diff --git a/packages/client/src/api/hermes/group-chat.ts b/packages/client/src/api/hermes/group-chat.ts
index 75fa15a4..7b427c3a 100644
--- a/packages/client/src/api/hermes/group-chat.ts
+++ b/packages/client/src/api/hermes/group-chat.ts
@@ -23,6 +23,15 @@ export interface RoomAgent {
     invited: number
 }
 
+export interface AgentAddResult {
+    profile: string
+    ok: boolean
+    agent?: RoomAgent
+    code?: string
+    error?: string
+    reason?: string
+}
+
 export interface ChatMessage {
     id: string
     roomId: string
@@ -133,7 +142,7 @@ export async function createRoom(data: {
     inviteCode: string
     agents?: { profile: string; name?: string; description?: string; invited?: boolean }[]
     compression?: { triggerTokens?: number; maxHistoryTokens?: number; tailMessageCount?: number }
-}): Promise<{ room: RoomInfo; agents: RoomAgent[] }> {
+}): Promise<{ room: RoomInfo; agents: RoomAgent[]; agentResults?: AgentAddResult[] }> {
     return request('/api/hermes/group-chat/rooms', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
@@ -141,7 +150,7 @@ export async function createRoom(data: {
     })
 }
 
-export async function cloneRoom(roomId: string, data?: { name?: string; inviteCode?: string }): Promise<{ room: RoomInfo; agents: RoomAgent[] }> {
+export async function cloneRoom(roomId: string, data?: { name?: string; inviteCode?: string }): Promise<{ room: RoomInfo; agents: RoomAgent[]; agentResults?: AgentAddResult[] }> {
     return request(`/api/hermes/group-chat/rooms/${roomId}/clone`, {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
diff --git a/packages/client/src/components/hermes/group-chat/GroupChatPanel.vue b/packages/client/src/components/hermes/group-chat/GroupChatPanel.vue
index 106b7537..902a0ee6 100644
--- a/packages/client/src/components/hermes/group-chat/GroupChatPanel.vue
+++ b/packages/client/src/components/hermes/group-chat/GroupChatPanel.vue
@@ -64,12 +64,36 @@ function generateCode(): string {
     return code
 }
 
+function formatAgentFailures(results?: Array<{ ok: boolean; profile: string; error?: string; reason?: string }>): string | null {
+    const failed = results?.filter(result => !result.ok) || []
+    if (failed.length === 0) return null
+    const details = failed.map(result => result.reason || result.error || result.profile).join('; ')
+    return t('groupChat.agentAddFailedCount', { count: failed.length, details })
+}
+
+function extractApiErrorMessage(err: any): string {
+    const raw = err?.message || ''
+    const jsonStart = raw.indexOf('{')
+    if (jsonStart >= 0) {
+        try {
+            const parsed = JSON.parse(raw.slice(jsonStart))
+            if (parsed?.code === 'PROFILE_AGENT_CONNECT_FAILED' && parsed?.error) {
+                return parsed.reason ? `${parsed.error}: ${parsed.reason}` : parsed.error
+            }
+            if (parsed?.error) return parsed.error
+        } catch { /* ignore */ }
+    }
+    return raw || t('common.saveFailed')
+}
+
 async function handleCreateRoom(name: string, inviteCode: string, userName: string, description: string, compression: { triggerTokens: number; maxHistoryTokens: number; tailMessageCount: number }) {
     try {
         store.setUserInfo(userName, description)
         const res = await store.createNewRoom(name, inviteCode, undefined, compression)
         showCreateModal.value = false
-        message.success(t('groupChat.roomCreated'))
+        const failureMessage = formatAgentFailures(res.agentResults)
+        if (failureMessage) message.warning(failureMessage)
+        else message.success(t('groupChat.roomCreated'))
         await store.joinRoom(res.room.id)
     } catch {
         message.error(t('common.saveFailed'))
@@ -105,7 +129,9 @@ async function confirmCloneRoom() {
         cloneRoomName.value = ''
         cloneInviteCode.value = ''
         await store.joinRoom(res.room.id)
-        message.success(t('groupChat.roomCloned'))
+        const failureMessage = formatAgentFailures(res.agentResults)
+        if (failureMessage) message.warning(failureMessage)
+        else message.success(t('groupChat.roomCloned'))
     } catch {
         message.error(t('common.saveFailed'))
     }
@@ -170,7 +196,7 @@ async function confirmAddAgent() {
         if (err.message?.includes('already')) {
             message.warning(t('groupChat.agentAlreadyInRoom'))
         } else {
-            message.error(t('common.saveFailed'))
+            message.error(extractApiErrorMessage(err))
         }
     }
 }
diff --git a/packages/client/src/i18n/locales/de.ts b/packages/client/src/i18n/locales/de.ts
index 816a7228..e8713941 100644
--- a/packages/client/src/i18n/locales/de.ts
+++ b/packages/client/src/i18n/locales/de.ts
@@ -1104,6 +1104,7 @@ jobTriggered: 'Job ausgelost',
     selectProfile: 'Wahlen Sie ein Profil',
     agentAdded: 'Agent hinzugefugt',
     agentAlreadyInRoom: 'Agent ist bereits in diesem Raum',
+    agentAddFailedCount: '{count} Agent(en) wurden nicht hinzugefugt: {details}',
     noAgents: 'Keine Agenten in diesem Raum',
     members: 'Mitglieder',
     roomCreated: 'Raum erstellt',
diff --git a/packages/client/src/i18n/locales/en.ts b/packages/client/src/i18n/locales/en.ts
index bbab7e68..770c0760 100644
--- a/packages/client/src/i18n/locales/en.ts
+++ b/packages/client/src/i18n/locales/en.ts
@@ -1053,6 +1053,7 @@ export default {
     selectProfile: 'Select a profile',
     agentAdded: 'Agent added',
     agentAlreadyInRoom: 'Agent already in this room',
+    agentAddFailedCount: '{count} agent(s) were not added: {details}',
     noAgents: 'No agents in this room',
     members: 'members',
     roomCreated: 'Room created',
diff --git a/packages/client/src/i18n/locales/es.ts b/packages/client/src/i18n/locales/es.ts
index 866363bf..2c7092ec 100644
--- a/packages/client/src/i18n/locales/es.ts
+++ b/packages/client/src/i18n/locales/es.ts
@@ -1104,6 +1104,7 @@ jobTriggered: 'Job ejecutado',
     selectProfile: 'Seleccione un perfil',
     agentAdded: 'Agente agregado',
     agentAlreadyInRoom: 'El agente ya esta en esta sala',
+    agentAddFailedCount: 'No se agregaron {count} agente(s): {details}',
     noAgents: 'No hay agentes en esta sala',
     members: 'Miembros',
     roomCreated: 'Sala creada',
diff --git a/packages/client/src/i18n/locales/fr.ts b/packages/client/src/i18n/locales/fr.ts
index c70aa448..efe4afb4 100644
--- a/packages/client/src/i18n/locales/fr.ts
+++ b/packages/client/src/i18n/locales/fr.ts
@@ -1104,6 +1104,7 @@ jobTriggered: 'Job declenche',
     selectProfile: 'Selectionnez un profil',
     agentAdded: 'Agent ajoute',
     agentAlreadyInRoom: "L'agent est deja dans ce salon",
+    agentAddFailedCount: "{count} agent(s) n'ont pas ete ajoutes : {details}",
     noAgents: 'Aucun agent dans ce salon',
     members: 'Membres',
     roomCreated: 'Salon cree',
diff --git a/packages/client/src/i18n/locales/ja.ts b/packages/client/src/i18n/locales/ja.ts
index c653f192..12caceb3 100644
--- a/packages/client/src/i18n/locales/ja.ts
+++ b/packages/client/src/i18n/locales/ja.ts
@@ -1104,6 +1104,7 @@ export default {
     selectProfile: 'プロファイルを選択',
     agentAdded: 'エージェントが追加されました',
     agentAlreadyInRoom: 'このエージェントは既にルームにいます',
+    agentAddFailedCount: '{count} 件のエージェントを追加できませんでした: {details}',
     noAgents: 'このルームにエージェントはいません',
     members: 'メンバー',
     roomCreated: 'ルームが作成されました',
diff --git a/packages/client/src/i18n/locales/ko.ts b/packages/client/src/i18n/locales/ko.ts
index e1355110..88f949f3 100644
--- a/packages/client/src/i18n/locales/ko.ts
+++ b/packages/client/src/i18n/locales/ko.ts
@@ -1104,6 +1104,7 @@ export default {
     selectProfile: '프로필 선택',
     agentAdded: '에이전트가 추가되었습니다',
     agentAlreadyInRoom: '해당 에이전트가 이미 방에 있습니다',
+    agentAddFailedCount: '{count}개의 에이전트를 추가하지 못했습니다: {details}',
     noAgents: '이 방에 에이전트가 없습니다',
     members: '멤버',
     roomCreated: '방이 생성되었습니다',
diff --git a/packages/client/src/i18n/locales/pt.ts b/packages/client/src/i18n/locales/pt.ts
index baed158a..a7d390d4 100644
--- a/packages/client/src/i18n/locales/pt.ts
+++ b/packages/client/src/i18n/locales/pt.ts
@@ -1104,6 +1104,7 @@ jobTriggered: 'Job acionado',
     selectProfile: 'Selecione um perfil',
     agentAdded: 'Agente adicionado',
     agentAlreadyInRoom: 'O agente ja esta nesta sala',
+    agentAddFailedCount: '{count} agente(s) nao foram adicionados: {details}',
     noAgents: 'Nenhum agente nesta sala',
     members: 'Membros',
     roomCreated: 'Sala criada',
diff --git a/packages/client/src/i18n/locales/zh-TW.ts b/packages/client/src/i18n/locales/zh-TW.ts
index 3effe88a..945de8d6 100644
--- a/packages/client/src/i18n/locales/zh-TW.ts
+++ b/packages/client/src/i18n/locales/zh-TW.ts
@@ -1056,6 +1056,7 @@ export default {
     selectProfile: '選擇一個設定檔',
     agentAdded: '智慧代理已新增',
     agentAlreadyInRoom: '該智慧代理已在房間中',
+    agentAddFailedCount: '{count} 個智慧代理未新增：{details}',
     noAgents: '目前房間無智慧代理',
     members: '成員',
     roomCreated: '房間已建立',
diff --git a/packages/client/src/i18n/locales/zh.ts b/packages/client/src/i18n/locales/zh.ts
index 4d4d545a..0ace8fca 100644
--- a/packages/client/src/i18n/locales/zh.ts
+++ b/packages/client/src/i18n/locales/zh.ts
@@ -1055,6 +1055,7 @@ export default {
     selectProfile: '选择一个配置',
     agentAdded: '智能体已添加',
     agentAlreadyInRoom: '该智能体已在房间中',
+    agentAddFailedCount: '{count} 个智能体未添加：{details}',
     noAgents: '当前房间暂无智能体',
     members: '成员',
     roomCreated: '房间已创建',
diff --git a/packages/server/src/routes/hermes/group-chat.ts b/packages/server/src/routes/hermes/group-chat.ts
index 5d07768d..5159c674 100644
--- a/packages/server/src/routes/hermes/group-chat.ts
+++ b/packages/server/src/routes/hermes/group-chat.ts
@@ -27,6 +27,47 @@ function generateInviteCode(): string {
     return code
 }
 
+type AgentInput = { profile: string; name?: string; description?: string; invited?: boolean | number }
+
+function sanitizeAgentConnectReason(reason?: string): string {
+    return (reason || 'agent runtime connection failed')
+        .replace(/Bearer\s+[A-Za-z0-9._~+\/-]+/gi, 'Bearer [REDACTED]')
+        .replace(/(api[_-]?key|token|secret|password)=([^\s]+)/gi, '$1=[REDACTED]')
+        .split('\n')[0]
+        .slice(0, 240)
+}
+
+function agentConnectFailureBody(profile: string, err: any) {
+    return {
+        code: 'PROFILE_AGENT_CONNECT_FAILED',
+        error: `Failed to connect agent "${profile}" to room`,
+        profile,
+        reason: sanitizeAgentConnectReason(err?.message),
+    }
+}
+
+async function connectAndPersistRoomAgent(server: GroupChatServer, roomId: string, input: AgentInput, agentId = generateId()) {
+    const profile = input.profile
+    const name = input.name || profile
+    const description = input.description || ''
+    const invited = input.invited ? 1 : 0
+    const client = await server.agentClients.createAgent({
+        agentId,
+        profile,
+        name,
+        description,
+        invited,
+    })
+
+    try {
+        await server.agentClients.addAgentToRoom(roomId, client)
+        return server.getStorage().addRoomAgent(roomId, agentId, profile, name, description, invited)
+    } catch (err) {
+        server.agentClients.removeAgentFromRoom(roomId, client.agentId)
+        throw err
+    }
+}
+
 // Create room
 groupChatRoutes.post('/api/hermes/group-chat/rooms', async (ctx) => {
     if (!chatServer) {
@@ -57,29 +98,26 @@ groupChatRoutes.post('/api/hermes/group-chat/rooms', async (ctx) => {
     const storage = chatServer.getStorage()
     storage.saveRoom(roomId, name, inviteCode, compression)
 
-    // Save agents to DB and auto-connect via Socket.IO
     const addedAgents = []
+    const agentResults = []
     for (const a of agents || []) {
-        const agentId = generateId()
-        const agent = storage.addRoomAgent(roomId, agentId, a.profile, a.name || a.profile, a.description || '', a.invited ? 1 : 0)
-        addedAgents.push(agent)
-
         try {
-            const client = await chatServer.agentClients.createAgent({
-                agentId: agent.agentId,
-                profile: agent.profile,
-                name: agent.name,
-                description: agent.description,
-                invited: agent.invited,
+            const agent = await connectAndPersistRoomAgent(chatServer, roomId, {
+                profile: a.profile,
+                name: a.name || a.profile,
+                description: a.description || '',
+                invited: a.invited,
             })
-            await chatServer.agentClients.addAgentToRoom(roomId, client)
+            addedAgents.push(agent)
+            agentResults.push({ profile: a.profile, ok: true, agent })
         } catch (err: any) {
-            console.error(`[GroupChat] Failed to connect agent ${a.profile} to room ${roomId}: ${err.message}`)
+            console.error(`[GroupChat] Failed to connect agent ${a.profile} to room ${roomId}: ${sanitizeAgentConnectReason(err.message)}`)
+            agentResults.push({ ok: false, ...agentConnectFailureBody(a.profile, err) })
         }
     }
 
     const room = storage.getRoom(roomId)
-    ctx.body = { room, agents: addedAgents }
+    ctx.body = { room, agents: addedAgents, agentResults }
 })
 
 // Clone room roles/config without copying the conversation context.
@@ -108,34 +146,25 @@ groupChatRoutes.post('/api/hermes/group-chat/rooms/:roomId/clone', async (ctx) =
     })
 
     const addedAgents = []
+    const agentResults = []
     for (const sourceAgent of storage.getRoomAgents(sourceRoom.id)) {
-        const agentId = generateId()
-        const agent = storage.addRoomAgent(
-            roomId,
-            agentId,
-            sourceAgent.profile,
-            sourceAgent.name,
-            sourceAgent.description,
-            sourceAgent.invited,
-        )
-        addedAgents.push(agent)
-
         try {
-            const client = await chatServer.agentClients.createAgent({
-                agentId: agent.agentId,
-                profile: agent.profile,
-                name: agent.name,
-                description: agent.description,
-                invited: agent.invited,
+            const agent = await connectAndPersistRoomAgent(chatServer, roomId, {
+                profile: sourceAgent.profile,
+                name: sourceAgent.name,
+                description: sourceAgent.description,
+                invited: sourceAgent.invited,
             })
-            await chatServer.agentClients.addAgentToRoom(roomId, client)
+            addedAgents.push(agent)
+            agentResults.push({ profile: sourceAgent.profile, ok: true, agent })
         } catch (err: any) {
-            console.error(`[GroupChat] Failed to connect cloned agent ${agent.profile} to room ${roomId}: ${err.message}`)
+            console.error(`[GroupChat] Failed to connect cloned agent ${sourceAgent.profile} to room ${roomId}: ${sanitizeAgentConnectReason(err.message)}`)
+            agentResults.push({ ok: false, ...agentConnectFailureBody(sourceAgent.profile, err) })
         }
     }
 
     const room = storage.getRoom(roomId)
-    ctx.body = { room, agents: addedAgents }
+    ctx.body = { room, agents: addedAgents, agentResults }
 })
 
 // Get room detail and messages
@@ -236,24 +265,19 @@ groupChatRoutes.post('/api/hermes/group-chat/rooms/:roomId/agents', async (ctx)
         return
     }
 
-    const agentId = generateId()
-    const agent = chatServer.getStorage().addRoomAgent(ctx.params.roomId, agentId, profile, name || profile, description || '', invited ? 1 : 0)
-
-    // Auto-connect agent via Socket.IO
     try {
-        const client = await chatServer.agentClients.createAgent({
-            agentId: agent.agentId,
-            profile: agent.profile,
-            name: agent.name,
-            description: agent.description,
-            invited: agent.invited,
+        const agent = await connectAndPersistRoomAgent(chatServer, ctx.params.roomId, {
+            profile,
+            name: name || profile,
+            description: description || '',
+            invited,
         })
-        await chatServer.agentClients.addAgentToRoom(ctx.params.roomId, client)
+        ctx.body = { agent }
     } catch (err: any) {
-        console.error(`[GroupChat] Failed to connect agent ${profile} to room ${ctx.params.roomId}: ${err.message}`)
+        console.error(`[GroupChat] Failed to connect agent ${profile} to room ${ctx.params.roomId}: ${sanitizeAgentConnectReason(err.message)}`)
+        ctx.status = 502
+        ctx.body = agentConnectFailureBody(profile, err)
     }
-
-    ctx.body = { agent }
 })
 
 // List agents in room
diff --git a/packages/server/src/services/hermes/group-chat/agent-clients.ts b/packages/server/src/services/hermes/group-chat/agent-clients.ts
index d1e1e676..26d9aed2 100644
--- a/packages/server/src/services/hermes/group-chat/agent-clients.ts
+++ b/packages/server/src/services/hermes/group-chat/agent-clients.ts
@@ -711,9 +711,16 @@ export class AgentClients {
         }
 
         room.set(client.agentId, client)
-        const result = await client.joinRoom(roomId)
-        logger.info(`[AgentClients] ${client.name} joined room: ${roomId}`)
-        return result
+        try {
+            const result = await client.joinRoom(roomId)
+            logger.info(`[AgentClients] ${client.name} joined room: ${roomId}`)
+            return result
+        } catch (err) {
+            room.delete(client.agentId)
+            if (room.size === 0) this.rooms.delete(roomId)
+            client.disconnect()
+            throw err
+        }
     }
 
     /**
diff --git a/tests/server/group-chat-member-sync.test.ts b/tests/server/group-chat-member-sync.test.ts
index ea754924..5be27312 100644
--- a/tests/server/group-chat-member-sync.test.ts
+++ b/tests/server/group-chat-member-sync.test.ts
@@ -101,6 +101,95 @@ describe('Group Chat member/agent identity sync', () => {
     }))
   })
 
+  it('does not persist an agent when the runtime client cannot connect', async () => {
+    const addRoomAgent = vi.fn()
+    const chatServer = {
+      getStorage: () => ({
+        getRoomAgents: vi.fn(() => []),
+        addRoomAgent,
+      }),
+      agentClients: {
+        createAgent: vi.fn(async () => {
+          throw new Error('Connection timeout')
+        }),
+        addAgentToRoom: vi.fn(),
+        removeAgentFromRoom: vi.fn(),
+      },
+    }
+    setGroupChatServer(chatServer as any)
+
+    const handler = routeHandler('/api/hermes/group-chat/rooms/:roomId/agents', 'POST')
+    const ctx: any = {
+      params: { roomId: 'room-1' },
+      request: { body: { profile: 'default', name: 'Worker' } },
+      status: 200,
+      body: undefined,
+    }
+    await handler(ctx, async () => {})
+
+    expect(ctx.status).toBe(502)
+    expect(ctx.body).toMatchObject({
+      code: 'PROFILE_AGENT_CONNECT_FAILED',
+      profile: 'default',
+      reason: 'Connection timeout',
+    })
+    expect(addRoomAgent).not.toHaveBeenCalled()
+  })
+
+  it('does not persist an agent and disconnects runtime state when room join fails', async () => {
+    const addRoomAgent = vi.fn()
+    const runtimeClient = { agentId: 'agent-stable-1' }
+    const chatServer = {
+      getStorage: () => ({
+        getRoomAgents: vi.fn(() => []),
+        addRoomAgent,
+      }),
+      agentClients: {
+        createAgent: vi.fn(async () => runtimeClient),
+        addAgentToRoom: vi.fn(async () => {
+          throw new Error('join failed')
+        }),
+        removeAgentFromRoom: vi.fn(),
+      },
+    }
+    setGroupChatServer(chatServer as any)
+
+    const handler = routeHandler('/api/hermes/group-chat/rooms/:roomId/agents', 'POST')
+    const ctx: any = {
+      params: { roomId: 'room-1' },
+      request: { body: { profile: 'default', name: 'Worker' } },
+      status: 200,
+      body: undefined,
+    }
+    await handler(ctx, async () => {})
+
+    expect(ctx.status).toBe(502)
+    expect(ctx.body).toMatchObject({
+      code: 'PROFILE_AGENT_CONNECT_FAILED',
+      profile: 'default',
+      reason: 'join failed',
+    })
+    expect(addRoomAgent).not.toHaveBeenCalled()
+    expect(chatServer.agentClients.removeAgentFromRoom).toHaveBeenCalledWith('room-1', 'agent-stable-1')
+  })
+
+  it('rolls back AgentClients room state when joining a room fails', async () => {
+    const clients = new AgentClients()
+    const runtimeClient = {
+      agentId: 'agent-stable-1',
+      name: 'Worker',
+      joinRoom: vi.fn(async () => {
+        throw new Error('join failed')
+      }),
+      disconnect: vi.fn(),
+    }
+
+    await expect(clients.addAgentToRoom('room-1', runtimeClient as any)).rejects.toThrow('join failed')
+
+    expect(runtimeClient.disconnect).toHaveBeenCalled()
+    expect(clients.getAgents('room-1')).toEqual([])
+  })
+
   it('removes the runtime agent by persisted agentId and returns synchronized room state', async () => {
     const agentsBefore = [{ id: 'row-1', roomId: 'room-1', agentId: 'agent-stable-1', profile: 'default', name: 'Worker', description: '', invited: 0 }]
     const storage = {