diff --git a/app/services/reporting_events/backfill_service.rb b/app/services/reporting_events/backfill_service.rb
new file mode 100644
index 000000000..b49a4f654
--- /dev/null
+++ b/app/services/reporting_events/backfill_service.rb
@@ -0,0 +1,129 @@
+# frozen_string_literal: true
+
+class ReportingEvents::BackfillService
+  def self.backfill_date(account, date)
+    new(account, date).perform
+  end
+
+  def initialize(account, date)
+    @account = account
+    @date = date
+    @timezone = account.reporting_timezone
+  end
+
+  def perform
+    # 1. Delete existing rollups for this date (idempotency)
+    delete_existing_rollups
+
+    # 2. Convert date in account timezone to UTC boundaries
+    start_utc, end_utc = date_boundaries_in_utc
+
+    # 3. Process each event type with SQL aggregation
+    rollup_rows = []
+    rollup_rows.concat(aggregate_event_type('conversation_resolved', start_utc, end_utc))
+    rollup_rows.concat(aggregate_event_type('first_response', start_utc, end_utc))
+    rollup_rows.concat(aggregate_event_type('reply_time', start_utc, end_utc))
+    rollup_rows.concat(aggregate_event_type('conversation_bot_resolved', start_utc, end_utc))
+    rollup_rows.concat(aggregate_event_type('conversation_bot_handoff', start_utc, end_utc))
+
+    # 4. Bulk insert all rollups at once
+    bulk_insert_rollups(rollup_rows) if rollup_rows.any?
+  end
+
+  private
+
+  def delete_existing_rollups
+    ReportingEventsRollup.where(account_id: @account.id, date: @date).delete_all
+  end
+
+  def date_boundaries_in_utc
+    tz = ActiveSupport::TimeZone[@timezone]
+    start_in_tz = tz.parse(@date.to_s)
+    end_in_tz = start_in_tz + 1.day
+    [start_in_tz.utc, end_in_tz.utc]
+  end
+
+  def aggregate_event_type(event_name, start_utc, end_utc)
+    events = @account.reporting_events
+                     .where(name: event_name, created_at: start_utc...end_utc)
+                     .includes(:conversation)
+
+    return [] if events.empty?
+
+    # Build in-memory aggregates by dimension
+    aggregates = build_aggregates(events, event_name)
+
+    # Convert to rollup row hashes
+    aggregates.map do |(dimension_type, dimension_id, metric), data|
+      {
+        account_id: @account.id,
+        date: @date,
+        dimension_type: dimension_type,
+        dimension_id: dimension_id,
+        metric: metric,
+        count: data[:count],
+        sum_value: data[:sum_value],
+        sum_value_business_hours: data[:sum_value_business_hours],
+        created_at: Time.current,
+        updated_at: Time.current
+      }
+    end
+  end
+
+  def build_aggregates(events, event_name)
+    aggregates = Hash.new { |h, k| h[k] = { count: 0, sum_value: 0.0, sum_value_business_hours: 0.0 } }
+
+    events.each do |event|
+      metrics = metrics_for_event(event_name, event)
+      dimensions = dimensions_for_event(event)
+
+      metrics.each do |metric, metric_data|
+        dimensions.each do |dimension_type, dimension_id|
+          next if dimension_id.nil?
+
+          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]
+        end
+      end
+    end
+
+    aggregates
+  end
+
+  def dimensions_for_event(event)
+    {
+      'account' => @account.id,
+      'agent' => event.user_id,
+      'inbox' => event.inbox_id,
+      'team' => event.conversation&.team_id
+    }
+  end
+
+  def metrics_for_event(event_name, event)
+    case event_name
+    when 'conversation_resolved'
+      {
+        'resolutions_count' => { count: 1, sum_value: 0, sum_value_business_hours: 0 },
+        'resolution_time' => { count: 1, sum_value: event.value, sum_value_business_hours: event.value_in_business_hours }
+      }
+    when 'first_response'
+      { 'first_response' => { count: 1, sum_value: event.value, sum_value_business_hours: event.value_in_business_hours } }
+    when 'reply_time'
+      { 'reply_time' => { count: 1, sum_value: event.value, sum_value_business_hours: event.value_in_business_hours } }
+    when 'conversation_bot_resolved'
+      { 'bot_resolutions_count' => { count: 1, sum_value: 0, sum_value_business_hours: 0 } }
+    when 'conversation_bot_handoff'
+      { 'bot_handoffs_count' => { count: 1, sum_value: 0, sum_value_business_hours: 0 } }
+    else
+      {}
+    end
+  end
+
+  def bulk_insert_rollups(rollup_rows)
+    # rubocop:disable Rails/SkipsModelValidations
+    ReportingEventsRollup.insert_all(rollup_rows)
+    # rubocop:enable Rails/SkipsModelValidations
+  end
+end
diff --git a/lib/tasks/reporting_events_rollup.rake b/lib/tasks/reporting_events_rollup.rake
new file mode 100644
index 000000000..7e8d87b22
--- /dev/null
+++ b/lib/tasks/reporting_events_rollup.rake
@@ -0,0 +1,197 @@
+# frozen_string_literal: true
+
+namespace :reporting_events_rollup do
+  desc 'Backfill rollup table from historical reporting events'
+  task backfill: :environment do
+    # 1. WELCOME & PROMPT FOR ACCOUNT ID
+    puts ''
+    puts '=' * 70
+    puts 'Reporting Events Rollup Backfill'
+    puts '=' * 70
+    puts ''
+
+    print 'Enter Account ID: '
+    account_id = STDIN.gets.chomp
+
+    if account_id.blank?
+      puts 'Error: Account ID is required'
+      exit(1)
+    end
+
+    # 2. LOAD & VALIDATE ACCOUNT
+    account = Account.find_by(id: account_id)
+    unless account
+      puts "Error: Account with ID #{account_id} not found"
+      exit(1)
+    end
+
+    puts "✓ Found account: #{account.name}"
+    puts ''
+
+    # 3. PROMPT FOR TIMEZONE
+    print 'Enter Timezone (e.g., America/New_York, UTC): '
+    timezone = STDIN.gets.chomp
+
+    if timezone.blank?
+      puts 'Error: Timezone is required'
+      exit(1)
+    end
+
+    # 4. TIMEZONE VALIDATION
+    unless ActiveSupport::TimeZone[timezone]
+      puts "Error: Invalid timezone '#{timezone}'"
+      puts ''
+      puts 'Must be a valid IANA timezone. Examples:'
+      puts '  America/New_York'
+      puts '  Asia/Kolkata'
+      puts '  Europe/London'
+      puts '  UTC'
+      puts ''
+      puts 'See: https://en.wikipedia.org/wiki/List_of_tz_database_time_zones'
+      exit(1)
+    end
+
+    # 5. DISCOVER DATE RANGE
+    first_event = account.reporting_events.order(:created_at).first
+    last_event = account.reporting_events.order(:created_at).last
+
+    if first_event.nil?
+      puts ''
+      puts "No reporting events found for account #{account_id}"
+      puts 'Nothing to backfill.'
+      exit(0)
+    end
+
+    # Convert to account timezone dates
+    tz = ActiveSupport::TimeZone[timezone]
+    discovered_start_date = first_event.created_at.in_time_zone(tz).to_date
+    discovered_end_date = last_event.created_at.in_time_zone(tz).to_date
+    discovered_total_days = (discovered_end_date - discovered_start_date).to_i + 1
+
+    puts "✓ Discovered date range: #{discovered_start_date} to #{discovered_end_date} (#{discovered_total_days} days)"
+    puts ''
+
+    # 6. PROMPT FOR DATE RANGE OVERRIDE
+    print 'Override date range? (y/N): '
+    override_range = STDIN.gets.chomp.downcase
+
+    if override_range == 'y' || override_range == 'yes'
+      print 'Enter start date (YYYY-MM-DD): '
+      start_date_input = STDIN.gets.chomp
+      start_date = start_date_input.present? ? start_date_input.to_date : discovered_start_date
+
+      print 'Enter end date (YYYY-MM-DD): '
+      end_date_input = STDIN.gets.chomp
+      end_date = end_date_input.present? ? end_date_input.to_date : discovered_end_date
+    else
+      start_date = discovered_start_date
+      end_date = discovered_end_date
+    end
+
+    total_days = (end_date - start_date).to_i + 1
+    puts ''
+
+    # 7. PROMPT FOR DRY RUN
+    print 'Dry run? (y/N): '
+    dry_run_input = STDIN.gets.chomp.downcase
+    dry_run = (dry_run_input == 'y' || dry_run_input == 'yes')
+    puts ''
+
+    # 8. SHOW BACKFILL PLAN
+    puts '=' * 70
+    puts 'Backfill Plan Summary'
+    puts '=' * 70
+    puts "Account:     #{account.name} (ID: #{account_id})"
+    puts "Timezone:    #{timezone}"
+    puts "Date Range:  #{start_date} to #{end_date} (#{total_days} days)"
+    puts "First Event: #{first_event.created_at.in_time_zone(tz).strftime('%Y-%m-%d %H:%M:%S %Z')}"
+    puts "Last Event:  #{last_event.created_at.in_time_zone(tz).strftime('%Y-%m-%d %H:%M:%S %Z')}"
+    puts "Dry Run:     #{dry_run ? 'YES (no data will be written)' : 'NO'}"
+    puts '=' * 70
+    puts ''
+
+    if dry_run
+      puts "DRY RUN MODE: Would process #{total_days} days"
+      puts "Would set reporting_timezone to '#{timezone}'"
+      puts 'Run without dry run to execute backfill'
+      exit(0)
+    end
+
+    # 9. CONFIRMATION PROMPT
+    if total_days > 730 # 2 years
+      puts "⚠️  WARNING: Large backfill detected (#{total_days} days / #{(total_days / 365.0).round(1)} years)"
+      puts ''
+    end
+
+    print 'Proceed with backfill? (y/N): '
+    confirm = STDIN.gets.chomp.downcase
+
+    unless confirm == 'y' || confirm == 'yes'
+      puts 'Backfill cancelled'
+      exit(0)
+    end
+
+    puts ''
+
+    # 10. SAVE TIMEZONE TO ACCOUNT
+    account.update!(reporting_timezone: timezone)
+    puts "✓ Set reporting_timezone to '#{timezone}' for account '#{account.name}'"
+    puts ''
+
+    # 11. PROCESS EACH DATE
+    puts 'Processing dates...'
+    puts ''
+
+    start_time = Time.current
+    days_processed = 0
+
+    begin
+      (start_date..end_date).each do |date|
+        # Process this date
+        ReportingEvents::BackfillService.backfill_date(account, date)
+
+        # Update progress
+        days_processed += 1
+        percentage = (days_processed.to_f / total_days * 100).round(1)
+
+        # Print on same line with carriage return
+        print "\r#{date} | #{days_processed}/#{total_days} days | #{percentage}%    "
+        $stdout.flush
+      end
+    rescue StandardError => e
+      # Fail fast: show error and exit immediately
+      puts "\n\n"
+      puts '=' * 70
+      puts '❌ BACKFILL FAILED'
+      puts '=' * 70
+      puts "Error processing date: #{date}"
+      puts "Error: #{e.class.name} - #{e.message}"
+      puts ''
+      puts 'Stack trace:'
+      puts e.backtrace.first(10).map { |line| "  #{line}" }.join("\n")
+      puts ''
+      puts "Processed: #{days_processed}/#{total_days} days (#{(days_processed.to_f / total_days * 100).round(1)}%)"
+      puts '=' * 70
+      exit(1)
+    end
+
+    # 12. SUCCESS SUMMARY
+    elapsed_time = Time.current - start_time
+    avg_time_per_day = (elapsed_time / days_processed).round(3)
+
+    puts "\n\n"
+    puts '=' * 70
+    puts '✅ BACKFILL COMPLETE'
+    puts '=' * 70
+    puts "Total Days Processed: #{days_processed}"
+    puts "Total Time:           #{elapsed_time.round(2)} seconds"
+    puts "Average per Day:      #{avg_time_per_day} seconds"
+    puts ''
+    puts 'Next steps:'
+    puts "1. Enable feature flag: Account.find(#{account_id}).enable_features!('reporting_events_rollup')"
+    puts '2. Verify rollups in database:'
+    puts "   ReportingEventsRollup.where(account_id: #{account_id}).count"
+    puts '3. Test reports to compare rollup vs raw performance'
+    puts '=' * 70
+  end
+end