Revert "Fix IntelliJ IDEA project open hang by removing FlutterProjec…

CHANGELOG.md

@@ -16,8 +16,6 @@
 
 ### Fixed
 
-- Silent failure when opening Flutter projects without `.idea` directory in IntelliJ IDEA, by removing `FlutterProjectOpenProcessor` and
-  migrating configuration logic to `FlutterInitializer`. (#8846)
 - Gutter buttons not running tests with non-ASCII characters in their names. (#7985)
 - Freeze from JX Browser close. (#8864)
 - Crash in split debugger mode in IntelliJ 2025.3+. (#8831)

resources/META-INF/plugin.xml

@@ -335,6 +335,8 @@
     <!-- See https://github.com/flutter/flutter-intellij/issues/8029 -->
     <projectService serviceImplementation="io.flutter.view.InspectorView" overrides="false"/>
 
+    <projectOpenProcessor id="flutter" implementation="io.flutter.project.FlutterProjectOpenProcessor" order="first"/>
+
     <editorNotificationProvider implementation="io.flutter.editor.FlutterPubspecNotificationProvider"/>
     <editorNotificationProvider implementation="io.flutter.inspections.SdkConfigurationNotificationProvider"/>
     <editorNotificationProvider implementation="io.flutter.editor.NativeEditorNotificationProvider"/>

src/io/flutter/FlutterInitializer.java

@@ -67,6 +67,8 @@
  * Runs actions after the project has started up and the index is up to date.
  *
  * @see ProjectOpenActivity for actions that run earlier.
+ * @see io.flutter.project.FlutterProjectOpenProcessor for additional actions that
+ * may run when a project is being imported.
  */
 public class FlutterInitializer extends FlutterProjectActivity {
   private boolean toolWindowsInitialized = false;
@@ -97,18 +99,6 @@ public void executeProjectStartup(@NotNull Project project) {
     // Start a DevTools server
     DevToolsService.getInstance(project);
 
-    // Ensure Flutter project configuration is applied for projects that may have been
-    // opened without a .idea directory. Previously this was handled by FlutterProjectOpenProcessor,
-    // but that processor silently failed when no delegate processor could open the project.
-    // Instead, we let the platform open the project normally and apply our configuration here.
-    // See https://github.com/flutter/flutter-intellij/issues/8661 (Android Studio equivalent)
-    for (Module module : FlutterModuleUtils.getModules(project)) {
-      if (FlutterModuleUtils.declaresFlutter(module) && !FlutterModuleUtils.isFlutterModule(module)) {
-        log().info("Fixing Flutter module configuration for " + module.getName());
-        FlutterModuleUtils.setFlutterModuleAndReload(module, project);
-      }
-    }
-
     // If the project declares a Flutter dependency, do some extra initialization.
     boolean hasFlutterModule = false;
 

src/io/flutter/project/FlutterProjectOpenProcessor.kt

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2025 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter.project
+
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.projectImport.ProjectOpenProcessor
+import icons.FlutterIcons
+import io.flutter.FlutterBundle
+import io.flutter.FlutterUtils
+import io.flutter.pub.PubRoot
+import io.flutter.utils.FlutterModuleUtils
+import java.util.*
+import javax.swing.Icon
+
+/**
+ * Originally `FlutterProjectOpenProcessor.java`.
+ *
+ * This processor handles opening Flutter projects when they are selected directly (e.g. via "Open" in the IDE).
+ * It delegates the actual opening to the platform's default processor (e.g. Gradle or Maven processor if applicable,
+ * or the generic project opener) and then ensures that any modules in the project are correctly configured as Flutter modules.
+ *
+ * Converted to Kotlin to support `openProjectAsync` which is a suspend function.
+ */
+open class FlutterProjectOpenProcessor : ProjectOpenProcessor() {
+  override val name: String
+    get() = FlutterBundle.message("flutter.module.name")
+
+  override fun getIcon(file: VirtualFile): Icon? {
+    return FlutterIcons.Flutter
+  }
+
+  override fun canOpenProject(file: VirtualFile): Boolean {
+    if (FlutterUtils.isAndroidStudio()) {
+      return false
+    }
+    val root = PubRoot.forDirectory(file)
+    return root != null && root.declaresFlutter()
+  }
+
+  /**
+   * Replaces the deprecated `doOpenProject`.
+   *
+   * This method is `suspend` and must be used instead of `doOpenProject` to avoid `IllegalStateException` in newer IDE versions.
+   *
+   * It performs the following steps:
+   * 1. Finds a delegate processor (e.g. Gradle) to open the project.
+   * 2. Opens the project asynchronously.
+   * 3. Once opened, checks if the project contains Flutter modules that are not yet configured as such (e.g. missing module type).
+   * 4. Configures these modules as Flutter modules within a write action.
+   */
+  override suspend fun openProjectAsync(
+    virtualFile: VirtualFile,
+    projectToClose: Project?,
+    forceOpenInNewFrame: Boolean,
+  ): Project? {
+    // Delegate opening to the platform open processor.
+    val importProvider = getDelegateImportProvider(virtualFile) ?: return null
+    val project = importProvider.openProjectAsync(virtualFile, projectToClose, forceOpenInNewFrame)
+    if (project == null || project.isDisposed) return project
+
+    // Convert any modules that use Flutter but don't have IntelliJ Flutter metadata.
+    convertToFlutterProject(project)
+
+    return project
+  }
+
+  /**
+   * Deprecated method, kept to satisfy the compiler/interface.
+   *
+   * We return `null` to indicate that this processor does not support the synchronous opening method
+   * and that `openProjectAsync` should be used instead.
+   */
+  override fun doOpenProject(
+    virtualFile: VirtualFile,
+    projectToClose: Project?,
+    forceOpenInNewFrame: Boolean,
+  ): Project? {
+    return null
+  }
+
+  protected open fun getDelegateImportProvider(file: VirtualFile): ProjectOpenProcessor? {
+    return EXTENSION_POINT_NAME.extensionList.stream().filter { processor: ProjectOpenProcessor ->
+      processor.canOpenProject(file) && !Objects.equals(
+        processor.name,
+        name
+      )
+    }.findFirst().orElse(null)
+  }
+}
+
+/**
+ * Sets up a project that doesn't have any Flutter modules.
+ *
+ *
+ * (It probably wasn't created with "flutter create" and probably didn't have any IntelliJ configuration before.)
+ */
+private fun convertToFlutterProject(project: Project) {
+  for (module in FlutterModuleUtils.getModules(project)) {
+    if (FlutterModuleUtils.declaresFlutter(module) && !FlutterModuleUtils.isFlutterModule(module)) {
+      FlutterModuleUtils.setFlutterModuleAndReload(module, project)
+    }
+  }
+}