TraceSpan

A single trace span capturing one pipeline stage or function invocation. Spans nest via the __frames field to form a tree representing the full execution (§3.6.1).

Class Diagram

---
title: TraceSpan
config:
  look: handDrawn
  theme: colorful
  class:
    hideEmptyMembersBox: true
---
classDiagram
    class TraceSpan {
        +string name
        +TraceTime __time
        +string signature
        +dictionary inputs
        +unknown output
        +string error
        +TokenUsage __usage
        +dictionary attributes
        +unknown[] __frames
    }
    class TraceTime {
        +string start
        +string end
        +float64 duration
    }
    TraceSpan *-- TraceTime
    class TokenUsage {
        +int32 promptTokens
        +int32 completionTokens
        +int32 totalTokens
    }
    TraceSpan *-- TokenUsage

Yaml Example

name: prompty.core.pipeline.run
signature: prompty.core.pipeline.run
error: Connection refused

Properties

Name	Type	Description
name	string	The name of this span (typically the function signature)
__time	TraceTime	Timing information for this span
signature	string	Fully-qualified function signature that produced this span
inputs	dictionary	Serialized input parameters (redacted per §3.4)
output	unknown	Serialized return value or error information (redacted per §3.4)
error	string	Error message if the span ended with an exception
__usage	TokenUsage	Aggregated token usage hoisted from child spans (§3.5)
attributes	dictionary	Additional span attributes (e.g., OpenTelemetry GenAI attributes)
__frames	unknown[]	Nested child spans forming the execution tree (recursive; each element is a TraceSpan)

Composed Types

The following types are composed within TraceSpan:

• TraceTime
• TokenUsage