fix: coerce nil rollup metric values to zero

app/services/reporting_events/backfill_service.rb

@@ -82,8 +82,8 @@ class ReportingEvents::BackfillService
 
           key = [dimension_type, dimension_id, metric]
           aggregates[key][:count] += metric_data[:count]
-          aggregates[key][:sum_value] += metric_data[:sum_value]
-          aggregates[key][:sum_value_business_hours] += metric_data[:sum_value_business_hours]
+          aggregates[key][:sum_value] += metric_data[:sum_value].to_f
+          aggregates[key][:sum_value_business_hours] += metric_data[:sum_value_business_hours].to_f
         end
       end
     end

app/services/reporting_events/rollup_service.rb

@@ -131,8 +131,8 @@ module ReportingEvents::RollupService
       {
         account_id: @account.id, date: event_date,
         dimension_type: dimension_type, dimension_id: dimension_id, metric: metric,
-        count: metric_data[:count], sum_value: metric_data[:sum_value],
-        sum_value_business_hours: metric_data[:sum_value_business_hours],
+        count: metric_data[:count], sum_value: metric_data[:sum_value].to_f,
+        sum_value_business_hours: metric_data[:sum_value_business_hours].to_f,
         created_at: Time.current, updated_at: Time.current
       }
     end

spec/services/reporting_events/backfill_service_spec.rb

@@ -0,0 +1,45 @@
+require 'rails_helper'
+
+describe ReportingEvents::BackfillService do
+  describe '.backfill_date' do
+    let(:account) { create(:account, reporting_timezone: 'America/New_York') }
+    let(:date) { Date.new(2026, 2, 11) }
+    let(:user) { create(:user, account: account) }
+    let(:inbox) { create(:inbox, account: account) }
+    let(:conversation) { create(:conversation, account: account, inbox: inbox, assignee: user) }
+
+    it 'treats nil metric values as zero during backfill' do
+      reporting_event = create(
+        :reporting_event,
+        account: account,
+        name: 'first_response',
+        value: 100,
+        value_in_business_hours: 50,
+        user: user,
+        inbox: inbox,
+        conversation: conversation,
+        created_at: Time.utc(2026, 2, 11, 15)
+      )
+      # Simulate a legacy row that already exists in the database with nil metrics.
+      # rubocop:disable Rails/SkipsModelValidations
+      reporting_event.update_columns(value: nil, value_in_business_hours: nil)
+      # rubocop:enable Rails/SkipsModelValidations
+
+      expect do
+        described_class.backfill_date(account, date)
+      end.not_to raise_error
+
+      rollup = ReportingEventsRollup.find_by!(
+        account_id: account.id,
+        date: date,
+        dimension_type: 'account',
+        dimension_id: account.id,
+        metric: 'first_response'
+      )
+
+      expect(rollup.count).to eq(1)
+      expect(rollup.sum_value).to eq(0)
+      expect(rollup.sum_value_business_hours).to eq(0)
+    end
+  end
+end

spec/services/reporting_events/rollup_service_spec.rb

@@ -186,6 +186,41 @@ describe ReportingEvents::RollupService do
         end
       end
 
+      describe 'when metric values are nil' do
+        [
+          %w[conversation_resolved resolution_time],
+          %w[first_response first_response],
+          %w[reply_time reply_time]
+        ].each do |event_name, metric|
+          it "treats nil values as zero for #{event_name}" do
+            reporting_event = create(:reporting_event,
+                                     account: account,
+                                     name: event_name,
+                                     value: 100,
+                                     value_in_business_hours: 50,
+                                     user: user,
+                                     inbox: inbox,
+                                     conversation: conversation)
+            reporting_event.assign_attributes(value: nil, value_in_business_hours: nil)
+
+            expect do
+              described_class.perform(reporting_event)
+            end.not_to raise_error
+
+            rollup = ReportingEventsRollup.find_by(
+              account_id: account.id,
+              dimension_type: 'account',
+              metric: metric
+            )
+
+            expect(rollup).to be_present
+            expect(rollup.count).to eq(1)
+            expect(rollup.sum_value).to eq(0)
+            expect(rollup.sum_value_business_hours).to eq(0)
+          end
+        end
+      end
+
       describe 'conversation_bot_resolved event' do
         let(:reporting_event) do
           create(:reporting_event,