[MCP Server] Pass project path through env var and headers to MCP server to identify a project on request

(cherry picked from commit 90ee5826e3d8d32b912da30b03e6bea776c57a90)

GitOrigin-RevId: d6dd878af851fe4b9ce1f82e39e6481a9e0b53a8

plugins/mcp-server/mcpserver.stdio/src/McpStdioRunner.kt

@@ -1,15 +1,6 @@
 package com.intellij.mcpserver.stdio
 
-import com.intellij.mcpserver.stdio.mcpProto.CallToolRequest
-import com.intellij.mcpserver.stdio.mcpProto.CallToolResult
-import com.intellij.mcpserver.stdio.mcpProto.Implementation
-import com.intellij.mcpserver.stdio.mcpProto.ListToolsRequest
-import com.intellij.mcpserver.stdio.mcpProto.ListToolsResult
-import com.intellij.mcpserver.stdio.mcpProto.Method
-import com.intellij.mcpserver.stdio.mcpProto.Response
-import com.intellij.mcpserver.stdio.mcpProto.ServerCapabilities
-import com.intellij.mcpserver.stdio.mcpProto.TextContent
-import com.intellij.mcpserver.stdio.mcpProto.Tool
+import com.intellij.mcpserver.stdio.mcpProto.*
 import com.intellij.mcpserver.stdio.mcpProto.server.Server
 import com.intellij.mcpserver.stdio.mcpProto.server.ServerOptions
 import com.intellij.mcpserver.stdio.mcpProto.server.StdioServerTransport
@@ -28,9 +19,10 @@ import kotlinx.coroutines.CompletableDeferred
 import kotlinx.io.asSink
 import kotlinx.io.buffered
 
-const val IJ_MCP_SERVER_PORT: String = "IJ_MCP_SERVER_PORT"
-const val IJ_MCP_SERVER_NAME: String = "IJ_MCP_SERVER_NAME"
-const val IJ_MCP_SERVER_VERSION: String = "IJ_MCP_SERVER_VERSION"
+val IJ_MCP_SERVER_PORT: String = ::IJ_MCP_SERVER_PORT.name
+val IJ_MCP_SERVER_NAME: String = ::IJ_MCP_SERVER_NAME.name
+val IJ_MCP_SERVER_VERSION: String = ::IJ_MCP_SERVER_VERSION.name
+val IJ_MCP_SERVER_PROJECT_PATH: String = ::IJ_MCP_SERVER_PROJECT_PATH.name
 
 suspend fun main() {
   val inputStream = System.`in`
@@ -56,7 +48,14 @@ suspend fun main() {
   val stdioServerTransport = StdioServerTransport(inputStream.asInput(), outputStream.asSink().buffered())
 
   server.setRequestHandler<ListToolsRequest>(Method.Defined.ToolsList) { request, extra ->
-    val response = httpClient.get(urlString = endpoint + "list_tools")
+    val response = httpClient.get(urlString = endpoint + "list_tools") {
+      headers {
+        val projectPath = System.getenv(IJ_MCP_SERVER_PROJECT_PATH)
+        if (!projectPath.isNullOrBlank()) {
+          this.append(IJ_MCP_SERVER_PROJECT_PATH, projectPath)
+        }
+      }
+    }
     when (response.status) {
       HttpStatusCode.OK -> {
         val responseText = response.bodyAsText()
@@ -74,6 +73,10 @@ suspend fun main() {
     val response = httpClient.post(urlString = endpoint + request.name) {
       headers {
         contentType(ContentType.Application.Json)
+        val projectPath = System.getenv(IJ_MCP_SERVER_PROJECT_PATH)
+        if (!projectPath.isNullOrBlank()) {
+          this.append(IJ_MCP_SERVER_PROJECT_PATH, projectPath)
+        }
       }
       setBody(McpJson.encodeToString(request.arguments))
     }

plugins/mcp-server/src/main/kotlin/com/intellij/mcpserver/MCPService.kt

@@ -1,10 +1,11 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.mcpserver
 
+import com.intellij.mcpserver.stdio.IJ_MCP_SERVER_PROJECT_PATH
 import com.intellij.openapi.components.Service
 import com.intellij.openapi.diagnostic.logger
-import com.intellij.openapi.progress.runBlockingCancellable
 import com.intellij.openapi.project.Project
+import com.intellij.openapi.project.ProjectManager
 import com.intellij.openapi.util.io.BufferExposingByteArrayOutputStream
 import io.netty.channel.ChannelHandlerContext
 import io.netty.handler.codec.http.FullHttpRequest
@@ -39,7 +40,14 @@ class MCPService : RestService() {
 
     override fun execute(urlDecoder: QueryStringDecoder, request: FullHttpRequest, context: ChannelHandlerContext): String? {
         val path = urlDecoder.path().split(serviceName).last().trimStart('/')
-        val project = getLastFocusedOrOpenedProject() ?: return null
+        val projectPath = request.headers().get(IJ_MCP_SERVER_PROJECT_PATH)
+        val project = if (!projectPath.isNullOrBlank()) {
+          ProjectManager.getInstance().openProjects.find { it.basePath == projectPath } ?: getLastFocusedOrOpenedProject()
+        }
+        else {
+          getLastFocusedOrOpenedProject()
+        } ?: return null
+
         val tools = McpToolManager.getAllTools()
 
         val result = when (path) {

plugins/mcp-server/src/main/kotlin/com/intellij/mcpserver/stdioRunnerUtil.kt

@@ -3,7 +3,7 @@
 package com.intellij.mcpserver
 
 import com.intellij.execution.configurations.GeneralCommandLine
-import com.intellij.mcpserver.stdio.main
+import com.intellij.mcpserver.stdio.*
 import com.intellij.openapi.application.PathManager
 import java.io.File
 import kotlin.io.path.pathString
@@ -12,13 +12,18 @@ import kotlin.reflect.jvm.javaMethod
 /**
  * Build a commandline to run MCP IDE server in a separate process
  */
-fun createStdioMcpServerCommandLine(): GeneralCommandLine {
+fun createStdioMcpServerCommandLine(ideServerPort: Int, serverName: String?, serverVersion: String?, projectBasePath: String?): GeneralCommandLine {
   val classpaths = McpStdioRunnerClasspath.CLASSPATH_CLASSES.map {
     (PathManager.getJarForClass(it) ?: error("No path for class $it")).pathString
   }.toSet()
 
-  return GeneralCommandLine()
+  val commandLine = GeneralCommandLine()
     .withExePath("${System.getProperty("java.home")}${File.separator}bin${File.separator}java")
     .withParameters("-classpath", classpaths.joinToString(File.pathSeparator))
     .withParameters(::main.javaMethod!!.declaringClass.name)
+    .withEnvironment(IJ_MCP_SERVER_PORT, ideServerPort.toString())
+  if (serverName != null) commandLine.withEnvironment(IJ_MCP_SERVER_NAME, serverName)
+  if (serverVersion != null) commandLine.withEnvironment(IJ_MCP_SERVER_VERSION, serverVersion)
+  if (projectBasePath != null) commandLine.withEnvironment(IJ_MCP_SERVER_PROJECT_PATH, projectBasePath)
+  return commandLine
 }