docs: pydantic ai integration example (#1633)

## Overview
Added PydanticAI traceability page under integrations

## Type of change

**Type:** New documentation page

## Checklist
<!-- Put an 'x' in all boxes that apply -->
- [x] I have read the [contributing guidelines](README.md)
- [x] I have tested my changes locally using `docs dev`
- [x] All code examples have been tested and work correctly
- [x] I have used **root relative** paths for internal links
- [x] I have updated navigation in `src/docs.json` if needed

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---------

Co-authored-by: Kathryn May <[email protected]>
Co-authored-by: Lauren Hirata Singh <[email protected]>
Co-authored-by: Kathryn May <[email protected]>

Author: 3 people

src/docs.json

@@ -943,6 +943,7 @@
                         "langsmith/trace-with-instructor",
                         "langsmith/trace-with-openai-agents-sdk",
                         "langsmith/trace-with-opentelemetry",
+                        "langsmith/trace-with-pydantic-ai",
                         "langsmith/trace-with-semantic-kernel",
                         "langsmith/trace-with-vercel-ai-sdk"
                       ]

src/langsmith/images/pydantic-icon.png

@@ -86,6 +86,11 @@ mode: wide
     icon="/langsmith/images/opentelemetry-icon.svg"
     href="/langsmith/trace-with-opentelemetry" horizontal />
 
+    <Card
+    title="PydanticAI"
+    icon="/langsmith/images/pydantic-icon.png"
+    href="/langsmith/trace-with-pydantic-ai" horizontal />
+
     <Card
     title="Semantic Kernel"
     icon="/langsmith/images/microsoft-icon.svg"

src/langsmith/integrations.mdx

@@ -0,0 +1,125 @@
+---
+title: Trace with PydanticAI
+sidebarTitle: PydanticAI
+---
+
+LangSmith can capture traces generated by PydanticAI using its built-in OpenTelemetry instrumentation. This guide shows you how to automatically capture traces from your PydanticAI agents and send them to LangSmith for monitoring and analysis.
+
+## Installation
+
+Install the required packages:
+
+<CodeGroup>
+
+```bash pip
+pip install langsmith pydantic-ai opentelemetry-exporter-otlp
+```
+
+```bash uv
+uv add langsmith pydantic-ai opentelemetry-exporter-otlp
+```
+
+</CodeGroup>
+
+<Info>
+Requires LangSmith Python SDK version `langsmith>=0.4.26` for optimal OpenTelemetry support.
+</Info>
+
+## Setup
+
+### 1. Configure environment variables
+
+Set your [API keys](/langsmith/create-account-api-key) and project name:
+
+```bash
+export LANGSMITH_API_KEY=<your_langsmith_api_key>
+export LANGSMITH_PROJECT=<your_project_name>
+export OPENAI_API_KEY=<your_openai_api_key>
+```
+
+### 2. Configure OpenTelemetry integration
+
+In your PydanticAI application, configure the LangSmith OpenTelemetry integration:
+
+```python
+from langsmith.integrations.otel import configure
+from pydantic_ai import Agent
+
+# Configure LangSmith tracing
+configure(project_name="pydantic-ai-demo")
+
+# Instrument all PydanticAI agents
+Agent.instrument_all()
+```
+
+<Note>
+You do not need to set any OpenTelemetry environment variables or configure exporters manually—`configure()` handles everything automatically.
+</Note>
+
+### 3. Create and run your PydanticAI agent
+
+Once configured, your PydanticAI agents will automatically send traces to LangSmith:
+
+```python
+from langsmith.integrations.otel import configure
+from pydantic_ai import Agent
+
+# Configure LangSmith tracing
+configure(project_name="pydantic-ai-demo")
+
+# Instrument all PydanticAI agents
+Agent.instrument_all()
+
+# Create and run an agent
+agent = Agent('openai:gpt-4o')
+result = agent.run_sync('What is the capital of France?')
+print(result.output)
+#> Paris
+```
+
+## Advanced usage
+
+### Custom metadata and tags
+
+You can add custom metadata to your traces using OpenTelemetry span attributes:
+
+```python
+from opentelemetry import trace
+from pydantic_ai import Agent
+from langsmith.integrations.otel import configure
+
+configure(project_name="pydantic-ai-metadata")
+Agent.instrument_all()
+
+tracer = trace.get_tracer(__name__)
+
+agent = Agent('openai:gpt-4o')
+
+with tracer.start_as_current_span("pydantic_ai_workflow") as span:
+    span.set_attribute("langsmith.metadata.user_id", "user_123")
+    span.set_attribute("langsmith.metadata.workflow_type", "question_answering")
+    span.set_attribute("langsmith.span.tags", "pydantic-ai,production")
+
+    result = agent.run_sync('Explain quantum computing in simple terms')
+    print(result.output)
+```
+
+### Combine with other instrumentors
+
+You can combine PydanticAI instrumentation with other OpenTelemetry instrumentors:
+
+```python
+from langsmith.integrations.otel import configure
+from pydantic_ai import Agent
+from openinference.instrumentation.openai import OpenAIInstrumentor
+
+# Configure LangSmith tracing
+configure(project_name="multi-framework-app")
+
+# Initialize multiple instrumentors
+Agent.instrument_all()
+OpenAIInstrumentor().instrument()
+
+# Your application code using multiple frameworks
+```
+