fix(server): drop inert eventStore from stateless Streamable HTTP (#909)

Removes the `eventStore` parameter from `mcpStatelessStreamableHttp`,
where it was never read or written.

closes #908 

## Breaking Changes
Source-breaking only

## Types of changes
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

kotlin-sdk-server/api/kotlin-sdk-server.api

@@ -58,7 +58,9 @@ public final class io/modelcontextprotocol/kotlin/sdk/server/KtorServerKt {
 	public static synthetic fun mcp$default (Lio/ktor/server/routing/Route;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;JLkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
 	public static synthetic fun mcp$default (Lio/ktor/server/routing/Route;ZLjava/util/List;Ljava/util/List;JLkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
 	public static final fun mcpStatelessStreamableHttp (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lio/modelcontextprotocol/kotlin/sdk/server/EventStore;Lkotlin/jvm/functions/Function1;)V
+	public static final fun mcpStatelessStreamableHttp (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lkotlin/jvm/functions/Function1;)V
 	public static synthetic fun mcpStatelessStreamableHttp$default (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lio/modelcontextprotocol/kotlin/sdk/server/EventStore;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
+	public static synthetic fun mcpStatelessStreamableHttp$default (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
 	public static final fun mcpStreamableHttp (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lio/modelcontextprotocol/kotlin/sdk/server/EventStore;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)V
 	public static synthetic fun mcpStreamableHttp$default (Lio/ktor/server/application/Application;Ljava/lang/String;ZLjava/util/List;Ljava/util/List;Lio/modelcontextprotocol/kotlin/sdk/server/EventStore;Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;ILjava/lang/Object;)V
 }

kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/KtorServer.kt

@@ -270,7 +270,6 @@ private fun Application.mcpStatelessStreamableHttp(
     block: RoutingContext.() -> Server,
 ) {
     installMcpContentNegotiation()
-    install(SSE)
 
     routing {
         route(path) {
@@ -297,10 +296,11 @@ private fun Application.mcpStatelessStreamableHttp(
  * over _stateless_ [Streamable HTTP Transport](https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http)
  *
  * Sets up an HTTP POST endpoint at [path]. GET and DELETE requests return 405 Method Not Allowed.
- * Simple request/response pairs are returned as JSON (not SSE streams).
+ * Every request/response pair is returned as JSON, so this endpoint opens no SSE stream and
+ * offers no resumability. Use [mcpStreamableHttp] when either is required.
  *
  * Automatically installs [ContentNegotiation][io.ktor.server.plugins.contentnegotiation.ContentNegotiation]
- * with [McpJson][io.modelcontextprotocol.kotlin.sdk.types.McpJson] and [SSE].
+ * with [McpJson][io.modelcontextprotocol.kotlin.sdk.types.McpJson].
  *
  * @param path The URL path where the server listens for incoming JSON-RPC requests. Defaults to "/mcp".
  * @param enableDnsRebindingProtection Determines whether DNS rebinding protection is enabled. Defaults to `true`.
@@ -309,7 +309,6 @@ private fun Application.mcpStatelessStreamableHttp(
  * @param allowedOrigins A list of allowed `Origin` header values, compared by hostname only
  *      (scheme and port are ignored). Requests without an `Origin` header are allowed.
  *      If `null`, origin validation is disabled.
- * @param eventStore An optional [EventStore] implementation to provide resumability and event replay support.
  * @param block factory block with access to the [RoutingContext] (for reading request headers)
  *          that creates and returns the [Server] to handle the connection.
  */
@@ -319,7 +318,6 @@ public fun Application.mcpStatelessStreamableHttp(
     enableDnsRebindingProtection: Boolean = true,
     allowedHosts: List<String>? = null,
     allowedOrigins: List<String>? = null,
-    eventStore: EventStore? = null,
     block: RoutingContext.() -> Server,
 ) {
     mcpStatelessStreamableHttp(
@@ -328,13 +326,42 @@ public fun Application.mcpStatelessStreamableHttp(
         allowedHosts = allowedHosts,
         allowedOrigins = allowedOrigins,
         configuration = StreamableHttpServerTransport.Configuration(
-            eventStore = eventStore,
             enableJsonResponse = true,
         ),
         block = block,
     )
 }
 
+/**
+ * Retained only so that existing call sites get a migration hint instead of an unresolved parameter name.
+ *
+ * @param eventStore never consulted by a stateless endpoint. Resumption is driven by a `GET` carrying
+ *          `Last-Event-ID`, and this endpoint answers `GET` with `405 Method Not Allowed`, so no stream
+ *          exists to store events on or replay them to. Use [mcpStreamableHttp] when you need resumability.
+ */
+@Deprecated(
+    "Use mcpStatelessStreamableHttp without eventStore.",
+    ReplaceWith("mcpStatelessStreamableHttp(path, enableDnsRebindingProtection, allowedHosts, allowedOrigins, block)"),
+    DeprecationLevel.ERROR,
+)
+@Suppress("UnusedParameter")
+public fun Application.mcpStatelessStreamableHttp(
+    path: String = "/mcp",
+    enableDnsRebindingProtection: Boolean = true,
+    allowedHosts: List<String>? = null,
+    allowedOrigins: List<String>? = null,
+    eventStore: EventStore?,
+    block: RoutingContext.() -> Server,
+) {
+    mcpStatelessStreamableHttp(
+        path = path,
+        enableDnsRebindingProtection = enableDnsRebindingProtection,
+        allowedHosts = allowedHosts,
+        allowedOrigins = allowedOrigins,
+        block = block,
+    )
+}
+
 private suspend fun ServerSSESession.mcpSseEndpoint(
     postEndpoint: String,
     transportManager: TransportManager<SseServerTransport>,