langfuse-tracing

name	langfuse-tracing
description	Add Langfuse observability and tracing to AI operations in Supabase Edge Functions. Use when creating functions with LLM calls that need monitoring, cost tracking, or debugging.

Langfuse Tracing for AI Operations

Available Modules

_shared/langfuse/
├── shared.ts      # Base: Tracer, withTrace()
├── gemini.ts      # Gemini: text, tools, images
├── anthropic.ts   # Anthropic: Claude text, tools
└── openai.ts      # OpenAI: text, tools, images

Basic Usage

Wrap Function with Tracing

import { withTrace, traceLLMGemini } from '../_shared/langfuse/gemini.ts';

Deno.serve(async (req: Request) => {
  return await withTrace(
    {
      name: 'my-function',
      userId: user.id,
      sessionId: item_id,
      input: { prompt: 'analyze this' },
      metadata: { function: 'my-function' },
      tags: ['ai', 'analysis'],
    },
    async (tracer) => {
      // Your AI calls here
      const { text } = await traceLLMGemini(tracer, {
        model: 'gemini-2.5-flash',
        messages: [{ role: 'user', content: 'Hello' }],
      });
      
      return new Response(JSON.stringify({ result: text }));
    }
  );
});

Gemini: Text Completion

const { text, usage } = await traceLLMGemini(tracer, {
  model: 'gemini-2.5-flash',
  messages: [{ role: 'user', content: 'Summarize this' }],
  temperature: 0.7,
  maxTokens: 500,
});

Gemini: Structured Output

const { data } = await traceLLMGemini<{ title: string; price: number }>(tracer, {
  model: 'gemini-2.5-flash',
  messages: [{ role: 'user', content: 'Extract product info' }],
  schema: {
    type: 'object',
    properties: {
      title: { type: 'string' },
      price: { type: 'number' },
    },
    required: ['title', 'price'],
  },
});
// data.title, data.price are typed!

Gemini: Function Calling

const result = await traceLLMWithToolsGemini(tracer, 'agent-name', {
  model: 'gemini-2.5-flash',
  messages: [{ role: 'user', content: 'Get weather in SF' }],
  tools: [{
    name: 'get_weather',
    description: 'Get current weather',
    parameters: {
      type: 'object',
      properties: { location: { type: 'string' } },
      required: ['location'],
    },
  }],
});

if (result.message.tool_calls) {
  // Execute tools
}

What Gets Tracked

✅ Traces: Function execution with nested operations
✅ Generations: LLM calls with prompts and responses
✅ Usage: Token counts and costs
✅ Latency: Timing for each operation
✅ Metadata: Custom tags and context
✅ Errors: Automatic error tracking

Setup

Set environment variables in .env.local:

LANGFUSE_PUBLIC_KEY=pk-lf-xxxxx
LANGFUSE_SECRET_KEY=sk-lf-xxxxx
LANGFUSE_HOST=https://cloud.langfuse.com

Available Functions

Gemini: traceLLMGemini, streamLLMGemini, traceLLMWithToolsGemini, traceImageEditGemini
Anthropic: traceLLMAnthropic, streamLLMAnthropic, traceLLMWithToolsAnthropic
OpenAI: traceLLMOpenAI, streamLLMOpenAI, traceLLMWithToolsOpenAI, traceImageEditOpenAI