refactor(reaction): link reactions to memo IDs (#6221)

CONTEXT.md

@@ -0,0 +1,21 @@
+# Memos
+
+Memos is the note-taking domain centered on short-form memos and the resources attached to them.
+
+## Language
+
+**Memo ID**:
+The stable internal identity of a memo. It does not change when a memo's public identifier changes.
+_Avoid_: Memo UID, slug
+
+**Memo UID**:
+The unique public identifier used in a memo resource name and URL. It may be user-defined when the memo is created or generated automatically.
+_Avoid_: Memo ID, database ID
+
+**Memo resource name**:
+The API identity of a memo in the form `memos/{memo UID}`.
+_Avoid_: Memo ID, content ID
+
+**Memo reaction**:
+A response attached to exactly one memo. Reactions are not a generic mechanism for targeting other kinds of content.
+_Avoid_: Content reaction, generic reaction, reaction target

proto/api/v1/memo_service.proto

@@ -96,8 +96,7 @@ service MemoService {
     option (google.api.http) = {get: "/api/v1/{name=memos/*}/reactions"};
     option (google.api.method_signature) = "name";
   }
-  // UpsertMemoReaction adds or updates the authenticated user's reaction on a
-  // memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+  // UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
   rpc UpsertMemoReaction(UpsertMemoReactionRequest) returns (Reaction) {
     option (google.api.http) = {
       post: "/api/v1/{name=memos/*}/reactions"
@@ -157,6 +156,7 @@ enum Visibility {
   PUBLIC = 3;
 }
 
+// Reaction is a reaction attached to a memo.
 message Reaction {
   option (google.api.resource) = {
     type: "memos.api.v1/Reaction"
@@ -180,13 +180,8 @@ message Reaction {
     (google.api.resource_reference) = {type: "memos.api.v1/User"}
   ];
 
-  // The resource name of the content.
-  // For memo reactions, this should be the memo's resource name.
-  // Format: memos/{memo}
-  string content_id = 3 [
-    (google.api.field_behavior) = REQUIRED,
-    (google.api.resource_reference) = {type: "memos.api.v1/Memo"}
-  ];
+  reserved 3;
+  reserved "content_id";
 
   // Required. The type of reaction (e.g., "👍", "❤️", "😄").
   string reaction_type = 4 [(google.api.field_behavior) = REQUIRED];

proto/gen/api/v1/apiv1connect/memo_service.connect.go

@@ -123,8 +123,7 @@ type MemoServiceClient interface {
 	ListMemoComments(context.Context, *connect.Request[v1.ListMemoCommentsRequest]) (*connect.Response[v1.ListMemoCommentsResponse], error)
 	// ListMemoReactions lists reactions for a memo.
 	ListMemoReactions(context.Context, *connect.Request[v1.ListMemoReactionsRequest]) (*connect.Response[v1.ListMemoReactionsResponse], error)
-	// UpsertMemoReaction adds or updates the authenticated user's reaction on a
-	// memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+	// UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
 	UpsertMemoReaction(context.Context, *connect.Request[v1.UpsertMemoReactionRequest]) (*connect.Response[v1.Reaction], error)
 	// DeleteMemoReaction deletes a reaction for a memo.
 	DeleteMemoReaction(context.Context, *connect.Request[v1.DeleteMemoReactionRequest]) (*connect.Response[emptypb.Empty], error)
@@ -433,8 +432,7 @@ type MemoServiceHandler interface {
 	ListMemoComments(context.Context, *connect.Request[v1.ListMemoCommentsRequest]) (*connect.Response[v1.ListMemoCommentsResponse], error)
 	// ListMemoReactions lists reactions for a memo.
 	ListMemoReactions(context.Context, *connect.Request[v1.ListMemoReactionsRequest]) (*connect.Response[v1.ListMemoReactionsResponse], error)
-	// UpsertMemoReaction adds or updates the authenticated user's reaction on a
-	// memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+	// UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
 	UpsertMemoReaction(context.Context, *connect.Request[v1.UpsertMemoReactionRequest]) (*connect.Response[v1.Reaction], error)
 	// DeleteMemoReaction deletes a reaction for a memo.
 	DeleteMemoReaction(context.Context, *connect.Request[v1.DeleteMemoReactionRequest]) (*connect.Response[emptypb.Empty], error)

proto/gen/api/v1/memo_service.pb.go

@@ -131,6 +131,7 @@ func (MemoRelation_Type) EnumDescriptor() ([]byte, []int) {
 	return file_api_v1_memo_service_proto_rawDescGZIP(), []int{12, 0}
 }
 
+// Reaction is a reaction attached to a memo.
 type Reaction struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// The resource name of the reaction.
@@ -139,10 +140,6 @@ type Reaction struct {
 	// The resource name of the creator.
 	// Format: users/{user}
 	Creator string `protobuf:"bytes,2,opt,name=creator,proto3" json:"creator,omitempty"`
-	// The resource name of the content.
-	// For memo reactions, this should be the memo's resource name.
-	// Format: memos/{memo}
-	ContentId string `protobuf:"bytes,3,opt,name=content_id,json=contentId,proto3" json:"content_id,omitempty"`
 	// Required. The type of reaction (e.g., "👍", "❤️", "😄").
 	ReactionType string `protobuf:"bytes,4,opt,name=reaction_type,json=reactionType,proto3" json:"reaction_type,omitempty"`
 	// Output only. The creation timestamp.
@@ -195,13 +192,6 @@ func (x *Reaction) GetCreator() string {
 	return ""
 }
 
-func (x *Reaction) GetContentId() string {
-	if x != nil {
-		return x.ContentId
-	}
-	return ""
-}
-
 func (x *Reaction) GetReactionType() string {
 	if x != nil {
 		return x.ReactionType
@@ -2316,18 +2306,16 @@ var File_api_v1_memo_service_proto protoreflect.FileDescriptor
 
 const file_api_v1_memo_service_proto_rawDesc = "" +
 	"\n" +
-	"\x19api/v1/memo_service.proto\x12\fmemos.api.v1\x1a\x1fapi/v1/attachment_service.proto\x1a\x13api/v1/common.proto\x1a\x1cgoogle/api/annotations.proto\x1a\x17google/api/client.proto\x1a\x1fgoogle/api/field_behavior.proto\x1a\x19google/api/resource.proto\x1a\x1bgoogle/protobuf/empty.proto\x1a google/protobuf/field_mask.proto\x1a\x1fgoogle/protobuf/timestamp.proto\"\xdb\x02\n" +
+	"\x19api/v1/memo_service.proto\x12\fmemos.api.v1\x1a\x1fapi/v1/attachment_service.proto\x1a\x13api/v1/common.proto\x1a\x1cgoogle/api/annotations.proto\x1a\x17google/api/client.proto\x1a\x1fgoogle/api/field_behavior.proto\x1a\x19google/api/resource.proto\x1a\x1bgoogle/protobuf/empty.proto\x1a google/protobuf/field_mask.proto\x1a\x1fgoogle/protobuf/timestamp.proto\"\xb3\x02\n" +
 	"\bReaction\x12\x1a\n" +
 	"\x04name\x18\x01 \x01(\tB\x06\xe0A\x03\xe0A\bR\x04name\x123\n" +
 	"\acreator\x18\x02 \x01(\tB\x19\xe0A\x03\xfaA\x13\n" +
-	"\x11memos.api.v1/UserR\acreator\x128\n" +
-	"\n" +
-	"content_id\x18\x03 \x01(\tB\x19\xe0A\x02\xfaA\x13\n" +
-	"\x11memos.api.v1/MemoR\tcontentId\x12(\n" +
+	"\x11memos.api.v1/UserR\acreator\x12(\n" +
 	"\rreaction_type\x18\x04 \x01(\tB\x03\xe0A\x02R\freactionType\x12@\n" +
 	"\vcreate_time\x18\x05 \x01(\v2\x1a.google.protobuf.TimestampB\x03\xe0A\x03R\n" +
 	"createTime:X\xeaAU\n" +
-	"\x15memos.api.v1/Reaction\x12!memos/{memo}/reactions/{reaction}\x1a\x04name*\treactions2\breaction\"\xbe\b\n" +
+	"\x15memos.api.v1/Reaction\x12!memos/{memo}/reactions/{reaction}\x1a\x04name*\treactions2\breactionJ\x04\b\x03\x10\x04R\n" +
+	"content_id\"\xbe\b\n" +
 	"\x04Memo\x12\x17\n" +
 	"\x04name\x18\x01 \x01(\tB\x03\xe0A\bR\x04name\x12.\n" +
 	"\x05state\x18\x02 \x01(\x0e2\x13.memos.api.v1.StateB\x03\xe0A\x02R\x05state\x123\n" +

proto/gen/api/v1/memo_service_grpc.pb.go

@@ -76,8 +76,7 @@ type MemoServiceClient interface {
 	ListMemoComments(ctx context.Context, in *ListMemoCommentsRequest, opts ...grpc.CallOption) (*ListMemoCommentsResponse, error)
 	// ListMemoReactions lists reactions for a memo.
 	ListMemoReactions(ctx context.Context, in *ListMemoReactionsRequest, opts ...grpc.CallOption) (*ListMemoReactionsResponse, error)
-	// UpsertMemoReaction adds or updates the authenticated user's reaction on a
-	// memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+	// UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
 	UpsertMemoReaction(ctx context.Context, in *UpsertMemoReactionRequest, opts ...grpc.CallOption) (*Reaction, error)
 	// DeleteMemoReaction deletes a reaction for a memo.
 	DeleteMemoReaction(ctx context.Context, in *DeleteMemoReactionRequest, opts ...grpc.CallOption) (*emptypb.Empty, error)
@@ -338,8 +337,7 @@ type MemoServiceServer interface {
 	ListMemoComments(context.Context, *ListMemoCommentsRequest) (*ListMemoCommentsResponse, error)
 	// ListMemoReactions lists reactions for a memo.
 	ListMemoReactions(context.Context, *ListMemoReactionsRequest) (*ListMemoReactionsResponse, error)
-	// UpsertMemoReaction adds or updates the authenticated user's reaction on a
-	// memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+	// UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
 	UpsertMemoReaction(context.Context, *UpsertMemoReactionRequest) (*Reaction, error)
 	// DeleteMemoReaction deletes a reaction for a memo.
 	DeleteMemoReaction(context.Context, *DeleteMemoReactionRequest) (*emptypb.Empty, error)

proto/gen/openapi.yaml

@@ -1054,9 +1054,7 @@ paths:
         post:
             tags:
                 - MemoService
-            description: |-
-                UpsertMemoReaction adds or updates the authenticated user's reaction on a
-                 memo. The reaction's content_id is the memo's resource name (memos/{memo}).
+            description: UpsertMemoReaction adds or updates the authenticated user's reaction on a memo.
             operationId: MemoService_UpsertMemoReaction
             parameters:
                 - name: memo
@@ -3599,7 +3597,6 @@ components:
                     format: double
         Reaction:
             required:
-                - contentId
                 - reactionType
             type: object
             properties:
@@ -3615,12 +3612,6 @@ components:
                     description: |-
                         The resource name of the creator.
                          Format: users/{user}
-                contentId:
-                    type: string
-                    description: |-
-                        The resource name of the content.
-                         For memo reactions, this should be the memo's resource name.
-                         Format: memos/{memo}
                 reactionType:
                     type: string
                     description: "Required. The type of reaction (e.g., \"\U0001F44D\", \"❤️\", \"\U0001F604\")."
@@ -3629,6 +3620,7 @@ components:
                     type: string
                     description: Output only. The creation timestamp.
                     format: date-time
+            description: Reaction is a reaction attached to a memo.
         RefreshTokenRequest:
             type: object
             properties: {}

server/router/api/v1/memo_service.go

@@ -287,24 +287,22 @@ func (s *APIV1Service) ListMemos(ctx context.Context, request *v1pb.ListMemosReq
 		return response, nil
 	}
 
-	reactionMap := make(map[string][]*store.Reaction)
-	contentIDs := make([]string, 0, len(memos))
+	reactionMap := make(map[int32][]*store.Reaction)
 
 	attachmentMap := make(map[int32][]*store.Attachment)
 	memoIDs := make([]int32, 0, len(memos))
 
 	for _, m := range memos {
-		contentIDs = append(contentIDs, fmt.Sprintf("%s%s", MemoNamePrefix, m.UID))
 		memoIDs = append(memoIDs, m.ID)
 	}
 
 	// REACTIONS
-	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{ContentIDList: contentIDs})
+	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{MemoIDList: memoIDs})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
 	}
 	for _, reaction := range reactions {
-		reactionMap[reaction.ContentID] = append(reactionMap[reaction.ContentID], reaction)
+		reactionMap[reaction.MemoID] = append(reactionMap[reaction.MemoID], reaction)
 	}
 
 	// ATTACHMENTS
@@ -333,8 +331,7 @@ func (s *APIV1Service) ListMemos(ctx context.Context, request *v1pb.ListMemosReq
 		return nil, status.Errorf(codes.Internal, "failed to list memo creators: %v", err)
 	}
 	for _, memo := range memos {
-		memoName := fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)
-		reactions := reactionMap[memoName]
+		reactions := reactionMap[memo.ID]
 		attachments := attachmentMap[memo.ID]
 		relations := relationMap[memo.ID]
 
@@ -381,7 +378,7 @@ func (s *APIV1Service) GetMemo(ctx context.Context, request *v1pb.GetMemoRequest
 	}
 
 	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
-		ContentID: &request.Name,
+		MemoID: &memo.ID,
 	})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
@@ -614,7 +611,7 @@ func (s *APIV1Service) DeleteMemo(ctx context.Context, request *v1pb.DeleteMemoR
 	}
 
 	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
-		ContentID: &request.Name,
+		MemoID: &memo.ID,
 	})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
@@ -635,7 +632,7 @@ func (s *APIV1Service) DeleteMemo(ctx context.Context, request *v1pb.DeleteMemoR
 		}
 	}
 
-	// Delete memo comments first (store.DeleteMemo handles their relations and attachments)
+	// Delete memo comments first (store.DeleteMemo handles their reactions, relations and attachments)
 	commentType := store.MemoRelationComment
 	relations, err := s.Store.ListMemoRelations(ctx, &store.FindMemoRelation{RelatedMemoID: &memo.ID, Type: &commentType})
 	if err != nil {
@@ -647,7 +644,7 @@ func (s *APIV1Service) DeleteMemo(ctx context.Context, request *v1pb.DeleteMemoR
 		}
 	}
 
-	// Delete the memo (store.DeleteMemo handles relation and attachment cleanup)
+	// Delete the memo (store.DeleteMemo handles reaction, relation and attachment cleanup)
 	if err = s.Store.DeleteMemo(ctx, &store.DeleteMemo{ID: memo.ID}); err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to delete memo")
 	}

server/router/api/v1/memo_service_comments.go

@@ -3,7 +3,6 @@ package v1
 import (
 	"context"
 	stderrors "errors"
-	"fmt"
 	"log/slog"
 
 	"github.com/pkg/errors"
@@ -203,27 +202,22 @@ func (s *APIV1Service) ListMemoComments(ctx context.Context, request *v1pb.ListM
 		return nil, status.Errorf(codes.Internal, "failed to list memos")
 	}
 
-	memoIDToNameMap := make(map[int32]string)
-	contentIDs := make([]string, 0, len(memos))
-	memoIDsForAttachments := make([]int32, 0, len(memos))
+	memoIDs := make([]int32, 0, len(memos))
 
 	for _, memo := range memos {
-		memoName := fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)
-		memoIDToNameMap[memo.ID] = memoName
-		contentIDs = append(contentIDs, memoName)
-		memoIDsForAttachments = append(memoIDsForAttachments, memo.ID)
+		memoIDs = append(memoIDs, memo.ID)
 	}
-	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{ContentIDList: contentIDs})
+	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{MemoIDList: memoIDs})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
 	}
 
-	memoReactionsMap := make(map[string][]*store.Reaction)
+	memoReactionsMap := make(map[int32][]*store.Reaction)
 	for _, reaction := range reactions {
-		memoReactionsMap[reaction.ContentID] = append(memoReactionsMap[reaction.ContentID], reaction)
+		memoReactionsMap[reaction.MemoID] = append(memoReactionsMap[reaction.MemoID], reaction)
 	}
 
-	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{MemoIDList: memoIDsForAttachments})
+	attachments, err := s.Store.ListAttachments(ctx, &store.FindAttachment{MemoIDList: memoIDs})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list attachments")
 	}
@@ -250,8 +244,7 @@ func (s *APIV1Service) ListMemoComments(ctx context.Context, request *v1pb.ListM
 	}
 	var memosResponse []*v1pb.Memo
 	for _, m := range memos {
-		memoName := memoIDToNameMap[m.ID]
-		reactions := memoReactionsMap[memoName]
+		reactions := memoReactionsMap[m.ID]
 		attachments := attachmentMap[m.ID]
 		relations := relationMap[m.ID]
 

server/router/api/v1/memo_service_converter.go

@@ -29,7 +29,7 @@ func (s *APIV1Service) convertMemoFromStore(ctx context.Context, memo *store.Mem
 }
 
 func (s *APIV1Service) convertMemoFromStoreWithCreators(ctx context.Context, memo *store.Memo, reactions []*store.Reaction, attachments []*store.Attachment, relations []*v1pb.MemoRelation, creatorMap map[int32]*store.User) (*v1pb.Memo, error) {
-	name := fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)
+	name := buildMemoName(memo.UID)
 	creator := creatorMap[memo.CreatorID]
 	if creator == nil {
 		return nil, errMemoCreatorNotFound
@@ -51,11 +51,11 @@ func (s *APIV1Service) convertMemoFromStoreWithCreators(ctx context.Context, mem
 	}
 
 	if memo.ParentUID != nil {
-		parentName := fmt.Sprintf("%s%s", MemoNamePrefix, *memo.ParentUID)
+		parentName := buildMemoName(*memo.ParentUID)
 		memoMessage.Parent = &parentName
 	}
 
-	reactionMessages, err := s.convertReactionsFromStoreWithCreators(ctx, reactions, creatorMap)
+	reactionMessages, err := s.convertReactionsFromStoreWithCreators(ctx, reactions, creatorMap, name)
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to convert reactions")
 	}
@@ -119,7 +119,7 @@ func (s *APIV1Service) listUsersByIDWithExisting(ctx context.Context, userIDs []
 	return usersByID, nil
 }
 
-func (s *APIV1Service) convertReactionsFromStoreWithCreators(ctx context.Context, reactions []*store.Reaction, creatorMap map[int32]*store.User) ([]*v1pb.Reaction, error) {
+func (s *APIV1Service) convertReactionsFromStoreWithCreators(ctx context.Context, reactions []*store.Reaction, creatorMap map[int32]*store.User, memoName string) ([]*v1pb.Reaction, error) {
 	if len(reactions) == 0 {
 		return []*v1pb.Reaction{}, nil
 	}
@@ -135,13 +135,13 @@ func (s *APIV1Service) convertReactionsFromStoreWithCreators(ctx context.Context
 
 	reactionMessages := make([]*v1pb.Reaction, 0, len(reactions))
 	for _, reaction := range reactions {
-		reactionMessage, err := convertReactionFromStoreWithCreators(reaction, creatorsByID)
+		reactionMessage, err := convertReactionFromStoreWithCreators(reaction, creatorsByID, memoName)
 		if err != nil {
 			if stderrors.Is(err, errReactionCreatorNotFound) {
 				slog.Warn("Skipping reaction with missing creator",
 					slog.Int64("reaction_id", int64(reaction.ID)),
 					slog.Int64("creator_id", int64(reaction.CreatorID)),
-					slog.String("content_id", reaction.ContentID),
+					slog.Int64("memo_id", int64(reaction.MemoID)),
 				)
 				continue
 			}
@@ -152,7 +152,7 @@ func (s *APIV1Service) convertReactionsFromStoreWithCreators(ctx context.Context
 	return reactionMessages, nil
 }
 
-func convertReactionFromStoreWithCreators(reaction *store.Reaction, creatorsByID map[int32]*store.User) (*v1pb.Reaction, error) {
+func convertReactionFromStoreWithCreators(reaction *store.Reaction, creatorsByID map[int32]*store.User, memoName string) (*v1pb.Reaction, error) {
 	creator := creatorsByID[reaction.CreatorID]
 	if creator == nil {
 		return nil, errReactionCreatorNotFound
@@ -160,9 +160,8 @@ func convertReactionFromStoreWithCreators(reaction *store.Reaction, creatorsByID
 
 	reactionUID := fmt.Sprintf("%d", reaction.ID)
 	return &v1pb.Reaction{
-		Name:         fmt.Sprintf("%s/%s%s", reaction.ContentID, ReactionNamePrefix, reactionUID),
+		Name:         fmt.Sprintf("%s/%s%s", memoName, ReactionNamePrefix, reactionUID),
 		Creator:      BuildUserName(creator.Username),
-		ContentId:    reaction.ContentID,
 		ReactionType: reaction.ReactionType,
 		CreateTime:   timestamppb.New(time.Unix(reaction.CreatedTs, 0)),
 	}, nil

server/router/api/v1/memo_share_service.go

@@ -172,7 +172,7 @@ func (s *APIV1Service) GetSharedMemo(ctx context.Context, request *v1pb.GetShare
 	}
 
 	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
-		ContentID: stringPointer(fmt.Sprintf("%s%s", MemoNamePrefix, memo.UID)),
+		MemoID: &memo.ID,
 	})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
@@ -212,10 +212,6 @@ func (s *APIV1Service) getActiveMemoShare(ctx context.Context, shareID string) (
 	return ms, nil
 }
 
-func stringPointer(s string) *string {
-	return &s
-}
-
 // convertMemoShareFromStore converts a store MemoShare to the proto MemoShare message.
 // name format: memos/{memoUID}/shares/{shareToken}.
 func convertMemoShareFromStore(ms *store.MemoShare, memoUID string) *v1pb.MemoShare {

server/router/api/v1/memo_update_helpers.go

@@ -19,9 +19,8 @@ func (s *APIV1Service) buildUpdatedMemoState(ctx context.Context, memoID int32)
 		return nil, nil, nil, errors.New("memo not found")
 	}
 
-	memoName := buildMemoName(memo.UID)
 	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
-		ContentID: &memoName,
+		MemoID: &memo.ID,
 	})
 	if err != nil {
 		return nil, nil, nil, errors.Wrap(err, "failed to list reactions")

server/router/api/v1/reaction_service.go

@@ -2,6 +2,7 @@ package v1
 
 import (
 	"context"
+	stderrors "errors"
 	"log/slog"
 
 	"google.golang.org/grpc/codes"
@@ -41,7 +42,7 @@ func (s *APIV1Service) ListMemoReactions(ctx context.Context, request *v1pb.List
 	}
 
 	reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
-		ContentID: &request.Name,
+		MemoID: &memo.ID,
 	})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to list reactions")
@@ -50,7 +51,7 @@ func (s *APIV1Service) ListMemoReactions(ctx context.Context, request *v1pb.List
 	response := &v1pb.ListMemoReactionsResponse{
 		Reactions: []*v1pb.Reaction{},
 	}
-	response.Reactions, err = s.convertReactionsFromStoreWithCreators(ctx, reactions, nil)
+	response.Reactions, err = s.convertReactionsFromStoreWithCreators(ctx, reactions, nil, buildMemoName(memo.UID))
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to convert reactions")
 	}
@@ -67,7 +68,7 @@ func (s *APIV1Service) UpsertMemoReaction(ctx context.Context, request *v1pb.Ups
 	}
 
 	// Extract memo UID and check visibility before allowing reaction.
-	memoUID, err := ExtractMemoUIDFromName(request.Reaction.ContentId)
+	memoUID, err := ExtractMemoUIDFromName(request.Name)
 	if err != nil {
 		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
 	}
@@ -86,14 +87,18 @@ func (s *APIV1Service) UpsertMemoReaction(ctx context.Context, request *v1pb.Ups
 
 	reaction, err := s.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    request.Reaction.ContentId,
+		MemoID:       memo.ID,
 		ReactionType: request.Reaction.ReactionType,
 	})
 	if err != nil {
+		if stderrors.Is(err, store.ErrReactionMemoNotFound) {
+			return nil, status.Errorf(codes.NotFound, "memo not found")
+		}
 		return nil, status.Errorf(codes.Internal, "failed to upsert reaction")
 	}
 
-	reactionMessage, err := s.convertReactionFromStore(ctx, reaction)
+	memoName := buildMemoName(memo.UID)
+	reactionMessage, err := s.convertReactionFromStore(ctx, reaction, memoName)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to convert reaction")
 	}
@@ -103,7 +108,7 @@ func (s *APIV1Service) UpsertMemoReaction(ctx context.Context, request *v1pb.Ups
 	if memo.ParentUID != nil {
 		parentMemo, _ = s.Store.GetMemo(ctx, &store.FindMemo{UID: memo.ParentUID})
 	}
-	s.SSEHub.Broadcast(buildMemoReactionSSEEvent(SSEEventReactionUpserted, request.Reaction.ContentId, memo, parentMemo))
+	s.SSEHub.Broadcast(buildMemoReactionSSEEvent(SSEEventReactionUpserted, memoName, memo, parentMemo))
 
 	return reactionMessage, nil
 }
@@ -137,43 +142,40 @@ func (s *APIV1Service) DeleteMemoReaction(ctx context.Context, request *v1pb.Del
 	if reaction.CreatorID != user.ID && !isSuperUser(user) {
 		return nil, status.Errorf(codes.PermissionDenied, "permission denied")
 	}
-
-	if err := s.Store.DeleteReaction(ctx, &store.DeleteReaction{
-		ID: reactionID,
-	}); err != nil {
-		return nil, status.Errorf(codes.Internal, "failed to delete reaction")
-	}
-
-	memoUID, err := ExtractMemoUIDFromName(reaction.ContentID)
-	if err != nil {
-		return nil, status.Errorf(codes.InvalidArgument, "invalid memo name: %v", err)
-	}
-	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{UID: &memoUID})
+	memo, err := s.Store.GetMemo(ctx, &store.FindMemo{ID: &reaction.MemoID})
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to get memo")
 	}
 
-	// Broadcast live refresh event (reaction belongs to a memo).
-	var parentMemo *store.Memo
-	if memo != nil && memo.ParentUID != nil {
-		parentMemo, _ = s.Store.GetMemo(ctx, &store.FindMemo{UID: memo.ParentUID})
+	if err := s.Store.DeleteReaction(ctx, &store.DeleteReaction{ID: &reactionID}); err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to delete reaction")
+	}
+
+	// A concurrent memo deletion also removes its reactions, so the delete above
+	// stays idempotent. There is no memo left to broadcast a refresh for.
+	if memo != nil {
+		// Broadcast live refresh event (reaction belongs to a memo).
+		var parentMemo *store.Memo
+		if memo.ParentUID != nil {
+			parentMemo, _ = s.Store.GetMemo(ctx, &store.FindMemo{UID: memo.ParentUID})
+		}
+		s.SSEHub.Broadcast(buildMemoReactionSSEEvent(SSEEventReactionDeleted, buildMemoName(memo.UID), memo, parentMemo))
 	}
-	s.SSEHub.Broadcast(buildMemoReactionSSEEvent(SSEEventReactionDeleted, reaction.ContentID, memo, parentMemo))
 
 	return &emptypb.Empty{}, nil
 }
 
-func (s *APIV1Service) convertReactionFromStore(ctx context.Context, reaction *store.Reaction) (*v1pb.Reaction, error) {
+func (s *APIV1Service) convertReactionFromStore(ctx context.Context, reaction *store.Reaction, memoName string) (*v1pb.Reaction, error) {
 	creatorsByID, err := s.listUsersByIDWithExisting(ctx, []int32{reaction.CreatorID}, nil)
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to get reaction creator")
 	}
-	reactionMessage, err := convertReactionFromStoreWithCreators(reaction, creatorsByID)
+	reactionMessage, err := convertReactionFromStoreWithCreators(reaction, creatorsByID, memoName)
 	if err != nil {
 		slog.Warn("Failed to convert reaction with missing creator",
 			slog.Int64("reaction_id", int64(reaction.ID)),
 			slog.Int64("creator_id", int64(reaction.CreatorID)),
-			slog.String("content_id", reaction.ContentID),
+			slog.Int64("memo_id", int64(reaction.MemoID)),
 		)
 		return nil, status.Errorf(codes.NotFound, "reaction creator not found")
 	}

server/router/api/v1/sse_event_helpers.go

@@ -21,7 +21,7 @@ func resolveSSECreatorID(memo *store.Memo, parentMemo *store.Memo) int32 {
 
 // buildMemoReactionSSEEvent constructs an SSEEvent for a reaction on a memo.
 // Pass parentMemo when the memo is a comment (memo.ParentUID != nil).
-func buildMemoReactionSSEEvent(eventType SSEEventType, contentID string, memo *store.Memo, parentMemo *store.Memo) *SSEEvent {
+func buildMemoReactionSSEEvent(eventType SSEEventType, memoName string, memo *store.Memo, parentMemo *store.Memo) *SSEEvent {
 	parent := ""
 	if memo != nil && memo.ParentUID != nil {
 		parent = buildMemoName(*memo.ParentUID)
@@ -32,7 +32,7 @@ func buildMemoReactionSSEEvent(eventType SSEEventType, contentID string, memo *s
 	}
 	return &SSEEvent{
 		Type:       eventType,
-		Name:       contentID,
+		Name:       memoName,
 		Parent:     parent,
 		Visibility: visibility,
 		CreatorID:  resolveSSECreatorID(memo, parentMemo),

server/router/api/v1/sse_service_test.go

@@ -178,7 +178,6 @@ func TestUpsertMemoReaction_SSEEvent(t *testing.T) {
 	_, err = svc.UpsertMemoReaction(uctx, &v1pb.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &v1pb.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "👍",
 		},
 	})
@@ -209,7 +208,6 @@ func TestDeleteMemoReaction_SSEEvent(t *testing.T) {
 	reaction, err := svc.UpsertMemoReaction(uctx, &v1pb.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &v1pb.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "❤️",
 		},
 	})

server/router/api/v1/test/memo_service_benchmark_test.go

@@ -141,7 +141,7 @@ func seedListMemosBenchmarkData(ctx context.Context, stores *store.Store, hostUs
 		if i%5 == 0 {
 			if _, err := stores.UpsertReaction(ctx, &store.Reaction{
 				CreatorID:    hostUser.ID,
-				ContentID:    "memos/" + memo.UID,
+				MemoID:       memo.ID,
 				ReactionType: "thumbs-up",
 			}); err != nil {
 				return "", err

server/router/api/v1/test/memo_service_test.go

@@ -177,7 +177,6 @@ func TestListMemos(t *testing.T) {
 	reactionOne, err := ts.Service.UpsertMemoReaction(userOneCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memoThree.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memoThree.Name,
 			ReactionType: "❤️",
 		},
 	})
@@ -189,7 +188,6 @@ func TestListMemos(t *testing.T) {
 	reactionTwo, err := ts.Service.UpsertMemoReaction(userTwoCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memoThree.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memoThree.Name,
 			ReactionType: "👍",
 		},
 	})
@@ -450,7 +448,6 @@ func TestListMemosSkipsReactionsWithMissingCreators(t *testing.T) {
 	_, err = ts.Service.UpsertMemoReaction(reactorCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "👍",
 		},
 	})

server/router/api/v1/test/memo_share_service_test.go

@@ -87,7 +87,6 @@ func TestGetSharedMemo_IncludesReactions(t *testing.T) {
 	reaction, err := ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "👍",
 		},
 	})
@@ -107,7 +106,7 @@ func TestGetSharedMemo_IncludesReactions(t *testing.T) {
 	require.NoError(t, err)
 	require.Len(t, sharedMemo.Reactions, 1)
 	require.Equal(t, "👍", sharedMemo.Reactions[0].ReactionType)
-	require.Equal(t, memo.Name, sharedMemo.Reactions[0].ContentId)
+	require.Equal(t, reaction.Name, sharedMemo.Reactions[0].Name)
 }
 
 func TestCreateMemoShare_RejectsComment(t *testing.T) {
@@ -185,7 +184,6 @@ func TestGetSharedMemo_SkipsReactionsWithMissingCreators(t *testing.T) {
 	_, err = ts.Service.UpsertMemoReaction(reactorCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "👍",
 		},
 	})

server/router/api/v1/test/reaction_service_test.go

@@ -2,6 +2,7 @@ package test
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -10,6 +11,82 @@ import (
 	"github.com/usememos/memos/store"
 )
 
+func TestMemoReactionResourceNames(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	user, err := ts.CreateRegularUser(ctx, "reaction-resource-user")
+	require.NoError(t, err)
+	userCtx := ts.CreateUserContext(ctx, user.ID)
+	memo, err := ts.Service.CreateMemo(userCtx, &apiv1.CreateMemoRequest{
+		MemoId: "reaction-resource-memo",
+		Memo: &apiv1.Memo{
+			Content:    "reaction resource names",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	reaction, err := ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
+		Name: memo.Name,
+		Reaction: &apiv1.Reaction{
+			ReactionType: "👍",
+		},
+	})
+	require.NoError(t, err)
+	require.True(t, strings.HasPrefix(reaction.Name, memo.Name+"/reactions/"))
+
+	memoID := parseMemoIDFromNameForTest(t, ts, memo.Name)
+	storedReaction, err := ts.Store.GetReaction(ctx, &store.FindReaction{MemoID: &memoID, CreatorID: &user.ID})
+	require.NoError(t, err)
+	require.NotNil(t, storedReaction)
+	require.Equal(t, memoID, storedReaction.MemoID)
+
+	listed, err := ts.Service.ListMemoReactions(ctx, &apiv1.ListMemoReactionsRequest{Name: memo.Name})
+	require.NoError(t, err)
+	require.Len(t, listed.Reactions, 1)
+	require.Equal(t, reaction.Name, listed.Reactions[0].Name)
+
+	fetchedMemo, err := ts.Service.GetMemo(ctx, &apiv1.GetMemoRequest{Name: memo.Name})
+	require.NoError(t, err)
+	require.Len(t, fetchedMemo.Reactions, 1)
+	require.Equal(t, reaction.Name, fetchedMemo.Reactions[0].Name)
+}
+
+func TestListMemoCommentsIncludesReactionResourceNames(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	user, err := ts.CreateRegularUser(ctx, "comment-reaction-user")
+	require.NoError(t, err)
+	userCtx := ts.CreateUserContext(ctx, user.ID)
+	parent, err := ts.Service.CreateMemo(userCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{Content: "parent", Visibility: apiv1.Visibility_PUBLIC},
+	})
+	require.NoError(t, err)
+	comment, err := ts.Service.CreateMemoComment(userCtx, &apiv1.CreateMemoCommentRequest{
+		Name:    parent.Name,
+		Comment: &apiv1.Memo{Content: "comment", Visibility: apiv1.Visibility_PUBLIC},
+	})
+	require.NoError(t, err)
+
+	_, err = ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
+		Name: comment.Name,
+		Reaction: &apiv1.Reaction{
+			ReactionType: "🔥",
+		},
+	})
+	require.NoError(t, err)
+
+	comments, err := ts.Service.ListMemoComments(userCtx, &apiv1.ListMemoCommentsRequest{Name: parent.Name})
+	require.NoError(t, err)
+	require.Len(t, comments.Memos, 1)
+	require.Len(t, comments.Memos[0].Reactions, 1)
+	require.True(t, strings.HasPrefix(comments.Memos[0].Reactions[0].Name, comment.Name+"/reactions/"))
+}
+
 func TestDeleteMemoReaction(t *testing.T) {
 	ctx := context.Background()
 
@@ -36,7 +113,6 @@ func TestDeleteMemoReaction(t *testing.T) {
 		reaction, err := ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
 			Name: memo.Name,
 			Reaction: &apiv1.Reaction{
-				ContentId:    memo.Name,
 				ReactionType: "👍",
 			},
 		})
@@ -51,6 +127,41 @@ func TestDeleteMemoReaction(t *testing.T) {
 		require.NoError(t, err)
 	})
 
+	t.Run("DeleteMemoReaction succeeds when memo was concurrently deleted", func(t *testing.T) {
+		ts := NewTestService(t)
+		defer ts.Cleanup()
+
+		user, err := ts.CreateRegularUser(ctx, "concurrent-delete-user")
+		require.NoError(t, err)
+		userCtx := ts.CreateUserContext(ctx, user.ID)
+		memo, err := ts.Service.CreateMemo(userCtx, &apiv1.CreateMemoRequest{
+			Memo: &apiv1.Memo{Content: "concurrent delete", Visibility: apiv1.Visibility_PUBLIC},
+		})
+		require.NoError(t, err)
+		reaction, err := ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
+			Name: memo.Name,
+			Reaction: &apiv1.Reaction{
+				ReactionType: "👍",
+			},
+		})
+		require.NoError(t, err)
+
+		memoID := parseMemoIDFromNameForTest(t, ts, memo.Name)
+		storedReaction, err := ts.Store.GetReaction(ctx, &store.FindReaction{MemoID: &memoID, CreatorID: &user.ID})
+		require.NoError(t, err)
+		require.NotNil(t, storedReaction)
+		// Simulate the state visible between DeleteMemoReaction's reaction and
+		// memo reads after a concurrent memo deletion commits.
+		_, err = ts.Store.GetDriver().GetDB().ExecContext(ctx, "DELETE FROM memo WHERE id = ?", memoID)
+		require.NoError(t, err)
+
+		_, err = ts.Service.DeleteMemoReaction(userCtx, &apiv1.DeleteMemoReactionRequest{Name: reaction.Name})
+		require.NoError(t, err)
+		deletedReaction, err := ts.Store.GetReaction(ctx, &store.FindReaction{ID: &storedReaction.ID})
+		require.NoError(t, err)
+		require.Nil(t, deletedReaction)
+	})
+
 	t.Run("DeleteMemoReaction success by host user", func(t *testing.T) {
 		ts := NewTestService(t)
 		defer ts.Cleanup()
@@ -79,7 +190,6 @@ func TestDeleteMemoReaction(t *testing.T) {
 		reaction, err := ts.Service.UpsertMemoReaction(regularUserCtx, &apiv1.UpsertMemoReactionRequest{
 			Name: memo.Name,
 			Reaction: &apiv1.Reaction{
-				ContentId:    memo.Name,
 				ReactionType: "👍",
 			},
 		})
@@ -121,7 +231,6 @@ func TestDeleteMemoReaction(t *testing.T) {
 		reaction, err := ts.Service.UpsertMemoReaction(user1Ctx, &apiv1.UpsertMemoReactionRequest{
 			Name: memo.Name,
 			Reaction: &apiv1.Reaction{
-				ContentId:    memo.Name,
 				ReactionType: "👍",
 			},
 		})
@@ -159,7 +268,6 @@ func TestDeleteMemoReaction(t *testing.T) {
 		reaction, err := ts.Service.UpsertMemoReaction(userCtx, &apiv1.UpsertMemoReactionRequest{
 			Name: memo.Name,
 			Reaction: &apiv1.Reaction{
-				ContentId:    memo.Name,
 				ReactionType: "👍",
 			},
 		})
@@ -220,7 +328,6 @@ func TestListMemoReactionsSkipsMissingCreators(t *testing.T) {
 	_, err = ts.Service.UpsertMemoReaction(reactorCtx, &apiv1.UpsertMemoReactionRequest{
 		Name: memo.Name,
 		Reaction: &apiv1.Reaction{
-			ContentId:    memo.Name,
 			ReactionType: "🔥",
 		},
 	})

server/router/api/v1/test/user_service_delete_test.go

@@ -146,6 +146,7 @@ func TestDeleteUserSelfDeleteRemovesOwnedResourcesAndMemoSubtrees(t *testing.T)
 	foreignMemoStore, err := ts.Store.GetMemo(ctx, &store.FindMemo{UID: &foreignMemoUID})
 	require.NoError(t, err)
 	require.NotNil(t, foreignMemoStore)
+	userCommentOnForeignMemoID := parseMemoIDFromNameForTest(t, ts, userCommentOnForeignMemo.Name)
 
 	attachedAttachment, err := ts.Store.CreateAttachment(ctx, &store.Attachment{
 		UID:       "attach-owner-memo",
@@ -187,25 +188,25 @@ func TestDeleteUserSelfDeleteRemovesOwnedResourcesAndMemoSubtrees(t *testing.T)
 
 	_, err = ts.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    peer.ID,
-		ContentID:    ownMemo.Name,
+		MemoID:       ownMemoStore.ID,
 		ReactionType: "👍",
 	})
 	require.NoError(t, err)
 	_, err = ts.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    peer.ID,
-		ContentID:    userCommentOnForeignMemo.Name,
+		MemoID:       userCommentOnForeignMemoID,
 		ReactionType: "🔥",
 	})
 	require.NoError(t, err)
 	_, err = ts.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    foreignMemo.Name,
+		MemoID:       foreignMemoStore.ID,
 		ReactionType: "👋",
 	})
 	require.NoError(t, err)
 	peerReactionOnForeignMemo, err := ts.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    peer.ID,
-		ContentID:    foreignMemo.Name,
+		MemoID:       foreignMemoStore.ID,
 		ReactionType: "✅",
 	})
 	require.NoError(t, err)
@@ -284,15 +285,15 @@ func TestDeleteUserSelfDeleteRemovesOwnedResourcesAndMemoSubtrees(t *testing.T)
 	_, err = os.Stat(motionCachePath)
 	require.ErrorIs(t, err, os.ErrNotExist)
 
-	ownMemoReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{ContentID: &ownMemo.Name})
+	ownMemoReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{MemoID: &ownMemoStore.ID})
 	require.NoError(t, err)
 	require.Empty(t, ownMemoReactions)
 
-	userCommentReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{ContentID: &userCommentOnForeignMemo.Name})
+	userCommentReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{MemoID: &userCommentOnForeignMemoID})
 	require.NoError(t, err)
 	require.Empty(t, userCommentReactions)
 
-	foreignMemoReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{ContentID: &foreignMemo.Name})
+	foreignMemoReactions, err := ts.Store.ListReactions(ctx, &store.FindReaction{MemoID: &foreignMemoStore.ID})
 	require.NoError(t, err)
 	require.Len(t, foreignMemoReactions, 1)
 	require.Equal(t, peerReactionOnForeignMemo.ID, foreignMemoReactions[0].ID)
@@ -365,7 +366,7 @@ func TestDeleteUserRollbackPreservesAllResources(t *testing.T) {
 
 	reaction, err := ts.Store.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    ownMemo.Name,
+		MemoID:       ownMemoStore.ID,
 		ReactionType: "💥",
 	})
 	require.NoError(t, err)

server/router/mcp/catalog_test.go

@@ -156,7 +156,6 @@ func TestBuildToolFromOperationTailorsRequestBodySchemas(t *testing.T) {
 				"memo": "memos/abc123",
 				"body": map[string]any{
 					"reaction": map[string]any{
-						"contentId":    "memos/abc123",
 						"reactionType": "👍",
 					},
 				},

server/router/mcp/service_test.go

@@ -266,7 +266,6 @@ func TestMCPToolCallBindsMemoFromPathForBodyStarOperations(t *testing.T) {
 			toolName: "memo_upsert_memo_reaction",
 			body: map[string]any{
 				"reaction": map[string]any{
-					"contentId":    "memos/abc123",
 					"reactionType": "👍",
 				},
 			},

store/db/mysql/memo.go

@@ -219,14 +219,22 @@ func (d *DB) UpdateMemo(ctx context.Context, update *store.UpdateMemo) error {
 }
 
 func (d *DB) DeleteMemo(ctx context.Context, delete *store.DeleteMemo) error {
-	where, args := []string{"`id` = ?"}, []any{delete.ID}
-	stmt := "DELETE FROM `memo` WHERE " + strings.Join(where, " AND ")
-	result, err := d.db.ExecContext(ctx, stmt, args...)
+	tx, err := d.db.BeginTx(ctx, nil)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "failed to start memo delete transaction")
 	}
-	if _, err := result.RowsAffected(); err != nil {
-		return err
+	defer func() {
+		_ = tx.Rollback()
+	}()
+
+	if _, err := tx.ExecContext(ctx, "DELETE FROM `memo` WHERE `id` = ?", delete.ID); err != nil {
+		return errors.Wrap(err, "failed to delete memo")
+	}
+	if _, err := tx.ExecContext(ctx, "DELETE FROM `reaction` WHERE `memo_id` = ?", delete.ID); err != nil {
+		return errors.Wrap(err, "failed to delete memo reactions")
+	}
+	if err := tx.Commit(); err != nil {
+		return errors.Wrap(err, "failed to commit memo delete transaction")
 	}
 	return nil
 }

store/db/mysql/reaction.go

@@ -10,28 +10,46 @@ import (
 )
 
 func (d *DB) UpsertReaction(ctx context.Context, upsert *store.Reaction) (*store.Reaction, error) {
-	fields := []string{"`creator_id`", "`content_id`", "`reaction_type`"}
-	placeholder := []string{"?", "?", "?"}
-	args := []interface{}{upsert.CreatorID, upsert.ContentID, upsert.ReactionType}
-	stmt := "INSERT INTO `reaction` (" + strings.Join(fields, ", ") + ") VALUES (" + strings.Join(placeholder, ", ") + ")"
-	result, err := d.db.ExecContext(ctx, stmt, args...)
+	// MySQL has no INSERT ... RETURNING, so keep the insert and readback in one
+	// transaction to match the other drivers' atomic operation.
+	tx, err := d.db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to start reaction upsert transaction")
+	}
+	defer func() {
+		_ = tx.Rollback()
+	}()
+
+	result, err := tx.ExecContext(ctx, `
+		INSERT INTO reaction (creator_id, memo_id, reaction_type)
+		SELECT ?, memo.id, ?
+		FROM memo
+		WHERE memo.id = ?
+		FOR SHARE
+	`, upsert.CreatorID, upsert.ReactionType, upsert.MemoID)
 	if err != nil {
 		return nil, err
 	}
+	rowsAffected, err := result.RowsAffected()
+	if err != nil {
+		return nil, err
+	}
+	if rowsAffected == 0 {
+		return nil, errors.Wrap(store.ErrReactionMemoNotFound, "failed to create reaction")
+	}
 
 	rawID, err := result.LastInsertId()
 	if err != nil {
 		return nil, err
 	}
-	id := int32(rawID)
-	reaction, err := d.GetReaction(ctx, &store.FindReaction{ID: &id})
-	if err != nil {
-		return nil, err
+	upsert.ID = int32(rawID)
+	if err := tx.QueryRowContext(ctx, "SELECT UNIX_TIMESTAMP(created_ts) FROM reaction WHERE id = ?", upsert.ID).Scan(&upsert.CreatedTs); err != nil {
+		return nil, errors.Wrap(err, "failed to read created reaction")
 	}
-	if reaction == nil {
-		return nil, errors.Errorf("failed to create reaction")
+	if err := tx.Commit(); err != nil {
+		return nil, errors.Wrap(err, "failed to commit reaction upsert transaction")
 	}
-	return reaction, nil
+	return upsert, nil
 }
 
 func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*store.Reaction, error) {
@@ -43,16 +61,16 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 	if find.CreatorID != nil {
 		where, args = append(where, "`creator_id` = ?"), append(args, *find.CreatorID)
 	}
-	if find.ContentID != nil {
-		where, args = append(where, "`content_id` = ?"), append(args, *find.ContentID)
+	if find.MemoID != nil {
+		where, args = append(where, "`memo_id` = ?"), append(args, *find.MemoID)
 	}
-	if len(find.ContentIDList) > 0 {
-		placeholders := make([]string, 0, len(find.ContentIDList))
-		for _, id := range find.ContentIDList {
+	if len(find.MemoIDList) > 0 {
+		placeholders := make([]string, 0, len(find.MemoIDList))
+		for _, id := range find.MemoIDList {
 			placeholders = append(placeholders, "?")
 			args = append(args, id)
 		}
-		where = append(where, "`content_id` IN ("+strings.Join(placeholders, ",")+")")
+		where = append(where, "`memo_id` IN ("+strings.Join(placeholders, ",")+")")
 	}
 
 	rows, err := d.db.QueryContext(ctx, `
@@ -60,7 +78,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			id,
 			UNIX_TIMESTAMP(created_ts) AS created_ts,
 			creator_id,
-			content_id,
+			memo_id,
 			reaction_type
 		FROM reaction
 		WHERE `+strings.Join(where, " AND ")+`
@@ -79,7 +97,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			&reaction.ID,
 			&reaction.CreatedTs,
 			&reaction.CreatorID,
-			&reaction.ContentID,
+			&reaction.MemoID,
 			&reaction.ReactionType,
 		); err != nil {
 			return nil, err
@@ -108,6 +126,17 @@ func (d *DB) GetReaction(ctx context.Context, find *store.FindReaction) (*store.
 }
 
 func (d *DB) DeleteReaction(ctx context.Context, delete *store.DeleteReaction) error {
-	_, err := d.db.ExecContext(ctx, "DELETE FROM `reaction` WHERE `id` = ?", delete.ID)
+	where, args := []string{}, []any{}
+	if delete.ID != nil {
+		where, args = append(where, "`id` = ?"), append(args, *delete.ID)
+	}
+	if delete.MemoID != nil {
+		where, args = append(where, "`memo_id` = ?"), append(args, *delete.MemoID)
+	}
+	if len(where) == 0 {
+		return nil
+	}
+
+	_, err := d.db.ExecContext(ctx, "DELETE FROM `reaction` WHERE "+strings.Join(where, " AND "), args...)
 	return err
 }

store/db/mysql/user_delete.go

@@ -13,13 +13,8 @@ import (
 
 const deleteUserBatchSize = 500
 
-type deleteUserMemoRef struct {
-	ID  int32
-	UID string
-}
-
 type deleteUserTargetSet struct {
-	memos           []deleteUserMemoRef
+	memoIDs         []int32
 	attachments     []*store.Attachment
 	attachmentIDs   []int32
 	userSettingKeys []storepb.UserSetting_Key
@@ -61,13 +56,13 @@ func (d *DB) DeleteUser(ctx context.Context, delete *store.DeleteUser) (*store.D
 func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*deleteUserTargetSet, error) {
 	targets := &deleteUserTargetSet{}
 
-	memos, err := listDeleteUserMemoTree(ctx, tx, userID)
+	memoIDs, err := listDeleteUserMemoTree(ctx, tx, userID)
 	if err != nil {
 		return nil, err
 	}
-	targets.memos = memos
+	targets.memoIDs = memoIDs
 
-	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDsFromRefs(memos))
+	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDs)
 	if err != nil {
 		return nil, err
 	}
@@ -80,7 +75,7 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 	}
 	targets.userSettingKeys = userSettingKeys
 
-	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSetFromRefs(memos))
+	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSet(memoIDs))
 	if err != nil {
 		return nil, err
 	}
@@ -90,10 +85,15 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 }
 
 func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets *deleteUserTargetSet) error {
-	memoIDs := memoIDsFromRefs(targets.memos)
-	contentIDs := memoContentIDsFromRefs(targets.memos)
+	memoIDs := targets.memoIDs
 
-	if err := deleteReactionsByContentIDsTx(ctx, tx, contentIDs); err != nil {
+	// Delete the memo rows before their reactions: a concurrent UpsertReaction
+	// then blocks on the uncommitted parent delete instead of inserting a row
+	// behind the reaction sweep. Do not reorder these two.
+	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
+		return err
+	}
+	if err := deleteReactionsByMemoIDsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
 	if err := deleteAttachmentsByIDsTx(ctx, tx, targets.attachmentIDs); err != nil {
@@ -117,38 +117,35 @@ func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets
 	if err := deleteMemoRelationsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
-	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
-		return err
-	}
 	if err := deleteUserRowTx(ctx, tx, userID); err != nil {
 		return err
 	}
 	return nil
 }
 
-func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
+func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
 	return listDeleteUserMemoTreeIterative(ctx, tx, userID)
 }
 
-func listDeleteUserMemoTreeIterative(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
-	roots, err := queryDeleteUserMemoRefs(ctx, tx, `
-		SELECT id, uid
+func listDeleteUserMemoTreeIterative(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
+	roots, err := queryDeleteUserMemoIDs(ctx, tx, `
+		SELECT id
 		FROM memo
 		WHERE creator_id = `+deleteUserPlaceholder(1), userID)
 	if err != nil {
 		return nil, err
 	}
 
-	memos := make([]deleteUserMemoRef, 0, len(roots))
+	memoIDs := make([]int32, 0, len(roots))
 	seen := make(map[int32]struct{})
 	frontier := make([]int32, 0, len(roots))
-	for _, memo := range roots {
-		if _, exists := seen[memo.ID]; exists {
+	for _, id := range roots {
+		if _, exists := seen[id]; exists {
 			continue
 		}
-		seen[memo.ID] = struct{}{}
-		memos = append(memos, memo)
-		frontier = append(frontier, memo.ID)
+		seen[id] = struct{}{}
+		memoIDs = append(memoIDs, id)
+		frontier = append(frontier, id)
 	}
 
 	for len(frontier) > 0 {
@@ -156,8 +153,8 @@ func listDeleteUserMemoTreeIterative(ctx context.Context, tx *sql.Tx, userID int
 		nextFrontier := make([]int32, 0)
 		for _, batch := range deleteUserBatches(currentFrontier, deleteUserBatchSize) {
 			clause, args := deleteUserInClause(1, batch)
-			children, err := queryDeleteUserMemoRefs(ctx, tx, `
-				SELECT child.id, child.uid
+			children, err := queryDeleteUserMemoIDs(ctx, tx, `
+				SELECT child.id
 				FROM memo child
 				JOIN memo_relation rel ON rel.memo_id = child.id AND rel.type = 'COMMENT'
 				WHERE rel.related_memo_id IN `+clause, args...)
@@ -165,41 +162,41 @@ func listDeleteUserMemoTreeIterative(ctx context.Context, tx *sql.Tx, userID int
 				return nil, err
 			}
 
-			for _, child := range children {
-				if _, exists := seen[child.ID]; exists {
+			for _, id := range children {
+				if _, exists := seen[id]; exists {
 					continue
 				}
-				seen[child.ID] = struct{}{}
-				memos = append(memos, child)
-				nextFrontier = append(nextFrontier, child.ID)
+				seen[id] = struct{}{}
+				memoIDs = append(memoIDs, id)
+				nextFrontier = append(nextFrontier, id)
 			}
 		}
 		frontier = nextFrontier
 	}
 
-	return memos, nil
+	return memoIDs, nil
 }
 
-func queryDeleteUserMemoRefs(ctx context.Context, tx *sql.Tx, query string, args ...any) ([]deleteUserMemoRef, error) {
+func queryDeleteUserMemoIDs(ctx context.Context, tx *sql.Tx, query string, args ...any) ([]int32, error) {
 	rows, err := tx.QueryContext(ctx, query, args...)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
 
-	memos := make([]deleteUserMemoRef, 0)
+	memoIDs := make([]int32, 0)
 	for rows.Next() {
-		var memo deleteUserMemoRef
-		if err := rows.Scan(&memo.ID, &memo.UID); err != nil {
+		var id int32
+		if err := rows.Scan(&id); err != nil {
 			return nil, err
 		}
-		memos = append(memos, memo)
+		memoIDs = append(memoIDs, id)
 	}
 	if err := rows.Err(); err != nil {
 		return nil, err
 	}
 
-	return memos, nil
+	return memoIDs, nil
 }
 
 func listDeleteUserAttachments(ctx context.Context, tx *sql.Tx, userID int32, memoIDs []int32) ([]*store.Attachment, error) {
@@ -414,10 +411,10 @@ func memoIDInSet(id int32, memoIDSet map[int32]struct{}) bool {
 	return exists
 }
 
-func deleteReactionsByContentIDsTx(ctx context.Context, tx *sql.Tx, contentIDs []string) error {
-	for _, batch := range deleteUserBatches(contentIDs, deleteUserBatchSize) {
+func deleteReactionsByMemoIDsTx(ctx context.Context, tx *sql.Tx, memoIDs []int32) error {
+	for _, batch := range deleteUserBatches(memoIDs, deleteUserBatchSize) {
 		clause, args := deleteUserInClause(1, batch)
-		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE content_id IN `+clause, args...); err != nil {
+		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE memo_id IN `+clause, args...); err != nil {
 			return err
 		}
 	}
@@ -530,30 +527,14 @@ func deleteUserBatches[T any](values []T, size int) [][]T {
 	return batches
 }
 
-func memoIDsFromRefs(memos []deleteUserMemoRef) []int32 {
-	ids := make([]int32, 0, len(memos))
-	for _, memo := range memos {
-		ids = append(ids, memo.ID)
-	}
-	return ids
-}
-
-func memoIDSetFromRefs(memos []deleteUserMemoRef) map[int32]struct{} {
-	idSet := make(map[int32]struct{}, len(memos))
-	for _, memo := range memos {
-		idSet[memo.ID] = struct{}{}
+func memoIDSet(memoIDs []int32) map[int32]struct{} {
+	idSet := make(map[int32]struct{}, len(memoIDs))
+	for _, id := range memoIDs {
+		idSet[id] = struct{}{}
 	}
 	return idSet
 }
 
-func memoContentIDsFromRefs(memos []deleteUserMemoRef) []string {
-	contentIDs := make([]string, 0, len(memos))
-	for _, memo := range memos {
-		contentIDs = append(contentIDs, "memos/"+memo.UID)
-	}
-	return contentIDs
-}
-
 func attachmentIDsFromList(attachments []*store.Attachment) []int32 {
 	ids := make([]int32, 0, len(attachments))
 	for _, attachment := range attachments {

store/db/postgres/memo.go

@@ -204,14 +204,22 @@ func (d *DB) UpdateMemo(ctx context.Context, update *store.UpdateMemo) error {
 }
 
 func (d *DB) DeleteMemo(ctx context.Context, delete *store.DeleteMemo) error {
-	where, args := []string{"id = " + placeholder(1)}, []any{delete.ID}
-	stmt := `DELETE FROM memo WHERE ` + strings.Join(where, " AND ")
-	result, err := d.db.ExecContext(ctx, stmt, args...)
+	tx, err := d.db.BeginTx(ctx, nil)
 	if err != nil {
+		return errors.Wrap(err, "failed to start memo delete transaction")
+	}
+	defer func() {
+		_ = tx.Rollback()
+	}()
+
+	if _, err := tx.ExecContext(ctx, "DELETE FROM memo WHERE id = "+placeholder(1), delete.ID); err != nil {
 		return errors.Wrap(err, "failed to delete memo")
 	}
-	if _, err := result.RowsAffected(); err != nil {
-		return err
+	if _, err := tx.ExecContext(ctx, "DELETE FROM reaction WHERE memo_id = "+placeholder(1), delete.ID); err != nil {
+		return errors.Wrap(err, "failed to delete memo reactions")
+	}
+	if err := tx.Commit(); err != nil {
+		return errors.Wrap(err, "failed to commit memo delete transaction")
 	}
 	return nil
 }

store/db/postgres/reaction.go

@@ -2,19 +2,29 @@ package postgres
 
 import (
 	"context"
+	"database/sql"
 	"strings"
 
+	"github.com/pkg/errors"
+
 	"github.com/usememos/memos/store"
 )
 
 func (d *DB) UpsertReaction(ctx context.Context, upsert *store.Reaction) (*store.Reaction, error) {
-	fields := []string{"creator_id", "content_id", "reaction_type"}
-	args := []interface{}{upsert.CreatorID, upsert.ContentID, upsert.ReactionType}
-	stmt := "INSERT INTO reaction (" + strings.Join(fields, ", ") + ") VALUES (" + placeholders(len(args)) + ") RETURNING id, created_ts"
-	if err := d.db.QueryRowContext(ctx, stmt, args...).Scan(
+	if err := d.db.QueryRowContext(ctx, `
+		INSERT INTO reaction (creator_id, memo_id, reaction_type)
+		SELECT $1, memo.id, $2
+		FROM memo
+		WHERE memo.id = $3
+		FOR KEY SHARE OF memo
+		RETURNING id, created_ts
+	`, upsert.CreatorID, upsert.ReactionType, upsert.MemoID).Scan(
 		&upsert.ID,
 		&upsert.CreatedTs,
 	); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, errors.Wrap(store.ErrReactionMemoNotFound, "failed to create reaction")
+		}
 		return nil, err
 	}
 
@@ -31,16 +41,16 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 	if find.CreatorID != nil {
 		where, args = append(where, "creator_id = "+placeholder(len(args)+1)), append(args, *find.CreatorID)
 	}
-	if find.ContentID != nil {
-		where, args = append(where, "content_id = "+placeholder(len(args)+1)), append(args, *find.ContentID)
+	if find.MemoID != nil {
+		where, args = append(where, "memo_id = "+placeholder(len(args)+1)), append(args, *find.MemoID)
 	}
-	if len(find.ContentIDList) > 0 {
-		holders := make([]string, 0, len(find.ContentIDList))
-		for _, id := range find.ContentIDList {
+	if len(find.MemoIDList) > 0 {
+		holders := make([]string, 0, len(find.MemoIDList))
+		for _, id := range find.MemoIDList {
 			holders = append(holders, placeholder(len(args)+1))
 			args = append(args, id)
 		}
-		where = append(where, "content_id IN ("+strings.Join(holders, ", ")+")")
+		where = append(where, "memo_id IN ("+strings.Join(holders, ", ")+")")
 	}
 
 	rows, err := d.db.QueryContext(ctx, `
@@ -48,7 +58,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			id,
 			created_ts,
 			creator_id,
-			content_id,
+			memo_id,
 			reaction_type
 		FROM reaction
 		WHERE `+strings.Join(where, " AND ")+`
@@ -67,7 +77,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			&reaction.ID,
 			&reaction.CreatedTs,
 			&reaction.CreatorID,
-			&reaction.ContentID,
+			&reaction.MemoID,
 			&reaction.ReactionType,
 		); err != nil {
 			return nil, err
@@ -96,6 +106,17 @@ func (d *DB) GetReaction(ctx context.Context, find *store.FindReaction) (*store.
 }
 
 func (d *DB) DeleteReaction(ctx context.Context, delete *store.DeleteReaction) error {
-	_, err := d.db.ExecContext(ctx, "DELETE FROM reaction WHERE id = $1", delete.ID)
+	where, args := []string{}, []any{}
+	if delete.ID != nil {
+		where, args = append(where, "id = "+placeholder(len(args)+1)), append(args, *delete.ID)
+	}
+	if delete.MemoID != nil {
+		where, args = append(where, "memo_id = "+placeholder(len(args)+1)), append(args, *delete.MemoID)
+	}
+	if len(where) == 0 {
+		return nil
+	}
+
+	_, err := d.db.ExecContext(ctx, "DELETE FROM reaction WHERE "+strings.Join(where, " AND "), args...)
 	return err
 }

store/db/postgres/user_delete.go

@@ -13,13 +13,8 @@ import (
 
 const deleteUserBatchSize = 500
 
-type deleteUserMemoRef struct {
-	ID  int32
-	UID string
-}
-
 type deleteUserTargetSet struct {
-	memos           []deleteUserMemoRef
+	memoIDs         []int32
 	attachments     []*store.Attachment
 	attachmentIDs   []int32
 	userSettingKeys []storepb.UserSetting_Key
@@ -61,13 +56,13 @@ func (d *DB) DeleteUser(ctx context.Context, delete *store.DeleteUser) (*store.D
 func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*deleteUserTargetSet, error) {
 	targets := &deleteUserTargetSet{}
 
-	memos, err := listDeleteUserMemoTree(ctx, tx, userID)
+	memoIDs, err := listDeleteUserMemoTree(ctx, tx, userID)
 	if err != nil {
 		return nil, err
 	}
-	targets.memos = memos
+	targets.memoIDs = memoIDs
 
-	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDsFromRefs(memos))
+	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDs)
 	if err != nil {
 		return nil, err
 	}
@@ -80,7 +75,7 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 	}
 	targets.userSettingKeys = userSettingKeys
 
-	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSetFromRefs(memos))
+	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSet(memoIDs))
 	if err != nil {
 		return nil, err
 	}
@@ -90,10 +85,15 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 }
 
 func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets *deleteUserTargetSet) error {
-	memoIDs := memoIDsFromRefs(targets.memos)
-	contentIDs := memoContentIDsFromRefs(targets.memos)
+	memoIDs := targets.memoIDs
 
-	if err := deleteReactionsByContentIDsTx(ctx, tx, contentIDs); err != nil {
+	// Delete the memo rows before their reactions: a concurrent UpsertReaction
+	// then blocks on the uncommitted parent delete instead of inserting a row
+	// behind the reaction sweep. Do not reorder these two.
+	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
+		return err
+	}
+	if err := deleteReactionsByMemoIDsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
 	if err := deleteAttachmentsByIDsTx(ctx, tx, targets.attachmentIDs); err != nil {
@@ -117,32 +117,29 @@ func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets
 	if err := deleteMemoRelationsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
-	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
-		return err
-	}
 	if err := deleteUserRowTx(ctx, tx, userID); err != nil {
 		return err
 	}
 	return nil
 }
 
-func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
+func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
 	return listDeleteUserMemoTreeRecursive(ctx, tx, userID)
 }
 
-func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
+func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
 	rows, err := tx.QueryContext(ctx, `
-		WITH RECURSIVE memo_tree(id, uid) AS (
-			SELECT id, uid
+		WITH RECURSIVE memo_tree(id) AS (
+			SELECT id
 			FROM memo
 			WHERE creator_id = `+deleteUserPlaceholder(1)+`
 			UNION
-			SELECT child.id, child.uid
+			SELECT child.id
 			FROM memo child
 			JOIN memo_relation rel ON rel.memo_id = child.id AND rel.type = 'COMMENT'
 			JOIN memo_tree parent ON rel.related_memo_id = parent.id
 		)
-		SELECT id, uid
+		SELECT id
 		FROM memo_tree
 	`, userID)
 	if err != nil {
@@ -150,19 +147,19 @@ func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int
 	}
 	defer rows.Close()
 
-	memos := make([]deleteUserMemoRef, 0)
+	memoIDs := make([]int32, 0)
 	for rows.Next() {
-		var memo deleteUserMemoRef
-		if err := rows.Scan(&memo.ID, &memo.UID); err != nil {
+		var id int32
+		if err := rows.Scan(&id); err != nil {
 			return nil, err
 		}
-		memos = append(memos, memo)
+		memoIDs = append(memoIDs, id)
 	}
 	if err := rows.Err(); err != nil {
 		return nil, err
 	}
 
-	return memos, nil
+	return memoIDs, nil
 }
 
 func listDeleteUserAttachments(ctx context.Context, tx *sql.Tx, userID int32, memoIDs []int32) ([]*store.Attachment, error) {
@@ -377,10 +374,10 @@ func memoIDInSet(id int32, memoIDSet map[int32]struct{}) bool {
 	return exists
 }
 
-func deleteReactionsByContentIDsTx(ctx context.Context, tx *sql.Tx, contentIDs []string) error {
-	for _, batch := range deleteUserBatches(contentIDs, deleteUserBatchSize) {
+func deleteReactionsByMemoIDsTx(ctx context.Context, tx *sql.Tx, memoIDs []int32) error {
+	for _, batch := range deleteUserBatches(memoIDs, deleteUserBatchSize) {
 		clause, args := deleteUserInClause(1, batch)
-		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE content_id IN `+clause, args...); err != nil {
+		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE memo_id IN `+clause, args...); err != nil {
 			return err
 		}
 	}
@@ -493,30 +490,14 @@ func deleteUserBatches[T any](values []T, size int) [][]T {
 	return batches
 }
 
-func memoIDsFromRefs(memos []deleteUserMemoRef) []int32 {
-	ids := make([]int32, 0, len(memos))
-	for _, memo := range memos {
-		ids = append(ids, memo.ID)
-	}
-	return ids
-}
-
-func memoIDSetFromRefs(memos []deleteUserMemoRef) map[int32]struct{} {
-	idSet := make(map[int32]struct{}, len(memos))
-	for _, memo := range memos {
-		idSet[memo.ID] = struct{}{}
+func memoIDSet(memoIDs []int32) map[int32]struct{} {
+	idSet := make(map[int32]struct{}, len(memoIDs))
+	for _, id := range memoIDs {
+		idSet[id] = struct{}{}
 	}
 	return idSet
 }
 
-func memoContentIDsFromRefs(memos []deleteUserMemoRef) []string {
-	contentIDs := make([]string, 0, len(memos))
-	for _, memo := range memos {
-		contentIDs = append(contentIDs, "memos/"+memo.UID)
-	}
-	return contentIDs
-}
-
 func attachmentIDsFromList(attachments []*store.Attachment) []int32 {
 	ids := make([]int32, 0, len(attachments))
 	for _, attachment := range attachments {

store/db/sqlite/memo.go

@@ -197,14 +197,22 @@ func (d *DB) UpdateMemo(ctx context.Context, update *store.UpdateMemo) error {
 }
 
 func (d *DB) DeleteMemo(ctx context.Context, delete *store.DeleteMemo) error {
-	where, args := []string{"`id` = ?"}, []any{delete.ID}
-	stmt := "DELETE FROM `memo` WHERE " + strings.Join(where, " AND ")
-	result, err := d.db.ExecContext(ctx, stmt, args...)
+	tx, err := d.db.BeginTx(ctx, nil)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "failed to start memo delete transaction")
 	}
-	if _, err := result.RowsAffected(); err != nil {
-		return err
+	defer func() {
+		_ = tx.Rollback()
+	}()
+
+	if _, err := tx.ExecContext(ctx, "DELETE FROM `memo` WHERE `id` = ?", delete.ID); err != nil {
+		return errors.Wrap(err, "failed to delete memo")
+	}
+	if _, err := tx.ExecContext(ctx, "DELETE FROM `reaction` WHERE `memo_id` = ?", delete.ID); err != nil {
+		return errors.Wrap(err, "failed to delete memo reactions")
+	}
+	if err := tx.Commit(); err != nil {
+		return errors.Wrap(err, "failed to commit memo delete transaction")
 	}
 	return nil
 }

store/db/sqlite/reaction.go

@@ -3,21 +3,27 @@ package sqlite
 import (
 	"context"
 	"database/sql"
-	"errors"
 	"strings"
 
+	"github.com/pkg/errors"
+
 	"github.com/usememos/memos/store"
 )
 
 func (d *DB) UpsertReaction(ctx context.Context, upsert *store.Reaction) (*store.Reaction, error) {
-	fields := []string{"`creator_id`", "`content_id`", "`reaction_type`"}
-	placeholder := []string{"?", "?", "?"}
-	args := []interface{}{upsert.CreatorID, upsert.ContentID, upsert.ReactionType}
-	stmt := "INSERT INTO `reaction` (" + strings.Join(fields, ", ") + ") VALUES (" + strings.Join(placeholder, ", ") + ") RETURNING `id`, `created_ts`"
-	if err := d.db.QueryRowContext(ctx, stmt, args...).Scan(
+	if err := d.db.QueryRowContext(ctx, `
+		INSERT INTO reaction (creator_id, memo_id, reaction_type)
+		SELECT ?, memo.id, ?
+		FROM memo
+		WHERE memo.id = ?
+		RETURNING id, created_ts
+	`, upsert.CreatorID, upsert.ReactionType, upsert.MemoID).Scan(
 		&upsert.ID,
 		&upsert.CreatedTs,
 	); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, errors.Wrap(store.ErrReactionMemoNotFound, "failed to create reaction")
+		}
 		return nil, err
 	}
 
@@ -34,20 +40,16 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 	if find.CreatorID != nil {
 		where, args = append(where, "creator_id = ?"), append(args, *find.CreatorID)
 	}
-	if find.ContentID != nil {
-		where, args = append(where, "content_id = ?"), append(args, *find.ContentID)
+	if find.MemoID != nil {
+		where, args = append(where, "memo_id = ?"), append(args, *find.MemoID)
 	}
-	if len(find.ContentIDList) > 0 {
-		placeholders := make([]string, 0, len(find.ContentIDList))
-		for range find.ContentIDList {
+	if len(find.MemoIDList) > 0 {
+		placeholders := make([]string, 0, len(find.MemoIDList))
+		for _, id := range find.MemoIDList {
 			placeholders = append(placeholders, "?")
+			args = append(args, id)
 		}
-		if len(placeholders) > 0 {
-			where = append(where, "content_id IN ("+strings.Join(placeholders, ",")+")")
-			for _, id := range find.ContentIDList {
-				args = append(args, id)
-			}
-		}
+		where = append(where, "memo_id IN ("+strings.Join(placeholders, ",")+")")
 	}
 
 	rows, err := d.db.QueryContext(ctx, `
@@ -55,7 +57,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			id,
 			created_ts,
 			creator_id,
-			content_id,
+			memo_id,
 			reaction_type
 		FROM reaction
 		WHERE `+strings.Join(where, " AND ")+`
@@ -74,7 +76,7 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 			&reaction.ID,
 			&reaction.CreatedTs,
 			&reaction.CreatorID,
-			&reaction.ContentID,
+			&reaction.MemoID,
 			&reaction.ReactionType,
 		); err != nil {
 			return nil, err
@@ -90,47 +92,29 @@ func (d *DB) ListReactions(ctx context.Context, find *store.FindReaction) ([]*st
 }
 
 func (d *DB) GetReaction(ctx context.Context, find *store.FindReaction) (*store.Reaction, error) {
-	where, args := []string{"1 = 1"}, []any{}
-
-	if find.ID != nil {
-		where, args = append(where, "id = ?"), append(args, *find.ID)
-	}
-	if find.CreatorID != nil {
-		where, args = append(where, "creator_id = ?"), append(args, *find.CreatorID)
-	}
-	if find.ContentID != nil {
-		where, args = append(where, "content_id = ?"), append(args, *find.ContentID)
-	}
-
-	reaction := &store.Reaction{}
-	if err := d.db.QueryRowContext(ctx, `
-		SELECT
-			id,
-			created_ts,
-			creator_id,
-			content_id,
-			reaction_type
-		FROM reaction
-		WHERE `+strings.Join(where, " AND ")+`
-		LIMIT 1`,
-		args...,
-	).Scan(
-		&reaction.ID,
-		&reaction.CreatedTs,
-		&reaction.CreatorID,
-		&reaction.ContentID,
-		&reaction.ReactionType,
-	); err != nil {
-		if errors.Is(err, sql.ErrNoRows) {
-			return nil, nil
-		}
+	list, err := d.ListReactions(ctx, find)
+	if err != nil {
 		return nil, err
 	}
+	if len(list) == 0 {
+		return nil, nil
+	}
 
-	return reaction, nil
+	return list[0], nil
 }
 
 func (d *DB) DeleteReaction(ctx context.Context, delete *store.DeleteReaction) error {
-	_, err := d.db.ExecContext(ctx, "DELETE FROM `reaction` WHERE `id` = ?", delete.ID)
+	where, args := []string{}, []any{}
+	if delete.ID != nil {
+		where, args = append(where, "`id` = ?"), append(args, *delete.ID)
+	}
+	if delete.MemoID != nil {
+		where, args = append(where, "`memo_id` = ?"), append(args, *delete.MemoID)
+	}
+	if len(where) == 0 {
+		return nil
+	}
+
+	_, err := d.db.ExecContext(ctx, "DELETE FROM `reaction` WHERE "+strings.Join(where, " AND "), args...)
 	return err
 }

store/db/sqlite/user_delete.go

@@ -13,13 +13,8 @@ import (
 
 const deleteUserBatchSize = 500
 
-type deleteUserMemoRef struct {
-	ID  int32
-	UID string
-}
-
 type deleteUserTargetSet struct {
-	memos           []deleteUserMemoRef
+	memoIDs         []int32
 	attachments     []*store.Attachment
 	attachmentIDs   []int32
 	userSettingKeys []storepb.UserSetting_Key
@@ -61,13 +56,13 @@ func (d *DB) DeleteUser(ctx context.Context, delete *store.DeleteUser) (*store.D
 func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*deleteUserTargetSet, error) {
 	targets := &deleteUserTargetSet{}
 
-	memos, err := listDeleteUserMemoTree(ctx, tx, userID)
+	memoIDs, err := listDeleteUserMemoTree(ctx, tx, userID)
 	if err != nil {
 		return nil, err
 	}
-	targets.memos = memos
+	targets.memoIDs = memoIDs
 
-	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDsFromRefs(memos))
+	attachments, err := listDeleteUserAttachments(ctx, tx, userID, memoIDs)
 	if err != nil {
 		return nil, err
 	}
@@ -80,7 +75,7 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 	}
 	targets.userSettingKeys = userSettingKeys
 
-	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSetFromRefs(memos))
+	inboxIDs, err := listDeleteUserInboxIDs(ctx, tx, userID, memoIDSet(memoIDs))
 	if err != nil {
 		return nil, err
 	}
@@ -90,10 +85,15 @@ func collectDeleteUserTargets(ctx context.Context, tx *sql.Tx, userID int32) (*d
 }
 
 func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets *deleteUserTargetSet) error {
-	memoIDs := memoIDsFromRefs(targets.memos)
-	contentIDs := memoContentIDsFromRefs(targets.memos)
+	memoIDs := targets.memoIDs
 
-	if err := deleteReactionsByContentIDsTx(ctx, tx, contentIDs); err != nil {
+	// Delete the memo rows before their reactions: a concurrent UpsertReaction
+	// then blocks on the uncommitted parent delete instead of inserting a row
+	// behind the reaction sweep. Do not reorder these two.
+	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
+		return err
+	}
+	if err := deleteReactionsByMemoIDsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
 	if err := deleteAttachmentsByIDsTx(ctx, tx, targets.attachmentIDs); err != nil {
@@ -117,32 +117,29 @@ func deleteUserTargetsTx(ctx context.Context, tx *sql.Tx, userID int32, targets
 	if err := deleteMemoRelationsTx(ctx, tx, memoIDs); err != nil {
 		return err
 	}
-	if err := deleteMemosTx(ctx, tx, memoIDs); err != nil {
-		return err
-	}
 	if err := deleteUserRowTx(ctx, tx, userID); err != nil {
 		return err
 	}
 	return nil
 }
 
-func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
+func listDeleteUserMemoTree(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
 	return listDeleteUserMemoTreeRecursive(ctx, tx, userID)
 }
 
-func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int32) ([]deleteUserMemoRef, error) {
+func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int32) ([]int32, error) {
 	rows, err := tx.QueryContext(ctx, `
-		WITH RECURSIVE memo_tree(id, uid) AS (
-			SELECT id, uid
+		WITH RECURSIVE memo_tree(id) AS (
+			SELECT id
 			FROM memo
 			WHERE creator_id = `+deleteUserPlaceholder(1)+`
 			UNION
-			SELECT child.id, child.uid
+			SELECT child.id
 			FROM memo child
 			JOIN memo_relation rel ON rel.memo_id = child.id AND rel.type = 'COMMENT'
 			JOIN memo_tree parent ON rel.related_memo_id = parent.id
 		)
-		SELECT id, uid
+		SELECT id
 		FROM memo_tree
 	`, userID)
 	if err != nil {
@@ -150,19 +147,19 @@ func listDeleteUserMemoTreeRecursive(ctx context.Context, tx *sql.Tx, userID int
 	}
 	defer rows.Close()
 
-	memos := make([]deleteUserMemoRef, 0)
+	memoIDs := make([]int32, 0)
 	for rows.Next() {
-		var memo deleteUserMemoRef
-		if err := rows.Scan(&memo.ID, &memo.UID); err != nil {
+		var id int32
+		if err := rows.Scan(&id); err != nil {
 			return nil, err
 		}
-		memos = append(memos, memo)
+		memoIDs = append(memoIDs, id)
 	}
 	if err := rows.Err(); err != nil {
 		return nil, err
 	}
 
-	return memos, nil
+	return memoIDs, nil
 }
 
 func listDeleteUserAttachments(ctx context.Context, tx *sql.Tx, userID int32, memoIDs []int32) ([]*store.Attachment, error) {
@@ -377,10 +374,10 @@ func memoIDInSet(id int32, memoIDSet map[int32]struct{}) bool {
 	return exists
 }
 
-func deleteReactionsByContentIDsTx(ctx context.Context, tx *sql.Tx, contentIDs []string) error {
-	for _, batch := range deleteUserBatches(contentIDs, deleteUserBatchSize) {
+func deleteReactionsByMemoIDsTx(ctx context.Context, tx *sql.Tx, memoIDs []int32) error {
+	for _, batch := range deleteUserBatches(memoIDs, deleteUserBatchSize) {
 		clause, args := deleteUserInClause(1, batch)
-		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE content_id IN `+clause, args...); err != nil {
+		if _, err := tx.ExecContext(ctx, `DELETE FROM reaction WHERE memo_id IN `+clause, args...); err != nil {
 			return err
 		}
 	}
@@ -493,30 +490,14 @@ func deleteUserBatches[T any](values []T, size int) [][]T {
 	return batches
 }
 
-func memoIDsFromRefs(memos []deleteUserMemoRef) []int32 {
-	ids := make([]int32, 0, len(memos))
-	for _, memo := range memos {
-		ids = append(ids, memo.ID)
-	}
-	return ids
-}
-
-func memoIDSetFromRefs(memos []deleteUserMemoRef) map[int32]struct{} {
-	idSet := make(map[int32]struct{}, len(memos))
-	for _, memo := range memos {
-		idSet[memo.ID] = struct{}{}
+func memoIDSet(memoIDs []int32) map[int32]struct{} {
+	idSet := make(map[int32]struct{}, len(memoIDs))
+	for _, id := range memoIDs {
+		idSet[id] = struct{}{}
 	}
 	return idSet
 }
 
-func memoContentIDsFromRefs(memos []deleteUserMemoRef) []string {
-	contentIDs := make([]string, 0, len(memos))
-	for _, memo := range memos {
-		contentIDs = append(contentIDs, "memos/"+memo.UID)
-	}
-	return contentIDs
-}
-
 func attachmentIDsFromList(attachments []*store.Attachment) []int32 {
 	ids := make([]int32, 0, len(attachments))
 	for _, attachment := range attachments {

store/migration/mysql/0.31/02__reaction_memo_id.sql

@@ -0,0 +1,24 @@
+-- Replaces the memo resource name stored in reaction.content_id with the
+-- memo's stable internal ID. The inner join intentionally drops orphaned
+-- reactions whose resource name no longer resolves to an existing memo.
+CREATE TABLE `reaction_new` (
+  `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  `created_ts` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  `creator_id` INT NOT NULL,
+  `memo_id` INT NOT NULL,
+  `reaction_type` VARCHAR(256) NOT NULL,
+  UNIQUE(`creator_id`, `memo_id`, `reaction_type`)
+);
+
+INSERT INTO `reaction_new` (`id`, `created_ts`, `creator_id`, `memo_id`, `reaction_type`)
+SELECT
+  `reaction`.`id`,
+  `reaction`.`created_ts`,
+  `reaction`.`creator_id`,
+  `memo`.`id`,
+  `reaction`.`reaction_type`
+FROM `reaction`
+JOIN `memo` ON `reaction`.`content_id` = CONCAT('memos/', `memo`.`uid`);
+
+DROP TABLE `reaction`;
+RENAME TABLE `reaction_new` TO `reaction`;

store/migration/mysql/LATEST.sql

@@ -87,14 +87,14 @@ CREATE TABLE `inbox` (
   `message` TEXT NOT NULL
 );
 
--- reaction
+-- memo reaction
 CREATE TABLE `reaction` (
   `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
   `created_ts` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
   `creator_id` INT NOT NULL,
-  `content_id` VARCHAR(256) NOT NULL,
+  `memo_id` INT NOT NULL,
   `reaction_type` VARCHAR(256) NOT NULL,
-  UNIQUE(`creator_id`,`content_id`,`reaction_type`)  
+  UNIQUE(`creator_id`,`memo_id`,`reaction_type`)
 );
 
 -- memo_share

store/migration/postgres/0.31/02__reaction_memo_id.sql

@@ -0,0 +1,17 @@
+-- Replaces the memo resource name stored in reaction.content_id with the
+-- memo's stable internal ID. Rows that cannot be resolved are intentionally
+-- deleted before memo_id is made non-nullable.
+ALTER TABLE reaction ADD COLUMN memo_id INTEGER;
+
+UPDATE reaction
+SET memo_id = memo.id
+FROM memo
+WHERE reaction.content_id = 'memos/' || memo.uid;
+
+DELETE FROM reaction WHERE memo_id IS NULL;
+
+ALTER TABLE reaction
+  DROP CONSTRAINT reaction_creator_id_content_id_reaction_type_key,
+  DROP COLUMN content_id,
+  ALTER COLUMN memo_id SET NOT NULL,
+  ADD UNIQUE (creator_id, memo_id, reaction_type);

store/migration/postgres/LATEST.sql

@@ -87,14 +87,14 @@ CREATE TABLE inbox (
   message TEXT NOT NULL
 );
 
--- reaction
+-- memo reaction
 CREATE TABLE reaction (
   id SERIAL PRIMARY KEY,
   created_ts BIGINT NOT NULL DEFAULT EXTRACT(EPOCH FROM NOW()),
   creator_id INTEGER NOT NULL,
-  content_id TEXT NOT NULL,
+  memo_id INTEGER NOT NULL,
   reaction_type TEXT NOT NULL,
-  UNIQUE(creator_id, content_id, reaction_type)
+  UNIQUE(creator_id, memo_id, reaction_type)
 );
 
 -- memo_share

store/migration/sqlite/0.31/02__reaction_memo_id.sql

@@ -0,0 +1,24 @@
+-- Replaces the memo resource name stored in reaction.content_id with the
+-- memo's stable internal ID. The inner join intentionally drops orphaned
+-- reactions whose resource name no longer resolves to an existing memo.
+CREATE TABLE reaction_new (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  created_ts BIGINT NOT NULL DEFAULT (strftime('%s', 'now')),
+  creator_id INTEGER NOT NULL,
+  memo_id INTEGER NOT NULL,
+  reaction_type TEXT NOT NULL,
+  UNIQUE(creator_id, memo_id, reaction_type)
+);
+
+INSERT INTO reaction_new (id, created_ts, creator_id, memo_id, reaction_type)
+SELECT
+  reaction.id,
+  reaction.created_ts,
+  reaction.creator_id,
+  memo.id,
+  reaction.reaction_type
+FROM reaction
+JOIN memo ON reaction.content_id = 'memos/' || memo.uid;
+
+DROP TABLE reaction;
+ALTER TABLE reaction_new RENAME TO reaction;

store/migration/sqlite/LATEST.sql

@@ -88,14 +88,14 @@ CREATE TABLE inbox (
   message TEXT NOT NULL DEFAULT '{}'
 );
 
--- reaction
+-- memo reaction
 CREATE TABLE reaction (
   id INTEGER PRIMARY KEY AUTOINCREMENT,
   created_ts BIGINT NOT NULL DEFAULT (strftime('%s', 'now')),
   creator_id INTEGER NOT NULL,
-  content_id TEXT NOT NULL,
+  memo_id INTEGER NOT NULL,
   reaction_type TEXT NOT NULL,
-  UNIQUE(creator_id, content_id, reaction_type)
+  UNIQUE(creator_id, memo_id, reaction_type)
 );
 
 -- memo_share

store/reaction.go

@@ -2,26 +2,32 @@ package store
 
 import (
 	"context"
+	"errors"
 )
 
+// ErrReactionMemoNotFound indicates that a reaction's memo no longer exists.
+var ErrReactionMemoNotFound = errors.New("reaction memo not found")
+
+// Reaction is a reaction attached to a memo.
 type Reaction struct {
 	ID        int32
 	CreatedTs int64
 	CreatorID int32
-	// ContentID is the id of the content that the reaction is for.
-	ContentID    string
+	// MemoID is the ID of the memo that the reaction is for.
+	MemoID       int32
 	ReactionType string
 }
 
 type FindReaction struct {
-	ID            *int32
-	CreatorID     *int32
-	ContentID     *string
-	ContentIDList []string
+	ID         *int32
+	CreatorID  *int32
+	MemoID     *int32
+	MemoIDList []int32
 }
 
 type DeleteReaction struct {
-	ID int32
+	ID     *int32
+	MemoID *int32
 }
 
 func (s *Store) UpsertReaction(ctx context.Context, upsert *Reaction) (*Reaction, error) {

store/seed/sqlite/01__dump.sql

@@ -152,41 +152,41 @@ INSERT INTO memo_relation VALUES(5,15,'REFERENCE');  -- weekly review → Deep W
 -- Reactions (types must come from the MEMO_RELATED reactions list below)
 -- ============================================================================
 
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(1,2,'memos/welcome0000001','🎉');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(2,3,'memos/welcome0000001','🎉');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(3,4,'memos/welcome0000001','👍');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(4,2,'memos/sponsors000001','🚀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(5,3,'memos/sponsors000001','👍');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(6,2,'memos/goldenhour0001','🔥');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(7,4,'memos/goldenhour0001','💛');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(8,1,'memos/goldenhour0001','👏');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(9,2,'memos/samquote000001','💛');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(10,3,'memos/samquote000001','👀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(11,1,'memos/johnnyweekly001','👏');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(12,4,'memos/johnnyweekly001','💡');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(13,1,'memos/johnnyshipped01','🚀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(14,4,'memos/johnnyshipped01','🎉');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(15,3,'memos/johnnyshipped01','🔥');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(16,3,'memos/johnnytilgit001','💡');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(17,4,'memos/johnnytilgit001','+1');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(18,3,'memos/samramen000001','👌');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(19,2,'memos/samramen000001','💛');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(20,1,'memos/sammovies00001','👍');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(21,4,'memos/bobnighttrain1','💛');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(22,3,'memos/johnnygitcheat1','🔥');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(23,4,'memos/johnnygitcheat1','💡');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(24,4,'memos/webclipper0001','💡');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(25,1,'memos/tagtipmemo0001','👍');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(26,2,'memos/protectedintro','👀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(27,3,'memos/protectedintro','✅');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(28,4,'memos/bobpacklist001','😂');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(29,3,'memos/sambookpile001','😂');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(30,2,'memos/v030changelog1','🎉');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(31,4,'memos/v030changelog1','🚀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(32,3,'memos/v030changelog1','🔥');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(33,1,'memos/johnnybookmark1','👀');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(34,2,'memos/rendertest0001','😂');
-INSERT INTO reaction (id,creator_id,content_id,reaction_type) VALUES(35,4,'memos/rendertest0001','💡');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(1,2,1,'🎉');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(2,3,1,'🎉');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(3,4,1,'👍');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(4,2,2,'🚀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(5,3,2,'👍');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(6,2,3,'🔥');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(7,4,3,'💛');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(8,1,3,'👏');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(9,2,4,'💛');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(10,3,4,'👀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(11,1,5,'👏');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(12,4,5,'💡');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(13,1,7,'🚀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(14,4,7,'🎉');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(15,3,7,'🔥');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(16,3,8,'💡');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(17,4,8,'+1');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(18,3,9,'👌');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(19,2,9,'💛');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(20,1,11,'👍');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(21,4,12,'💛');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(22,3,14,'🔥');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(23,4,14,'💡');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(24,4,10,'💡');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(25,1,6,'👍');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(26,2,16,'👀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(27,3,16,'✅');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(28,4,18,'😂');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(29,3,19,'😂');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(30,2,27,'🎉');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(31,4,27,'🚀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(32,3,27,'🔥');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(33,1,29,'👀');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(34,2,30,'😂');
+INSERT INTO reaction (id,creator_id,memo_id,reaction_type) VALUES(35,4,30,'💡');
 
 -- ============================================================================
 -- Attachment: Bob's golden-hour art (stored in the database blob column;

store/test/migrator_test.go

@@ -348,6 +348,60 @@ func assertStorageMigrationAttachments(ctx context.Context, t *testing.T, ts *st
 	require.Equal(t, "existing-s3", named.GetStorageId())
 }
 
+// TestMigrationReactionMemoID verifies that the reaction migration resolves
+// legacy memo resource names to internal memo IDs and discards orphaned rows.
+func TestMigrationReactionMemoID(t *testing.T) {
+	ctx := context.Background()
+	driver := getDriverFromEnv()
+	dsn := getTestingProfileForDriver(t, driver).DSN
+
+	db, err := sql.Open(driver, dsn)
+	require.NoError(t, err)
+	_, err = db.ExecContext(ctx, legacySchemaFixture(driver))
+	require.NoError(t, err)
+
+	basicSetting, err := protojson.Marshal(&storepb.InstanceBasicSetting{SchemaVersion: "0.31.2"})
+	require.NoError(t, err)
+	insertSetting := "INSERT INTO system_setting (name, value, description) VALUES (?, ?, '')"
+	insertMemo := "INSERT INTO memo (id, uid) VALUES (?, ?)"
+	insertReaction := "INSERT INTO reaction (id, creator_id, content_id, reaction_type) VALUES (?, ?, ?, ?)"
+	if driver == "postgres" {
+		insertSetting = "INSERT INTO system_setting (name, value, description) VALUES ($1, $2, '')"
+		insertMemo = "INSERT INTO memo (id, uid) VALUES ($1, $2)"
+		insertReaction = "INSERT INTO reaction (id, creator_id, content_id, reaction_type) VALUES ($1, $2, $3, $4)"
+	}
+	_, err = db.ExecContext(ctx, insertSetting, "BASIC", string(basicSetting))
+	require.NoError(t, err)
+	_, err = db.ExecContext(ctx, insertMemo, 42, "reaction-migration-target")
+	require.NoError(t, err)
+	_, err = db.ExecContext(ctx, insertReaction, 100, 7, "memos/reaction-migration-target", "valid")
+	require.NoError(t, err)
+	_, err = db.ExecContext(ctx, insertReaction, 101, 7, "memos/missing-target", "orphan")
+	require.NoError(t, err)
+	require.NoError(t, db.Close())
+
+	ts := NewTestingStoreWithDSN(ctx, t, driver, dsn)
+	require.NoError(t, ts.Migrate(ctx))
+	defer ts.Close()
+
+	var reactionID, creatorID, memoID int32
+	var reactionType string
+	err = ts.GetDriver().GetDB().QueryRowContext(
+		ctx,
+		"SELECT id, creator_id, memo_id, reaction_type FROM reaction",
+	).Scan(&reactionID, &creatorID, &memoID, &reactionType)
+	require.NoError(t, err)
+	require.Equal(t, int32(100), reactionID)
+	require.Equal(t, int32(7), creatorID)
+	require.Equal(t, int32(42), memoID)
+	require.Equal(t, "valid", reactionType)
+
+	var reactionCount int
+	err = ts.GetDriver().GetDB().QueryRowContext(ctx, "SELECT COUNT(*) FROM reaction").Scan(&reactionCount)
+	require.NoError(t, err)
+	require.Equal(t, 1, reactionCount, "orphaned reactions must be discarded")
+}
+
 // TestMigrationLegacyS3AttachmentMinIO verifies the storage upgrade path for an
 // attachment created before storage IDs existed. The migration must bind the
 // payload to the migrated registry entry, after which the production resolver
@@ -550,41 +604,7 @@ func TestMigrationCopiesInstanceTagsToUserSettings(t *testing.T) {
 	db, err := sql.Open("sqlite", dsn)
 	require.NoError(t, err)
 
-	_, err = db.ExecContext(ctx, `
-		CREATE TABLE system_setting (
-			name TEXT NOT NULL,
-			value TEXT NOT NULL,
-			description TEXT NOT NULL DEFAULT '',
-			UNIQUE(name)
-		);
-		CREATE TABLE user (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			created_ts BIGINT NOT NULL DEFAULT (strftime('%s', 'now')),
-			updated_ts BIGINT NOT NULL DEFAULT (strftime('%s', 'now')),
-			row_status TEXT NOT NULL CHECK (row_status IN ('NORMAL', 'ARCHIVED')) DEFAULT 'NORMAL',
-			username TEXT NOT NULL UNIQUE,
-			role TEXT NOT NULL DEFAULT 'USER',
-			email TEXT NOT NULL DEFAULT '',
-			nickname TEXT NOT NULL DEFAULT '',
-			password_hash TEXT NOT NULL,
-			avatar_url TEXT NOT NULL DEFAULT '',
-			description TEXT NOT NULL DEFAULT ''
-		);
-		CREATE TABLE user_setting (
-			user_id INTEGER NOT NULL,
-			key TEXT NOT NULL,
-			value TEXT NOT NULL,
-			UNIQUE(user_id, key)
-		);
-		CREATE TABLE memo (
-			id INTEGER PRIMARY KEY AUTOINCREMENT
-		);
-		CREATE TABLE attachment (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			storage_type TEXT NOT NULL DEFAULT '',
-			payload TEXT NOT NULL DEFAULT '{}'
-		);
-	`)
+	_, err = db.ExecContext(ctx, legacySchemaFixture("sqlite"))
 	require.NoError(t, err)
 
 	basicSettingBytes, err := protojson.Marshal(&storepb.InstanceBasicSetting{SchemaVersion: "0.29.1"})
@@ -729,7 +749,18 @@ func legacySchemaFixture(driver string) string {
 				value LONGTEXT NOT NULL,
 				UNIQUE(user_id, ` + "`key`" + `)
 			);
-			CREATE TABLE memo (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY);
+			CREATE TABLE memo (
+				id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+				uid VARCHAR(256) NOT NULL UNIQUE
+			);
+			CREATE TABLE reaction (
+				id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+				created_ts TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+				creator_id INT NOT NULL,
+				content_id VARCHAR(256) NOT NULL,
+				reaction_type VARCHAR(256) NOT NULL,
+				UNIQUE(creator_id, content_id, reaction_type)
+			);
 			CREATE TABLE attachment (
 				id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 				uid VARCHAR(256) NOT NULL UNIQUE,
@@ -771,7 +802,18 @@ func legacySchemaFixture(driver string) string {
 				value TEXT NOT NULL,
 				UNIQUE(user_id, key)
 			);
-			CREATE TABLE memo (id SERIAL PRIMARY KEY);
+			CREATE TABLE memo (
+				id SERIAL PRIMARY KEY,
+				uid TEXT NOT NULL UNIQUE
+			);
+			CREATE TABLE reaction (
+				id SERIAL PRIMARY KEY,
+				created_ts BIGINT NOT NULL DEFAULT EXTRACT(EPOCH FROM NOW()),
+				creator_id INTEGER NOT NULL,
+				content_id TEXT NOT NULL,
+				reaction_type TEXT NOT NULL,
+				UNIQUE(creator_id, content_id, reaction_type)
+			);
 			CREATE TABLE attachment (
 				id SERIAL PRIMARY KEY,
 				uid TEXT NOT NULL UNIQUE,
@@ -815,7 +857,18 @@ func legacySchemaFixture(driver string) string {
 				value TEXT NOT NULL,
 				UNIQUE(user_id, key)
 			);
-			CREATE TABLE memo (id INTEGER PRIMARY KEY AUTOINCREMENT);
+			CREATE TABLE memo (
+				id INTEGER PRIMARY KEY AUTOINCREMENT,
+				uid TEXT NOT NULL UNIQUE
+			);
+			CREATE TABLE reaction (
+				id INTEGER PRIMARY KEY AUTOINCREMENT,
+				created_ts BIGINT NOT NULL DEFAULT (strftime('%s', 'now')),
+				creator_id INTEGER NOT NULL,
+				content_id TEXT NOT NULL,
+				reaction_type TEXT NOT NULL,
+				UNIQUE(creator_id, content_id, reaction_type)
+			);
 			CREATE TABLE attachment (
 				id INTEGER PRIMARY KEY AUTOINCREMENT,
 				uid TEXT NOT NULL UNIQUE,

store/test/reaction_test.go

@@ -3,10 +3,12 @@ package test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 
 	"github.com/usememos/memos/store"
+	"github.com/usememos/memos/store/db"
 )
 
 func TestReactionStore(t *testing.T) {
@@ -16,11 +18,11 @@ func TestReactionStore(t *testing.T) {
 
 	user, err := createTestingHostUser(ctx, ts)
 	require.NoError(t, err)
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-store")
 
-	contentID := "test_content_id"
 	reaction, err := ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    contentID,
+		MemoID:       memo.ID,
 		ReactionType: "💗",
 	})
 	require.NoError(t, err)
@@ -28,7 +30,7 @@ func TestReactionStore(t *testing.T) {
 	require.NotEmpty(t, reaction.ID)
 
 	reactions, err := ts.ListReactions(ctx, &store.FindReaction{
-		ContentID: &contentID,
+		MemoID: &memo.ID,
 	})
 	require.NoError(t, err)
 	require.Len(t, reactions, 1)
@@ -42,7 +44,7 @@ func TestReactionStore(t *testing.T) {
 	require.NotNil(t, gotReaction)
 	require.Equal(t, reaction.ID, gotReaction.ID)
 	require.Equal(t, reaction.CreatorID, gotReaction.CreatorID)
-	require.Equal(t, reaction.ContentID, gotReaction.ContentID)
+	require.Equal(t, reaction.MemoID, gotReaction.MemoID)
 	require.Equal(t, reaction.ReactionType, gotReaction.ReactionType)
 
 	// Test GetReaction with non-existent ID.
@@ -53,13 +55,19 @@ func TestReactionStore(t *testing.T) {
 	require.NoError(t, err)
 	require.Nil(t, notFoundReaction)
 
+	// An empty delete filter must not remove every reaction.
+	require.NoError(t, ts.DeleteReaction(ctx, &store.DeleteReaction{}))
+	reactions, err = ts.ListReactions(ctx, &store.FindReaction{MemoID: &memo.ID})
+	require.NoError(t, err)
+	require.Len(t, reactions, 1)
+
 	err = ts.DeleteReaction(ctx, &store.DeleteReaction{
-		ID: reaction.ID,
+		ID: &reaction.ID,
 	})
 	require.NoError(t, err)
 
 	reactions, err = ts.ListReactions(ctx, &store.FindReaction{
-		ContentID: &contentID,
+		MemoID: &memo.ID,
 	})
 	require.NoError(t, err)
 	require.Len(t, reactions, 0)
@@ -67,6 +75,69 @@ func TestReactionStore(t *testing.T) {
 	ts.Close()
 }
 
+func TestReactionDeleteByMemoID(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	ts := NewTestingStore(ctx, t)
+
+	user, err := createTestingHostUser(ctx, ts)
+	require.NoError(t, err)
+	memo1 := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-delete-memo-1")
+	memo2 := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-delete-memo-2")
+
+	for _, reaction := range []*store.Reaction{
+		{CreatorID: user.ID, MemoID: memo1.ID, ReactionType: "👍"},
+		{CreatorID: user.ID, MemoID: memo1.ID, ReactionType: "❤️"},
+		{CreatorID: user.ID, MemoID: memo2.ID, ReactionType: "👍"},
+	} {
+		_, err := ts.UpsertReaction(ctx, reaction)
+		require.NoError(t, err)
+	}
+
+	require.NoError(t, ts.DeleteReaction(ctx, &store.DeleteReaction{MemoID: &memo1.ID}))
+	reactions, err := ts.ListReactions(ctx, &store.FindReaction{})
+	require.NoError(t, err)
+	require.Len(t, reactions, 1)
+	require.Equal(t, memo2.ID, reactions[0].MemoID)
+
+	ts.Close()
+}
+
+func TestReactionRejectsDeletedMemo(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	ts := NewTestingStore(ctx, t)
+
+	user, err := createTestingHostUser(ctx, ts)
+	require.NoError(t, err)
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-deleted-memo")
+	require.NoError(t, ts.DeleteMemo(ctx, &store.DeleteMemo{ID: memo.ID}))
+
+	reaction, err := ts.UpsertReaction(ctx, &store.Reaction{
+		CreatorID:    user.ID,
+		MemoID:       memo.ID,
+		ReactionType: "👍",
+	})
+	require.ErrorIs(t, err, store.ErrReactionMemoNotFound)
+	require.Nil(t, reaction)
+
+	reactions, err := ts.ListReactions(ctx, &store.FindReaction{MemoID: &memo.ID})
+	require.NoError(t, err)
+	require.Empty(t, reactions)
+
+	existingMemo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-existing-after-rejection")
+	reaction, err = ts.UpsertReaction(ctx, &store.Reaction{
+		CreatorID:    user.ID,
+		MemoID:       existingMemo.ID,
+		ReactionType: "👍",
+	})
+	require.NoError(t, err)
+	require.NotNil(t, reaction)
+	require.Equal(t, existingMemo.ID, reaction.MemoID)
+
+	ts.Close()
+}
+
 func TestReactionListByCreatorID(t *testing.T) {
 	t.Parallel()
 	ctx := context.Background()
@@ -77,13 +148,12 @@ func TestReactionListByCreatorID(t *testing.T) {
 
 	user2, err := createTestingUserWithRole(ctx, ts, "user2", store.RoleUser)
 	require.NoError(t, err)
-
-	contentID := "shared_content"
+	memo := createReactionTestMemo(ctx, t, ts, user1.ID, "reaction-list-by-creator")
 
 	// User 1 creates reaction
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user1.ID,
-		ContentID:    contentID,
+		MemoID:       memo.ID,
 		ReactionType: "👍",
 	})
 	require.NoError(t, err)
@@ -91,14 +161,14 @@ func TestReactionListByCreatorID(t *testing.T) {
 	// User 2 creates reaction
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user2.ID,
-		ContentID:    contentID,
+		MemoID:       memo.ID,
 		ReactionType: "❤️",
 	})
 	require.NoError(t, err)
 
-	// List all reactions for content
+	// List all reactions for the memo.
 	reactions, err := ts.ListReactions(ctx, &store.FindReaction{
-		ContentID: &contentID,
+		MemoID: &memo.ID,
 	})
 	require.NoError(t, err)
 	require.Len(t, reactions, 2)
@@ -114,38 +184,50 @@ func TestReactionListByCreatorID(t *testing.T) {
 	ts.Close()
 }
 
-func TestReactionMultipleContentIDs(t *testing.T) {
+func TestReactionMultipleMemoIDs(t *testing.T) {
 	t.Parallel()
 	ctx := context.Background()
 	ts := NewTestingStore(ctx, t)
 
 	user, err := createTestingHostUser(ctx, ts)
 	require.NoError(t, err)
+	memo1 := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-memo-1")
+	memo2 := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-memo-2")
+	memo3 := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-memo-3")
 
-	contentID1 := "content_1"
-	contentID2 := "content_2"
-
-	// Create reactions for different contents
+	// Create reactions for different memos.
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    contentID1,
+		MemoID:       memo1.ID,
 		ReactionType: "👍",
 	})
 	require.NoError(t, err)
 
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    contentID2,
+		MemoID:       memo2.ID,
 		ReactionType: "❤️",
 	})
 	require.NoError(t, err)
+	_, err = ts.UpsertReaction(ctx, &store.Reaction{
+		CreatorID:    user.ID,
+		MemoID:       memo3.ID,
+		ReactionType: "🔥",
+	})
+	require.NoError(t, err)
 
-	// List by content ID list
+	// List by memo ID list, excluding the third memo.
 	reactions, err := ts.ListReactions(ctx, &store.FindReaction{
-		ContentIDList: []string{contentID1, contentID2},
+		MemoIDList: []int32{memo1.ID, memo2.ID},
 	})
 	require.NoError(t, err)
 	require.Len(t, reactions, 2)
+	require.ElementsMatch(t, []int32{memo1.ID, memo2.ID}, []int32{reactions[0].MemoID, reactions[1].MemoID})
+
+	reaction, err := ts.GetReaction(ctx, &store.FindReaction{MemoIDList: []int32{memo2.ID}})
+	require.NoError(t, err)
+	require.NotNil(t, reaction)
+	require.Equal(t, memo2.ID, reaction.MemoID)
 
 	ts.Close()
 }
@@ -157,13 +239,12 @@ func TestReactionUpsertDifferentTypes(t *testing.T) {
 
 	user, err := createTestingHostUser(ctx, ts)
 	require.NoError(t, err)
-
-	contentID := "test_content"
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-different-types")
 
 	// Create first reaction
 	reaction1, err := ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    contentID,
+		MemoID:       memo.ID,
 		ReactionType: "👍",
 	})
 	require.NoError(t, err)
@@ -171,7 +252,7 @@ func TestReactionUpsertDifferentTypes(t *testing.T) {
 	// Create second reaction with different type (should create new, not update)
 	reaction2, err := ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    contentID,
+		MemoID:       memo.ID,
 		ReactionType: "❤️",
 	})
 	require.NoError(t, err)
@@ -180,10 +261,233 @@ func TestReactionUpsertDifferentTypes(t *testing.T) {
 	require.NotEqual(t, reaction1.ID, reaction2.ID)
 
 	reactions, err := ts.ListReactions(ctx, &store.FindReaction{
-		ContentID: &contentID,
+		MemoID: &memo.ID,
 	})
 	require.NoError(t, err)
 	require.Len(t, reactions, 2)
 
 	ts.Close()
 }
+
+func TestReactionDeletedWithMemo(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	ts := NewTestingStore(ctx, t)
+
+	user, err := createTestingHostUser(ctx, ts)
+	require.NoError(t, err)
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-delete-with-memo")
+	reaction, err := ts.UpsertReaction(ctx, &store.Reaction{
+		CreatorID:    user.ID,
+		MemoID:       memo.ID,
+		ReactionType: "👍",
+	})
+	require.NoError(t, err)
+
+	require.NoError(t, ts.DeleteMemo(ctx, &store.DeleteMemo{ID: memo.ID}))
+	got, err := ts.GetReaction(ctx, &store.FindReaction{ID: &reaction.ID})
+	require.NoError(t, err)
+	require.Nil(t, got)
+
+	ts.Close()
+}
+
+func TestReactionInsertedAfterMemoCleanupStartsIsRemoved(t *testing.T) {
+	setupContext := context.Background()
+	barrierDriver := &memoDeleteBarrierDriver{
+		deleteStarted:  make(chan struct{}),
+		continueDelete: make(chan struct{}),
+	}
+	ts := newReactionTestingStoreWithDriver(setupContext, t, func(driver store.Driver) store.Driver {
+		barrierDriver.Driver = driver
+		return barrierDriver
+	})
+	ctx, cancel := context.WithTimeout(setupContext, 10*time.Second)
+	defer cancel()
+
+	user, err := createTestingHostUser(ctx, ts)
+	require.NoError(t, err)
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-insert-during-delete")
+
+	deleteResult := make(chan error, 1)
+	go func() {
+		deleteResult <- ts.DeleteMemo(ctx, &store.DeleteMemo{ID: memo.ID})
+	}()
+	deleteReleased := false
+	defer func() {
+		if !deleteReleased {
+			close(barrierDriver.continueDelete)
+		}
+	}()
+
+	select {
+	case <-barrierDriver.deleteStarted:
+	case err := <-deleteResult:
+		require.FailNowf(t, "memo delete returned before reaching barrier", "error: %v", err)
+	case <-ctx.Done():
+		require.FailNow(t, "timed out waiting for memo delete barrier")
+	}
+
+	// Store.DeleteMemo has completed its application-managed relation and
+	// attachment cleanup, but the physical memo delete has not started. This
+	// recreates the old window where a prior reaction cleanup could be bypassed.
+	reaction, err := ts.UpsertReaction(ctx, &store.Reaction{
+		CreatorID:    user.ID,
+		MemoID:       memo.ID,
+		ReactionType: "👍",
+	})
+	require.NoError(t, err)
+	require.NotNil(t, reaction)
+
+	close(barrierDriver.continueDelete)
+	deleteReleased = true
+	select {
+	case err := <-deleteResult:
+		require.NoError(t, err)
+	case <-ctx.Done():
+		require.FailNow(t, "timed out waiting for memo delete")
+	}
+
+	reactions, err := ts.ListReactions(ctx, &store.FindReaction{MemoID: &memo.ID})
+	require.NoError(t, err)
+	require.Empty(t, reactions)
+}
+
+func TestReactionUpsertBlocksWhileMemoDeleteIsUncommitted(t *testing.T) {
+	setupContext := context.Background()
+	ts := NewTestingStore(setupContext, t)
+	t.Cleanup(func() {
+		require.NoError(t, ts.Close())
+	})
+	ctx, cancel := context.WithTimeout(setupContext, 10*time.Second)
+	defer cancel()
+
+	user, err := createTestingHostUser(ctx, ts)
+	require.NoError(t, err)
+	memo := createReactionTestMemo(ctx, t, ts, user.ID, "reaction-waits-for-delete")
+
+	dbTx, err := ts.GetDriver().GetDB().BeginTx(ctx, nil)
+	require.NoError(t, err)
+	txOpen := true
+	defer func() {
+		if txOpen {
+			_ = dbTx.Rollback()
+		}
+	}()
+
+	deleteMemoQuery := "DELETE FROM memo WHERE id = ?"
+	if getDriverFromEnv() == "postgres" {
+		deleteMemoQuery = "DELETE FROM memo WHERE id = $1"
+	}
+	_, err = dbTx.ExecContext(ctx, deleteMemoQuery, memo.ID)
+	require.NoError(t, err)
+
+	var reaction *store.Reaction
+	var upsertErr error
+	if getDriverFromEnv() == "sqlite" {
+		type upsertResult struct {
+			reaction *store.Reaction
+			err      error
+		}
+		resultChannel := make(chan upsertResult, 1)
+		go func() {
+			reaction, err := ts.UpsertReaction(ctx, &store.Reaction{
+				CreatorID:    user.ID,
+				MemoID:       memo.ID,
+				ReactionType: "👍",
+			})
+			resultChannel <- upsertResult{reaction: reaction, err: err}
+		}()
+
+		poll := time.NewTicker(time.Millisecond)
+		defer poll.Stop()
+		for ts.GetDriver().GetDB().Stats().InUse < 2 {
+			select {
+			case result := <-resultChannel:
+				require.FailNowf(t, "reaction upsert completed before memo delete committed", "reaction: %+v, error: %v", result.reaction, result.err)
+			case <-poll.C:
+			case <-ctx.Done():
+				require.FailNow(t, "timed out waiting for reaction upsert to reach SQLite")
+			}
+		}
+
+		require.NoError(t, dbTx.Commit())
+		txOpen = false
+		select {
+		case result := <-resultChannel:
+			reaction, upsertErr = result.reaction, result.err
+		case <-ctx.Done():
+			require.FailNow(t, "timed out waiting for SQLite reaction upsert")
+		}
+	} else {
+		// Both client/server database engines must wait for the uncommitted
+		// parent deletion before deciding whether the memo still exists.
+		lockWaitContext, lockWaitCancel := context.WithTimeout(ctx, 500*time.Millisecond)
+		startTime := time.Now()
+		reaction, upsertErr = ts.UpsertReaction(lockWaitContext, &store.Reaction{
+			CreatorID:    user.ID,
+			MemoID:       memo.ID,
+			ReactionType: "👍",
+		})
+		lockWaitCancel()
+		require.Error(t, upsertErr)
+		require.Nil(t, reaction)
+		require.GreaterOrEqual(t, time.Since(startTime), 450*time.Millisecond, "reaction upsert must wait for the memo delete transaction")
+
+		require.NoError(t, dbTx.Commit())
+		txOpen = false
+		reaction, upsertErr = ts.UpsertReaction(ctx, &store.Reaction{
+			CreatorID:    user.ID,
+			MemoID:       memo.ID,
+			ReactionType: "👍",
+		})
+	}
+	require.ErrorIs(t, upsertErr, store.ErrReactionMemoNotFound)
+	require.Nil(t, reaction)
+
+	reactions, err := ts.ListReactions(ctx, &store.FindReaction{MemoID: &memo.ID})
+	require.NoError(t, err)
+	require.Empty(t, reactions)
+}
+
+type memoDeleteBarrierDriver struct {
+	store.Driver
+	deleteStarted  chan struct{}
+	continueDelete chan struct{}
+}
+
+func (d *memoDeleteBarrierDriver) DeleteMemo(ctx context.Context, delete *store.DeleteMemo) error {
+	close(d.deleteStarted)
+	select {
+	case <-d.continueDelete:
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+	return d.Driver.DeleteMemo(ctx, delete)
+}
+
+func newReactionTestingStoreWithDriver(ctx context.Context, t *testing.T, wrap func(store.Driver) store.Driver) *store.Store {
+	t.Helper()
+	testingProfile := getTestingProfileForDriver(t, getDriverFromEnv())
+	databaseDriver, err := db.NewDBDriver(testingProfile)
+	require.NoError(t, err)
+
+	ts := store.New(wrap(databaseDriver), testingProfile)
+	require.NoError(t, ts.Migrate(ctx))
+	t.Cleanup(func() {
+		require.NoError(t, ts.Close())
+	})
+	return ts
+}
+
+func createReactionTestMemo(ctx context.Context, t *testing.T, ts *store.Store, creatorID int32, uid string) *store.Memo {
+	t.Helper()
+	memo, err := ts.CreateMemo(ctx, &store.Memo{
+		UID:        uid,
+		CreatorID:  creatorID,
+		Content:    uid,
+		Visibility: store.Private,
+	})
+	require.NoError(t, err)
+	return memo
+}

store/test/user_delete_test.go

@@ -96,19 +96,19 @@ func TestDeleteUserCleansRelatedData(t *testing.T) {
 
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    peer.ID,
-		ContentID:    "memos/" + ownMemo.UID,
+		MemoID:       ownMemo.ID,
 		ReactionType: "thumbs-up",
 	})
 	require.NoError(t, err)
 	_, err = ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    user.ID,
-		ContentID:    "memos/" + peerMemo.UID,
+		MemoID:       peerMemo.ID,
 		ReactionType: "heart",
 	})
 	require.NoError(t, err)
 	peerReactionToKeep, err := ts.UpsertReaction(ctx, &store.Reaction{
 		CreatorID:    peer.ID,
-		ContentID:    "memos/" + peerMemo.UID,
+		MemoID:       peerMemo.ID,
 		ReactionType: "sparkle",
 	})
 	require.NoError(t, err)
@@ -213,8 +213,7 @@ func TestDeleteUserCleansRelatedData(t *testing.T) {
 	require.NoError(t, err)
 	require.Empty(t, deletedMemoRelations)
 
-	peerMemoContentID := "memos/" + peerMemo.UID
-	keptReactions, err := ts.ListReactions(ctx, &store.FindReaction{ContentID: &peerMemoContentID})
+	keptReactions, err := ts.ListReactions(ctx, &store.FindReaction{MemoID: &peerMemo.ID})
 	require.NoError(t, err)
 	require.Len(t, keptReactions, 1)
 	require.Equal(t, peerReactionToKeep.ID, keptReactions[0].ID)

web/src/components/MemoReactionListView/hooks.ts

@@ -52,7 +52,7 @@ export const useReactionActions = ({ memo, onComplete }: UseReactionActionsOptio
       } else {
         await memoServiceClient.upsertMemoReaction({
           name: memo.name,
-          reaction: { contentId: memo.name, reactionType },
+          reaction: { reactionType },
         });
       }
       // Refetch the memo to get updated reactions and invalidate cache