lazyConfiguredProjectsFromExternalProject as userpreference instead of command line option

src/server/editorServices.ts

@@ -323,7 +323,6 @@ namespace ts.server {
         cancellationToken: HostCancellationToken;
         useSingleInferredProject: boolean;
         useInferredProjectPerProjectRoot: boolean;
-        lazyConfiguredProjectsFromExternalProject?: boolean;
         typingsInstaller: ITypingsInstaller;
         eventHandler?: ProjectServiceEventHandler;
         suppressDiagnosticEvents?: boolean;
@@ -441,7 +440,6 @@ namespace ts.server {
         public readonly cancellationToken: HostCancellationToken;
         public readonly useSingleInferredProject: boolean;
         public readonly useInferredProjectPerProjectRoot: boolean;
-        private readonly lazyConfiguredProjectsFromExternalProject?: boolean;
         public readonly typingsInstaller: ITypingsInstaller;
         private readonly globalCacheLocationDirectoryPath: Path | undefined;
         public readonly throttleWaitMilliseconds?: number;
@@ -467,7 +465,6 @@ namespace ts.server {
             this.cancellationToken = opts.cancellationToken;
             this.useSingleInferredProject = opts.useSingleInferredProject;
             this.useInferredProjectPerProjectRoot = opts.useInferredProjectPerProjectRoot;
-            this.lazyConfiguredProjectsFromExternalProject = opts.lazyConfiguredProjectsFromExternalProject;
             this.typingsInstaller = opts.typingsInstaller || nullTypingsInstaller;
             this.throttleWaitMilliseconds = opts.throttleWaitMilliseconds;
             this.eventHandler = opts.eventHandler;
@@ -1989,7 +1986,19 @@ namespace ts.server {
                     this.logger.info("Format host information updated");
                 }
                 if (args.preferences) {
+                    const { lazyConfiguredProjectsFromExternalProject } = this.hostConfiguration.preferences;
                     this.hostConfiguration.preferences = { ...this.hostConfiguration.preferences, ...args.preferences };
+                    if (lazyConfiguredProjectsFromExternalProject && !this.hostConfiguration.preferences.lazyConfiguredProjectsFromExternalProject) {
+                        // Load configured projects for external projects that are pending reload
+                        this.configuredProjects.forEach(project => {
+                            if (project.hasExternalProjectRef() &&
+                                project.pendingReload === ConfigFileProgramReloadLevel.Full &&
+                                !this.pendingProjectUpdates.has(project.getProjectName())) {
+                                this.loadConfiguredProject(project);
+                                project.updateGraph();
+                            }
+                        });
+                    }
                 }
                 if (args.extraFileExtensions) {
                     this.hostConfiguration.extraFileExtensions = args.extraFileExtensions;
@@ -2642,7 +2651,7 @@ namespace ts.server {
                     let project = this.findConfiguredProjectByProjectName(tsconfigFile);
                     if (!project) {
                         // errors are stored in the project, do not need to update the graph
-                        project = this.lazyConfiguredProjectsFromExternalProject ?
+                        project = this.getHostPreferences().lazyConfiguredProjectsFromExternalProject ?
                             this.createConfiguredProjectWithDelayLoad(tsconfigFile) :
                             this.createLoadAndUpdateConfiguredProject(tsconfigFile);
                     }

src/server/project.ts

@@ -1520,6 +1520,11 @@ namespace ts.server {
             ) || false;
         }
 
+        /*@internal*/
+        hasExternalProjectRef() {
+            return !!this.externalProjectRefCount;
+        }
+
         getEffectiveTypeRoots() {
             return getEffectiveTypeRoots(this.getCompilationSettings(), this.directoryStructureHost) || [];
         }

src/server/protocol.ts

@@ -2823,6 +2823,7 @@ namespace ts.server.protocol {
         readonly includeCompletionsWithInsertText?: boolean;
         readonly importModuleSpecifierPreference?: "relative" | "non-relative";
         readonly allowTextChangesInNewFiles?: boolean;
+        readonly lazyConfiguredProjectsFromExternalProject?: boolean;
     }
 
     export interface CompilerOptions {

src/server/session.ts

@@ -465,7 +465,6 @@ namespace ts.server {
         cancellationToken: ServerCancellationToken;
         useSingleInferredProject: boolean;
         useInferredProjectPerProjectRoot: boolean;
-        lazyConfiguredProjectsFromExternalProject?: boolean;
         typingsInstaller: ITypingsInstaller;
         byteLength: (buf: string, encoding?: string) => number;
         hrtime: (start?: number[]) => number[];
@@ -537,7 +536,6 @@ namespace ts.server {
                 cancellationToken: this.cancellationToken,
                 useSingleInferredProject: opts.useSingleInferredProject,
                 useInferredProjectPerProjectRoot: opts.useInferredProjectPerProjectRoot,
-                lazyConfiguredProjectsFromExternalProject: opts.lazyConfiguredProjectsFromExternalProject,
                 typingsInstaller: this.typingsInstaller,
                 throttleWaitMilliseconds,
                 eventHandler: this.eventHandler,