diff --git a/lib/optimizely.rb b/lib/optimizely.rb
index c64ea794..860401e4 100644
--- a/lib/optimizely.rb
+++ b/lib/optimizely.rb
@@ -220,8 +220,16 @@ def create_optimizely_decision(user_context, flag_key, decision, reasons, decide
         decision_source = decision.source
       end
 
-      if !decide_options.include?(OptimizelyDecideOption::DISABLE_DECISION_EVENT) && (decision_source == Optimizely::DecisionService::DECISION_SOURCES['FEATURE_TEST'] || config.send_flag_decisions)
-        send_impression(config, experiment, variation_key || '', flag_key, rule_key || '', feature_enabled, decision_source, user_id, attributes, decision&.cmab_uuid)
+      # For holdout decisions, ensure campaign_id is empty string, not nil
+      campaign_id = nil
+      if decision_source == Optimizely::DecisionService::DECISION_SOURCES['HOLDOUT']
+        campaign_id = ''
+      elsif experiment
+        campaign_id = experiment['campaignId'] || experiment['layerId']
+      end
+
+      if !decide_options.include?(OptimizelyDecideOption::DISABLE_DECISION_EVENT) && (decision_source == Optimizely::DecisionService::DECISION_SOURCES['FEATURE_TEST'] || decision_source == Optimizely::DecisionService::DECISION_SOURCES['HOLDOUT'] || config.send_flag_decisions)
+        send_impression(config, experiment, variation_key || '', flag_key, rule_key || '', feature_enabled, decision_source, user_id, attributes, decision&.cmab_uuid, campaign_id)
         decision_event_dispatched = true
       end
 
@@ -1271,16 +1279,25 @@ def send_impression(config, experiment, variation_key, flag_key, rule_key, enabl
         variation_id = variation ? variation['id'] : ''
       end
 
+      # For holdout decisions, filter attributes to only include $opt_bot_filtering
+      filtered_attributes = attributes
+      if rule_type == Optimizely::DecisionService::DECISION_SOURCES['HOLDOUT']
+        bot_filtering = attributes&.dig('$opt_bot_filtering')
+        filtered_attributes = bot_filtering ? {'$opt_bot_filtering' => bot_filtering} : {}
+      end
+
       metadata = {
         flag_key: flag_key,
         rule_key: rule_key,
         rule_type: rule_type,
-        variation_key: variation_key,
-        enabled: enabled
+        variation_key: variation_key
       }
+
+      # Only include enabled field for non-holdout rule types
+      metadata[:enabled] = enabled unless rule_type == Optimizely::DecisionService::DECISION_SOURCES['HOLDOUT']
       metadata[:cmab_uuid] = cmab_uuid unless cmab_uuid.nil?
 
-      user_event = UserEventFactory.create_impression_event(config, experiment, variation_id, metadata, user_id, attributes)
+      user_event = UserEventFactory.create_impression_event(config, experiment, variation_id, metadata, user_id, filtered_attributes)
       @event_processor.process(user_event)
       return unless @notification_center.notification_count(NotificationCenter::NOTIFICATION_TYPES[:ACTIVATE]).positive?
 
diff --git a/lib/optimizely/config/datafile_project_config.rb b/lib/optimizely/config/datafile_project_config.rb
index d6f1d27b..f11cff20 100644
--- a/lib/optimizely/config/datafile_project_config.rb
+++ b/lib/optimizely/config/datafile_project_config.rb
@@ -205,7 +205,7 @@ def initialize(datafile, logger, error_handler)
           applicable_holdouts << holdout unless excluded_flag_ids.include?(flag_id)
         end
 
-        @flag_holdouts_map[key] = applicable_holdouts unless applicable_holdouts.empty?
+        @flag_holdouts_map[flag_id] = applicable_holdouts unless applicable_holdouts.empty?
       end
 
       # Adding Holdout variations in variation id and key maps
diff --git a/lib/optimizely/decision_service.rb b/lib/optimizely/decision_service.rb
index f1bc92e2..d2e8911d 100644
--- a/lib/optimizely/decision_service.rb
+++ b/lib/optimizely/decision_service.rb
@@ -196,7 +196,13 @@ def get_decision_for_flag(feature_flag, user_context, project_config, decide_opt
       # Check holdouts
       holdouts = project_config.get_holdouts_for_flag(feature_flag['id'])
 
-      holdouts.each do |holdout|
+      # Sort holdouts: global holdouts (empty includedFlags) should be evaluated first
+      sorted_holdouts = holdouts.sort_by do |holdout|
+        included_flags = holdout['includedFlags'] || []
+        included_flags.empty? ? 0 : 1
+      end
+
+      sorted_holdouts.each do |holdout|
         holdout_decision = get_variation_for_holdout(holdout, user_context, project_config)
         reasons.push(*holdout_decision.reasons)
 
@@ -313,12 +319,18 @@ def get_variations_for_feature_list(project_config, feature_flags, user_context,
       decisions = []
       feature_flags.each do |feature_flag|
         # check if the feature is being experiment on and whether the user is bucketed into the experiment
-        decision_result = get_variation_for_feature_experiment(project_config, feature_flag, user_context, user_profile_tracker, decide_options)
-        # Only process rollout if no experiment decision was found and no error
-        if decision_result.decision.nil? && !decision_result.error
-          decision_result_rollout = get_variation_for_feature_rollout(project_config, feature_flag, user_context) unless decision_result.decision
-          decision_result.decision = decision_result_rollout.decision
-          decision_result.reasons.push(*decision_result_rollout.reasons)
+        holdouts = project_config.get_holdouts_for_flag(feature_flag['id'])
+
+        if holdouts && !holdouts.empty?
+          decision_result = get_decision_for_flag(feature_flag, user_context, project_config, decide_options, user_profile_tracker)
+        else
+          decision_result = get_variation_for_feature_experiment(project_config, feature_flag, user_context, user_profile_tracker, decide_options)
+          # Only process rollout if no experiment decision was found and no error
+          if decision_result.decision.nil? && !decision_result.error
+            decision_result_rollout = get_variation_for_feature_rollout(project_config, feature_flag, user_context) unless decision_result.decision
+            decision_result.decision = decision_result_rollout.decision
+            decision_result.reasons.push(*decision_result_rollout.reasons)
+          end
         end
         decisions << decision_result
       end
diff --git a/lib/optimizely/event_builder.rb b/lib/optimizely/event_builder.rb
index a5ee82a9..e63fde51 100644
--- a/lib/optimizely/event_builder.rb
+++ b/lib/optimizely/event_builder.rb
@@ -171,14 +171,22 @@ def get_impression_params(project_config, experiment, variation_id)
       experiment_key = experiment['key']
       experiment_id = experiment['id']
 
+      campaign_id = project_config.experiment_key_map[experiment_key]['layerId'] || project_config.experiment_key_map[experiment_key]['campaignId']
+      if decision_source == Optimizely::DecisionService::DECISION_SOURCES['HOLDOUT']
+        campaign_id = ''
+        entity_id = ''
+      else
+        entity_id = campaign_id
+      end
+
       {
         decisions: [{
-          campaign_id: project_config.experiment_key_map[experiment_key]['layerId'],
+          campaign_id: campaign_id,
           experiment_id: experiment_id,
           variation_id: variation_id
         }],
         events: [{
-          entity_id: project_config.experiment_key_map[experiment_key]['layerId'],
+          entity_id: entity_id,
           timestamp: create_timestamp,
           key: ACTIVATE_EVENT_KEY,
           uuid: create_uuid