PY-91932: do not claim a notebook when the non-modal Welcome screen is off

PyCharm failed with `NoProjectStateHandler not found, but it must be registered`
when a user opened an .ipynb file from Finder while the IDE was not running.

Two gates disagreed. The provider claimed the file from the registry key
`welcome.screen.open.files`, which defaults to true. The only registered
`NoProjectStateHandler` declines when the advanced setting
`welcome.screen.non.modal.enabled` is off, so the `requireNotNull` threw.
PY-89419 made this reachable, because it writes that setting to false for a
paying user.

The provider now checks the setting too. A paying user gets the default file
opening path instead of the Welcome screen project. The test module needs
`intellij.platform.welcomeScreen` to instantiate the provider.

This fix is for 262 only. IJPL-249071 removed the handler call on master, so
master opens the Welcome screen project for every user and must not get this
gate.


(cherry picked from commit 8b180e632c3832fd7bdf34e26bbfdbc931e5e5ab)

IJ-MR-221009

GitOrigin-RevId: 388058443109958124cd6d61297003c4ec56969a

python/ide/impl/BUILD.bazel

@@ -346,6 +346,8 @@ jvm_library(
         "//libraries/kotlinx/collections-immutable:libraries-kotlinx-collections-immutable_test_lib",
         "//platform/util/concurrency",
         "//platform/util/concurrency:concurrency_test_lib",
+        "//platform/welcome-screen",
+        "//platform/welcome-screen:welcome-screen_test_lib",
     ],
 )
 ### auto-generated section `build intellij.pycharm.community.ide.impl.tests` end

python/ide/impl/intellij.pycharm.community.ide.impl.tests.iml

@@ -97,6 +97,7 @@
     <orderEntry type="module" module-name="intellij.libraries.kotlinx.collections.immutable" scope="TEST" />
     <orderEntry type="module" module-name="intellij.platform.concurrency" scope="TEST" />
     <orderEntry type="module" module-name="intellij.pycharm.community.ide.impl" scope="TEST" />
+    <orderEntry type="module" module-name="intellij.platform.welcomeScreen" scope="TEST" />
   </component>
   <component name="TestModuleProperties" production-module="intellij.pycharm.community.ide.impl" />
 </module>

python/ide/impl/src/com/intellij/pycharm/community/ide/impl/welcomeScreen/PyCharmWelcomeScreenProjectProvider.kt

@@ -7,6 +7,7 @@ import com.intellij.openapi.project.ex.ProjectEx
 import com.intellij.openapi.util.registry.Registry
 import com.intellij.openapi.wm.ex.WelcomeScreenProjectProvider
 import com.intellij.platform.PlatformProjectOpenProcessor
+import com.intellij.platform.ide.nonModalWelcomeScreen.isNonModalWelcomeScreenEnabled
 import com.intellij.pycharm.community.ide.impl.miscProject.impl.MISC_PROJECT_WITH_WELCOME_NAME
 import com.intellij.pycharm.community.ide.impl.miscProject.impl.miscProjectDefaultPath
 import com.jetbrains.python.orLogException
@@ -38,8 +39,14 @@ internal class PyCharmWelcomeScreenProjectProvider : WelcomeScreenProjectProvide
   // We explicitly want to open existing project if the file already belongs to it
   override fun shouldOpenInWelcomeScreenIfFileBelongsToProject(filePath: Path): Boolean = false
 
+  /**
+   * The non-modal Welcome screen must be on. The file opening path creates the Welcome screen project through
+   * [com.intellij.openapi.wm.ex.NoProjectStateHandler], and the only handler declines when the setting is off.
+   */
   override fun canOpenFilesFromSystemFileManager(filePath: Path): Boolean {
-    return Registry.`is`("welcome.screen.open.files", false) && filePath.extension == "ipynb"
+    return isNonModalWelcomeScreenEnabled &&
+           Registry.`is`("welcome.screen.open.files", false) &&
+           filePath.extension == "ipynb"
   }
 
   override suspend fun doCreateOrOpenWelcomeScreenProject(path: Path): Project {

python/ide/impl/testResources/intellij.pycharm.community.ide.impl.tests.xml

@@ -28,6 +28,7 @@
     <module name="intellij.platform.usageView"/>
     <module name="intellij.platform.usageView.impl"/>
     <module name="intellij.platform.util.coroutines"/>
+    <module name="intellij.platform.welcomeScreen"/>
   </dependencies>
   <!-- endregion -->
 </idea-plugin>

python/ide/impl/tests/com/intellij/python/junit5Tests/unit/PyCharmWelcomeScreenProjectProviderTest.kt

@@ -0,0 +1,60 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.python.junit5Tests.unit
+
+import com.intellij.openapi.options.advanced.AdvancedSettings
+import com.intellij.platform.ide.nonModalWelcomeScreen.NON_MODAL_WELCOME_SCREEN_SETTING_ID
+import com.intellij.pycharm.community.ide.impl.welcomeScreen.PyCharmWelcomeScreenProjectProvider
+import com.intellij.testFramework.junit5.RegistryKey
+import com.intellij.testFramework.junit5.SystemProperty
+import com.intellij.testFramework.junit5.TestApplication
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
+
+/**
+ * The two gates must agree. If the provider claims a file while the non-modal Welcome screen is off,
+ * the file opening path finds no `NoProjectStateHandler` and the IDE fails with an internal error (PY-91932).
+ */
+@TestApplication
+@SystemProperty(propertyKey = "idea.force.disable.non.modal.welcome.screen", propertyValue = "false")
+internal class PyCharmWelcomeScreenProjectProviderTest {
+  private val provider = PyCharmWelcomeScreenProjectProvider()
+
+  @Test
+  @RegistryKey(key = "welcome.screen.open.files", value = "true")
+  fun `notebook is claimed when both settings are enabled`(@TempDir tempDir: Path) = withNonModalWelcomeScreen(true) {
+    assertTrue(provider.canOpenFilesFromSystemFileManager(tempDir.resolve("notebook.ipynb")))
+  }
+
+  @Test
+  @RegistryKey(key = "welcome.screen.open.files", value = "true")
+  fun `notebook is not claimed when the non-modal welcome screen is disabled`(@TempDir tempDir: Path) = withNonModalWelcomeScreen(false) {
+    assertFalse(provider.canOpenFilesFromSystemFileManager(tempDir.resolve("notebook.ipynb")))
+  }
+
+  @Test
+  @RegistryKey(key = "welcome.screen.open.files", value = "false")
+  fun `notebook is not claimed when the registry key is disabled`(@TempDir tempDir: Path) = withNonModalWelcomeScreen(true) {
+    assertFalse(provider.canOpenFilesFromSystemFileManager(tempDir.resolve("notebook.ipynb")))
+  }
+
+  @Test
+  @RegistryKey(key = "welcome.screen.open.files", value = "true")
+  fun `a file that is not a notebook is not claimed`(@TempDir tempDir: Path) = withNonModalWelcomeScreen(true) {
+    assertFalse(provider.canOpenFilesFromSystemFileManager(tempDir.resolve("script.py")))
+    assertFalse(provider.canOpenFilesFromSystemFileManager(tempDir))
+  }
+
+  private fun withNonModalWelcomeScreen(value: Boolean, action: () -> Unit) {
+    val previousValue = AdvancedSettings.getBoolean(NON_MODAL_WELCOME_SCREEN_SETTING_ID)
+    try {
+      AdvancedSettings.setBoolean(NON_MODAL_WELCOME_SCREEN_SETTING_ID, value)
+      action()
+    }
+    finally {
+      AdvancedSettings.setBoolean(NON_MODAL_WELCOME_SCREEN_SETTING_ID, previousValue)
+    }
+  }
+}