feat: cap warmup for active campaign senders

Limit warmup volume to 5 messages per day when a mailbox is part of an active campaign sender pool. This keeps warmup as a low-volume reputation heartbeat while campaign traffic is already active.

internal/repository/pg_campaign.go

@@ -37,6 +37,7 @@ type CampaignRepository interface {
 	ValidateCampaignReady(ctx context.Context, campaignID uuid.UUID) error
 	GetPendingCampaignTasks(ctx context.Context, campaignID uuid.UUID) ([]Task, error)
 	CountActiveForOrganization(ctx context.Context, orgID uuid.UUID) (int, error)
+	AccountHasActiveCampaign(ctx context.Context, accountID uuid.UUID) (bool, error)
 }
 
 type campaignRepository struct {
@@ -1020,6 +1021,24 @@ func (r *campaignRepository) CountActiveForOrganization(ctx context.Context, org
 	return count, err
 }
 
+func (r *campaignRepository) AccountHasActiveCampaign(ctx context.Context, accountID uuid.UUID) (bool, error) {
+	query := `
+		SELECT EXISTS (
+			SELECT 1
+			FROM email_accounts ea
+			JOIN email_tags et ON et.email_id = ea.id
+			JOIN campaign_email_tags cet ON cet.tag_id = et.tag_id
+			JOIN campaigns c ON c.id = cet.campaign_id
+			WHERE ea.id = $1
+			  AND ea.status = 'active'
+			  AND c.status = 'active'
+		)
+	`
+	var exists bool
+	err := r.DB.QueryRow(ctx, query, accountID).Scan(&exists)
+	return exists, err
+}
+
 // UpdateStatusWithLock updates campaign status using a PostgreSQL advisory lock to prevent concurrent updates.
 // The WHERE clause guards against races: only updates if the campaign is currently 'active'.
 func (r *campaignRepository) UpdateStatusWithLock(ctx context.Context, campaignID uuid.UUID, status string) error {

internal/scheduler/warmup_scheduler.go

@@ -15,6 +15,7 @@ var poolTypesForHealthLookup = []string{"premium", "free"}
 const (
 	minWarmupRecipientRecheck = 4 * time.Hour
 	maxWarmupRecipientRecheck = 8 * time.Hour
+	activeCampaignWarmupCap   = 5
 )
 
 // healthAdjustment captures how the throttled/watch health state should
@@ -112,6 +113,16 @@ func (s *schedulerService) CalculateNextWarmupTime(ctx context.Context, accountI
 		account.WarmupMax,
 	)
 
+	// Active campaign mailboxes already have production sending pressure.
+	// Keep warmup as a lightweight reputation heartbeat instead of stacking
+	// the full warmup ramp on top of campaign traffic.
+	if s.campaignRepo != nil {
+		hasActiveCampaign, err := s.campaignRepo.AccountHasActiveCampaign(ctx, accountID)
+		if err == nil && hasActiveCampaign && targetVolume > activeCampaignWarmupCap {
+			targetVolume = activeCampaignWarmupCap
+		}
+	}
+
 	// STEP 2.1: Cap per-mailbox volume to actual recipient capacity. The
 	// sender should not send multiple warmup messages to the same recipient
 	// in a single day just to hit an arbitrary target; that creates obvious