Add create and update methods to client API

[kxzk]

Summary

• Add create_prompt and update_prompt methods to the Client API for programmatic prompt management
• Enable creating new prompts (or versions) and updating labels without the Langfuse UI
• Fix URL encoding for prompt names containing special characters (e.g., /, ?, spaces)

Key Changes

File	Change
lib/langfuse/client.rb	Add create_prompt and update_prompt with validation
lib/langfuse/api_client.rb	Add HTTP methods + URL encoding fix
docs/PROMPTS.md	Document new methods with examples
spec/	Add 30+ test cases for new functionality

API Example

# Create
prompt = client.create_prompt(
  name: "greeting",
  prompt: "Hello {{name}}!",
  type: :text,
  labels: ["staging"]
)

# Update labels
client.update_prompt(name: "greeting", version: 1, labels: ["production"])

[kxzk]

Validation

Platform output

Script used to validate

#!/usr/bin/env ruby
# frozen_string_literal: true

require "bundler/setup"
require "langfuse"
require "dotenv/load"
require "securerandom"

Langfuse.configure do |config|
  config.public_key = ENV.fetch("LANGFUSE_PUBLIC_KEY")
  config.secret_key = ENV.fetch("LANGFUSE_SECRET_KEY")
  config.base_url = ENV.fetch("LANGFUSE_HOST")
end

client = Langfuse.client
unique_id = SecureRandom.hex(4)

puts "=" * 60
puts "Validating Langfuse Prompt Create/Update API"
puts "=" * 60

puts "\n[1] Creating text prompt..."
text_prompt_name = "test-text-prompt-#{unique_id}"
text_prompt = client.create_prompt(
  name: text_prompt_name,
  prompt: "Hello {{name}}! Welcome to {{place}}.",
  type: :text,
  labels: ["staging"],
  config: { model: "gpt-4o", temperature: 0.7 }
)

puts "  ✓ Created: #{text_prompt.name} v#{text_prompt.version}"
puts "  ✓ Labels: #{text_prompt.labels.inspect}"
puts "  ✓ Compiled: #{text_prompt.compile(name: 'Alice', place: 'Wonderland')}"

puts "\n[2] Creating chat prompt..."
chat_prompt_name = "test-chat-prompt-#{unique_id}"
chat_prompt = client.create_prompt(
  name: chat_prompt_name,
  prompt: [
    { role: "system", content: "You are a helpful {{role}} assistant." },
    { role: "user", content: "{{question}}" }
  ],
  type: :chat,
  labels: ["staging"],
  tags: ["validation-test"]
)

puts "  ✓ Created: #{chat_prompt.name} v#{chat_prompt.version}"
puts "  ✓ Labels: #{chat_prompt.labels.inspect}"
compiled_chat = chat_prompt.compile(role: "coding", question: "How do I write Ruby?")
puts "  ✓ Compiled messages:"
compiled_chat.each { |msg| puts "      [#{msg[:role]}] #{msg[:content]}" }

puts "\n[3] Creating new version of text prompt..."
text_prompt_v2 = client.create_prompt(
  name: text_prompt_name,
  prompt: "Greetings {{name}}! Welcome aboard to {{place}}.",
  type: :text,
  labels: ["staging"]
)

puts "  ✓ Created: #{text_prompt_v2.name} v#{text_prompt_v2.version}"
raise "Expected version 2" unless text_prompt_v2.version == 2

puts "\n[4] Updating prompt labels (promote v2 to production)..."
updated_prompt = client.update_prompt(
  name: text_prompt_name,
  version: 2,
  labels: ["production"]
)

puts "  ✓ Updated: #{updated_prompt.name} v#{updated_prompt.version}"
puts "  ✓ New labels: #{updated_prompt.labels.inspect}"
raise "Expected production label" unless updated_prompt.labels.include?("production")

puts "\n[5] Fetching prompt by label..."
production_prompt = client.get_prompt(text_prompt_name, label: "production")
puts "  ✓ Fetched v#{production_prompt.version} with label 'production'"
raise "Expected version 2" unless production_prompt.version == 2

puts "\n[6] Using compile_prompt shorthand..."
compiled = client.compile_prompt(text_prompt_name, variables: { name: "Bob", place: "Earth" }, label: "production")
puts "  ✓ Result: #{compiled}"

puts "\n" + "=" * 60
puts "All validations passed!"
puts "=" * 60
puts "\nCreated prompts (clean up manually if needed):"
puts "  - #{text_prompt_name}"
puts "  - #{chat_prompt_name}"

[Copilot]

Pull request overview

This PR adds programmatic prompt management capabilities to the Langfuse Ruby SDK by introducing create_prompt and update_prompt methods, enabling users to create and update prompts without using the Langfuse UI. Additionally, it fixes URL encoding for prompt names containing special characters.

Key Changes:

• Added create_prompt method for creating new prompts or versions programmatically with full parameter support (config, labels, tags, commit messages)
• Added update_prompt method for updating labels on existing prompt versions to support promotion workflows
• Fixed URL encoding for prompt names with special characters (e.g., /, ?, spaces) using URI.encode_uri_component

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/langfuse/client.rb	Adds create_prompt and update_prompt methods with validation, type checking, and normalization of chat message keys
lib/langfuse/api_client.rb	Implements HTTP methods for create/update operations, adds URL encoding fix, updates retry configuration to include PATCH, handles 201 status code
spec/langfuse/client_spec.rb	Adds comprehensive test coverage for create/update methods including text/chat prompts, validation, and compilation
spec/langfuse/api_client_spec.rb	Adds detailed API client tests for create/update operations, error handling, URL encoding, and edge cases
docs/PROMPTS.md	Documents new methods with usage examples, quick reference table, and promotion workflow patterns

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