Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

[0.2.0] - 2026-03-31

Fixed

• Langfuse.Prompt.get/2 now returns prompt data correctly; the underlying HTTP call was sending the prompt name as a query parameter instead of in the URL path

Changed

• Relaxed Elixir version constraint from ~> 1.19 to ~> 1.17 to support projects on Elixir 1.17 and 1.18

Added

• :resolve option for Langfuse.Prompt.get/2, Langfuse.Prompt.fetch/2, Langfuse.Client.get_prompt/2, and Langfuse.HTTP.get_prompt/2 to control server-side prompt dependency resolution
• :cacertfile config option and LANGFUSE_CACERTFILE env var for custom CA certificates (self-hosted Langfuse with self-signed certs)
• GitHub Actions CI with matrix testing across Elixir 1.17/OTP 26, 1.18/OTP 27, and 1.19/OTP 28

[0.1.0] - 2025-11-29

Added

Core Tracing

• Langfuse.trace/1 for creating traces with version and release field support
• Langfuse.span/2 for creating spans with observation types (agent, tool, chain, retriever, embedding, etc.)
• Langfuse.generation/2 for tracking LLM generations with flexible usage fields
• Langfuse.event/2 for recording discrete events
• Environment field support across all event payloads
• SDK metadata included in ingestion batch requests

Scoring

• Langfuse.score/2 with numeric, categorical, and boolean score types
• Session ID and metadata support for scores

Sessions

• Langfuse.Session for grouping related traces into conversations

Prompt Management

• Langfuse.Prompt.get/2 for fetching prompts with automatic caching
• Langfuse.Prompt.compile/2 for variable substitution in prompts
• Fallback prompt support when fetch fails
• Cache invalidation functions (invalidate/2, invalidate_all/0)

Client API

• Langfuse.Client module for direct REST API access
• auth_check/0 for connection verification
• Prompts API: get_prompt/2
• Datasets API: create, get, list, delete datasets and items
• Dataset items: create, get, update (PATCH), delete
• Dataset runs: create and get
• Observations API: get and list observations
• Models API: create, get, list, delete models
• Score configs API: create, get, list

OpenTelemetry Integration

• Optional OpenTelemetry dependency integration
• Langfuse.OpenTelemetry.SpanProcessor for converting OTEL spans to Langfuse observations
• Langfuse.OpenTelemetry.TraceContext for W3C distributed tracing
• Langfuse.OpenTelemetry.AttributeMapper for field mapping
• Langfuse.OpenTelemetry.Setup module for configuration helpers

Instrumentation

• Langfuse.Instrumentation macros for automatic function tracing
• Custom instrumentation support via telemetry

Security

• Langfuse.Masking module for sensitive data redaction
• Configurable masking patterns and functions

Infrastructure

• Langfuse.Ingestion GenServer for async event batching
• Configurable batch size, flush intervals, and retry settings
• Graceful shutdown with automatic pending event flush
• Langfuse.Config with reload/0 for runtime configuration updates
• Configurable GenServer names for multi-instance support
• HTTP client with exponential backoff retry
• Debug logging configuration option

Telemetry

• Langfuse.Telemetry events for observability:

  • [:langfuse, :ingestion, :flush, :start | :stop | :exception]

  • [:langfuse, :http, :request, :start | :stop | :exception]

  • [:langfuse, :prompt, :fetch, :start | :stop | :exception]

  • [:langfuse, :prompt, :cache, :hit | :miss]