diff --git a/openapi/user/README.md b/openapi/user/README.md
index c1f1632f..6251c989 100644
--- a/openapi/user/README.md
+++ b/openapi/user/README.md
@@ -78,16 +78,16 @@ This module provides comprehensive user management APIs including authentication
 | DELETE | `/user/api-keys/:key_id`            | Required | Delete API key                     |
 | POST   | `/user/api-keys/:key_id/regenerate` | Required | Regenerate API key                 |
 
-### Balance & Credits
+### Credits & Top-up
 
 | Method | Endpoint                        | Auth     | Description                |
 | ------ | ------------------------------- | -------- | -------------------------- |
-| GET    | `/user/balance`                 | Required | Get user balance info      |
-| GET    | `/user/balance/history`         | Required | Get balance change history |
-| GET    | `/user/balance/topup`           | Required | Get topup records          |
-| POST   | `/user/balance/topup`           | Required | Create topup order         |
-| GET    | `/user/balance/topup/:order_id` | Required | Get topup order status     |
-| POST   | `/user/balance/topup/card-code` | Required | Redeem card code           |
+| GET    | `/user/credits`                 | Required | Get user credits info      |
+| GET    | `/user/credits/history`         | Required | Get credits change history |
+| GET    | `/user/credits/topup`           | Required | Get topup records          |
+| POST   | `/user/credits/topup`           | Required | Create topup order         |
+| GET    | `/user/credits/topup/:order_id` | Required | Get topup order status     |
+| POST   | `/user/credits/topup/card-code` | Required | Redeem card code           |
 
 ### Subscription Management
 
@@ -105,33 +105,61 @@ This module provides comprehensive user management APIs including authentication
 
 ### Billing & Invoices
 
-| Method | Endpoint                | Auth     | Description                 |
-| ------ | ----------------------- | -------- | --------------------------- |
-| PUT    | `/user/billing/history` | Required | Update user billing history |
+| Method | Endpoint                 | Auth     | Description              |
+| ------ | ------------------------ | -------- | ------------------------ |
+| GET    | `/user/billing/history`  | Required | Get user billing history |
+| GET    | `/user/billing/invoices` | Required | Get user invoices list   |
 
 ### Referral & Invitations
 
-| Method | Endpoint                   | Auth     | Description                 |
-| ------ | -------------------------- | -------- | --------------------------- |
-| GET    | `/user/invite/code`        | Required | Get user invite code        |
-| GET    | `/user/invite/statistics`  | Required | Get user invite statistics  |
-| GET    | `/user/invite/history`     | Required | Get user invite history     |
-| GET    | `/user/invite/commissions` | Required | Get user invite commissions |
+| Method | Endpoint                     | Auth     | Description                   |
+| ------ | ---------------------------- | -------- | ----------------------------- |
+| GET    | `/user/referral/code`        | Required | Get user referral code        |
+| GET    | `/user/referral/statistics`  | Required | Get user referral statistics  |
+| GET    | `/user/referral/history`     | Required | Get user referral history     |
+| GET    | `/user/referral/commissions` | Required | Get user referral commissions |
 
 ### Team Management
 
-| Method | Endpoint                                  | Auth     | Description                  |
-| ------ | ----------------------------------------- | -------- | ---------------------------- |
-| GET    | `/user/teams`                             | Required | Get user teams               |
-| POST   | `/user/teams`                             | Required | Create user team             |
-| GET    | `/user/teams/:team_id`                    | Required | Get user team details        |
-| PUT    | `/user/teams/:team_id`                    | Required | Update user team             |
-| DELETE | `/user/teams/:team_id`                    | Required | Delete user team             |
-| GET    | `/user/teams/:team_id/members`            | Required | Get user team members        |
-| GET    | `/user/teams/:team_id/members/:member_id` | Required | Get user team member details |
-| POST   | `/user/teams/:team_id/members/:type`      | Required | Create user team member      |
-| PUT    | `/user/teams/:team_id/members/:member_id` | Required | Update user team member      |
-| DELETE | `/user/teams/:team_id/members/:member_id` | Required | Remove user team member      |
+#### Team CRUD
+
+| Method | Endpoint               | Auth     | Description           |
+| ------ | ---------------------- | -------- | --------------------- |
+| GET    | `/user/teams`          | Required | Get user teams        |
+| POST   | `/user/teams`          | Required | Create user team      |
+| GET    | `/user/teams/:team_id` | Required | Get user team details |
+| PUT    | `/user/teams/:team_id` | Required | Update user team      |
+| DELETE | `/user/teams/:team_id` | Required | Delete user team      |
+
+#### Member Management
+
+| Method | Endpoint                                  | Auth     | Description                       |
+| ------ | ----------------------------------------- | -------- | --------------------------------- |
+| GET    | `/user/teams/:team_id/members`            | Required | Get user team members             |
+| GET    | `/user/teams/:team_id/members/:member_id` | Required | Get user team member details      |
+| POST   | `/user/teams/:team_id/members/direct`     | Required | Add member directly (bots/system) |
+| PUT    | `/user/teams/:team_id/members/:member_id` | Required | Update user team member           |
+| DELETE | `/user/teams/:team_id/members/:member_id` | Required | Remove user team member           |
+
+#### Team Invitations
+
+| Method | Endpoint                                                 | Auth     | Description            |
+| ------ | -------------------------------------------------------- | -------- | ---------------------- |
+| POST   | `/user/teams/:team_id/invitations`                       | Required | Send team invitation   |
+| GET    | `/user/teams/:team_id/invitations`                       | Required | Get team invitations   |
+| GET    | `/user/teams/:team_id/invitations/:invitation_id`        | Required | Get invitation details |
+| PUT    | `/user/teams/:team_id/invitations/:invitation_id/resend` | Required | Resend invitation      |
+| DELETE | `/user/teams/:team_id/invitations/:invitation_id`        | Required | Cancel invitation      |
+
+### Invitation Response (Cross-module)
+
+_Universal invitation response endpoints that handle invitations from any module (teams, organizations, etc.)_
+
+| Method | Endpoint                           | Auth     | Description                  |
+| ------ | ---------------------------------- | -------- | ---------------------------- |
+| GET    | `/user/invitations/:token`         | Public   | Get invitation info by token |
+| POST   | `/user/invitations/:token/accept`  | Required | Accept invitation            |
+| POST   | `/user/invitations/:token/decline` | Public   | Decline invitation           |
 
 ### User Preferences
 
@@ -170,3 +198,17 @@ This module provides comprehensive user management APIs including authentication
 - Rate limiting may apply to sensitive operations (password reset, verification codes)
 - This module is designed to eventually replace the `signin` module
 - OAuth callbacks support both GET (Google, GitHub) and POST (Apple, WeChat) methods
+
+## Architecture
+
+### Modular Design
+
+- **Team Management**: Handles team CRUD, member management, and invitation sending
+- **Invitation Response**: Universal cross-module invitation handling (accept/decline)
+- **Dual Member Addition**: Supports both direct addition (bots/system) and invitation flow (users)
+
+### Invitation Flow
+
+1. **Send Invitation**: `POST /user/teams/:team_id/invitations`
+2. **Manage Invitations**: View, resend, or cancel via team-specific endpoints
+3. **Respond to Invitation**: Universal endpoints handle acceptance/decline regardless of source module
diff --git a/openapi/user/user.go b/openapi/user/user.go
index 40c60d0f..fb2e31e4 100644
--- a/openapi/user/user.go
+++ b/openapi/user/user.go
@@ -22,13 +22,14 @@ func Attach(group *gin.RouterGroup, oauth types.OAuth) {
 	attachAccount(group, oauth)      // Account settings
 	attachThirdParty(group, oauth)   // Third party login
 	attachMFA(group, oauth)          // MFA settings
-	attachBalance(group, oauth)      // User balance management
+	attachCredits(group, oauth)      // User credits management
 	attachSubscription(group, oauth) // User subscription management
 	attachAPIKeys(group, oauth)      // User API keys management
 	attachUsage(group, oauth)        // User usage management
 	attachBilling(group, oauth)      // User billing management
-	attachInvite(group, oauth)       // User invite management
+	attachReferral(group, oauth)     // User referral management
 	attachTeam(group, oauth)         // User team management
+	attachInvitations(group, oauth)  // Invitation response management
 	attachPrivacy(group, oauth)      // User privacy management
 
 	// User Management
@@ -39,6 +40,8 @@ func Attach(group *gin.RouterGroup, oauth types.OAuth) {
 func attachTeam(group *gin.RouterGroup, oauth types.OAuth) {
 	team := group.Group("/teams")
 	team.Use(oauth.Guard)
+
+	// Team CRUD
 	team.GET("/", placeholder)            // Get user teams
 	team.GET("/:team_id", placeholder)    // Get user team details
 	team.POST("/", placeholder)           // Create user team
@@ -48,9 +51,24 @@ func attachTeam(group *gin.RouterGroup, oauth types.OAuth) {
 	// Member Management
 	team.GET("/:team_id/members", placeholder)               // Get user team members
 	team.GET("/:team_id/members/:member_id", placeholder)    // Get user team member details
-	team.POST("/:team_id/members/:type", placeholder)        // Create user team member
+	team.POST("/:team_id/members/direct", placeholder)       // Add member directly (for bots/system)
 	team.PUT("/:team_id/members/:member_id", placeholder)    // Update user team member
 	team.DELETE("/:team_id/members/:member_id", placeholder) // Remove user team member
+
+	// Member Invitation Management
+	team.POST("/:team_id/invitations", placeholder)                      // Send team invitation
+	team.GET("/:team_id/invitations", placeholder)                       // Get team invitations
+	team.GET("/:team_id/invitations/:invitation_id", placeholder)        // Get invitation details
+	team.PUT("/:team_id/invitations/:invitation_id/resend", placeholder) // Resend invitation
+	team.DELETE("/:team_id/invitations/:invitation_id", placeholder)     // Cancel invitation
+}
+
+// Invitation Response Management (Cross-module invitation handling)
+func attachInvitations(group *gin.RouterGroup, oauth types.OAuth) {
+	// Public endpoints for invitation recipients
+	group.GET("/invitations/:token", placeholder)                      // Get invitation info by token (public)
+	group.POST("/invitations/:token/accept", oauth.Guard, placeholder) // Accept invitation (requires login)
+	group.POST("/invitations/:token/decline", placeholder)             // Decline invitation (public)
 }
 
 // User Privacy
@@ -76,30 +94,31 @@ func attachPreferences(group *gin.RouterGroup, oauth types.OAuth) {
 func attachBilling(group *gin.RouterGroup, oauth types.OAuth) {
 	billing := group.Group("/billing")
 	billing.Use(oauth.Guard)
-	billing.PUT("/history", placeholder) // Update user billing history
+	billing.GET("/history", placeholder)  // Get user billing history
+	billing.GET("/invoices", placeholder) // Get user invoices list
 }
 
-// Invite Management
-func attachInvite(group *gin.RouterGroup, oauth types.OAuth) {
-	invite := group.Group("/invite")
-	invite.Use(oauth.Guard)
+// Referral Management
+func attachReferral(group *gin.RouterGroup, oauth types.OAuth) {
+	referral := group.Group("/referral")
+	referral.Use(oauth.Guard)
 
-	invite.GET("/code", placeholder)        // Get user invite code
-	invite.GET("/statistics", placeholder)  // Get user invite statistics
-	invite.GET("/history", placeholder)     // Get user invite history
-	invite.GET("/commissions", placeholder) // Get user invite commissions
+	referral.GET("/code", placeholder)        // Get user referral code
+	referral.GET("/statistics", placeholder)  // Get user referral statistics
+	referral.GET("/history", placeholder)     // Get user referral history
+	referral.GET("/commissions", placeholder) // Get user referral commissions
 }
 
-// User Balance Management
-func attachBalance(group *gin.RouterGroup, oauth types.OAuth) {
-	balance := group.Group("/balance")
-	balance.Use(oauth.Guard)
+// User Credits Management
+func attachCredits(group *gin.RouterGroup, oauth types.OAuth) {
+	credits := group.Group("/credits")
+	credits.Use(oauth.Guard)
 
-	balance.GET("/", placeholder)        // Get user balance info
-	balance.GET("/history", placeholder) // Get balance change history
+	credits.GET("/", placeholder)        // Get user credits info
+	credits.GET("/history", placeholder) // Get credits change history
 
 	// Top-up Management
-	topup := balance.Group("/topup")
+	topup := credits.Group("/topup")
 	topup.GET("/", placeholder)           // Get topup records
 	topup.POST("/", placeholder)          // Create topup order
 	topup.GET("/:order_id", placeholder)  // Get topup order status