diff --git a/pkg/connector/connector.go b/pkg/connector/connector.go
index a8a0764..313d839 100644
--- a/pkg/connector/connector.go
+++ b/pkg/connector/connector.go
@@ -39,7 +39,7 @@ func (lc *LineConnector) Start(ctx context.Context) error {
 }
 
 func (lc *LineConnector) GetBridgeInfoVersion() (info, capabilities int) {
-	return 1, 1
+	return 1, 2
 }
 
 func (lc *LineConnector) GetCapabilities() *bridgev2.NetworkGeneralCapabilities {
diff --git a/pkg/connector/creategroup.go b/pkg/connector/creategroup.go
index eb6ddbc..b43ab5d 100644
--- a/pkg/connector/creategroup.go
+++ b/pkg/connector/creategroup.go
@@ -126,8 +126,9 @@ func (lc *LineClient) CreateGroup(ctx context.Context, params *bridgev2.GroupCre
 			Type: &ct,
 			Name: &chatName,
 			Members: &bridgev2.ChatMemberList{
-				IsFull:  true,
-				Members: members,
+				IsFull:      true,
+				Members:     members,
+				PowerLevels: lineGroupPowerLevelOverrides(),
 			},
 		},
 	}, nil
diff --git a/pkg/connector/handle_room_meta.go b/pkg/connector/handle_room_meta.go
new file mode 100644
index 0000000..d4ee1c3
--- /dev/null
+++ b/pkg/connector/handle_room_meta.go
@@ -0,0 +1,142 @@
+package connector
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"maunium.net/go/mautrix/bridgev2"
+	"maunium.net/go/mautrix/bridgev2/database"
+	"maunium.net/go/mautrix/bridgev2/networkid"
+
+	"github.com/highesttt/matrix-line-messenger/pkg/line"
+)
+
+var (
+	_ bridgev2.RoomNameHandlingNetworkAPI   = (*LineClient)(nil)
+	_ bridgev2.RoomAvatarHandlingNetworkAPI = (*LineClient)(nil)
+)
+
+func (lc *LineClient) HandleMatrixRoomName(ctx context.Context, msg *bridgev2.MatrixRoomName) (bool, error) {
+	chatMid, err := matrixGroupChatMID(msg.Portal)
+	if err != nil {
+		return false, err
+	}
+
+	name := msg.Content.Name
+	if strings.TrimSpace(name) == "" {
+		return false, fmt.Errorf("LINE group name cannot be empty")
+	}
+	if len([]rune(name)) > 50 {
+		return false, fmt.Errorf("LINE group name cannot be longer than 50 characters")
+	}
+
+	err = lc.withLineClientRetry(ctx, func(client *line.Client) error {
+		chat, err := client.GetChatForUpdate(chatMid)
+		if err != nil {
+			return err
+		}
+		chat["chatName"] = name
+		return client.UpdateChat(chat, line.ChatAttributeName)
+	})
+	if err != nil {
+		return false, err
+	}
+
+	msg.Portal.Name = name
+	msg.Portal.NameSet = true
+	return true, nil
+}
+
+func (lc *LineClient) HandleMatrixRoomAvatar(ctx context.Context, msg *bridgev2.MatrixRoomAvatar) (bool, error) {
+	chatMid, err := matrixGroupChatMID(msg.Portal)
+	if err != nil {
+		return false, err
+	}
+
+	avatarURL := msg.Content.URL
+	if avatarURL == "" && msg.Content.MSC3414File != nil {
+		avatarURL = msg.Content.MSC3414File.URL
+	}
+
+	if avatarURL == "" {
+		err = lc.withLineClientRetry(ctx, func(client *line.Client) error {
+			chat, err := client.GetChatForUpdate(chatMid)
+			if err != nil {
+				return err
+			}
+			chat["picturePath"] = ""
+			return client.UpdateChat(chat, line.ChatAttributePictureStatus)
+		})
+		if err != nil {
+			return false, err
+		}
+
+		msg.Portal.AvatarMXC = ""
+		msg.Portal.AvatarHash = [32]byte{}
+		msg.Portal.AvatarID = "remove"
+		msg.Portal.AvatarSet = true
+		return true, nil
+	}
+
+	data, err := msg.Portal.Bridge.Bot.DownloadMedia(ctx, avatarURL, msg.Content.MSC3414File)
+	if err != nil {
+		return false, fmt.Errorf("failed to download Matrix room avatar: %w", err)
+	}
+
+	contentType := http.DetectContentType(data)
+	if msg.Content.Info != nil && msg.Content.Info.MimeType != "" {
+		contentType = msg.Content.Info.MimeType
+	}
+	if !strings.HasPrefix(contentType, "image/") {
+		return false, fmt.Errorf("LINE group avatar must be an image, got %s", contentType)
+	}
+
+	err = lc.withLineClientRetry(ctx, func(client *line.Client) error {
+		return client.UploadProfileImage(chatMid, data, contentType)
+	})
+	if err != nil {
+		return false, err
+	}
+
+	hash := sha256.Sum256(data)
+	msg.Portal.AvatarMXC = avatarURL
+	msg.Portal.AvatarHash = hash
+	msg.Portal.AvatarID = networkid.AvatarID(hex.EncodeToString(hash[:]))
+	msg.Portal.AvatarSet = true
+	return true, nil
+}
+
+func (lc *LineClient) withLineClientRetry(ctx context.Context, fn func(*line.Client) error) error {
+	client := line.NewClient(lc.AccessToken)
+	err := fn(client)
+	if err != nil && (lc.isRefreshRequired(err) || lc.isLoggedOut(err)) {
+		if errRecover := lc.recoverToken(ctx); errRecover == nil {
+			client = line.NewClient(lc.AccessToken)
+			err = fn(client)
+		}
+	}
+	return err
+}
+
+func matrixGroupChatMID(portal *bridgev2.Portal) (string, error) {
+	if portal == nil {
+		return "", fmt.Errorf("portal is nil")
+	}
+	if portal.RoomType == database.RoomTypeDM {
+		return "", fmt.Errorf("LINE does not support setting names or avatars for DMs")
+	}
+	chatMid := string(portal.ID)
+	if !isLineGroupPortalID(chatMid) {
+		return "", fmt.Errorf("LINE chat %s is not a group or room", chatMid)
+	}
+	return chatMid, nil
+}
+
+func isLineGroupPortalID(chatMid string) bool {
+	chatMid = strings.ToLower(chatMid)
+	return strings.HasPrefix(chatMid, "c") || strings.HasPrefix(chatMid, "r")
+}
diff --git a/pkg/connector/powerlevels.go b/pkg/connector/powerlevels.go
new file mode 100644
index 0000000..aa6ec79
--- /dev/null
+++ b/pkg/connector/powerlevels.go
@@ -0,0 +1,15 @@
+package connector
+
+import (
+	"maunium.net/go/mautrix/bridgev2"
+	"maunium.net/go/mautrix/event"
+)
+
+func lineGroupPowerLevelOverrides() *bridgev2.PowerLevelOverrides {
+	return &bridgev2.PowerLevelOverrides{
+		Events: map[event.Type]int{
+			event.StateRoomName:   0,
+			event.StateRoomAvatar: 0,
+		},
+	}
+}
diff --git a/pkg/connector/sync.go b/pkg/connector/sync.go
index 9768215..5178d53 100644
--- a/pkg/connector/sync.go
+++ b/pkg/connector/sync.go
@@ -625,6 +625,7 @@ func (lc *LineClient) chatToChatInfo(ctx context.Context, chat *line.Chat, exclu
 		Members: &bridgev2.ChatMemberList{
 			IsFull:                     true,
 			Members:                    members,
+			PowerLevels:                lineGroupPowerLevelOverrides(),
 			ExcludeChangesFromTimeline: excludeFromTimeline,
 		},
 		ExcludeChangesFromTimeline: excludeFromTimeline,
diff --git a/pkg/connector/userinfo.go b/pkg/connector/userinfo.go
index a6d4388..67facd5 100644
--- a/pkg/connector/userinfo.go
+++ b/pkg/connector/userinfo.go
@@ -42,7 +42,7 @@ func (lc *LineClient) HandleMatrixReadReceipt(ctx context.Context, read *bridgev
 }
 
 func (lc *LineClient) GetCapabilities(ctx context.Context, portal *bridgev2.Portal) *event.RoomFeatures {
-	return &event.RoomFeatures{
+	features := &event.RoomFeatures{
 		MaxTextLength:         5000,
 		Reply:                 event.CapLevelFullySupported,
 		Reaction:              event.CapLevelPartialSupport,
@@ -130,6 +130,15 @@ func (lc *LineClient) GetCapabilities(ctx context.Context, portal *bridgev2.Port
 			},
 		},
 	}
+
+	if portal != nil && portal.RoomType != database.RoomTypeDM && isLineGroupPortalID(string(portal.ID)) {
+		features.State = event.StateFeatureMap{
+			event.StateRoomName.Type:   {Level: event.CapLevelFullySupported},
+			event.StateRoomAvatar.Type: {Level: event.CapLevelFullySupported},
+		}
+	}
+
+	return features
 }
 
 func (lc *LineClient) IsThisUser(ctx context.Context, userID networkid.UserID) bool {
diff --git a/pkg/line/client.go b/pkg/line/client.go
index d65f06e..308d68f 100644
--- a/pkg/line/client.go
+++ b/pkg/line/client.go
@@ -415,12 +415,18 @@ func (c *Client) ConfirmE2EELogin(verifier, serverPublicKeyB64, encryptedKeyChai
 // postWithHMAC is a small helper for non-standard RPC endpoints that still expect
 // the same headers and HMAC signature as the Talk endpoints.
 func (c *Client) postWithHMAC(fullURL string, body []byte) ([]byte, error) {
+	return c.postWithHMACContentType(fullURL, body, "application/json")
+}
+
+func (c *Client) postWithHMACContentType(fullURL string, body []byte, contentType string) ([]byte, error) {
 	req, err := http.NewRequest("POST", fullURL, bytes.NewBuffer(body))
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
-	req.Header.Set("Content-Type", "application/json")
+	if contentType != "" {
+		req.Header.Set("Content-Type", contentType)
+	}
 	req.Header.Set("User-Agent", UserAgent)
 	req.Header.Set("x-line-chrome-version", ExtensionVersion)
 	req.Header.Set("x-line-application", "CHROMEOS\t3.7.2\tChrome_OS")
@@ -456,6 +462,29 @@ func (c *Client) postWithHMAC(fullURL string, body []byte) ([]byte, error) {
 	return io.ReadAll(resp.Body)
 }
 
+func (c *Client) UploadProfileImage(mid string, data []byte, contentType string) error {
+	if contentType == "" {
+		contentType = http.DetectContentType(data)
+	}
+	fullURL := fmt.Sprintf(
+		"https://line-chrome-gw.line-apps.com/api/obs/uploadProfile?mid=%s",
+		url.QueryEscape(mid),
+	)
+	respBytes, err := c.postWithHMACContentType(fullURL, data, contentType)
+	if err != nil {
+		return err
+	}
+
+	var wrapper struct {
+		Code    int    `json:"code"`
+		Message string `json:"message"`
+	}
+	if err := json.Unmarshal(respBytes, &wrapper); err == nil && wrapper.Code != 0 {
+		return fmt.Errorf("uploadProfile failed: %s", wrapper.Message)
+	}
+	return nil
+}
+
 func (c *Client) RefreshAccessToken(refreshToken string) (*TokenV3IssueResult, error) {
 	url := "https://line-chrome-gw.line-apps.com/api/auth/tokenRefresh"
 
diff --git a/pkg/line/methods.go b/pkg/line/methods.go
index b976573..0bf1e05 100644
--- a/pkg/line/methods.go
+++ b/pkg/line/methods.go
@@ -1,6 +1,7 @@
 package line
 
 import (
+	"bytes"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
@@ -30,6 +31,12 @@ func InvalidateOBSTokenCache() {
 	obsTokenMu.Unlock()
 }
 
+func unmarshalJSONUseNumber(data []byte, v any) error {
+	dec := json.NewDecoder(bytes.NewReader(data))
+	dec.UseNumber()
+	return dec.Decode(v)
+}
+
 // LoginV2 performs the loginV2 RPC call to authenticate a user
 func (c *Client) LoginV2(email, password, certificate, secret string) ([]byte, error) {
 	return c.LoginV2WithType(2, email, password, certificate, secret)
@@ -610,6 +617,63 @@ func (c *Client) GetChats(mids []string, withMembers, withInvitees bool) (*GetCh
 	return &wrapper.Data, nil
 }
 
+// GetChatForUpdate fetches a raw chat object that can be round-tripped back to
+// updateChat. LINE's Chrome extension mutates its current Redux chat object, and
+// groupExtra member maps contain timestamp values that the bridge's typed Chat
+// struct intentionally normalizes away for membership checks.
+func (c *Client) GetChatForUpdate(chatMid string) (map[string]any, error) {
+	req := GetChatsRequest{
+		ChatMids:     []string{chatMid},
+		WithMembers:  true,
+		WithInvitees: true,
+	}
+	resp, err := c.callRPC("TalkService", "getChats", req, 2)
+	if err != nil {
+		return nil, err
+	}
+	var wrapper struct {
+		Code    int    `json:"code"`
+		Message string `json:"message"`
+		Data    struct {
+			Chats []map[string]any `json:"chats"`
+		} `json:"data"`
+	}
+	if err := unmarshalJSONUseNumber(resp, &wrapper); err != nil {
+		return nil, err
+	}
+	if wrapper.Code != 0 {
+		return nil, fmt.Errorf("getChats failed: %s", wrapper.Message)
+	}
+	if len(wrapper.Data.Chats) == 0 {
+		return nil, fmt.Errorf("chat %s not found", chatMid)
+	}
+	return wrapper.Data.Chats[0], nil
+}
+
+func (c *Client) UpdateChat(chat map[string]any, updatedAttribute int) error {
+	req := UpdateChatRequest{
+		ReqSeq:           int(time.Now().UnixMilli() % 1_000_000_000),
+		Chat:             chat,
+		UpdatedAttribute: updatedAttribute,
+	}
+	resp, err := c.callRPC("TalkService", "updateChat", req)
+	if err != nil {
+		return err
+	}
+	var wrapper struct {
+		Code    int             `json:"code"`
+		Message string          `json:"message"`
+		Data    json.RawMessage `json:"data"`
+	}
+	if err := json.Unmarshal(resp, &wrapper); err != nil {
+		return fmt.Errorf("failed to parse updateChat response: %w", err)
+	}
+	if wrapper.Code != 0 {
+		return fmt.Errorf("updateChat failed: %s", wrapper.Message)
+	}
+	return nil
+}
+
 func (c *Client) GetLastOpRevision() (int64, error) {
 	resp, err := c.callRPC("TalkService", "getLastOpRevision")
 	if err != nil {
diff --git a/pkg/line/structs.go b/pkg/line/structs.go
index d81e1d7..3d72e3a 100644
--- a/pkg/line/structs.go
+++ b/pkg/line/structs.go
@@ -5,9 +5,12 @@ import "encoding/json"
 type FlexibleMidMap map[string]bool
 
 func (f *FlexibleMidMap) UnmarshalJSON(data []byte) error {
-	var m map[string]bool
+	var m map[string]json.RawMessage
 	if err := json.Unmarshal(data, &m); err == nil {
-		*f = m
+		*f = make(FlexibleMidMap, len(m))
+		for mid := range m {
+			(*f)[mid] = true
+		}
 		return nil
 	}
 
@@ -347,3 +350,14 @@ type CreateChatRequest struct {
 type CreateChatResponse2 struct {
 	Chat Chat `json:"chat"`
 }
+
+const (
+	ChatAttributeName          = 1
+	ChatAttributePictureStatus = 2
+)
+
+type UpdateChatRequest struct {
+	ReqSeq           int            `json:"reqSeq"`
+	Chat             map[string]any `json:"chat"`
+	UpdatedAttribute int            `json:"updatedAttribute"`
+}