LangSmith - PraisonAI

LangSmith stores every trace from your agents so you can replay, debug, and share runs — PraisonAI delivers them live over LangSmith’s Runs API.

Quick Start

Simple Usage

import { Agent, createObservabilityAdapter, setObservabilityAdapter } from 'praisonai';

const obs = await createObservabilityAdapter('langsmith');
setObservabilityAdapter(obs);

const agent = new Agent({
  name: 'TracedAgent',
  instructions: 'You are helpful.',
  observability: true
});

await agent.chat('Hello!');
await obs.flush();

With Configuration

import { Agent, createObservabilityAdapter, setObservabilityAdapter } from 'praisonai';

const obs = await createObservabilityAdapter('langsmith', {
  name: 'langsmith',
  apiKey: process.env.LANGSMITH_API_KEY,
  baseUrl: process.env.LANGSMITH_ENDPOINT,   // e.g. https://langsmith.my-company.com
  projectId: 'production-agents'
});
setObservabilityAdapter(obs);

How It Works

Spans are posted to LangSmith as runs, asynchronously, while your agent keeps working.

PraisonAI concept	LangSmith concept
Agent trace	Root run (`run_type: chain`)
Tool span	Child run (`run_type: tool`)
LLM span	Child run (`run_type: llm`)
Retrieval span	Child run (`run_type: retriever`)
Span event	Entry in run’s `extra.events[]`

Configuration Options

Secrets are read from the environment only and never logged; programmatic values override the env.

Option	Env variable (alt)	Default	Description
API key	`LANGSMITH_API_KEY` (`LANGCHAIN_API_KEY`)	—	Required for delivery; sent as `x-api-key`.
Endpoint	`LANGSMITH_ENDPOINT` (`LANGCHAIN_ENDPOINT`)	`https://api.smith.langchain.com`	Must be `http(s)`. Plaintext `http://` is only accepted for loopback hosts.
Project	`LANGSMITH_PROJECT` (`LANGCHAIN_PROJECT`)	(none)	Shows up as the LangSmith session name.

When self-hosting over http://, use localhost, 127.0.0.1, or ::1 — the adapter refuses non-loopback plaintext endpoints so the API key cannot leak on the wire.

When does delivery happen?

Spans are posted asynchronously; your agent’s hot path never waits for LangSmith. Call await obs.flush() before the process exits (e.g. in a serverless handler) to drain the queue. If a request fails, flush() warns how many runs did not reach LangSmith — the key, endpoint and network are not silently swallowed.

Common Patterns

Multiple agents sharing one trace keep their tree in LangSmith via parent_run_id.

import { Agent, Agents, createObservabilityAdapter, setObservabilityAdapter } from 'praisonai';

const obs = await createObservabilityAdapter('langsmith');
setObservabilityAdapter(obs);

const researcher = new Agent({
  name: 'Researcher',
  instructions: 'Research topics thoroughly.',
  observability: true
});

const writer = new Agent({
  name: 'Writer',
  instructions: 'Write clear summaries.',
  observability: true
});

const agents = new Agents({ agents: [researcher, writer] });
await agents.start('Summarize AI trends 2024');
await obs.flush();

Self-hosted LangSmith is one env var away.

import { Agent, createObservabilityAdapter, setObservabilityAdapter } from 'praisonai';

process.env.LANGSMITH_ENDPOINT = 'https://langsmith.my-company.com';

const obs = await createObservabilityAdapter('langsmith');
setObservabilityAdapter(obs);

const agent = new Agent({
  name: 'InternalAgent',
  instructions: 'You are helpful.',
  observability: true
});

await agent.chat('Hello!');
await obs.flush();

Missing key degrades gracefully: spans record to memory and flush() warns nothing was delivered.

import { createObservabilityAdapter } from 'praisonai';

const obs = await createObservabilityAdapter('langsmith');
console.log(obs.isEnabled);
// false when LANGSMITH_API_KEY is unset — traces stay in memory; safe for local dev.

Best Practices

Set LANGSMITH_API_KEY once per process

Prefer the environment variable over the programmatic apiKey so the key stays out of source control. The env key is read on initialize().

Always await obs.flush() before exiting

Delivery is async. In short-lived processes (scripts, serverless handlers) call await obs.flush() so queued runs reach LangSmith before the process ends.

Keep LANGSMITH_ENDPOINT on https://

The API key travels as x-api-key. Plaintext http:// is refused for non-loopback hosts; use https:// unless the endpoint is localhost.

Use LANGSMITH_PROJECT per environment

Set a different LANGSMITH_PROJECT for dev, staging, and prod so traces land in separate LangSmith sessions.

LangSmith CLI

CLI commands

Observability

Overview and delivery matrix

​Quick Start

​How It Works

​Configuration Options

​When does delivery happen?

​Common Patterns

​Best Practices

​Related

LangSmith CLI

Observability

Quick Start

How It Works

Configuration Options

When does delivery happen?

Common Patterns

Best Practices

Related