LangfuseTraceExporter class

Streams trial events to Langfuse via /api/public/ingestion.

映射方式（一个 trial = 一棵 langfuse trace）：

dart_agent_core	Langfuse
Trial	trace-create：traceId = <runName>:<taskId>:<trialIndex>
LLM call	generation-create：observationId = uuid，parent = trace
Tool call	span-create：observationId = uuid，parent = trace
Score	score-create：traceId 关联到 trial 的 trace，dataType=NUMERIC
run-level aggregate	trace 上挂一个 run-summary trace + score

配置从 LangfuseConfig.fromEnv 或显式构造，支持云端 / 自托管：

final exporter = LangfuseTraceExporter(LangfuseConfig.fromEnv());
final runner = EvalRunner(
  environment: env,
  harnessFactory: harness,
  exporters: [JsonlTraceExporter(file), exporter],
  ...
);

所有 HTTP 都跑在后台 queue 里。即使 langfuse server 临时挂了或网络 抖动，也不会拖慢 eval run（最多丢几条 event）。

Implemented types

• TraceExporter

Constructors

LangfuseTraceExporter(LangfuseConfig config, {LangfuseClient? client})

Properties

config → LangfuseConfig

final

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

dispose() → Future<void>

Flush + release resources. Called once at the end of the run.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

onLLMCall({required Trial trial, required List<LLMMessage> requestMessages, required ModelConfig modelConfig, required ModelMessage? response, required Duration duration, Object? error}) → Future<void>

Called for each LLM call. response is null on errors.

override

onRunEnd({required String runName, required String suiteName, required Map<String, double> aggregateScores}) → Future<void>

Called when a dataset run completes. Implementations may use this hook to record run-level aggregate scores (pass@k, F1 …).

override

onToolCall({required Trial trial, required ToolCallRecord record}) → Future<void>

Called for each tool call.

override

onTrialEnd({required Trial trial, required Transcript transcript, required Outcome outcome, required List<Score> scores}) → Future<void>

Called when trial finishes with the final transcript, outcome, and scores. Implementations should attach all scores here.

override

onTrialStart(Trial trial, EvalTask task) → Future<void>

Called when a trial starts.

override

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited