[rd debugger] Provide a way to handle mutable XDescriptors

GitOrigin-RevId: 28cebb63cc78d9b73c1003209aa027b07eb6cf5e

platform/xdebugger-impl/frontend/resources/intellij.platform.debugger.impl.frontend.xml

@@ -10,6 +10,8 @@
   <extensionPoints>
     <extensionPoint name="xdebugger.customQuickEvaluateActionProvider"
                     interface="com.intellij.platform.debugger.impl.frontend.actions.CustomQuickEvaluateActionProvider" dynamic="true"/>
+    <extensionPoint name="xdebugger.descriptorStateManager"
+                    interface="com.intellij.platform.debugger.impl.frontend.FrontendDescriptorStateManagerExtension" dynamic="true"/>
   </extensionPoints>
   <actions resource-bundle="messages.FrontendDebuggerImplBundle">
     <action id="QuickEvaluateExpression" class="com.intellij.platform.debugger.impl.frontend.actions.QuickEvaluateAction"/>

platform/xdebugger-impl/frontend/src/com/intellij/platform/debugger/impl/frontend/FrontendDescriptorStateManager.kt

@@ -0,0 +1,50 @@
+// 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.platform.debugger.impl.frontend
+
+import com.intellij.openapi.components.Service
+import com.intellij.openapi.components.service
+import com.intellij.openapi.extensions.ExtensionPointName
+import com.intellij.openapi.project.Project
+import com.intellij.xdebugger.frame.XDescriptor
+import fleet.multiplatform.shims.ConcurrentHashMap
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.job
+import org.jetbrains.annotations.ApiStatus
+
+/**
+ * Creates a plugin-specific state for a given [XDescriptor].
+ * For example, if a [XDescriptor] contains a flow, this extension should create an object which will keep the flow's state.
+ */
+@ApiStatus.Internal
+interface FrontendDescriptorStateManagerExtension {
+  fun createState(descriptor: XDescriptor, cs: CoroutineScope): Any?
+
+  companion object {
+    private val EP_NAME = ExtensionPointName.create<FrontendDescriptorStateManagerExtension>("com.intellij.xdebugger.descriptorStateManager")
+
+    fun createState(descriptor: XDescriptor, cs: CoroutineScope): Any? {
+      return EP_NAME.extensionList.firstNotNullOfOrNull { it.createState(descriptor, cs) }
+    }
+  }
+}
+
+@ApiStatus.Internal
+@Service(Service.Level.PROJECT)
+class FrontendDescriptorStateManager {
+  private val states = ConcurrentHashMap<XDescriptor, Any>()
+
+  internal fun registerDescriptor(descriptor: XDescriptor, cs: CoroutineScope) {
+    val state = FrontendDescriptorStateManagerExtension.createState(descriptor, cs) ?: return
+    states[descriptor] = state
+    cs.coroutineContext.job.invokeOnCompletion { states.remove(descriptor) }
+  }
+
+  fun getState(descriptor: XDescriptor): Any? {
+    return states[descriptor]
+  }
+
+  companion object {
+    @JvmStatic
+    fun getInstance(project: Project): FrontendDescriptorStateManager = project.service()
+  }
+}

platform/xdebugger-impl/frontend/src/com/intellij/platform/debugger/impl/frontend/evaluate/quick/FrontendXValue.kt

@@ -8,6 +8,7 @@ import com.intellij.openapi.components.service
 import com.intellij.openapi.diagnostic.thisLogger
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.NlsSafe
+import com.intellij.platform.debugger.impl.frontend.FrontendDescriptorStateManager
 import com.intellij.platform.debugger.impl.rpc.*
 import com.intellij.platform.util.coroutines.childScope
 import com.intellij.util.ConcurrencyUtil
@@ -38,6 +39,13 @@ class FrontendXValue private constructor(
   private val presentation: StateFlow<XValueSerializedPresentation>,
 ) : XValue(), XValueTextProvider {
 
+  init {
+    cs.launch {
+      val descriptor = xValueDto.descriptor?.await() ?: return@launch
+      FrontendDescriptorStateManager.getInstance(project).registerDescriptor(descriptor, cs)
+    }
+  }
+
   @Volatile
   private var modifier: XValueModifier? = null