diff --git a/internal/module/friend/entity/request.go b/internal/module/friend/entity/request.go
index 37e719e..b169692 100644
--- a/internal/module/friend/entity/request.go
+++ b/internal/module/friend/entity/request.go
@@ -20,13 +20,14 @@ const (
 	SourceQRCode  Source = 1
 	SourceEmail   Source = 2
 	SourceSparkID Source = 3
+	SourceFollow  Source = 4
 )
 
 // Source is friend add origin on the request and the directed edge.
 type Source int
 
 func (s Source) Valid() bool {
-	return s == SourceUnknown || s == SourceQRCode || s == SourceEmail || s == SourceSparkID
+	return s == SourceUnknown || s == SourceQRCode || s == SourceEmail || s == SourceSparkID || s == SourceFollow
 }
 
 const (
diff --git a/internal/module/friend/logic/follow.go b/internal/module/friend/logic/follow.go
new file mode 100644
index 0000000..0344737
--- /dev/null
+++ b/internal/module/friend/logic/follow.go
@@ -0,0 +1,150 @@
+package logic
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"spark-server/internal/module/friend/entity"
+	"spark-server/internal/pkg/errs"
+	"spark-server/internal/pkg/i18n"
+	"spark-server/internal/pkg/reqctx"
+)
+
+// FollowView is the viewer's follow state toward one user.
+type FollowView struct {
+	UID        int64 `json:"uid"`
+	Following  bool  `json:"following"`
+	FollowedBy bool  `json:"followed_by"`
+	Mutual     bool  `json:"mutual"`
+	Friend     bool  `json:"friend"`
+}
+
+func (s *Service) Follow(ctx context.Context, userID, targetID int64) (*FollowView, error) {
+	if err := s.followReady(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	if _, err := s.activeUser(ctx, targetID); err != nil {
+		return nil, err
+	}
+	if err := s.followBlocks(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	if err := s.repo.PutFollow(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	if err := s.friendIfMutual(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	return s.followView(ctx, userID, targetID)
+}
+
+func (s *Service) Unfollow(ctx context.Context, userID, targetID int64) (*FollowView, error) {
+	if err := s.followReady(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	mutual, err := s.mutualFollow(ctx, userID, targetID)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.repo.DeleteFollow(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	if mutual {
+		if err := s.repo.DeleteFriend(ctx, userID, targetID); err != nil && !errors.Is(err, errs.ErrNotFound) {
+			return nil, err
+		}
+	}
+	return s.followView(ctx, userID, targetID)
+}
+
+func (s *Service) GetFollow(ctx context.Context, userID, targetID int64) (*FollowView, error) {
+	if err := s.followReady(ctx, userID, targetID); err != nil {
+		return nil, err
+	}
+	if _, err := s.activeUser(ctx, targetID); err != nil {
+		return nil, err
+	}
+	return s.followView(ctx, userID, targetID)
+}
+
+func (s *Service) followReady(ctx context.Context, userID, targetID int64) error {
+	if !s.ready() || userID <= 0 {
+		return errs.ErrUnauthorized
+	}
+	if targetID <= 0 {
+		return errs.ErrInvalidArgument
+	}
+	if entity.SameUser(userID, targetID) {
+		return errs.ErrInvalidArgument.WithMsg(i18n.T(reqctx.Lang(ctx), i18n.KeyFriendSelf, nil))
+	}
+	return nil
+}
+
+func (s *Service) followBlocks(ctx context.Context, from, to int64) error {
+	lang := reqctx.Lang(ctx)
+	blockedMe, err := s.repo.IsBlocked(ctx, from, to)
+	if err != nil {
+		return err
+	}
+	if blockedMe {
+		return errs.ErrForbidden.WithMsg(i18n.T(lang, i18n.KeyFriendBlocked, nil))
+	}
+	blockedBy, err := s.repo.IsBlocked(ctx, to, from)
+	if err != nil {
+		return err
+	}
+	if blockedBy {
+		return errs.ErrNotFound
+	}
+	return nil
+}
+
+func (s *Service) friendIfMutual(ctx context.Context, userID, targetID int64) error {
+	mutual, err := s.mutualFollow(ctx, userID, targetID)
+	if err != nil || !mutual {
+		return err
+	}
+	ok, err := s.AreFriends(ctx, userID, targetID)
+	if err != nil || ok {
+		return err
+	}
+	now := time.Now()
+	if err := s.repo.AcceptFriend(ctx, entity.AcceptParams{Edges: []*entity.Relation{
+		entity.NewFriendEdge(userID, targetID, "", entity.SourceFollow, now),
+		entity.NewFriendEdge(targetID, userID, "", entity.SourceFollow, now),
+	}}); err != nil {
+		return err
+	}
+	if s.greeter != nil {
+		_ = s.greeter.BecameFriends(ctx, userID, targetID)
+	}
+	return nil
+}
+
+func (s *Service) mutualFollow(ctx context.Context, userID, targetID int64) (bool, error) {
+	following, err := s.repo.HasFollow(ctx, userID, targetID)
+	if err != nil || !following {
+		return false, err
+	}
+	return s.repo.HasFollow(ctx, targetID, userID)
+}
+
+func (s *Service) followView(ctx context.Context, userID, targetID int64) (*FollowView, error) {
+	following, err := s.repo.HasFollow(ctx, userID, targetID)
+	if err != nil {
+		return nil, err
+	}
+	followedBy, err := s.repo.HasFollow(ctx, targetID, userID)
+	if err != nil {
+		return nil, err
+	}
+	friend, err := s.AreFriends(ctx, userID, targetID)
+	if err != nil {
+		return nil, err
+	}
+	return &FollowView{
+		UID: targetID, Following: following, FollowedBy: followedBy,
+		Mutual: following && followedBy, Friend: friend,
+	}, nil
+}
diff --git a/internal/module/friend/logic/follow_test.go b/internal/module/friend/logic/follow_test.go
new file mode 100644
index 0000000..6a57e72
--- /dev/null
+++ b/internal/module/friend/logic/follow_test.go
@@ -0,0 +1,145 @@
+package logic
+
+import (
+	"errors"
+	"testing"
+
+	"spark-server/internal/infrastructure/id"
+	convlogic "spark-server/internal/module/conversation/logic"
+	convmodel "spark-server/internal/module/conversation/model"
+	"spark-server/internal/module/friend/entity"
+	friendmodel "spark-server/internal/module/friend/model"
+	msgmodel "spark-server/internal/module/message/model"
+	userentity "spark-server/internal/module/user/entity"
+	"spark-server/internal/module/user/logictest"
+	"spark-server/internal/pkg/errs"
+)
+
+func TestOneWayFollowDoesNotFriend(t *testing.T) {
+	svc, users, g := testFriends(t)
+	ctx := t.Context()
+	a, b := twoUsers(t, users)
+	view, err := svc.Follow(ctx, a.ID, b.ID)
+	if err != nil || !view.Following || view.FollowedBy || view.Mutual || view.Friend {
+		t.Fatalf("%+v %v", view, err)
+	}
+	if g.n != 0 {
+		t.Fatalf("greeting %d", g.n)
+	}
+	ok, err := svc.AreFriends(ctx, a.ID, b.ID)
+	if err != nil || ok {
+		t.Fatalf("friends %v %v", ok, err)
+	}
+}
+
+func TestMutualFollowCreatesFriendsOnce(t *testing.T) {
+	svc, users, g := testFriends(t)
+	ctx := t.Context()
+	a, b := twoUsers(t, users)
+	if _, err := svc.Follow(ctx, a.ID, b.ID); err != nil {
+		t.Fatal(err)
+	}
+	view, err := svc.Follow(ctx, b.ID, a.ID)
+	if err != nil || !view.Mutual || !view.Friend || !view.Following || !view.FollowedBy {
+		t.Fatalf("%+v %v", view, err)
+	}
+	if g.n != 1 {
+		t.Fatalf("greeting %d", g.n)
+	}
+	again, err := svc.Follow(ctx, b.ID, a.ID)
+	if err != nil || !again.Friend || g.n != 1 {
+		t.Fatalf("repeat %+v greet %d %v", again, g.n, err)
+	}
+	rel, err := svc.Relation(ctx, a.ID, b.ID)
+	if err != nil || rel.Source != entity.SourceFollow {
+		t.Fatalf("source %+v %v", rel, err)
+	}
+}
+
+func TestUnfollowMutualDropsFriendsKeepsMessage(t *testing.T) {
+	ids, err := id.New(1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	users := logictest.Users(ids, nil)
+	ctx := t.Context()
+	a, err := users.AuthenticateEmail(ctx, "test01@spark.com", "1", &userentity.LoginDevice{DeviceID: 1, DeviceType: userentity.DeviceIOS})
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, err := users.AuthenticateEmail(ctx, "test02@spark.com", "1", &userentity.LoginDevice{DeviceID: 2, DeviceType: userentity.DeviceWeb})
+	if err != nil {
+		t.Fatal(err)
+	}
+	chats := convmodel.NewMemoryP2P()
+	msgs := msgmodel.NewMemoryRepo()
+	p2p := convlogic.NewP2PService(chats, ids)
+	svc := NewService(friendmodel.NewMemoryRepo(), users, ids, NewGreeter(p2p, msgs, ids, nil))
+	if _, err := svc.Follow(ctx, a.ID, b.ID); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.Follow(ctx, b.ID, a.ID); err != nil {
+		t.Fatal(err)
+	}
+	conv, err := chats.GetP2P(ctx, a.ID, b.ID)
+	if err != nil || conv == nil || conv.ID <= 0 {
+		t.Fatalf("conversation %+v %v", conv, err)
+	}
+	before, err := msgs.ListByConversation(ctx, conv.ID, a.ID, 0, 20)
+	if err != nil || len(before) != 1 {
+		t.Fatalf("before %d %v", len(before), err)
+	}
+	view, err := svc.Unfollow(ctx, a.ID, b.ID)
+	if err != nil || view.Following || view.Mutual || view.Friend || !view.FollowedBy {
+		t.Fatalf("%+v %v", view, err)
+	}
+	after, err := msgs.ListByConversation(ctx, conv.ID, a.ID, 0, 20)
+	if err != nil || len(after) != 1 || after[0].ID != before[0].ID {
+		t.Fatalf("after %d %v", len(after), err)
+	}
+	ok, err := svc.AreFriends(ctx, a.ID, b.ID)
+	if err != nil || ok {
+		t.Fatalf("still friends %v %v", ok, err)
+	}
+}
+
+func TestUnfollowOneWayKeepsAcceptedFriend(t *testing.T) {
+	svc, users, g := testFriends(t)
+	ctx := t.Context()
+	a, b := twoUsers(t, users)
+	applied, err := svc.Apply(ctx, a.ID, &ApplyInput{UID: b.ID})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.Accept(ctx, b.ID, AcceptInput{RequestID: applied.RequestID}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.Follow(ctx, a.ID, b.ID); err != nil {
+		t.Fatal(err)
+	}
+	view, err := svc.Unfollow(ctx, a.ID, b.ID)
+	if err != nil || view.Following || !view.Friend || view.Mutual {
+		t.Fatalf("%+v %v", view, err)
+	}
+	if g.n != 1 {
+		t.Fatalf("greeting %d", g.n)
+	}
+}
+
+func TestFollowRejectsSelfAndBlock(t *testing.T) {
+	svc, users, _ := testFriends(t)
+	ctx := t.Context()
+	a, b := twoUsers(t, users)
+	if _, err := svc.Follow(ctx, a.ID, a.ID); !errors.Is(err, errs.ErrInvalidArgument) {
+		t.Fatalf("self %v", err)
+	}
+	if err := svc.Block(ctx, a.ID, b.ID); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := svc.Follow(ctx, a.ID, b.ID); !errors.Is(err, errs.ErrForbidden) {
+		t.Fatalf("blocked by me %v", err)
+	}
+	if _, err := svc.Follow(ctx, b.ID, a.ID); !errors.Is(err, errs.ErrNotFound) {
+		t.Fatalf("blocked by peer %v", err)
+	}
+}
diff --git a/internal/module/friend/logic/service.go b/internal/module/friend/logic/service.go
index 45da92c..c06b5a0 100644
--- a/internal/module/friend/logic/service.go
+++ b/internal/module/friend/logic/service.go
@@ -26,6 +26,9 @@ type Repository interface {
 	CreateReport(ctx context.Context, r *entity.Report) error
 	AcceptFriend(ctx context.Context, in entity.AcceptParams) error
 	DeleteFriend(ctx context.Context, a, b int64) error
+	PutFollow(ctx context.Context, userID, targetID int64) error
+	DeleteFollow(ctx context.Context, userID, targetID int64) error
+	HasFollow(ctx context.Context, userID, targetID int64) (bool, error)
 	PurgeUser(ctx context.Context, userID int64) error
 }
 
diff --git a/internal/module/friend/model/friend_relation.go b/internal/module/friend/model/friend_relation.go
index da3b83d..c8b04c4 100644
--- a/internal/module/friend/model/friend_relation.go
+++ b/internal/module/friend/model/friend_relation.go
@@ -20,7 +20,7 @@ type FriendRelation struct {
 	Remark    string    `gorm:"column:remark;comment:备注，仅自己可见"`
 	Blocked   bool      `gorm:"column:is_blocked;comment:是否拉黑对方"`
 	Pinned    bool      `gorm:"column:is_pinned;comment:会话消息置顶"`
-	Source    int       `gorm:"column:source;comment:添加来源：0=未知 1=二维码 2=邮箱 3=spark_id"`
+	Source    int       `gorm:"column:source;comment:添加来源：0=未知 1=二维码 2=邮箱 3=spark_id 4=互关"`
 	CreatedAt time.Time `gorm:"column:created_at;comment:成为好友或建边时间"`
 	UpdatedAt time.Time `gorm:"column:updated_at;comment:最近更新时间"`
 }
diff --git a/internal/module/friend/model/memory.go b/internal/module/friend/model/memory.go
index ccf26d2..bdcdb6e 100644
--- a/internal/module/friend/model/memory.go
+++ b/internal/module/friend/model/memory.go
@@ -27,6 +27,7 @@ type MemoryRepo struct {
 	requests  map[int64]*entity.Request
 	byPair    map[requestKey]int64
 	reports   []*entity.Report
+	follows   map[followKey]struct{}
 }
 
 func NewMemoryRepo() *MemoryRepo {
@@ -34,6 +35,7 @@ func NewMemoryRepo() *MemoryRepo {
 		relations: make(map[edgeKey]*entity.Relation),
 		requests:  make(map[int64]*entity.Request),
 		byPair:    make(map[requestKey]int64),
+		follows:   make(map[followKey]struct{}),
 	}
 }
 
diff --git a/internal/module/friend/model/purge.go b/internal/module/friend/model/purge.go
index 93c31d3..bf3946d 100644
--- a/internal/module/friend/model/purge.go
+++ b/internal/module/friend/model/purge.go
@@ -23,6 +23,9 @@ func (m *Repo) PurgeUser(ctx context.Context, userID int64) error {
 	if err := db.Where("user_id = ? OR target_id = ?", userID, userID).Delete(&FriendReport{}).Error; err != nil {
 		return mapDBErr(err)
 	}
+	if err := db.Where("user_id = ? OR target_id = ?", userID, userID).Delete(&UserFollow{}).Error; err != nil {
+		return mapDBErr(err)
+	}
 	return nil
 }
 
@@ -51,5 +54,10 @@ func (m *MemoryRepo) PurgeUser(_ context.Context, userID int64) error {
 		}
 	}
 	m.reports = kept
+	for key := range m.follows {
+		if key.UserID == userID || key.TargetID == userID {
+			delete(m.follows, key)
+		}
+	}
 	return nil
 }
diff --git a/internal/module/friend/model/user_follow.go b/internal/module/friend/model/user_follow.go
new file mode 100644
index 0000000..c61982d
--- /dev/null
+++ b/internal/module/friend/model/user_follow.go
@@ -0,0 +1,98 @@
+package model
+
+import (
+	"context"
+	"time"
+
+	"spark-server/internal/pkg/errs"
+)
+
+type followKey struct {
+	UserID   int64
+	TargetID int64
+}
+
+// UserFollow maps table t_user_follows (one directed follow per row).
+type UserFollow struct {
+	ID        int64     `gorm:"column:id;primaryKey;autoIncrement;comment:行 id，表内自增"`
+	UserID    int64     `gorm:"column:user_id;comment:关注人 user_id"`
+	TargetID  int64     `gorm:"column:target_id;comment:被关注人 user_id"`
+	CreatedAt time.Time `gorm:"column:created_at;comment:关注时间"`
+}
+
+func (UserFollow) TableName() string { return "t_user_follows" }
+
+func (m *Repo) PutFollow(ctx context.Context, userID, targetID int64) error {
+	if userID <= 0 || targetID <= 0 || userID == targetID {
+		return errs.ErrInvalidArgument
+	}
+	db, err := m.session(ctx)
+	if err != nil {
+		return err
+	}
+	row := UserFollow{UserID: userID, TargetID: targetID, CreatedAt: time.Now()}
+	err = db.Where("user_id = ? AND target_id = ?", userID, targetID).
+		Attrs(row).FirstOrCreate(&row).Error
+	return mapDBErr(err)
+}
+
+func (m *Repo) DeleteFollow(ctx context.Context, userID, targetID int64) error {
+	if userID <= 0 || targetID <= 0 {
+		return errs.ErrInvalidArgument
+	}
+	db, err := m.session(ctx)
+	if err != nil {
+		return err
+	}
+	err = db.Where("user_id = ? AND target_id = ?", userID, targetID).Delete(&UserFollow{}).Error
+	return mapDBErr(err)
+}
+
+func (m *Repo) HasFollow(ctx context.Context, userID, targetID int64) (bool, error) {
+	if userID <= 0 || targetID <= 0 {
+		return false, nil
+	}
+	db, err := m.session(ctx)
+	if err != nil {
+		return false, err
+	}
+	var n int64
+	err = db.Model(&UserFollow{}).Where("user_id = ? AND target_id = ?", userID, targetID).Count(&n).Error
+	if err != nil {
+		return false, mapDBErr(err)
+	}
+	return n > 0, nil
+}
+
+func (m *MemoryRepo) PutFollow(_ context.Context, userID, targetID int64) error {
+	if userID <= 0 || targetID <= 0 || userID == targetID {
+		return errs.ErrInvalidArgument
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.follows == nil {
+		m.follows = make(map[followKey]struct{})
+	}
+	m.follows[followKey{UserID: userID, TargetID: targetID}] = struct{}{}
+	return nil
+}
+
+func (m *MemoryRepo) DeleteFollow(_ context.Context, userID, targetID int64) error {
+	if userID <= 0 || targetID <= 0 {
+		return errs.ErrInvalidArgument
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	delete(m.follows, followKey{UserID: userID, TargetID: targetID})
+	return nil
+}
+
+func (m *MemoryRepo) HasFollow(_ context.Context, userID, targetID int64) (bool, error) {
+	if userID <= 0 || targetID <= 0 {
+		return false, nil
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	_, ok := m.follows[followKey{UserID: userID, TargetID: targetID}]
+	return ok, nil
+}
diff --git a/internal/module/meta/logic/enums_friend.go b/internal/module/meta/logic/enums_friend.go
index 992a0f3..fd6dd96 100644
--- a/internal/module/meta/logic/enums_friend.go
+++ b/internal/module/meta/logic/enums_friend.go
@@ -28,6 +28,7 @@ func friendSource(lang i18n.Lang) []entity.Item {
 		item(lang, "friend_source", "qrcode", int(friendentity.SourceQRCode)),
 		item(lang, "friend_source", "email", int(friendentity.SourceEmail)),
 		item(lang, "friend_source", "spark_id", int(friendentity.SourceSparkID)),
+		item(lang, "friend_source", "follow", int(friendentity.SourceFollow)),
 	}
 }
 
diff --git a/internal/pkg/i18n/catalog_enum.go b/internal/pkg/i18n/catalog_enum.go
index d11de98..c62372b 100644
--- a/internal/pkg/i18n/catalog_enum.go
+++ b/internal/pkg/i18n/catalog_enum.go
@@ -33,6 +33,7 @@ func init() {
 		"enum.friend_source.qrcode":              {ZhCN: "二维码", En: "QR code", ZhTW: "二維碼"},
 		"enum.friend_source.email":               {ZhCN: "邮箱", En: "Email", ZhTW: "電子郵件"},
 		"enum.friend_source.spark_id":            {ZhCN: "Spark账号", En: "Spark ID", ZhTW: "Spark帳號"},
+		"enum.friend_source.follow":              {ZhCN: "互关", En: "Mutual follow", ZhTW: "互關"},
 		"enum.report_reason.spam":                {ZhCN: "垃圾信息", En: "Spam", ZhTW: "垃圾訊息"},
 		"enum.report_reason.harassment":          {ZhCN: "骚扰", En: "Harassment", ZhTW: "騷擾"},
 		"enum.report_reason.fake":                {ZhCN: "不实身份", En: "Fake identity", ZhTW: "不實身分"},
diff --git a/internal/transport/http/handler/friend/follow.go b/internal/transport/http/handler/friend/follow.go
new file mode 100644
index 0000000..8479313
--- /dev/null
+++ b/internal/transport/http/handler/friend/follow.go
@@ -0,0 +1,61 @@
+package friendhandler
+
+import (
+	"github.com/gin-gonic/gin"
+
+	"spark-server/internal/transport/http/respond"
+)
+
+func (h *Handler) GetFollow(c *gin.Context) {
+	uid, ok := currentUID(c)
+	if !ok {
+		return
+	}
+	targetID, err := pathUID(c)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	out, err := h.friends.GetFollow(c.Request.Context(), uid, targetID)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	respond.JSON(c, out)
+}
+
+func (h *Handler) Follow(c *gin.Context) {
+	uid, ok := currentUID(c)
+	if !ok {
+		return
+	}
+	targetID, err := pathUID(c)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	out, err := h.friends.Follow(c.Request.Context(), uid, targetID)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	respond.JSON(c, out)
+}
+
+func (h *Handler) Unfollow(c *gin.Context) {
+	uid, ok := currentUID(c)
+	if !ok {
+		return
+	}
+	targetID, err := pathUID(c)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	out, err := h.friends.Unfollow(c.Request.Context(), uid, targetID)
+	if err != nil {
+		respond.JSONError(c, err)
+		return
+	}
+	respond.JSON(c, out)
+}
diff --git a/internal/transport/http/router.go b/internal/transport/http/router.go
index a1a1b3a..1025e43 100644
--- a/internal/transport/http/router.go
+++ b/internal/transport/http/router.go
@@ -155,6 +155,10 @@ func registerFriendRoutes(v1 *gin.RouterGroup, deps *EngineDeps) {
 	g.PUT("/:uid/block", h.Block)
 	g.DELETE("/:uid/block", h.Unblock)
 	g.POST("/:uid/reports", h.Report)
+	f := v1.Group("/follows")
+	f.GET("/:uid", h.GetFollow)
+	f.PUT("/:uid", h.Follow)
+	f.DELETE("/:uid", h.Unfollow)
 }
 
 func registerGroupRoutes(v1 *gin.RouterGroup, deps *EngineDeps) {
diff --git a/migrations/0033_user_follows.sql b/migrations/0033_user_follows.sql
new file mode 100644
index 0000000..660ed66
--- /dev/null
+++ b/migrations/0033_user_follows.sql
@@ -0,0 +1,11 @@
+-- One directed follow per pair. Mutual follows become friend edges in logic; unfollowing does not delete messages.
+
+CREATE TABLE IF NOT EXISTS t_user_follows (
+    id          BIGINT NOT NULL AUTO_INCREMENT COMMENT '行 id，表内自增',
+    user_id     BIGINT NOT NULL COMMENT '关注人 user_id',
+    target_id   BIGINT NOT NULL COMMENT '被关注人 user_id',
+    created_at  DATETIME(3) NOT NULL COMMENT '关注时间',
+    PRIMARY KEY (id),
+    UNIQUE KEY uk_user_target (user_id, target_id),
+    KEY idx_target (target_id)
+) COMMENT='单向关注。双方互相关注时写入已有双向好友边；取消关注只删关注，不再互关时删好友边，不删消息';