feat(assistants): add attachments.fileId field to MessageRequest (#367)

Author: 0chil

openai-core/src/commonMain/kotlin/com.aallam.openai.api/message/Attachment.kt

@@ -0,0 +1,16 @@
+package com.aallam.openai.api.message
+
+import com.aallam.openai.api.file.FileId
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+/**
+ * References an Attachment in the message request.
+ */
+@Serializable
+public data class Attachment(
+    /**
+     * The ID of the file to attach to the message.
+     */
+    @SerialName("file_id") val fileId: FileId
+)

openai-core/src/commonMain/kotlin/com.aallam.openai.api/message/MessageRequest.kt

@@ -2,7 +2,6 @@ package com.aallam.openai.api.message
 
 import com.aallam.openai.api.BetaOpenAI
 import com.aallam.openai.api.core.Role
-import com.aallam.openai.api.file.FileId
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 
@@ -22,6 +21,11 @@ public class MessageRequest(
      */
     @SerialName("content") public val content: String,
 
+    /**
+     * A list of files attached to the message.
+     */
+    @SerialName("attachments") public val attachments: List<Attachment>? = null,
+
     /**
      * Set of 16 key-value pairs that can be attached to an object.
      * This can be useful for storing additional information about the object in a structured format.
@@ -52,6 +56,11 @@ public class MessageRequestBuilder {
      */
     public var content: String? = null
 
+    /**
+     * A list of files attached to the message.
+     */
+    public var attachments: List<Attachment>? = null
+
     /**
      * Set of 16 key-value pairs that can be attached to an object.
      * This can be useful for storing additional information about the object in a structured format.
@@ -62,6 +71,7 @@ public class MessageRequestBuilder {
     public fun build(): MessageRequest = MessageRequest(
         role = requireNotNull(role) { "role is required" },
         content = requireNotNull(content) { "content is required" },
+        attachments = attachments,
         metadata = metadata
     )
 }