diff --git a/db/types.go b/db/types.go
index 534d6168..137753a4 100644
--- a/db/types.go
+++ b/db/types.go
@@ -11,6 +11,12 @@ type Beginner interface {
 	Begin() (*sql.Tx, error)
 }
 
+// Querier is an interface for types that can execute SQL queries.
+// *sql.DB, *sql.Tx, and *DB all implement this.
+type Querier interface {
+	Query(query string, args ...any) (*sql.Rows, error)
+}
+
 // Host pairs a *sql.DB with the host:port it was opened against.
 type Host struct {
 	Addr    string // "host:port"
diff --git a/docs/releases.md b/docs/releases.md
index fe3e2bd9..4d5e6c02 100644
--- a/docs/releases.md
+++ b/docs/releases.md
@@ -1795,4 +1795,5 @@ and the [ntfy Android app](https://github.com/binwiederhier/ntfy-android/release
 
 **Bug fixes + maintenance:**
 
+* Fix race condition in web push subscription causing FK constraint violation when concurrent requests hit the same endpoint
 * Route authorization query to read-only database replica to reduce primary database load
diff --git a/go.mod b/go.mod
index c073d6aa..c5bb4968 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,7 @@ go 1.25.0
 
 require (
 	cloud.google.com/go/firestore v1.21.0 // indirect
-	cloud.google.com/go/storage v1.61.1 // indirect
+	cloud.google.com/go/storage v1.61.3 // indirect
 	github.com/BurntSushi/toml v1.6.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.7 // indirect
 	github.com/emersion/go-smtp v0.18.0
diff --git a/go.sum b/go.sum
index 1c6eada9..781b9856 100644
--- a/go.sum
+++ b/go.sum
@@ -18,8 +18,8 @@ cloud.google.com/go/longrunning v0.8.0 h1:LiKK77J3bx5gDLi4SMViHixjD2ohlkwBi+mKA7
 cloud.google.com/go/longrunning v0.8.0/go.mod h1:UmErU2Onzi+fKDg2gR7dusz11Pe26aknR4kHmJJqIfk=
 cloud.google.com/go/monitoring v1.24.3 h1:dde+gMNc0UhPZD1Azu6at2e79bfdztVDS5lvhOdsgaE=
 cloud.google.com/go/monitoring v1.24.3/go.mod h1:nYP6W0tm3N9H/bOw8am7t62YTzZY+zUeQ+Bi6+2eonI=
-cloud.google.com/go/storage v1.61.1 h1:VELCSvZKiSw0AS1k3so5mKGy3CB7bTCYD8EHhTF42bY=
-cloud.google.com/go/storage v1.61.1/go.mod h1:k30/hwYfd0M8aULYbPkQLgNf+SFcdjlRHvLMXggw18E=
+cloud.google.com/go/storage v1.61.3 h1:VS//ZfBuPGDvakfD9xyPW1RGF1Vy3BWUoVZXgW1KMOg=
+cloud.google.com/go/storage v1.61.3/go.mod h1:JtqK8BBB7TWv0HVGHubtUdzYYrakOQIsMLffZ2Z/HWk=
 cloud.google.com/go/trace v1.11.7 h1:kDNDX8JkaAG3R2nq1lIdkb7FCSi1rCmsEtKVsty7p+U=
 cloud.google.com/go/trace v1.11.7/go.mod h1:TNn9d5V3fQVf6s4SCveVMIBS2LJUqo73GACmq/Tky0s=
 firebase.google.com/go/v4 v4.19.0 h1:f5NMlC2YHFsncz00c2+ecBr+ZYlRMhKIhj1z8Iz0lD8=
diff --git a/server/log.go b/server/log.go
index e4ddc178..432f6743 100644
--- a/server/log.go
+++ b/server/log.go
@@ -35,7 +35,7 @@ const (
 )
 
 var (
-	normalErrorCodes       = []int{http.StatusNotFound, http.StatusBadRequest, http.StatusTooManyRequests, http.StatusUnauthorized, http.StatusForbidden, http.StatusInsufficientStorage}
+	normalErrorCodes       = []int{http.StatusNotFound, http.StatusBadRequest, http.StatusTooManyRequests, http.StatusUnauthorized, http.StatusForbidden, http.StatusInsufficientStorage, http.StatusRequestEntityTooLarge}
 	rateLimitingErrorCodes = []int{http.StatusTooManyRequests, http.StatusRequestEntityTooLarge}
 )
 
diff --git a/server/server_account.go b/server/server_account.go
index 19a14042..7b719533 100644
--- a/server/server_account.go
+++ b/server/server_account.go
@@ -3,14 +3,15 @@ package server
 import (
 	"encoding/json"
 	"errors"
-	"heckel.io/ntfy/v2/log"
-	"heckel.io/ntfy/v2/model"
-	"heckel.io/ntfy/v2/user"
-	"heckel.io/ntfy/v2/util"
 	"net/http"
 	"net/netip"
 	"strings"
 	"time"
+
+	"heckel.io/ntfy/v2/log"
+	"heckel.io/ntfy/v2/model"
+	"heckel.io/ntfy/v2/user"
+	"heckel.io/ntfy/v2/util"
 )
 
 const (
@@ -455,21 +456,8 @@ func (s *Server) handleAccountReservationAdd(w http.ResponseWriter, r *http.Requ
 		return errHTTPUnauthorized
 	} else if err := s.userManager.AllowReservation(u.Name, req.Topic); err != nil {
 		return errHTTPConflictTopicReserved
-	} else if u.IsUser() {
-		hasReservation, err := s.userManager.HasReservation(u.Name, req.Topic)
-		if err != nil {
-			return err
-		}
-		if !hasReservation {
-			reservations, err := s.userManager.ReservationsCount(u.Name)
-			if err != nil {
-				return err
-			} else if reservations >= u.Tier.ReservationLimit {
-				return errHTTPTooManyRequestsLimitReservations
-			}
-		}
 	}
-	// Actually add the reservation
+	// Actually add the reservation (with limit check inside the transaction to avoid races)
 	logvr(v, r).
 		Tag(tagAccount).
 		Fields(log.Context{
@@ -477,7 +465,14 @@ func (s *Server) handleAccountReservationAdd(w http.ResponseWriter, r *http.Requ
 			"everyone": everyone.String(),
 		}).
 		Debug("Adding topic reservation")
-	if err := s.userManager.AddReservation(u.Name, req.Topic, everyone); err != nil {
+	var limit int64
+	if u.IsUser() && u.Tier != nil {
+		limit = u.Tier.ReservationLimit
+	}
+	if err := s.userManager.AddReservation(u.Name, req.Topic, everyone, limit); err != nil {
+		if errors.Is(err, user.ErrTooManyReservations) {
+			return errHTTPTooManyRequestsLimitReservations
+		}
 		return err
 	}
 	// Kill existing subscribers
@@ -530,22 +525,15 @@ func (s *Server) handleAccountReservationDelete(w http.ResponseWriter, r *http.R
 // and marks associated messages for the topics as deleted. This also eventually deletes attachments.
 // The process relies on the manager to perform the actual deletions (see runManager).
 func (s *Server) maybeRemoveMessagesAndExcessReservations(r *http.Request, v *visitor, u *user.User, reservationsLimit int64) error {
-	reservations, err := s.userManager.Reservations(u.Name)
+	removedTopics, err := s.userManager.RemoveExcessReservations(u.Name, reservationsLimit)
 	if err != nil {
 		return err
-	} else if int64(len(reservations)) <= reservationsLimit {
+	} else if len(removedTopics) == 0 {
 		logvr(v, r).Tag(tagAccount).Debug("No excess reservations to remove")
 		return nil
 	}
-	topics := make([]string, 0)
-	for i := int64(len(reservations)) - 1; i >= reservationsLimit; i-- {
-		topics = append(topics, reservations[i].Topic)
-	}
-	logvr(v, r).Tag(tagAccount).Info("Removing excess reservations for topics %s", strings.Join(topics, ", "))
-	if err := s.userManager.RemoveReservations(u.Name, topics...); err != nil {
-		return err
-	}
-	if err := s.messageCache.ExpireMessages(topics...); err != nil {
+	logvr(v, r).Tag(tagAccount).Info("Removed excess topic reservations, now removing messages for topics %s", strings.Join(removedTopics, ", "))
+	if err := s.messageCache.ExpireMessages(removedTopics...); err != nil {
 		return err
 	}
 	go s.pruneMessages()
diff --git a/server/server_account_test.go b/server/server_account_test.go
index 7bf6f6d5..0360fcd4 100644
--- a/server/server_account_test.go
+++ b/server/server_account_test.go
@@ -503,7 +503,7 @@ func TestAccount_Reservation_AddAdminSuccess(t *testing.T) {
 		}))
 		require.Nil(t, s.userManager.AddUser("noadmin1", "pass", user.RoleUser, false))
 		require.Nil(t, s.userManager.ChangeTier("noadmin1", "pro"))
-		require.Nil(t, s.userManager.AddReservation("noadmin1", "mytopic", user.PermissionDenyAll))
+		require.Nil(t, s.userManager.AddReservation("noadmin1", "mytopic", user.PermissionDenyAll, 0))
 
 		require.Nil(t, s.userManager.AddUser("noadmin2", "pass", user.RoleUser, false))
 		require.Nil(t, s.userManager.ChangeTier("noadmin2", "pro"))
diff --git a/server/server_payments_test.go b/server/server_payments_test.go
index 06523edc..9873d6d8 100644
--- a/server/server_payments_test.go
+++ b/server/server_payments_test.go
@@ -478,8 +478,8 @@ func TestPayments_Webhook_Subscription_Updated_Downgrade_From_PastDue_To_Active(
 		}))
 		require.Nil(t, s.userManager.AddUser("phil", "phil", user.RoleUser, false))
 		require.Nil(t, s.userManager.ChangeTier("phil", "pro"))
-		require.Nil(t, s.userManager.AddReservation("phil", "atopic", user.PermissionDenyAll))
-		require.Nil(t, s.userManager.AddReservation("phil", "ztopic", user.PermissionDenyAll))
+		require.Nil(t, s.userManager.AddReservation("phil", "atopic", user.PermissionDenyAll, 0))
+		require.Nil(t, s.userManager.AddReservation("phil", "ztopic", user.PermissionDenyAll, 0))
 
 		// Add billing details
 		u, err := s.userManager.User("phil")
@@ -589,7 +589,7 @@ func TestPayments_Webhook_Subscription_Deleted(t *testing.T) {
 		}))
 		require.Nil(t, s.userManager.AddUser("phil", "phil", user.RoleUser, false))
 		require.Nil(t, s.userManager.ChangeTier("phil", "pro"))
-		require.Nil(t, s.userManager.AddReservation("phil", "atopic", user.PermissionDenyAll))
+		require.Nil(t, s.userManager.AddReservation("phil", "atopic", user.PermissionDenyAll, 0))
 
 		// Add billing details
 		u, err := s.userManager.User("phil")
diff --git a/user/manager.go b/user/manager.go
index 28243a24..99bd705e 100644
--- a/user/manager.go
+++ b/user/manager.go
@@ -288,33 +288,41 @@ func (a *Manager) ChangeTier(username, tier string) error {
 	t, err := a.Tier(tier)
 	if err != nil {
 		return err
-	} else if err := a.checkReservationsLimit(username, t.ReservationLimit); err != nil {
-		return err
 	}
-	if _, err := a.db.Exec(a.queries.updateUserTier, tier, username); err != nil {
-		return err
-	}
-	return nil
+	return db.ExecTx(a.db, func(tx *sql.Tx) error {
+		if err := a.checkReservationsLimitTx(tx, username, t.ReservationLimit); err != nil {
+			return err
+		}
+		if _, err := tx.Exec(a.queries.updateUserTier, tier, username); err != nil {
+			return err
+		}
+		return nil
+	})
 }
 
 // ResetTier removes the tier from the given user
 func (a *Manager) ResetTier(username string) error {
 	if !AllowedUsername(username) && username != Everyone && username != "" {
 		return ErrInvalidArgument
-	} else if err := a.checkReservationsLimit(username, 0); err != nil {
-		return err
 	}
-	_, err := a.db.Exec(a.queries.deleteUserTier, username)
-	return err
+	return db.ExecTx(a.db, func(tx *sql.Tx) error {
+		if err := a.checkReservationsLimitTx(tx, username, 0); err != nil {
+			return err
+		}
+		if _, err := tx.Exec(a.queries.deleteUserTier, username); err != nil {
+			return err
+		}
+		return nil
+	})
 }
 
-func (a *Manager) checkReservationsLimit(username string, reservationsLimit int64) error {
-	u, err := a.User(username)
+func (a *Manager) checkReservationsLimitTx(tx *sql.Tx, username string, reservationsLimit int64) error {
+	u, err := a.userTx(tx, username)
 	if err != nil {
 		return err
 	}
 	if u.Tier != nil && reservationsLimit < u.Tier.ReservationLimit {
-		reservations, err := a.Reservations(username)
+		reservations, err := a.reservationsTx(tx, username)
 		if err != nil {
 			return err
 		} else if int64(len(reservations)) > reservationsLimit {
@@ -388,7 +396,11 @@ func (a *Manager) writeUserStatsQueue() error {
 
 // User returns the user with the given username if it exists, or ErrUserNotFound otherwise
 func (a *Manager) User(username string) (*User, error) {
-	rows, err := a.db.Query(a.queries.selectUserByName, username)
+	return a.userTx(a.db, username)
+}
+
+func (a *Manager) userTx(tx db.Querier, username string) (*User, error) {
+	rows, err := tx.Query(a.queries.selectUserByName, username)
 	if err != nil {
 		return nil, err
 	}
@@ -415,7 +427,7 @@ func (a *Manager) userByToken(token string) (*User, error) {
 
 // UserByStripeCustomer returns the user with the given Stripe customer ID if it exists, or ErrUserNotFound otherwise
 func (a *Manager) UserByStripeCustomer(customerID string) (*User, error) {
-	rows, err := a.db.ReadOnly().Query(a.queries.selectUserByStripeCustomerID, customerID)
+	rows, err := a.db.Query(a.queries.selectUserByStripeCustomerID, customerID)
 	if err != nil {
 		return nil, err
 	}
@@ -713,16 +725,35 @@ func (a *Manager) Grants(username string) ([]Grant, error) {
 
 // AddReservation creates two access control entries for the given topic: one with full read/write
 // access for the given user, and one for Everyone with the given permission. Both entries are
-// created atomically in a single transaction.
-func (a *Manager) AddReservation(username string, topic string, everyone Permission) error {
+// created atomically in a single transaction. If limit is > 0, the reservation count is checked
+// inside the transaction and ErrTooManyReservations is returned if the limit would be exceeded.
+func (a *Manager) AddReservation(username string, topic string, everyone Permission, limit int64) error {
 	if !AllowedUsername(username) || username == Everyone || !AllowedTopic(topic) {
 		return ErrInvalidArgument
 	}
 	return db.ExecTx(a.db, func(tx *sql.Tx) error {
-		if err := a.addReservationAccessTx(tx, username, topic, true, true, username); err != nil {
+		if limit > 0 {
+			hasReservation, err := a.hasReservationTx(tx, username, topic)
+			if err != nil {
+				return err
+			}
+			if !hasReservation {
+				count, err := a.reservationsCountTx(tx, username)
+				if err != nil {
+					return err
+				}
+				if count >= limit {
+					return ErrTooManyReservations
+				}
+			}
+		}
+		if _, err := tx.Exec(a.queries.upsertUserAccess, username, toSQLWildcard(topic), true, true, username, username, false); err != nil {
 			return err
 		}
-		return a.addReservationAccessTx(tx, Everyone, topic, everyone.IsRead(), everyone.IsWrite(), username)
+		if _, err := tx.Exec(a.queries.upsertUserAccess, Everyone, toSQLWildcard(topic), everyone.IsRead(), everyone.IsWrite(), username, username, false); err != nil {
+			return err
+		}
+		return nil
 	})
 }
 
@@ -740,10 +771,7 @@ func (a *Manager) RemoveReservations(username string, topics ...string) error {
 	}
 	return db.ExecTx(a.db, func(tx *sql.Tx) error {
 		for _, topic := range topics {
-			if err := a.resetTopicAccessTx(tx, username, topic); err != nil {
-				return err
-			}
-			if err := a.resetTopicAccessTx(tx, Everyone, topic); err != nil {
+			if err := a.removeReservationAccessTx(tx, username, topic); err != nil {
 				return err
 			}
 		}
@@ -753,7 +781,11 @@ func (a *Manager) RemoveReservations(username string, topics ...string) error {
 
 // Reservations returns all user-owned topics, and the associated everyone-access
 func (a *Manager) Reservations(username string) ([]Reservation, error) {
-	rows, err := a.db.ReadOnly().Query(a.queries.selectUserReservations, Everyone, username)
+	return a.reservationsTx(a.db.ReadOnly(), username)
+}
+
+func (a *Manager) reservationsTx(tx db.Querier, username string) ([]Reservation, error) {
+	rows, err := tx.Query(a.queries.selectUserReservations, Everyone, username)
 	if err != nil {
 		return nil, err
 	}
@@ -779,7 +811,11 @@ func (a *Manager) Reservations(username string) ([]Reservation, error) {
 
 // HasReservation returns true if the given topic access is owned by the user
 func (a *Manager) HasReservation(username, topic string) (bool, error) {
-	rows, err := a.db.Query(a.queries.selectUserHasReservation, username, escapeUnderscore(topic))
+	return a.hasReservationTx(a.db, username, topic)
+}
+
+func (a *Manager) hasReservationTx(tx db.Querier, username, topic string) (bool, error) {
+	rows, err := tx.Query(a.queries.selectUserHasReservation, username, escapeUnderscore(topic))
 	if err != nil {
 		return false, err
 	}
@@ -796,7 +832,11 @@ func (a *Manager) HasReservation(username, topic string) (bool, error) {
 
 // ReservationsCount returns the number of reservations owned by this user
 func (a *Manager) ReservationsCount(username string) (int64, error) {
-	rows, err := a.db.ReadOnly().Query(a.queries.selectUserReservationsCount, username)
+	return a.reservationsCountTx(a.db, username)
+}
+
+func (a *Manager) reservationsCountTx(tx db.Querier, username string) (int64, error) {
+	rows, err := tx.Query(a.queries.selectUserReservationsCount, username)
 	if err != nil {
 		return 0, err
 	}
@@ -828,6 +868,30 @@ func (a *Manager) ReservationOwner(topic string) (string, error) {
 	return ownerUserID, nil
 }
 
+// RemoveExcessReservations removes reservations that exceed the given limit for the user.
+// It returns the list of topics whose reservations were removed. The read and removal are
+// performed atomically in a single transaction to avoid issues with stale replica data.
+func (a *Manager) RemoveExcessReservations(username string, limit int64) ([]string, error) {
+	return db.QueryTx(a.db, func(tx *sql.Tx) ([]string, error) {
+		reservations, err := a.reservationsTx(tx, username)
+		if err != nil {
+			return nil, err
+		}
+		if int64(len(reservations)) <= limit {
+			return []string{}, nil
+		}
+		removedTopics := make([]string, 0)
+		for i := int64(len(reservations)) - 1; i >= limit; i-- {
+			topic := reservations[i].Topic
+			if err := a.removeReservationAccessTx(tx, username, topic); err != nil {
+				return nil, err
+			}
+			removedTopics = append(removedTopics, topic)
+		}
+		return removedTopics, nil
+	})
+}
+
 // otherAccessCount returns the number of access entries for the given topic that are not owned by the user
 func (a *Manager) otherAccessCount(username, topic string) (int, error) {
 	rows, err := a.db.Query(a.queries.selectOtherAccessCount, escapeUnderscore(topic), escapeUnderscore(topic), username)
@@ -845,14 +909,11 @@ func (a *Manager) otherAccessCount(username, topic string) (int, error) {
 	return count, nil
 }
 
-func (a *Manager) addReservationAccessTx(tx *sql.Tx, username, topic string, read, write bool, ownerUsername string) error {
-	if !AllowedUsername(username) && username != Everyone {
-		return ErrInvalidArgument
-	} else if !AllowedTopicPattern(topic) {
-		return ErrInvalidArgument
+func (a *Manager) removeReservationAccessTx(tx *sql.Tx, username, topic string) error {
+	if err := a.resetTopicAccessTx(tx, username, topic); err != nil {
+		return err
 	}
-	_, err := tx.Exec(a.queries.upsertUserAccess, username, toSQLWildcard(topic), read, write, ownerUsername, ownerUsername, false)
-	return err
+	return a.resetTopicAccessTx(tx, Everyone, topic)
 }
 
 func (a *Manager) resetUserAccessTx(tx *sql.Tx, username string) error {
@@ -1134,7 +1195,7 @@ func (a *Manager) Tiers() ([]*Tier, error) {
 
 // Tier returns a Tier based on the code, or ErrTierNotFound if it does not exist
 func (a *Manager) Tier(code string) (*Tier, error) {
-	rows, err := a.db.ReadOnly().Query(a.queries.selectTierByCode, code)
+	rows, err := a.db.Query(a.queries.selectTierByCode, code)
 	if err != nil {
 		return nil, err
 	}
@@ -1144,7 +1205,7 @@ func (a *Manager) Tier(code string) (*Tier, error) {
 
 // TierByStripePrice returns a Tier based on the Stripe price ID, or ErrTierNotFound if it does not exist
 func (a *Manager) TierByStripePrice(priceID string) (*Tier, error) {
-	rows, err := a.db.ReadOnly().Query(a.queries.selectTierByPriceID, priceID, priceID)
+	rows, err := a.db.Query(a.queries.selectTierByPriceID, priceID, priceID)
 	if err != nil {
 		return nil, err
 	}
diff --git a/user/manager_test.go b/user/manager_test.go
index 3e023909..c8e619cf 100644
--- a/user/manager_test.go
+++ b/user/manager_test.go
@@ -226,7 +226,7 @@ func TestManager_MarkUserRemoved_RemoveDeletedUsers(t *testing.T) {
 
 		// Create user, add reservations and token
 		require.Nil(t, a.AddUser("user", "pass", RoleAdmin, false))
-		require.Nil(t, a.AddReservation("user", "mytopic", PermissionRead))
+		require.Nil(t, a.AddReservation("user", "mytopic", PermissionRead, 0))
 
 		u, err := a.User("user")
 		require.Nil(t, err)
@@ -439,8 +439,8 @@ func TestManager_Reservations(t *testing.T) {
 		a := newTestManager(t, newManager, PermissionDenyAll)
 		require.Nil(t, a.AddUser("phil", "phil", RoleUser, false))
 		require.Nil(t, a.AddUser("ben", "ben", RoleUser, false))
-		require.Nil(t, a.AddReservation("ben", "ztopic_", PermissionDenyAll))
-		require.Nil(t, a.AddReservation("ben", "readme", PermissionRead))
+		require.Nil(t, a.AddReservation("ben", "ztopic_", PermissionDenyAll, 0))
+		require.Nil(t, a.AddReservation("ben", "readme", PermissionRead, 0))
 		require.Nil(t, a.AllowAccess("ben", "something-else", PermissionRead))
 
 		reservations, err := a.Reservations("ben")
@@ -523,7 +523,7 @@ func TestManager_ChangeRoleFromTierUserToAdmin(t *testing.T) {
 		}))
 		require.Nil(t, a.AddUser("ben", "ben", RoleUser, false))
 		require.Nil(t, a.ChangeTier("ben", "pro"))
-		require.Nil(t, a.AddReservation("ben", "mytopic", PermissionDenyAll))
+		require.Nil(t, a.AddReservation("ben", "mytopic", PermissionDenyAll, 0))
 
 		ben, err := a.User("ben")
 		require.Nil(t, err)
@@ -1076,7 +1076,7 @@ func TestManager_Tier_Change_And_Reset(t *testing.T) {
 
 		// Add 10 reservations (pro tier allows that)
 		for i := 0; i < 4; i++ {
-			require.Nil(t, a.AddReservation("phil", fmt.Sprintf("topic%d", i), PermissionWrite))
+			require.Nil(t, a.AddReservation("phil", fmt.Sprintf("topic%d", i), PermissionWrite, 0))
 		}
 
 		// Downgrading will not work (too many reservations)
@@ -2118,7 +2118,7 @@ func TestStoreAuthorizeTopicAccessDenyAll(t *testing.T) {
 func TestStoreReservations(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
-		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionRead))
+		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionRead, 0))
 
 		reservations, err := manager.Reservations("phil")
 		require.Nil(t, err)
@@ -2133,8 +2133,8 @@ func TestStoreReservations(t *testing.T) {
 func TestStoreReservationsCount(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
-		require.Nil(t, manager.AddReservation("phil", "topic1", PermissionReadWrite))
-		require.Nil(t, manager.AddReservation("phil", "topic2", PermissionReadWrite))
+		require.Nil(t, manager.AddReservation("phil", "topic1", PermissionReadWrite, 0))
+		require.Nil(t, manager.AddReservation("phil", "topic2", PermissionReadWrite, 0))
 
 		count, err := manager.ReservationsCount("phil")
 		require.Nil(t, err)
@@ -2145,7 +2145,7 @@ func TestStoreReservationsCount(t *testing.T) {
 func TestStoreHasReservation(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
-		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionReadWrite))
+		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionReadWrite, 0))
 
 		has, err := manager.HasReservation("phil", "mytopic")
 		require.Nil(t, err)
@@ -2160,7 +2160,7 @@ func TestStoreHasReservation(t *testing.T) {
 func TestStoreReservationOwner(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
-		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionReadWrite))
+		require.Nil(t, manager.AddReservation("phil", "mytopic", PermissionReadWrite, 0))
 
 		owner, err := manager.ReservationOwner("mytopic")
 		require.Nil(t, err)
@@ -2172,6 +2172,26 @@ func TestStoreReservationOwner(t *testing.T) {
 	})
 }
 
+func TestStoreAddReservationWithLimit(t *testing.T) {
+	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
+		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
+
+		// Adding reservations within limit succeeds
+		require.Nil(t, manager.AddReservation("phil", "topic1", PermissionReadWrite, 2))
+		require.Nil(t, manager.AddReservation("phil", "topic2", PermissionRead, 2))
+
+		// Adding a third reservation exceeds the limit
+		require.Equal(t, ErrTooManyReservations, manager.AddReservation("phil", "topic3", PermissionRead, 2))
+
+		// Updating an existing reservation within the limit succeeds
+		require.Nil(t, manager.AddReservation("phil", "topic1", PermissionRead, 2))
+
+		reservations, err := manager.Reservations("phil")
+		require.Nil(t, err)
+		require.Len(t, reservations, 2)
+	})
+}
+
 func TestStoreTiers(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		tier := &Tier{
@@ -2431,7 +2451,7 @@ func TestStoreOtherAccessCount(t *testing.T) {
 	forEachStoreBackend(t, func(t *testing.T, manager *Manager) {
 		require.Nil(t, manager.AddUser("phil", "mypass", RoleUser, false))
 		require.Nil(t, manager.AddUser("ben", "benpass", RoleUser, false))
-		require.Nil(t, manager.AddReservation("ben", "mytopic", PermissionReadWrite))
+		require.Nil(t, manager.AddReservation("ben", "mytopic", PermissionReadWrite, 0))
 
 		count, err := manager.otherAccessCount("phil", "mytopic")
 		require.Nil(t, err)
diff --git a/web/package-lock.json b/web/package-lock.json
index bec8660f..29c0845e 100644
--- a/web/package-lock.json
+++ b/web/package-lock.json
@@ -3642,9 +3642,9 @@
       "license": "MIT"
     },
     "node_modules/baseline-browser-mapping": {
-      "version": "2.10.0",
-      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.10.0.tgz",
-      "integrity": "sha512-lIyg0szRfYbiy67j9KN8IyeD7q7hcmqnJ1ddWmNt19ItGpNN64mnllmxUNFIOdOm6by97jlL6wfpTTJrmnjWAA==",
+      "version": "2.10.8",
+      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.10.8.tgz",
+      "integrity": "sha512-PCLz/LXGBsNTErbtB6i5u4eLpHeMfi93aUv5duMmj6caNu6IphS4q6UevDnL36sZQv9lrP11dbPKGMaXPwMKfQ==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {
@@ -3766,9 +3766,9 @@
       }
     },
     "node_modules/caniuse-lite": {
-      "version": "1.0.30001777",
-      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001777.tgz",
-      "integrity": "sha512-tmN+fJxroPndC74efCdp12j+0rk0RHwV5Jwa1zWaFVyw2ZxAuPeG8ZgWC3Wz7uSjT3qMRQ5XHZ4COgQmsCMJAQ==",
+      "version": "1.0.30001779",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001779.tgz",
+      "integrity": "sha512-U5og2PN7V4DMgF50YPNtnZJGWVLFjjsN3zb6uMT5VGYIewieDj1upwfuVNXf4Kor+89c3iCRJnSzMD5LmTvsfA==",
       "dev": true,
       "funding": [
         {
@@ -4203,9 +4203,9 @@
       }
     },
     "node_modules/electron-to-chromium": {
-      "version": "1.5.307",
-      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.307.tgz",
-      "integrity": "sha512-5z3uFKBWjiNR44nFcYdkcXjKMbg5KXNdciu7mhTPo9tB7NbqSNP2sSnGR+fqknZSCwKkBN+oxiiajWs4dT6ORg==",
+      "version": "1.5.313",
+      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.313.tgz",
+      "integrity": "sha512-QBMrTWEf00GXZmJyx2lbYD45jpI3TUFnNIzJ5BBc8piGUDwMPa1GV6HJWTZVvY/eiN3fSopl7NRbgGp9sZ9LTA==",
       "dev": true,
       "license": "ISC"
     },
@@ -4324,9 +4324,9 @@
       }
     },
     "node_modules/es-iterator-helpers": {
-      "version": "1.3.0",
-      "resolved": "https://registry.npmjs.org/es-iterator-helpers/-/es-iterator-helpers-1.3.0.tgz",
-      "integrity": "sha512-04cg8iJFDOxWcYlu0GFFWgs7vtaEPCmr5w1nrj9V3z3axu/48HCMwK6VMp45Zh3ZB+xLP1ifbJfrq86+1ypKKQ==",
+      "version": "1.3.1",
+      "resolved": "https://registry.npmjs.org/es-iterator-helpers/-/es-iterator-helpers-1.3.1.tgz",
+      "integrity": "sha512-zWwRvqWiuBPr0muUG/78cW3aHROFCNIQ3zpmYDpwdbnt2m+xlNyRWpHBpa2lJjSBit7BQ+RXA1iwbSmu5yJ/EQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -7043,9 +7043,9 @@
       }
     },
     "node_modules/path-scurry/node_modules/lru-cache": {
-      "version": "11.2.6",
-      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-11.2.6.tgz",
-      "integrity": "sha512-ESL2CrkS/2wTPfuend7Zhkzo2u0daGJ/A2VucJOgQ/C48S/zB8MMeMHSGKYpXhIjbPxfuezITkaBH1wqv00DDQ==",
+      "version": "11.2.7",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-11.2.7.tgz",
+      "integrity": "sha512-aY/R+aEsRelme17KGQa/1ZSIpLpNYYrhcrepKTZgE+W3WM16YMCaPwOHLHsmopZHELU0Ojin1lPVxKR0MihncA==",
       "dev": true,
       "license": "BlueOak-1.0.0",
       "engines": {
@@ -8307,9 +8307,9 @@
       }
     },
     "node_modules/terser": {
-      "version": "5.46.0",
-      "resolved": "https://registry.npmjs.org/terser/-/terser-5.46.0.tgz",
-      "integrity": "sha512-jTwoImyr/QbOWFFso3YoU3ik0jBBDJ6JTOQiy/J2YxVJdZCc+5u7skhNwiOR3FQIygFqVUPHl7qbbxtjW2K3Qg==",
+      "version": "5.46.1",
+      "resolved": "https://registry.npmjs.org/terser/-/terser-5.46.1.tgz",
+      "integrity": "sha512-vzCjQO/rgUuK9sf8VJZvjqiqiHFaZLnOiimmUuOKODxWL8mm/xua7viT7aqX7dgPY60otQjUotzFMmCB4VdmqQ==",
       "dev": true,
       "license": "BSD-2-Clause",
       "dependencies": {
diff --git a/webpush/store.go b/webpush/store.go
index 02b7552e..1a9825f5 100644
--- a/webpush/store.go
+++ b/webpush/store.go
@@ -63,9 +63,10 @@ func (s *Store) UpsertSubscription(endpoint string, auth, p256dh, userID string,
 		} else if err != nil {
 			return err
 		}
-		// Insert or update subscription
+		// Insert or update subscription, and read back the actual ID (which may differ from
+		// the generated one if another request for the same endpoint raced us and inserted first)
 		updatedAt, warnedAt := time.Now().Unix(), 0
-		if _, err := tx.Exec(s.queries.upsertSubscription, subscriptionID, endpoint, auth, p256dh, userID, subscriberIP.String(), updatedAt, warnedAt); err != nil {
+		if err := tx.QueryRow(s.queries.upsertSubscription, subscriptionID, endpoint, auth, p256dh, userID, subscriberIP.String(), updatedAt, warnedAt).Scan(&subscriptionID); err != nil {
 			return err
 		}
 		// Replace all subscription topics
diff --git a/webpush/store_postgres.go b/webpush/store_postgres.go
index 1c9adf0a..84168d89 100644
--- a/webpush/store_postgres.go
+++ b/webpush/store_postgres.go
@@ -53,6 +53,7 @@ const (
 		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
 		ON CONFLICT (endpoint)
 		DO UPDATE SET key_auth = excluded.key_auth, key_p256dh = excluded.key_p256dh, user_id = excluded.user_id, subscriber_ip = excluded.subscriber_ip, updated_at = excluded.updated_at, warned_at = excluded.warned_at
+		RETURNING id
 	`
 	postgresUpdateSubscriptionWarningSentQuery = `UPDATE webpush_subscription SET warned_at = $1 WHERE id = $2`
 	postgresUpdateSubscriptionUpdatedAtQuery   = `UPDATE webpush_subscription SET updated_at = $1 WHERE endpoint = $2`
diff --git a/webpush/store_sqlite.go b/webpush/store_sqlite.go
index fcf49fcf..7677f1ce 100644
--- a/webpush/store_sqlite.go
+++ b/webpush/store_sqlite.go
@@ -56,8 +56,9 @@ const (
 	sqliteUpsertSubscriptionQuery = `
 		INSERT INTO subscription (id, endpoint, key_auth, key_p256dh, user_id, subscriber_ip, updated_at, warned_at)
 		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
-		ON CONFLICT (endpoint) 
+		ON CONFLICT (endpoint)
 		DO UPDATE SET key_auth = excluded.key_auth, key_p256dh = excluded.key_p256dh, user_id = excluded.user_id, subscriber_ip = excluded.subscriber_ip, updated_at = excluded.updated_at, warned_at = excluded.warned_at
+		RETURNING id
 	`
 	sqliteUpdateSubscriptionWarningSentQuery = `UPDATE subscription SET warned_at = ? WHERE id = ?`
 	sqliteUpdateSubscriptionUpdatedAtQuery   = `UPDATE subscription SET updated_at = ? WHERE endpoint = ?`