diff --git a/core/services/studio/connectors/connectorstest/suite.go b/core/services/studio/connectors/connectorstest/suite.go
index 8c299f8526..5c65dcf38b 100644
--- a/core/services/studio/connectors/connectorstest/suite.go
+++ b/core/services/studio/connectors/connectorstest/suite.go
@@ -94,6 +94,15 @@ func Run(newStore NewStore) {
 		Expect(err).NotTo(HaveOccurred())
 		Expect(got.ReadsThread()).To(BeFalse())
 	})
+	It("keeps the file limits an owner set for a binding", func() {
+		s := newStore()
+		b := binding("limits", "u1", "Limits")
+		b.FileReceiveMax, b.FileSendMax = 512<<10, 2<<20
+		Expect(s.PutBinding(ctx, b)).To(Succeed())
+		got, err := s.GetBinding(ctx, "limits")
+		Expect(err).NotTo(HaveOccurred())
+		Expect([]int64{got.FileReceiveMax, got.FileSendMax}).To(Equal([]int64{512 << 10, 2 << 20}))
+	})
 	It("gives an old binding the add-on of its kind", func() {
 		// A binding stored before connectors became add-ons has no add-on ID.
 		s := newStore()
diff --git a/core/services/studio/connectors/gorm.go b/core/services/studio/connectors/gorm.go
index 1c8dca7e8d..7f573d5777 100644
--- a/core/services/studio/connectors/gorm.go
+++ b/core/services/studio/connectors/gorm.go
@@ -33,9 +33,13 @@ type bindingRow struct {
 	ThreadContextOff bool
 	// Options is JSON, added by AutoMigrate.
 	Options string
-	Token   []byte
-	Created time.Time
-	Updated time.Time
+	// The columns of the file limits are added by AutoMigrate; a row stored
+	// before them has no limit of the owner.
+	FileReceiveMax int64
+	FileSendMax    int64
+	Token          []byte
+	Created        time.Time
+	Updated        time.Time
 }
 
 func (bindingRow) TableName() string { return "studio_connectors" }
@@ -90,6 +94,7 @@ func NewGORM(db *gorm.DB) (Store, error) {
 func (r bindingRow) binding() (Binding, error) {
 	b := Binding{ID: r.ID, Owner: r.Owner, Kind: r.Kind, AddonID: r.AddonID, Name: r.Name, AgentID: r.AgentID, Enabled: r.Enabled, AcceptAny: r.AcceptAny,
 		NotifyChat: r.NotifyChat, Reply: r.Reply, Conversation: r.Conversation, WindowMinutes: r.WindowMinutes, FilesOff: r.FilesOff, ThreadContextOff: r.ThreadContextOff,
+		FileReceiveMax: r.FileReceiveMax, FileSendMax: r.FileSendMax,
 		Token: append([]byte(nil), r.Token...), Created: r.Created.UTC(), Updated: r.Updated.UTC()}
 	if r.Allow != "" {
 		if err := json.Unmarshal([]byte(r.Allow), &b.Allow); err != nil {
@@ -117,7 +122,8 @@ func (s *gormStore) PutBinding(ctx context.Context, b Binding) error {
 	}
 	return s.db.WithContext(ctx).Save(&bindingRow{ID: b.ID, Owner: b.Owner, Kind: b.Kind, AddonID: b.AddonID, Name: b.Name, AgentID: b.AgentID, Enabled: b.Enabled,
 		AcceptAny: b.AcceptAny, Allow: allow, NotifyChat: b.NotifyChat, Reply: b.Reply, Conversation: b.Conversation, WindowMinutes: b.WindowMinutes,
-		FilesOff: b.FilesOff, ThreadContextOff: b.ThreadContextOff, Options: options, Token: b.Token, Created: b.Created, Updated: b.Updated}).Error
+		FilesOff: b.FilesOff, ThreadContextOff: b.ThreadContextOff, Options: options, FileReceiveMax: b.FileReceiveMax, FileSendMax: b.FileSendMax,
+		Token: b.Token, Created: b.Created, Updated: b.Updated}).Error
 }
 
 func (s *gormStore) GetBinding(ctx context.Context, id string) (Binding, error) {
diff --git a/core/services/studio/connectors/seal_test.go b/core/services/studio/connectors/seal_test.go
index 83f5cb35dd..eabd05ffbe 100644
--- a/core/services/studio/connectors/seal_test.go
+++ b/core/services/studio/connectors/seal_test.go
@@ -46,16 +46,18 @@ var _ = Describe("sealing and validating bindings", func() {
 			many[i] = "1"
 		}
 		for name, b := range map[string]connectors.Binding{
-			"no name":    {Kind: connectors.KindTelegram, AgentID: "a"},
-			"long name":  {Name: strings.Repeat("n", 81), Kind: connectors.KindTelegram, AgentID: "a"},
-			"bad kind":   {Name: "b", Kind: "Not A Kind", AgentID: "a"},
-			"no agent":   {Name: "b", Kind: connectors.KindTelegram},
-			"bad allow":  {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: []string{"alice"}},
-			"short name": {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: []string{"@ab"}},
-			"many":       {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: many},
-			"bad notify": {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", NotifyChat: "me"},
-			"lower id":   {Name: "b", Kind: "slack", AgentID: "a", Allow: []string{"u012ab"}},
-			"id notify":  {Name: "b", Kind: "slack", AgentID: "a", NotifyChat: "@ada"},
+			"no name":                {Kind: connectors.KindTelegram, AgentID: "a"},
+			"long name":              {Name: strings.Repeat("n", 81), Kind: connectors.KindTelegram, AgentID: "a"},
+			"bad kind":               {Name: "b", Kind: "Not A Kind", AgentID: "a"},
+			"no agent":               {Name: "b", Kind: connectors.KindTelegram},
+			"bad allow":              {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: []string{"alice"}},
+			"short name":             {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: []string{"@ab"}},
+			"many":                   {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", Allow: many},
+			"bad notify":             {Name: "b", Kind: connectors.KindTelegram, AgentID: "a", NotifyChat: "me"},
+			"lower id":               {Name: "b", Kind: "slack", AgentID: "a", Allow: []string{"u012ab"}},
+			"id notify":              {Name: "b", Kind: "slack", AgentID: "a", NotifyChat: "@ada"},
+			"negative receive limit": {Name: "b", Kind: "slack", AgentID: "a", FileReceiveMax: -1},
+			"huge send limit":        {Name: "b", Kind: "slack", AgentID: "a", FileSendMax: connectors.MaxFileLimit + 1},
 		} {
 			Expect(connectors.Validate(b)).To(MatchError(connectors.ErrInvalid), name)
 		}
diff --git a/core/services/studio/connectors/types.go b/core/services/studio/connectors/types.go
index 1010ece55d..c2d7e5f819 100644
--- a/core/services/studio/connectors/types.go
+++ b/core/services/studio/connectors/types.go
@@ -68,6 +68,8 @@ const (
 	MaxSendersKept   = 200
 	MaxOptions       = 8
 	MaxOptionRunes   = 32
+	// MaxFileLimit is the largest file limit a binding can hold: 1 TiB.
+	MaxFileLimit int64 = 1 << 40
 )
 
 // Errors.
@@ -116,6 +118,11 @@ type Binding struct {
 	// the binding declares (contract.ConnectorKind.Options), by option ID. An
 	// option that is not here has its default.
 	Options map[string]string
+	// FileReceiveMax and FileSendMax are the largest file, in bytes, that the
+	// owner lets the bot read and send. Zero means no limit of the owner: the
+	// limit of the kind applies. A value can only lower what the kind allows;
+	// the host takes the smaller one.
+	FileReceiveMax, FileSendMax int64
 	// Token is the bot token. In a Store it is sealed bytes; the Store returns
 	// what it was given.
 	Token   []byte
@@ -193,6 +200,9 @@ func Validate(b Binding) error {
 			return bad("%q is not a chat ID, user ID or @username", a)
 		}
 	}
+	if b.FileReceiveMax < 0 || b.FileReceiveMax > MaxFileLimit || b.FileSendMax < 0 || b.FileSendMax > MaxFileLimit {
+		return bad("a file limit must be 0 (the limit of the kind) or 1 to %d bytes", MaxFileLimit)
+	}
 	if b.NotifyChat != "" && !chatShape.MatchString(b.NotifyChat) {
 		return bad("the notification chat must be a chat ID")
 	}