight version of Span without methods or circular references.

```typescript
interface ExportedSpan<TType extends SpanType> extends BaseSpan<TType> {
  /** Parent span id reference (undefined for root spans) */
  parentSpanId?: string

  /** TRUE if the span is the root span of a trace */
  isRootSpan: boolean
}
```

## Span lifecycle events

Events emitted during the span lifecycle.

### `TracingEventType`

```typescript
enum TracingEventType {
  /** Emitted when a span is created and started */
  SPAN_STARTED = 'span_started',

  /** Emitted when a span is updated via update() */
  SPAN_UPDATED = 'span_updated',

  /** Emitted when a span is ended via end() or error() */
  SPAN_ENDED = 'span_ended',
}
```

### `TracingEvent`

```typescript
type TracingEvent =
  | { type: 'span_started'; exportedSpan: AnyExportedSpan }
  | { type: 'span_updated'; exportedSpan: AnyExportedSpan }
  | { type: 'span_ended'; exportedSpan: AnyExportedSpan }
```

Exporters receive these events to process and send trace data to observability platforms.

## Union types

### `AnySpan`

```typescript
type AnySpan = Span<keyof SpanTypeMap>
```

Union type for cases that need to handle any span type.

### `AnyExportedSpan`

```typescript
type AnyExportedSpan = ExportedSpan<keyof SpanTypeMap>
```

Union type for cases that need to handle any exported span type.

## NO-OP spans

When tracing is disabled (sampling returns false), NO-OP spans are returned:

### `NoOpSpan`

```typescript
class NoOpSpan<TType extends SpanType> extends BaseSpan<TType>
```

A span that performs no operations. All methods are no-ops:

- `id` returns `'no-op'`
- `traceId` returns `'no-op-trace'`
- `isValid` returns `false`
- `end()`, `error()`, `update()` do nothing
- `createChildSpan()` returns another NO-OP span

## See also

### Documentation

- [Tracing Overview](https://mastra.ai/docs/observability/tracing/overview): Concepts and usage
- [Creating Child Spans](https://mastra.ai/docs/observability/tracing/overview): Practical examples
- [Retrieving Trace IDs](https://mastra.ai/docs/observability/tracing/overview): Using trace IDs

### Reference

- [Tracing Classes](https://mastra.ai/reference/observability/tracing/instances): Core tracing classes
- [Interfaces](https://mastra.ai/reference/observability/tracing/interfaces): Complete type reference
- [Configuration](https://mastra.ai/reference/observability/tracing/configuration): Configuration options