@intentface/latch-langfuse

Langfuse observability for Latch. Implements @intentface/latch-core's dependency-free telemetry seam so any Latch host gets tracing, online evals, and user feedback with one line — and exposes score/trace helpers platforms use to read data back.

Tracing

import { createRuntime } from "@intentface/latch-core";
import { langfuseTelemetry, isLangfuseConfigured } from "@intentface/latch-langfuse";

const runtime = createRuntime({
  // …storage, agents, etc…
  telemetry: isLangfuseConfigured()
    ? langfuseTelemetry({ ownerTag: (p) => ownerKey(p) })
    : undefined,
});

Every agent run becomes one Langfuse trace whose id is derived deterministically from the run id (traceIdForRun), tagged owner: / agent: / run:, with sessionId = the chat id and userId = ownerTag(principal). Reads and scores address a trace from the run id alone — no lookup.

Configuration is read from the environment by the Langfuse SDK: LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY, LANGFUSE_BASE_URL (defaults to https://cloud.langfuse.com). With no keys, isLangfuseConfigured() is false and the seam should be left undefined — zero behavior change.

Scores

import { postScore } from "@intentface/latch-langfuse";

// judge verdict or user feedback on a run's trace
await postScore({ runId, name: "helpfulness", value: 1, comment, dataType: "BOOLEAN" });

Reading traces (server-side, owner-scoped)

import { listOwnerTraces } from "@intentface/latch-langfuse";

// the tenant's recent traces + their scores, newest first
const traces = await listOwnerTraces({ ownerTag, agent, limit: 50 });

ownerTag is the tenancy boundary — the platform proxies all reads and filters on it, so end users never receive Langfuse credentials.

Public API

| Export | Purpose | | --- | --- | | langfuseTelemetry(opts) | The LatchTelemetry implementation for RuntimeConfig.telemetry. | | traceIdForRun(runId) | Deterministic Langfuse trace id for a run. | | postScore(input) | Attach a score (judge/feedback) to a run's trace. | | listOwnerTraces(args) | Owner-scoped trace feed with scores joined in. | | isLangfuseConfigured() | Whether the env credentials are present. | | getLangfuseClient() | The shared LangfuseClient. | | ensureTracing() / flushLangfuse() | OTEL provider setup + serverless flush. |