Clarify UFC acronym throughout codebase for better developer understanding

- Add class documentation to InternalEvaluator explaining UFC format
- Spell out "Universal Flag Configuration" in comments and variable definitions
- Create README in spec/fixtures/ufc/ directory explaining UFC purpose
- Enhance parameter documentation for UFC-related methods

Author: sameerank

lib/datadog/open_feature/binding/configuration.rb

@@ -3,7 +3,7 @@
 module Datadog
   module OpenFeature
     module Binding
-      # Variation types supported by UFC
+      # Variation types supported by UFC (Universal Flag Configuration)
       module VariationType
         STRING = 'STRING'
         INTEGER = 'INTEGER'

lib/datadog/open_feature/binding/internal_evaluator.rb

@@ -33,6 +33,9 @@ def initialize(code, message)
         end
       end
 
+      # Internal evaluator for UFC (Universal Flag Configuration) format.
+      # UFC is a flexible format for representing feature flag targeting rules
+      # using splits with shard ranges and salts, accommodating most targeting use cases.
       class InternalEvaluator
         # NativeEvaluator-aligned error code mapping
         ERROR_CODE_MAPPING = {
@@ -60,6 +63,8 @@ class InternalEvaluator
           'JSON' => 'object'
         }.freeze
 
+        # Initialize evaluator with UFC (Universal Flag Configuration) JSON string.
+        # @param ufc_json [String] JSON string containing feature flag configuration in UFC format
         def initialize(ufc_json)
           @ufc_json = ufc_json
           @parsed_config = parse_and_validate_json(ufc_json)
@@ -132,12 +137,12 @@ def parse_and_validate_json(ufc_json)
             return create_parse_error(Ext::CONFIGURATION_PARSE_ERROR, 'failed to parse configuration')
           end
 
-          # Handle both UFC format and libdatadog format
+          # Handle both UFC (Universal Flag Configuration) format and libdatadog format
           config_to_parse = if has_libdatadog_format?(parsed_json)
             # Extract flags from libdatadog format
             extract_flags_from_libdatadog_format(parsed_json)
           else
-            # Use UFC format directly
+            # Use UFC (Universal Flag Configuration) format directly
             parsed_json
           end
 

spec/datadog/open_feature/binding/internal_evaluator_spec.rb

@@ -7,7 +7,7 @@
 RSpec.describe Datadog::OpenFeature::Binding::InternalEvaluator do
   let(:flags_v1_path) { File.join(__dir__, '../../../fixtures/ufc/flags-v1.json') }
   let(:flags_v1_json) { JSON.parse(File.read(flags_v1_path)) }
-  let(:ufc_attributes) { flags_v1_json['data']['attributes'] }
+  let(:ufc_attributes) { flags_v1_json['data']['attributes'] } # UFC = Universal Flag Configuration
   let(:valid_ufc_json) { ufc_attributes.to_json }
 
   describe '#initialize' do

spec/datadog/open_feature/evaluation_engine_spec.rb

@@ -8,7 +8,7 @@
   let(:reporter) { instance_double(Datadog::OpenFeature::Exposures::Reporter) }
   let(:telemetry) { instance_double(Datadog::Core::Telemetry::Component) }
   let(:logger) { instance_double(Datadog::Core::Logger) }
-  let(:ufc) do
+  let(:ufc) do # UFC = Universal Flag Configuration
     <<~JSON
       {
         "data": {

spec/fixtures/ufc/README.md

@@ -0,0 +1,26 @@
+# UFC (Universal Flag Configuration) Test Fixtures
+
+This directory contains test fixtures in UFC (Universal Flag Configuration) format.
+
+## What is UFC?
+
+UFC stands for **Universal Flag Configuration**. It's a flexible format for representing feature flag targeting rules using splits with shard ranges and salts. This approach accommodates most targeting use cases and provides a universal way to configure feature flags across different SDKs and platforms.
+
+## Directory Contents
+
+- `flags-v1.json` - Main UFC configuration fixture used across multiple test suites
+- `test_cases/` - Individual test cases demonstrating various UFC scenarios including:
+  - Boolean, integer, numeric, and string flag variations
+  - Targeting rules with different operators (ONE_OF, MATCHES, GTE, etc.)
+  - Traffic splitting with shard ranges
+  - Edge cases like disabled flags and empty configurations
+
+## Format Overview
+
+The UFC format typically includes:
+- **flags**: Feature flag definitions with variations and targeting rules
+- **allocations**: Traffic splitting rules with shard-based distribution
+- **variations**: Different values a flag can return
+- **rules**: Targeting conditions based on user attributes
+
+This format is used consistently across DataDog SDKs to ensure compatible feature flag behavior.