Improved types, added comment and added test (#158)

Author: dstibbe

kotlin-sdk-core/api/kotlin-sdk-core.api

@@ -458,6 +458,10 @@ public final class io/modelcontextprotocol/kotlin/sdk/ContentBlock$Companion {
 	public final fun serializer ()Lkotlinx/serialization/KSerializer;
 }
 
+public abstract interface class io/modelcontextprotocol/kotlin/sdk/ContentWithType {
+	public abstract fun getType ()Ljava/lang/String;
+}
+
 public final class io/modelcontextprotocol/kotlin/sdk/CreateElicitationRequest : io/modelcontextprotocol/kotlin/sdk/ServerRequest, io/modelcontextprotocol/kotlin/sdk/WithMeta {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/CreateElicitationRequest$Companion;
 	public fun <init> (Ljava/lang/String;Lio/modelcontextprotocol/kotlin/sdk/CreateElicitationRequest$RequestedSchema;Lkotlinx/serialization/json/JsonObject;)V
@@ -664,7 +668,7 @@ public final class io/modelcontextprotocol/kotlin/sdk/CreateMessageResult$Compan
 	public final fun serializer ()Lkotlinx/serialization/KSerializer;
 }
 
-public abstract interface class io/modelcontextprotocol/kotlin/sdk/CreateMessageResultContent : io/modelcontextprotocol/kotlin/sdk/ContentBlock {
+public abstract interface class io/modelcontextprotocol/kotlin/sdk/CreateMessageResultContent : io/modelcontextprotocol/kotlin/sdk/ContentWithType {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/CreateMessageResultContent$Companion;
 }
 
@@ -2039,8 +2043,7 @@ public final class io/modelcontextprotocol/kotlin/sdk/PromptMessage$Companion {
 	public final fun serializer ()Lkotlinx/serialization/KSerializer;
 }
 
-public abstract interface class io/modelcontextprotocol/kotlin/sdk/PromptMessageContent {
-	public abstract fun getType ()Ljava/lang/String;
+public abstract interface class io/modelcontextprotocol/kotlin/sdk/PromptMessageContent : io/modelcontextprotocol/kotlin/sdk/ContentWithType {
 }
 
 public abstract interface class io/modelcontextprotocol/kotlin/sdk/PromptMessageContentMultimodal : io/modelcontextprotocol/kotlin/sdk/PromptMessageContent {
@@ -2635,7 +2638,7 @@ public final class io/modelcontextprotocol/kotlin/sdk/SamplingMessage$Companion
 	public final fun serializer ()Lkotlinx/serialization/KSerializer;
 }
 
-public abstract interface class io/modelcontextprotocol/kotlin/sdk/SamplingMessageContent : io/modelcontextprotocol/kotlin/sdk/ContentBlock {
+public abstract interface class io/modelcontextprotocol/kotlin/sdk/SamplingMessageContent : io/modelcontextprotocol/kotlin/sdk/ContentWithType {
 	public static final field Companion Lio/modelcontextprotocol/kotlin/sdk/SamplingMessageContent$Companion;
 }
 

kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt

@@ -974,11 +974,22 @@ public data class GetPromptRequest(
     override val method: Method = Method.Defined.PromptsGet
 }
 
-@Deprecated("For backwards compatibility; use ContentBlock instead", ReplaceWith("ContentBlock"))
-public sealed interface PromptMessageContent {
+/**
+ * The server's response content indicating the type of content.
+ */
+public sealed interface ContentWithType {
     public val type: String
 }
 
+/**
+ * Represents the content of a prompt message. Deprecated.
+ */
+@Deprecated("For backwards compatibility; use ContentBlock instead", ReplaceWith("ContentBlock"))
+public sealed interface PromptMessageContent : ContentWithType
+
+/**
+ * Represents multimodal content of a prompt message. Deprecated.
+ */
 @Deprecated(
     "For backwards compatibility; use CreateMessageResultContent or SamplingMessageContent instead",
     ReplaceWith("CreateMessageResultContent"),
@@ -995,13 +1006,13 @@ public sealed interface ContentBlock : PromptMessageContent
  * Represents content for the CreateMessageResult
  */
 @Serializable(with = CreateMessageResultContentMultimodalPolymorphicSerializer::class)
-public sealed interface CreateMessageResultContent : ContentBlock
+public sealed interface CreateMessageResultContent : ContentWithType
 
 /**
  * Represents content for the SamplingMessage
  */
 @Serializable(with = SamplingMessageContentMultimodalPolymorphicSerializer::class)
-public sealed interface SamplingMessageContent : ContentBlock
+public sealed interface SamplingMessageContent : ContentWithType
 
 /**
  * Text provided to or from an LLM.

kotlin-sdk-core/src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/RequestSerializerTest.kt

@@ -281,6 +281,57 @@ class RequestSerializerTest {
         assertEquals(buildJsonObject { put("result", "Legacy tool result") }, decoded.toolResult)
     }
 
+    // Only supported content types
+    @Test
+    fun `should not deserialize ResourceLink in CreateMessageResult`() {
+        val json = """{
+            "model": "test-model",
+            "role": "assistant", 
+            "content": {
+              "type": "resource_link",
+              "uri": "file:///project/src/main.rs",
+              "name": "main.rs",
+              "description": "Primary application entry point",
+              "mimeType": "text/x-rust"
+            },
+            "stopReason": "endTurn"
+        }"""
+
+        val decoded = McpJson.decodeFromString<RequestResult>(json)
+
+        assertIs<CreateMessageResult>(decoded)
+        assertEquals("test-model", decoded.model)
+        assertEquals(Role.assistant, decoded.role)
+        assertEquals(StopReason.EndTurn, decoded.stopReason)
+        assertIs<UnknownContent>(decoded.content)
+    }
+
+    // Only supported content types
+    @Test
+    fun `should not deserialize EmbeddedResource in CreateMessageResult`() {
+        val json = """{
+            "model": "test-model",
+            "role": "assistant", 
+            "content": {
+                "type": "resource", 
+                "resource": {
+                    "uri": "file:///test.txt",
+                    "mimeType": "text/plain",
+                    "text": "content"
+                }
+            },
+            "stopReason": "endTurn"
+        }"""
+
+        val decoded = McpJson.decodeFromString<RequestResult>(json)
+
+        assertIs<CreateMessageResult>(decoded)
+        assertEquals("test-model", decoded.model)
+        assertEquals(Role.assistant, decoded.role)
+        assertEquals(StopReason.EndTurn, decoded.stopReason)
+        assertIs<UnknownContent>(decoded.content)
+    }
+
     // Fallback Test
     @Test
     fun `should deserialize EmptyRequestResult for unknown result type`() {