Interface: FusionSpan

Defined in: packages/core/src/observability/Tracing.ts:98

Minimal span interface — structural subtype of OTel's Span.

All methods match OTel's signatures so that an OTel Span satisfies this interface without any adapter.

See

OTel Spec: Span

Methods

addEvent()?

optional addEvent(name, attributes?): void;

Defined in: packages/core/src/observability/Tracing.ts:125

Add a timestamped event to this span.

Optional — not all tracer implementations support events. The pipeline uses span.addEvent?.() (optional chaining).

Parameters

Parameter	Type	Description
name	string	Event name (e.g. 'mcp.route', 'mcp.validate')
attributes?	Record<string, FusionAttributeValue>	Optional event attributes

Returns

void

---

end()

end(): void;

Defined in: packages/core/src/observability/Tracing.ts:131

End this span. Must be called exactly once. The pipeline calls this in a finally block to prevent span leaks.

Returns

void

---

recordException()

recordException(exception): void;

Defined in: packages/core/src/observability/Tracing.ts:139

Record an exception as a span event. Called before setStatus(ERROR) when a handler throws.

Parameters

Parameter	Type	Description
exception	string | Error	The caught error or string message

Returns

void

---

setAttribute()

setAttribute(key, value): void;

Defined in: packages/core/src/observability/Tracing.ts:104

Set a single attribute on this span.

Parameters

Parameter	Type	Description
key	string	Attribute key (use mcp.* namespace for MCP Fusion attributes)
value	FusionAttributeValue	Primitive or array of primitives

Returns

void

---

setStatus()

setStatus(status): void;

Defined in: packages/core/src/observability/Tracing.ts:114

Set the span's status.

Use SpanStatusCode.UNSET for AI/validation errors. Use SpanStatusCode.ERROR only for system failures (handler exceptions).

Parameters

Parameter	Type	Description
status	{ code: number; message?: string; }	Object with code and optional message
status.code	number	-
status.message?	string	-

Returns

void