This is where we can multiplex commands

build.sbt

@@ -176,6 +176,7 @@ lazy val actionsProj = (project in file("main-actions")).
 
 // General command support and core commands not specific to a build system
 lazy val commandProj = (project in file("main-command")).
+  dependsOn(serverProj).
   settings(
     testedBaseSettings,
     name := "Command",

main-command/src/main/scala/sbt/BasicCommands.scala

@@ -13,6 +13,7 @@ import BasicCommandStrings._
 import CommandUtil._
 import BasicKeys._
 
+import sbt.server.Server
 import java.io.File
 import sbt.io.IO
 
@@ -179,6 +180,9 @@ object BasicCommands {
     }
 
   def shell = Command.command(Shell, Help.more(Shell, ShellDetailed)) { s =>
+    // TODO hook it in, start in the right place, shutdown on termination
+    val server = Server.start("127.0.0.1", 12700)
+
     val history = (s get historyPath) getOrElse Some(new File(s.baseDir, ".history"))
     val prompt = (s get shellPrompt) match { case Some(pf) => pf(s); case None => "> " }
     val reader = new FullReader(history, s.combinedParser)

main/server/src/main/scala/sbt/server/Server.scala

@@ -7,12 +7,12 @@ import java.net.{ SocketTimeoutException, InetAddress, ServerSocket }
 import java.util.concurrent.ConcurrentLinkedQueue
 import java.util.concurrent.atomic.AtomicBoolean
 
+sealed trait ServerInstance {
+  def shutdown(): Unit
+  def nextCommand(): Option[Command]
+}
+
 object Server {
-
-  trait ServerInstance {
-    def shutdown(): Unit
-  }
-
   def start(host: String, port: Int): ServerInstance =
     new ServerInstance {
 

main/src/main/scala/sbt/Main.scala

@@ -84,9 +84,6 @@ object StandardMain {
   /** The common interface to standard output, used for all built-in ConsoleLoggers. */
   val console = ConsoleOut.systemOutOverwrite(ConsoleOut.overwriteContaining("Resolving "))
 
-  // TODO hook it in, start in the right place, shutdown on termination
-  val server = sbt.server.Server.start("127.0.0.1", 12700)
-
   def initialGlobalLogging: GlobalLogging = GlobalLogging.initial(MainLogging.globalDefault(console), File.createTempFile("sbt", ".log"), console)
 
   def initialState(configuration: xsbti.AppConfiguration, initialDefinitions: Seq[Command], preCommands: Seq[String]): State =