[AI-FSSDK] [FSSDK-12369] Add local holdouts support with includedRules field

[Mat001]

Summary

This PR adds local holdouts support to the Ruby SDK, allowing holdouts to target specific rules within a flag via an includedRules field.

Jira Ticket: FSSDK-12369

Changes

Configuration (lib/optimizely/config/datafile_project_config.rb)

• Added @global_holdouts (Array) and @rule_holdouts_map (Hash) instance variables
• Added global_holdouts and rule_holdouts_map to attr_reader
• During holdout initialization: classify each holdout as global (includedRules absent/nil) or local (includedRules is an array), populating the respective data structures
• Added get_global_holdouts method: returns all global holdouts (nil includedRules)
• Added get_holdouts_for_rule(rule_id) method: returns local holdouts targeting a specific rule

Decision Logic (lib/optimizely/decision_service.rb)

• Updated get_decision_for_flag to use get_global_holdouts instead of holdout_id_map.values for flag-level holdout evaluation
• Added local holdout checks in get_variation_from_experiment_rule (after forced decisions, before regular bucketing)
• Added local holdout checks in get_variation_from_delivery_rule (after forced decisions, before audience/bucketing evaluation)

Tests

• spec/local_holdouts_spec.rb (new): 10 tests covering:
  • Backward compatibility (holdouts without includedRules field treated as global)
  • Global/local holdout classification
  • rule_holdouts_map population
  • get_global_holdouts and get_holdouts_for_rule helper methods
  • Edge cases (empty includedRules array, no global holdouts)
• spec/spec_params.rb: Added CONFIG_BODY_WITH_LOCAL_HOLDOUTS fixture with both global and local holdouts

Decision Flow

Flag evaluation
  └── Global holdouts (includedRules == nil) → checked at flag level
        └── If not in global holdout:
              └── Forced decisions → checked per rule
                    └── Local holdouts (includedRules is array) → checked per rule
                          └── Regular bucketing / audience evaluation

Backward Compatibility

Old datafiles without includedRules key: Ruby JSON parsing returns nil for missing keys → treated as global holdout → behavior unchanged.

🤖 Generated with Claude Code