diff --git a/app/src/main/java/com/example/login_v3/data/api/Main_API_Service.kt b/app/src/main/java/com/example/login_v3/data/api/Main_API_Service.kt
index 9ce0edb..1a75667 100644
--- a/app/src/main/java/com/example/login_v3/data/api/Main_API_Service.kt
+++ b/app/src/main/java/com/example/login_v3/data/api/Main_API_Service.kt
@@ -96,4 +96,11 @@ interface TecnologiaApi {
         @Path("room_id") roomId: String
     ): Response<Unit>
 
+    //send DM message
+    @POST("api/dm/{room_id}/messages")
+    suspend fun sendMessage(
+        @Path("room_id") roomId: String,
+        @Body request: SendMessageRequest
+    ): Response<Message>
+
 }
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diff --git a/app/src/main/java/com/example/login_v3/data/api/api_class/DM_Basic.kt b/app/src/main/java/com/example/login_v3/data/api/api_class/DM_Basic.kt
index bc357a7..2b6c04f 100644
--- a/app/src/main/java/com/example/login_v3/data/api/api_class/DM_Basic.kt
+++ b/app/src/main/java/com/example/login_v3/data/api/api_class/DM_Basic.kt
@@ -114,4 +114,14 @@ data class Message(
         @Json(name = "count") val count: Int,
         @Json(name = "me_reacted") val meReacted: Boolean
     )
-}
\ No newline at end of file
+}
+
+
+
+
+//send message
+@JsonClass(generateAdapter = true)
+data class SendMessageRequest(
+    @Json(name = "content") val content: String,
+    @Json(name = "reply_to_id") val replyToId: String? = null
+)
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diff --git a/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt b/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
index a457817..8c1e772 100644
--- a/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
+++ b/app/src/main/java/com/example/login_v3/data/repository/dm/DM_Basic_Repository.kt
@@ -2,8 +2,10 @@ package com.example.login_v3.data.repository.dm
 
 import com.example.login_v3.data.api.TecnologiaApi
 import com.example.login_v3.data.api.api_class.ChatRoom
+import com.example.login_v3.data.api.api_class.Message
 import com.example.login_v3.data.api.api_class.MessageResponse
 import com.example.login_v3.data.api.api_class.RoomListResponse
+import com.example.login_v3.data.api.api_class.SendMessageRequest
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -81,4 +83,38 @@ class ChatRoomsRepository @Inject constructor(
             Result.failure(e)
         }
     }
+
+    //send message
+    suspend fun sendMessage(
+        roomId: String,
+        content: String,
+        replyToId: String? = null
+    ): Result<Message> {
+        return try {
+            // 打包 Request Body
+            val requestBody = SendMessageRequest(
+                content = content,
+                replyToId = replyToId
+            )
+
+            // 呼叫 API
+            val response = api.sendMessage(roomId, requestBody)
+
+            if (response.isSuccessful) {
+                val body = response.body()
+                if (body != null) {
+                    Result.success(body)
+                } else {
+                    Result.failure(Exception("發送成功但回應身體為空 (Empty response body)"))
+                }
+            } else {
+                // 抓取後端傳回的錯誤訊息
+                val errorMsg = response.errorBody()?.string() ?: "未知錯誤"
+                Result.failure(Exception("發送訊息失敗，錯誤碼: ${response.code()}, 訊息: $errorMsg"))
+            }
+        } catch (e: Exception) {
+            // 捕捉網路斷線或解析 JSON 失敗等狀況
+            Result.failure(e)
+        }
+    }
 }
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