diff --git a/rollup/plugins/feature-isolation-check-plugin.ts b/rollup/plugins/feature-isolation-check-plugin.ts
new file mode 100644
index 00000000..50ad3e23
--- /dev/null
+++ b/rollup/plugins/feature-isolation-check-plugin.ts
@@ -0,0 +1,92 @@
+import type { Plugin, PluginContext } from 'rollup'
+
+interface FeatureIsolationCheckOptions {
+  /** Matches the modules of the optional features (e.g. chat, notebook, mcp) */
+  featureModules: RegExp
+  /** Matches the entry points that are allowed to load feature modules (their service overrides) */
+  allowedEntries: RegExp
+  /**
+   * Maximum size (in bytes of transformed code) of the feature modules statically reachable from
+   * the other entry points. It covers the known remaining dependencies, and fails the build when a
+   * VSCode update (or a change here) makes more of the features load unconditionally
+   */
+  maxSize: number
+}
+
+/**
+ * Checks that optional features are only loaded by their own service overrides, so that a workbench
+ * without them doesn't load (and bundle) their implementation
+ */
+export default ({
+  featureModules,
+  allowedEntries,
+  maxSize
+}: FeatureIsolationCheckOptions): Plugin => {
+  function getSize(context: PluginContext, id: string) {
+    return context.getModuleInfo(id)?.code?.length ?? 0
+  }
+
+  function collectStaticImports(context: PluginContext, from: string[]) {
+    const seen = new Set<string>(from)
+    const queue = [...from]
+    while (queue.length > 0) {
+      const id = queue.pop()!
+      for (const imported of context.getModuleInfo(id)?.importedIds ?? []) {
+        if (!seen.has(imported)) {
+          seen.add(imported)
+          queue.push(imported)
+        }
+      }
+    }
+    return seen
+  }
+
+  return {
+    name: 'feature-isolation-check',
+    buildEnd(error) {
+      if (error != null) {
+        return
+      }
+      const entries = Array.from(this.getModuleIds()).filter(
+        (id) => this.getModuleInfo(id)!.isEntry && !allowedEntries.test(id)
+      )
+      const reachable = collectStaticImports(this, entries)
+      const reachableFeatureModules = Array.from(reachable).filter((id) => featureModules.test(id))
+      const totalSize = reachableFeatureModules.reduce((acc, id) => acc + getSize(this, id), 0)
+
+      // Where the other modules start depending on the features, and how much each of them loads
+      const crossings = Array.from(reachable)
+        .filter((id) => !featureModules.test(id))
+        .flatMap((importer) =>
+          this.getModuleInfo(importer)!
+            .importedIds.filter((id) => featureModules.test(id))
+            .map((imported) => ({ importer, imported }))
+        )
+        .map(({ importer, imported }) => ({
+          importer,
+          imported,
+          size: Array.from(collectStaticImports(this, [imported]))
+            .filter((id) => featureModules.test(id))
+            .reduce((acc, id) => acc + getSize(this, id), 0)
+        }))
+        .sort((a, b) => b.size - a.size)
+
+      const kb = (size: number) => `${Math.round(size / 1024)}KB`
+      const shorten = (id: string) => id.replace(/^.*?\/(vs|src)\//, '$1/')
+      const report = [
+        `${reachableFeatureModules.length} feature modules (${kb(totalSize)}) are loaded without their service overrides (max ${kb(maxSize)})`,
+        ...crossings
+          .slice(0, 20)
+          .map(
+            ({ importer, imported, size }) =>
+              `  ${kb(size).padStart(7)}  ${shorten(importer)} -> ${shorten(imported)}`
+          )
+      ].join('\n')
+
+      if (totalSize > maxSize) {
+        this.error(report)
+      }
+      this.info(report)
+    }
+  }
+}
diff --git a/rollup/rollup.config.ts b/rollup/rollup.config.ts
index f95d0b63..4acf3065 100644
--- a/rollup/rollup.config.ts
+++ b/rollup/rollup.config.ts
@@ -20,6 +20,7 @@ import {
 import vscodeAssetGlobMetaUrl from './plugins/vscode-asset-glob-meta-url-plugin.js'
 import dynamicImportPolyfillPlugin from './plugins/dynamic-import-polyfill-plugin.js'
 import resolveAssetUrlPlugin from './plugins/resolve-asset-url-plugin.js'
+import featureIsolationCheckPlugin from './plugins/feature-isolation-check-plugin.js'
 import { typeDedupReplaceTransformer } from './tools/typeDedup.js'
 import {
   DIST_DIR_MAIN,
@@ -191,6 +192,15 @@ export default (args: Record<string, string>): rollup.RollupOptions => {
           return undefined
         }
       },
+      featureIsolationCheckPlugin({
+        // Service identifiers (`.service` files) are shared on purpose
+        featureModules: /\/vs\/workbench\/contrib\/(chat|notebook|mcp)\/(?!.*\.service\.js$)/,
+        // Service overrides that build on top of those features
+        allowedEntries:
+          /\/src\/service-override\/(chat|notebook|mcp|interactive|ai|speech|welcome)\.ts$/,
+        // ~910KB with VSCode 1.138: mostly dictation, go to symbol in chat, editor tabs and chat context keys
+        maxSize: 1000 * 1024
+      }),
       configuredSubpackagePlugin(),
       copy({
         hook: 'writeBundle',
diff --git a/scripts/check-unsupported-decorator.ts b/scripts/check-unsupported-decorator.ts
index 2c435cdb..c5cd828a 100644
--- a/scripts/check-unsupported-decorator.ts
+++ b/scripts/check-unsupported-decorator.ts
@@ -1,11 +1,14 @@
 import { Project } from 'ts-morph'
 
 const project = new Project({ tsConfigFilePath: 'tsconfig.json' })
-const sourceFile = project.getSourceFileOrThrow('src/missing-services.ts')
+const sourceFiles = [
+  'src/missing-services.ts',
+  'src/service-override/tools/missingMainThreadCustomers.ts'
+].map((path) => project.getSourceFileOrThrow(path))
 
 const issues: string[] = []
 
-for (const cls of sourceFile.getClasses()) {
+for (const cls of sourceFiles.flatMap((sourceFile) => sourceFile.getClasses())) {
   for (const prop of cls.getProperties()) {
     const initText = prop.getInitializer()?.getText().trim()
     const usesUnsupported = initText === 'unsupported'
@@ -26,4 +29,4 @@ if (issues.length) {
   console.error(issues.join('\n'))
   process.exit(1)
 }
-console.log('✅ All consistent')
\ No newline at end of file
+console.log('✅ All consistent')
diff --git a/src/missing-services.ts b/src/missing-services.ts
index 2a67f876..5fedfaef 100644
--- a/src/missing-services.ts
+++ b/src/missing-services.ts
@@ -511,7 +511,7 @@ import {
   getBuiltInExtensionTranslationsUris,
   getExtensionIdProvidingCurrentLocale
 } from './l10n.js'
-import { unsupported } from './tools.js'
+import { Unsupported, unsupported } from './tools.js'
 
 import { NullAgentHostService } from 'vs/platform/agentHost/browser/nullAgentHostService'
 import { NullSSHRemoteAgentHostService } from 'vs/platform/agentHost/browser/nullSshRemoteAgentHostService'
@@ -543,7 +543,7 @@ import { IChatInputNotificationService } from 'vs/workbench/contrib/chat/browser
 import { IChatPhoneInputPresenter } from 'vs/workbench/contrib/chat/browser/widget/input/chatPhoneInputPresenter.service'
 import { IChatImageCarouselService } from 'vs/workbench/contrib/chat/browser/chatImageCarouselService.service.js'
 import { IChatDebugService } from 'vs/workbench/contrib/chat/common/chatDebugService.service.js'
-import { createVSCodeHarnessDescriptor } from 'vs/workbench/contrib/chat/common/customizationHarnessService'
+import type { IHarnessDescriptor } from 'vs/workbench/contrib/chat/common/customizationHarnessService'
 import { ICustomizationHarnessService } from 'vs/workbench/contrib/chat/common/customizationHarnessService.service'
 import type { IEnablementModel } from 'vs/workbench/contrib/chat/common/enablement.js'
 import { IPluginGitService } from 'vs/workbench/contrib/chat/common/plugins/pluginGitService.service.js'
@@ -583,29 +583,6 @@ import { IAgentHostCustomizationService } from 'vs/workbench/contrib/chat/browse
 import { IAgentHostActiveClientService } from 'vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostActiveClientService.service'
 import { IGitHubService } from 'vs/platform/github/common/githubService.service.js'
 
-function Unsupported(target: object, propertyKey: string, descriptor?: PropertyDescriptor) {
-  function unsupported() {
-    throw new Error(
-      `Unsupported: ${target.constructor.name}.${propertyKey} is not supported. You are using a feature without registering the corresponding service override.`
-    )
-  }
-  if (descriptor != null) {
-    if (descriptor.value != null) {
-      descriptor.value = unsupported
-    } else if (descriptor.get != null) {
-      descriptor.get = unsupported
-    }
-  } else {
-    Object.defineProperty(target, propertyKey, {
-      get() {
-        unsupported()
-      },
-      set() {},
-      configurable: true,
-      enumerable: true
-    })
-  }
-}
 /**
  * Editor services: all editor service that are not defined in vs/editor/standalone/
  */
@@ -7270,8 +7247,15 @@ class CustomizationHarnessService implements ICustomizationHarnessService {
     URI.parse('chat-session://local/default')
   )
   activeHarness: ICustomizationHarnessService['activeHarness'] = constObservable(SessionType.Local)
-  availableHarnesses: ICustomizationHarnessService['availableHarnesses'] = constObservable([
-    createVSCodeHarnessDescriptor()
+  // Not using `createVSCodeHarnessDescriptor` on purpose: importing it loads most of the chat implementation
+  availableHarnesses: ICustomizationHarnessService['availableHarnesses'] = constObservable<
+    IHarnessDescriptor[]
+  >([
+    {
+      id: SessionType.Local,
+      label: 'Local',
+      icon: Codicon.vm
+    }
   ])
   onDidChangeSlashCommands: ICustomizationHarnessService['onDidChangeSlashCommands'] = Event.None
   onDidChangeCustomAgents: ICustomizationHarnessService['onDidChangeCustomAgents'] = Event.None
diff --git a/src/service-override/chat.ts b/src/service-override/chat.ts
index f5a22709..b046dc11 100644
--- a/src/service-override/chat.ts
+++ b/src/service-override/chat.ts
@@ -262,6 +262,7 @@ import 'vs/workbench/contrib/chat/browser/agentSessions/experiments/agentSession
 import 'vs/workbench/contrib/chat/browser/aiCustomization/aiCustomizationManagement.contribution'
 import 'vs/workbench/contrib/chat/browser/attachments/chatReferenceAttachmentWidget.contribution'
 import 'vs/workbench/contrib/chat/browser/attachments/transcriptContextAttachmentWidget.contribution'
+import 'vs/workbench/api/browser/extensionHost.chat.contribution'
 
 class DefaultAccountService implements IDefaultAccountService {
   declare _serviceBrand: undefined
diff --git a/src/service-override/extensions.ts b/src/service-override/extensions.ts
index ad4cc155..868bad80 100644
--- a/src/service-override/extensions.ts
+++ b/src/service-override/extensions.ts
@@ -69,7 +69,8 @@ import {
 } from 'vs/platform/extensionManagement/common/extensionsScannerService.js'
 import * as platform from 'vs/base/common/platform'
 import { getBuiltInExtensionTranslationsUris } from '../l10n.js'
-import 'vs/workbench/api/browser/extensionHost.contribution'
+import 'vs/workbench/api/browser/extensionHost.base.contribution'
+import './tools/missingMainThreadCustomers.js'
 
 export interface WorkerConfig {
   url: string
diff --git a/src/service-override/mcp.ts b/src/service-override/mcp.ts
index b207c864..615935b5 100644
--- a/src/service-override/mcp.ts
+++ b/src/service-override/mcp.ts
@@ -36,6 +36,7 @@ import { IWorkbenchMcpGatewayService } from 'vs/workbench/contrib/mcp/common/mcp
 import { BrowserMcpGatewayService } from 'vs/workbench/contrib/mcp/browser/mcpGatewayService'
 import 'vs/workbench/contrib/mcp/browser/mcp.contribution'
 import 'vs/workbench/contrib/mcp/browser/mcp.view.contribution'
+import 'vs/workbench/api/browser/extensionHost.mcp.contribution'
 
 export default function getServiceOverride(): IEditorOverrideServices {
   return {
diff --git a/src/service-override/notebook.ts b/src/service-override/notebook.ts
index 5562b461..d797fc75 100644
--- a/src/service-override/notebook.ts
+++ b/src/service-override/notebook.ts
@@ -40,6 +40,7 @@ import { NotebookOutlineEntryFactory } from 'vs/workbench/contrib/notebook/brows
 import { INotebookOutlineEntryFactory } from 'vs/workbench/contrib/notebook/browser/viewModel/notebookOutlineEntryFactory.service'
 import 'vs/workbench/contrib/replNotebook/browser/repl.contribution'
 import 'vs/workbench/contrib/notebook/browser/notebook.contribution'
+import 'vs/workbench/api/browser/extensionHost.notebook.contribution'
 
 export default function getServiceOverride(): IEditorOverrideServices {
   return {
diff --git a/src/service-override/tools/missingMainThreadCustomers.ts b/src/service-override/tools/missingMainThreadCustomers.ts
new file mode 100644
index 00000000..1c195770
--- /dev/null
+++ b/src/service-override/tools/missingMainThreadCustomers.ts
@@ -0,0 +1,291 @@
+import type { IDisposable } from 'vs/base/common/lifecycle'
+import {
+  MainContext,
+  type MainThreadChatAgentsShape2,
+  type MainThreadChatContextShape,
+  type MainThreadChatDebugShape,
+  type MainThreadChatInputNotificationShape,
+  type MainThreadChatQuotaShape,
+  type MainThreadChatSessionsShape,
+  type MainThreadChatStatusShape,
+  type MainThreadCodeMapperShape,
+  type MainThreadLanguageModelToolsShape,
+  type MainThreadLanguageModelsShape,
+  type MainThreadMcpShape,
+  type MainThreadNotebookDocumentsShape,
+  type MainThreadNotebookEditorsShape,
+  type MainThreadNotebookKernelsShape,
+  type MainThreadNotebookRenderersShape,
+  type MainThreadNotebookShape
+} from 'vs/workbench/api/common/extHost.protocol'
+import {
+  extHostCustomer,
+  type IExtHostContext
+} from 'vs/workbench/services/extensions/common/extHostCustomers'
+import type { ProxyIdentifier } from 'vs/workbench/services/extensions/common/proxyIdentifier'
+import { noop, Unsupported, unsupported } from '../../tools.js'
+
+// Main thread counterparts of the extension host API of optional features (chat, language models, notebooks, mcp)
+// Their actual implementations are only registered by the corresponding service overrides, but the extension host
+// requires all of them to be registered, and some of them are called when the extension host starts
+// (e.g. `ExtHostLanguageModelTools` calls `$getTools`)
+
+class MissingMainThreadLanguageModels implements MainThreadLanguageModelsShape {
+  $registerLanguageModelProvider: MainThreadLanguageModelsShape['$registerLanguageModelProvider'] =
+    noop
+  $onLMProviderChange: MainThreadLanguageModelsShape['$onLMProviderChange'] = noop
+  $unregisterProvider: MainThreadLanguageModelsShape['$unregisterProvider'] = noop
+  @Unsupported
+  $tryStartChatRequest: MainThreadLanguageModelsShape['$tryStartChatRequest'] = unsupported
+  $reportResponsePart: MainThreadLanguageModelsShape['$reportResponsePart'] = async () => {}
+  $reportResponseDone: MainThreadLanguageModelsShape['$reportResponseDone'] = async () => {}
+  $selectChatModels: MainThreadLanguageModelsShape['$selectChatModels'] = async () => []
+  @Unsupported
+  $countTokens: MainThreadLanguageModelsShape['$countTokens'] = unsupported
+  $cancelLanguageModelChatRequest: MainThreadLanguageModelsShape['$cancelLanguageModelChatRequest'] =
+    noop
+  $fileIsIgnored: MainThreadLanguageModelsShape['$fileIsIgnored'] = async () => false
+  $registerFileIgnoreProvider: MainThreadLanguageModelsShape['$registerFileIgnoreProvider'] = noop
+  $unregisterFileIgnoreProvider: MainThreadLanguageModelsShape['$unregisterFileIgnoreProvider'] =
+    noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatAgents2 implements MainThreadChatAgentsShape2 {
+  $handleProgressChunk: MainThreadChatAgentsShape2['$handleProgressChunk'] = async () => {}
+  $handleAnchorResolve: MainThreadChatAgentsShape2['$handleAnchorResolve'] = noop
+  $registerAgent: MainThreadChatAgentsShape2['$registerAgent'] = noop
+  $registerChatParticipantDetectionProvider: MainThreadChatAgentsShape2['$registerChatParticipantDetectionProvider'] =
+    noop
+  $unregisterChatParticipantDetectionProvider: MainThreadChatAgentsShape2['$unregisterChatParticipantDetectionProvider'] =
+    noop
+  $registerPromptFileProvider: MainThreadChatAgentsShape2['$registerPromptFileProvider'] = noop
+  $unregisterPromptFileProvider: MainThreadChatAgentsShape2['$unregisterPromptFileProvider'] = noop
+  $onDidChangePromptFiles: MainThreadChatAgentsShape2['$onDidChangePromptFiles'] = noop
+  $registerChatSessionCustomizationProvider: MainThreadChatAgentsShape2['$registerChatSessionCustomizationProvider'] =
+    noop
+  $unregisterChatSessionCustomizationProvider: MainThreadChatAgentsShape2['$unregisterChatSessionCustomizationProvider'] =
+    noop
+  $onDidChangeCustomizations: MainThreadChatAgentsShape2['$onDidChangeCustomizations'] = noop
+  $registerAgentCompletionsProvider: MainThreadChatAgentsShape2['$registerAgentCompletionsProvider'] =
+    noop
+  $unregisterAgentCompletionsProvider: MainThreadChatAgentsShape2['$unregisterAgentCompletionsProvider'] =
+    noop
+  $updateAgent: MainThreadChatAgentsShape2['$updateAgent'] = noop
+  $unregisterAgent: MainThreadChatAgentsShape2['$unregisterAgent'] = noop
+  @Unsupported
+  $transferActiveChatSession: MainThreadChatAgentsShape2['$transferActiveChatSession'] = unsupported
+  $provideCustomAgents: MainThreadChatAgentsShape2['$provideCustomAgents'] = async () => []
+  $provideInstructions: MainThreadChatAgentsShape2['$provideInstructions'] = async () => []
+  $provideSkills: MainThreadChatAgentsShape2['$provideSkills'] = async () => []
+  $provideSlashCommands: MainThreadChatAgentsShape2['$provideSlashCommands'] = async () => []
+  $provideHooks: MainThreadChatAgentsShape2['$provideHooks'] = async () => []
+  $providePlugins: MainThreadChatAgentsShape2['$providePlugins'] = async () => []
+  dispose(): void {}
+}
+
+class MissingMainThreadCodeMapper implements MainThreadCodeMapperShape {
+  $registerCodeMapperProvider: MainThreadCodeMapperShape['$registerCodeMapperProvider'] = noop
+  $unregisterCodeMapperProvider: MainThreadCodeMapperShape['$unregisterCodeMapperProvider'] = noop
+  $handleProgress: MainThreadCodeMapperShape['$handleProgress'] = async () => {}
+  dispose(): void {}
+}
+
+class MissingMainThreadLanguageModelTools implements MainThreadLanguageModelToolsShape {
+  $getTools: MainThreadLanguageModelToolsShape['$getTools'] = async () => []
+  $acceptToolProgress: MainThreadLanguageModelToolsShape['$acceptToolProgress'] = noop
+  @Unsupported
+  $invokeTool: MainThreadLanguageModelToolsShape['$invokeTool'] = unsupported
+  @Unsupported
+  $countTokensForInvocation: MainThreadLanguageModelToolsShape['$countTokensForInvocation'] =
+    unsupported
+  $registerTool: MainThreadLanguageModelToolsShape['$registerTool'] = noop
+  $registerToolWithDefinition: MainThreadLanguageModelToolsShape['$registerToolWithDefinition'] =
+    noop
+  $unregisterTool: MainThreadLanguageModelToolsShape['$unregisterTool'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatContext implements MainThreadChatContextShape {
+  $registerChatWorkspaceContextProvider: MainThreadChatContextShape['$registerChatWorkspaceContextProvider'] =
+    noop
+  $registerChatExplicitContextProvider: MainThreadChatContextShape['$registerChatExplicitContextProvider'] =
+    noop
+  $registerChatResourceContextProvider: MainThreadChatContextShape['$registerChatResourceContextProvider'] =
+    noop
+  $unregisterChatContextProvider: MainThreadChatContextShape['$unregisterChatContextProvider'] =
+    noop
+  $updateWorkspaceContextItems: MainThreadChatContextShape['$updateWorkspaceContextItems'] = noop
+  @Unsupported
+  $executeChatContextItemCommand: MainThreadChatContextShape['$executeChatContextItemCommand'] =
+    unsupported
+  dispose(): void {}
+}
+
+class MissingMainThreadChatDebug implements MainThreadChatDebugShape {
+  $registerChatDebugLogProvider: MainThreadChatDebugShape['$registerChatDebugLogProvider'] = noop
+  $unregisterChatDebugLogProvider: MainThreadChatDebugShape['$unregisterChatDebugLogProvider'] =
+    noop
+  $acceptChatDebugEvent: MainThreadChatDebugShape['$acceptChatDebugEvent'] = noop
+  $subscribeToCoreDebugEvents: MainThreadChatDebugShape['$subscribeToCoreDebugEvents'] = noop
+  $unsubscribeFromCoreDebugEvents: MainThreadChatDebugShape['$unsubscribeFromCoreDebugEvents'] =
+    noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatStatus implements MainThreadChatStatusShape {
+  $setEntry: MainThreadChatStatusShape['$setEntry'] = noop
+  $disposeEntry: MainThreadChatStatusShape['$disposeEntry'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatQuota implements MainThreadChatQuotaShape {
+  $updateQuotas: MainThreadChatQuotaShape['$updateQuotas'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatInputNotification implements MainThreadChatInputNotificationShape {
+  $setNotification: MainThreadChatInputNotificationShape['$setNotification'] = noop
+  $disposeNotification: MainThreadChatInputNotificationShape['$disposeNotification'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadChatSessions implements MainThreadChatSessionsShape {
+  $registerChatSessionItemController: MainThreadChatSessionsShape['$registerChatSessionItemController'] =
+    noop
+  $updateChatSessionItemControllerCapabilities: MainThreadChatSessionsShape['$updateChatSessionItemControllerCapabilities'] =
+    noop
+  $unregisterChatSessionItemController: MainThreadChatSessionsShape['$unregisterChatSessionItemController'] =
+    noop
+  $updateChatSessionItems: MainThreadChatSessionsShape['$updateChatSessionItems'] = async () => {}
+  $addOrUpdateChatSessionItem: MainThreadChatSessionsShape['$addOrUpdateChatSessionItem'] =
+    async () => {}
+  $onDidCommitChatSessionItem: MainThreadChatSessionsShape['$onDidCommitChatSessionItem'] = noop
+  $registerChatSessionContentProvider: MainThreadChatSessionsShape['$registerChatSessionContentProvider'] =
+    noop
+  $unregisterChatSessionContentProvider: MainThreadChatSessionsShape['$unregisterChatSessionContentProvider'] =
+    noop
+  $onDidChangeChatSessionOptions: MainThreadChatSessionsShape['$onDidChangeChatSessionOptions'] =
+    noop
+  $onDidChangeChatSessionProviderOptions: MainThreadChatSessionsShape['$onDidChangeChatSessionProviderOptions'] =
+    noop
+  $updateChatSessionInputState: MainThreadChatSessionsShape['$updateChatSessionInputState'] = noop
+  $handleProgressChunk: MainThreadChatSessionsShape['$handleProgressChunk'] = async () => {}
+  $handleAnchorResolve: MainThreadChatSessionsShape['$handleAnchorResolve'] = noop
+  $handleProgressComplete: MainThreadChatSessionsShape['$handleProgressComplete'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadNotebook implements MainThreadNotebookShape {
+  $registerNotebookSerializer: MainThreadNotebookShape['$registerNotebookSerializer'] = noop
+  $unregisterNotebookSerializer: MainThreadNotebookShape['$unregisterNotebookSerializer'] = noop
+  $registerNotebookCellStatusBarItemProvider: MainThreadNotebookShape['$registerNotebookCellStatusBarItemProvider'] =
+    async () => {}
+  $unregisterNotebookCellStatusBarItemProvider: MainThreadNotebookShape['$unregisterNotebookCellStatusBarItemProvider'] =
+    async () => {}
+  $emitCellStatusBarEvent: MainThreadNotebookShape['$emitCellStatusBarEvent'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadNotebookKernels implements MainThreadNotebookKernelsShape {
+  $postMessage: MainThreadNotebookKernelsShape['$postMessage'] = async () => false
+  $addKernel: MainThreadNotebookKernelsShape['$addKernel'] = async () => {}
+  $updateKernel: MainThreadNotebookKernelsShape['$updateKernel'] = noop
+  $removeKernel: MainThreadNotebookKernelsShape['$removeKernel'] = noop
+  $updateNotebookPriority: MainThreadNotebookKernelsShape['$updateNotebookPriority'] = noop
+  $createExecution: MainThreadNotebookKernelsShape['$createExecution'] = noop
+  $updateExecution: MainThreadNotebookKernelsShape['$updateExecution'] = noop
+  $completeExecution: MainThreadNotebookKernelsShape['$completeExecution'] = noop
+  $createNotebookExecution: MainThreadNotebookKernelsShape['$createNotebookExecution'] = noop
+  $beginNotebookExecution: MainThreadNotebookKernelsShape['$beginNotebookExecution'] = noop
+  $completeNotebookExecution: MainThreadNotebookKernelsShape['$completeNotebookExecution'] = noop
+  $addKernelDetectionTask: MainThreadNotebookKernelsShape['$addKernelDetectionTask'] =
+    async () => {}
+  $removeKernelDetectionTask: MainThreadNotebookKernelsShape['$removeKernelDetectionTask'] = noop
+  $addKernelSourceActionProvider: MainThreadNotebookKernelsShape['$addKernelSourceActionProvider'] =
+    async () => {}
+  $removeKernelSourceActionProvider: MainThreadNotebookKernelsShape['$removeKernelSourceActionProvider'] =
+    noop
+  $emitNotebookKernelSourceActionsChangeEvent: MainThreadNotebookKernelsShape['$emitNotebookKernelSourceActionsChangeEvent'] =
+    noop
+  $receiveVariable: MainThreadNotebookKernelsShape['$receiveVariable'] = noop
+  $variablesUpdated: MainThreadNotebookKernelsShape['$variablesUpdated'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadNotebookDocuments implements MainThreadNotebookDocumentsShape {
+  @Unsupported
+  $tryCreateNotebook: MainThreadNotebookDocumentsShape['$tryCreateNotebook'] = unsupported
+  @Unsupported
+  $tryOpenNotebook: MainThreadNotebookDocumentsShape['$tryOpenNotebook'] = unsupported
+  @Unsupported
+  $trySaveNotebook: MainThreadNotebookDocumentsShape['$trySaveNotebook'] = unsupported
+  dispose(): void {}
+}
+
+class MissingMainThreadNotebookEditors implements MainThreadNotebookEditorsShape {
+  @Unsupported
+  $tryShowNotebookDocument: MainThreadNotebookEditorsShape['$tryShowNotebookDocument'] = unsupported
+  @Unsupported
+  $tryRevealRange: MainThreadNotebookEditorsShape['$tryRevealRange'] = unsupported
+  $trySetSelections: MainThreadNotebookEditorsShape['$trySetSelections'] = noop
+  dispose(): void {}
+}
+
+class MissingMainThreadNotebookRenderers implements MainThreadNotebookRenderersShape {
+  $postMessage: MainThreadNotebookRenderersShape['$postMessage'] = async () => false
+  dispose(): void {}
+}
+
+class MissingMainThreadMcp implements MainThreadMcpShape {
+  $onDidChangeState: MainThreadMcpShape['$onDidChangeState'] = noop
+  $onDidPublishLog: MainThreadMcpShape['$onDidPublishLog'] = noop
+  $onDidReceiveMessage: MainThreadMcpShape['$onDidReceiveMessage'] = noop
+  $upsertMcpCollection: MainThreadMcpShape['$upsertMcpCollection'] = noop
+  $deleteMcpCollection: MainThreadMcpShape['$deleteMcpCollection'] = noop
+  @Unsupported
+  $getTokenFromServerMetadata: MainThreadMcpShape['$getTokenFromServerMetadata'] = unsupported
+  @Unsupported
+  $getTokenForProviderId: MainThreadMcpShape['$getTokenForProviderId'] = unsupported
+  $logMcpAuthSetup: MainThreadMcpShape['$logMcpAuthSetup'] = noop
+  @Unsupported
+  $startMcpGateway: MainThreadMcpShape['$startMcpGateway'] = unsupported
+  $disposeMcpGateway: MainThreadMcpShape['$disposeMcpGateway'] = noop
+  dispose(): void {}
+}
+
+const missingMainThreadCustomers: [ProxyIdentifier<unknown>, new () => IDisposable][] = [
+  [MainContext.MainThreadLanguageModels, MissingMainThreadLanguageModels],
+  [MainContext.MainThreadChatAgents2, MissingMainThreadChatAgents2],
+  [MainContext.MainThreadCodeMapper, MissingMainThreadCodeMapper],
+  [MainContext.MainThreadLanguageModelTools, MissingMainThreadLanguageModelTools],
+  [MainContext.MainThreadChatContext, MissingMainThreadChatContext],
+  [MainContext.MainThreadChatDebug, MissingMainThreadChatDebug],
+  [MainContext.MainThreadChatStatus, MissingMainThreadChatStatus],
+  [MainContext.MainThreadChatQuota, MissingMainThreadChatQuota],
+  [MainContext.MainThreadChatInputNotification, MissingMainThreadChatInputNotification],
+  [MainContext.MainThreadChatSessions, MissingMainThreadChatSessions],
+  [MainContext.MainThreadNotebook, MissingMainThreadNotebook],
+  [MainContext.MainThreadNotebookKernels, MissingMainThreadNotebookKernels],
+  [MainContext.MainThreadNotebookDocuments, MissingMainThreadNotebookDocuments],
+  [MainContext.MainThreadNotebookEditors, MissingMainThreadNotebookEditors],
+  [MainContext.MainThreadNotebookRenderers, MissingMainThreadNotebookRenderers],
+  [MainContext.MainThreadMcp, MissingMainThreadMcp]
+]
+
+// Unnamed customers are instantiated after the named ones, and a real implementation set later replaces the missing one,
+// so it only registers the missing implementations whatever the import order is
+class MissingMainThreadCustomers implements IDisposable {
+  constructor(extHostContext: IExtHostContext) {
+    for (const [id, ctor] of missingMainThreadCustomers) {
+      try {
+        extHostContext.assertRegistered([id])
+      } catch {
+        extHostContext.set(id, new ctor())
+      }
+    }
+  }
+
+  dispose(): void {}
+}
+extHostCustomer(MissingMainThreadCustomers)
diff --git a/src/tools.ts b/src/tools.ts
index 4a84e67a..04f1072f 100644
--- a/src/tools.ts
+++ b/src/tools.ts
@@ -4,6 +4,33 @@ export function unsupported(): never {
 
 export const noop = (): void => {}
 
+/**
+ * Makes a property, method or getter of a missing implementation throw an explicit error
+ */
+export function Unsupported(target: object, propertyKey: string, descriptor?: PropertyDescriptor) {
+  function unsupported() {
+    throw new Error(
+      `Unsupported: ${target.constructor.name}.${propertyKey} is not supported. You are using a feature without registering the corresponding service override.`
+    )
+  }
+  if (descriptor != null) {
+    if (descriptor.value != null) {
+      descriptor.value = unsupported
+    } else if (descriptor.get != null) {
+      descriptor.get = unsupported
+    }
+  } else {
+    Object.defineProperty(target, propertyKey, {
+      get() {
+        unsupported()
+      },
+      set() {},
+      configurable: true,
+      enumerable: true
+    })
+  }
+}
+
 export function memoized<A extends unknown[], T>(fct: (...args: A) => T): (...args: A) => T {
   let v: T | null = null
   return (...args) => {
diff --git a/vscode-patches/0109-refactor-avoid-runtime-dependencies-from-core-on-cha.patch b/vscode-patches/0109-refactor-avoid-runtime-dependencies-from-core-on-cha.patch
new file mode 100644
index 00000000..6e061657
--- /dev/null
+++ b/vscode-patches/0109-refactor-avoid-runtime-dependencies-from-core-on-cha.patch
@@ -0,0 +1,383 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Brian Jenkins <brianjenkins94@gmail.com>
+Date: Mon, 28 Sep 2026 00:29:33 -0400
+Subject: [PATCH] refactor: avoid runtime dependencies from core on chat and
+ notebook implementations
+
+Search, terminal decorations, SCM, tasks, getting started and the extension
+host only needed a type, a lazily-used class, a command/tool id or a small
+helper from chat/notebook, but imported them from modules that load the whole
+chat implementation or notebook editor, which made them part of every
+workbench, even without the chat/notebook service overrides.
+
+Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
+---
+ .../api/common/extHostLanguageModelTools.ts   |  3 +-
+ .../api/common/extHostTypeConverters.ts       |  2 +-
+ .../chat/browser/actions/chatConstants.ts     |  1 +
+ .../contrib/chat/common/chatImageBuffer.ts    | 34 +++++++++++++++++++
+ .../chat/common/chatImageExtraction.ts        | 31 ++---------------
+ .../common/tools/builtinTools/editFileTool.ts |  5 +--
+ .../chat/common/tools/builtinTools/toolIds.ts |  9 +++++
+ .../chat/common/tools/builtinTools/tools.ts   |  2 +-
+ .../contrib/scm/browser/scm.contribution.ts   |  2 +-
+ .../workbench/contrib/scm/browser/scmInput.ts |  2 +-
+ .../browser/searchTreeModel/searchResult.ts   |  8 ++---
+ .../contrib/search/browser/searchView.ts      |  9 +++--
+ .../tasks/browser/abstractTaskService.ts      |  2 +-
+ .../terminal/browser/xterm/decorationAddon.ts |  4 ++-
+ .../browser/agentSessionsWelcome.ts           |  4 +--
+ .../browser/agentSessionsWelcomeInput.ts      |  1 +
+ .../browser/gettingStarted.contribution.ts    |  4 +--
+ 17 files changed, 74 insertions(+), 49 deletions(-)
+ create mode 100644 src/vs/workbench/contrib/chat/common/chatImageBuffer.ts
+ create mode 100644 src/vs/workbench/contrib/chat/common/tools/builtinTools/toolIds.ts
+
+diff --git a/src/vs/workbench/api/common/extHostLanguageModelTools.ts b/src/vs/workbench/api/common/extHostLanguageModelTools.ts
+index f34d76c9..782d83e6 100644
+--- a/src/vs/workbench/api/common/extHostLanguageModelTools.ts
++++ b/src/vs/workbench/api/common/extHostLanguageModelTools.ts
+@@ -13,8 +13,7 @@ import { generateUuid } from '../../../base/common/uuid.js';
+ import { IExtensionDescription } from '../../../platform/extensions/common/extensions.js';
+ import { IPreparedToolInvocation, IStreamedToolInvocation, isToolInvocationContext, IToolInvocation, IToolInvocationContext, IToolInvocationPreparationContext, IToolInvocationStreamContext, IToolResult, ToolInvocationPresentation } from '../../contrib/chat/common/tools/languageModelToolsService.js';
+ import { computeCombinationKey } from '../../contrib/chat/common/tools/languageModelToolsConfirmationService.js';
+-import { ExtensionEditToolId, InternalEditToolId } from '../../contrib/chat/common/tools/builtinTools/editFileTool.js';
+-import { InternalFetchWebPageToolId } from '../../contrib/chat/common/tools/builtinTools/tools.js';
++import { ExtensionEditToolId, InternalEditToolId, InternalFetchWebPageToolId } from '../../contrib/chat/common/tools/builtinTools/toolIds.js';
+ import { SearchExtensionsToolId } from '../../contrib/extensions/common/searchExtensionsTool.js';
+ import { checkProposedApiEnabled, isProposedApiEnabled } from '../../services/extensions/common/extensions.js';
+ import { Dto, SerializableObjectWithBuffers } from '../../services/extensions/common/proxyIdentifier.js';
+diff --git a/src/vs/workbench/api/common/extHostTypeConverters.ts b/src/vs/workbench/api/common/extHostTypeConverters.ts
+index b3e6860b..36aa3bf9 100644
+--- a/src/vs/workbench/api/common/extHostTypeConverters.ts
++++ b/src/vs/workbench/api/common/extHostTypeConverters.ts
+@@ -46,7 +46,7 @@ import { IChatRequestModeInstructions } from '../../contrib/chat/common/model/ch
+ import { IChatAgentMarkdownContentWithVulnerability, IChatAutoModeResolutionPart, IChatCodeCitation, IChatCommandButton, IChatConfirmation, IChatContentInlineReference, IChatContentReference, IChatExtensionsContent, IChatExternalToolInvocationUpdate, IChatFollowup, IChatHookPart, IChatMarkdownContent, IChatMoveMessage, IChatMultiDiffDataSerialized, IChatProgressMessage, IChatPullRequestContent, IChatQuestionCarousel, IChatResponseCodeblockUriPart, IChatTaskDto, IChatTaskResult, IChatTerminalToolInvocationData, IChatTextEdit, IChatThinkingPart, IChatToolInvocationSerialized, IChatTreeData, IChatUserActionEvent, IChatVoiceProgressPart, IChatWarningMessage, IChatInfoMessage, IChatWorkspaceEdit } from '../../contrib/chat/common/chatService/chatService.js';
+ import { LocalChatSessionUri } from '../../contrib/chat/common/model/chatUri.js';
+ import { ChatRequestToolReferenceEntry, IChatRequestVariableEntry, isElementVariableEntry, isImageVariableEntry, isPromptFileVariableEntry, isPromptTextVariableEntry } from '../../contrib/chat/common/attachments/chatVariableEntries.js';
+-import { coerceImageBuffer } from '../../contrib/chat/common/chatImageExtraction.js';
++import { coerceImageBuffer } from '../../contrib/chat/common/chatImageBuffer.js';
+ import { ChatSessionStatus, IChatSessionItem } from '../../contrib/chat/common/chatSessionsService.js';
+ import { ChatAgentLocation } from '../../contrib/chat/common/constants.js';
+ import { ChatRequestHooks, resolveEffectiveCommand } from '../../contrib/chat/common/promptSyntax/hookSchema.js';
+diff --git a/src/vs/workbench/contrib/chat/browser/actions/chatConstants.ts b/src/vs/workbench/contrib/chat/browser/actions/chatConstants.ts
+index 17e137b5..71002004 100644
+--- a/src/vs/workbench/contrib/chat/browser/actions/chatConstants.ts
++++ b/src/vs/workbench/contrib/chat/browser/actions/chatConstants.ts
+@@ -6,6 +6,7 @@ import { localize2 } from '../../../../../nls.js';
+ 
+ export const CHAT_CATEGORY = localize2('chat.category', 'Chat');
+ export const CHAT_OPEN_ACTION_ID = 'workbench.action.chat.open';
++export const CHAT_SETUP_SUPPORT_ANONYMOUS_ACTION_ID = 'workbench.action.chat.triggerSetupSupportAnonymousAction';
+ export const ASK_QUICK_QUESTION_ACTION_ID = 'workbench.action.quickchat.toggle';
+ export const AcceptToolConfirmationActionId = 'workbench.action.chat.acceptTool';
+ export const SkipToolConfirmationActionId = 'workbench.action.chat.skipTool';
+diff --git a/src/vs/workbench/contrib/chat/common/chatImageBuffer.ts b/src/vs/workbench/contrib/chat/common/chatImageBuffer.ts
+new file mode 100644
+index 00000000..4d0b845d
+--- /dev/null
++++ b/src/vs/workbench/contrib/chat/common/chatImageBuffer.ts
+@@ -0,0 +1,34 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++// Kept in its own dependency-free module so that code outside of chat (e.g. extHostTypeConverters)
++// can use it without loading the chat model
++export function coerceImageBuffer(value: unknown): Uint8Array | undefined {
++	if (value instanceof Uint8Array) {
++		return value;
++	}
++	if (value instanceof ArrayBuffer) {
++		return new Uint8Array(value);
++	}
++	if (!value || typeof value !== 'object' || Array.isArray(value)) {
++		return undefined;
++	}
++
++	const record = value as Record<string, unknown>;
++	const keys = Object.keys(record).sort((a, b) => Number(a) - Number(b));
++	if (keys.length === 0) {
++		return undefined;
++	}
++
++	const result = new Uint8Array(keys.length);
++	for (let index = 0; index < keys.length; index++) {
++		const byte = record[keys[index]];
++		if (keys[index] !== String(index) || typeof byte !== 'number' || !Number.isInteger(byte) || byte < 0 || byte > 255) {
++			return undefined;
++		}
++		result[index] = byte;
++	}
++	return result;
++}
+diff --git a/src/vs/workbench/contrib/chat/common/chatImageExtraction.ts b/src/vs/workbench/contrib/chat/common/chatImageExtraction.ts
+index cc289ef3..d0ae0f2d 100644
+--- a/src/vs/workbench/contrib/chat/common/chatImageExtraction.ts
++++ b/src/vs/workbench/contrib/chat/common/chatImageExtraction.ts
+@@ -14,6 +14,9 @@ import { ChatResponseResource } from './model/chatModel.js';
+ import { IChatContentInlineReference, IChatToolInvocation, IChatToolInvocationSerialized, IToolResultOutputDetailsSerialized } from './chatService/chatService.js';
+ import { isToolResultInputOutputDetails, isToolResultOutputDetails, IToolResultOutputDetails } from './tools/languageModelToolsService.js';
+ import { getExplicitFileOrImageAttachmentSummary, type IChatRequestVariableEntry, isImageVariableEntry } from './attachments/chatVariableEntries.js';
++import { coerceImageBuffer } from './chatImageBuffer.js';
++
++export { coerceImageBuffer };
+ 
+ export interface IChatExtractedImage {
+ 	readonly id: string;
+@@ -188,34 +191,6 @@ async function extractImageFromInlineReference(
+ 	};
+ }
+ 
+-export function coerceImageBuffer(value: unknown): Uint8Array | undefined {
+-	if (value instanceof Uint8Array) {
+-		return value;
+-	}
+-	if (value instanceof ArrayBuffer) {
+-		return new Uint8Array(value);
+-	}
+-	if (!value || typeof value !== 'object' || Array.isArray(value)) {
+-		return undefined;
+-	}
+-
+-	const record = value as Record<string, unknown>;
+-	const keys = Object.keys(record).sort((a, b) => Number(a) - Number(b));
+-	if (keys.length === 0) {
+-		return undefined;
+-	}
+-
+-	const result = new Uint8Array(keys.length);
+-	for (let index = 0; index < keys.length; index++) {
+-		const byte = record[keys[index]];
+-		if (keys[index] !== String(index) || typeof byte !== 'number' || !Number.isInteger(byte) || byte < 0 || byte > 255) {
+-			return undefined;
+-		}
+-		result[index] = byte;
+-	}
+-	return result;
+-}
+-
+ /**
+  * Extract images from a chat request's variable attachments (user-attached images).
+  */
+diff --git a/src/vs/workbench/contrib/chat/common/tools/builtinTools/editFileTool.ts b/src/vs/workbench/contrib/chat/common/tools/builtinTools/editFileTool.ts
+index addfc96f..fc33b652 100644
+--- a/src/vs/workbench/contrib/chat/common/tools/builtinTools/editFileTool.ts
++++ b/src/vs/workbench/contrib/chat/common/tools/builtinTools/editFileTool.ts
+@@ -15,9 +15,10 @@ import { ICodeMapperService } from '../../editing/chatCodeMapperService.js';
+ import { ChatModel } from '../../model/chatModel.js';
+ import { IChatService } from '../../chatService/chatService.js';
+ import { CountTokensCallback, IPreparedToolInvocation, IToolData, IToolImpl, IToolInvocation, IToolInvocationPreparationContext, IToolResult, ToolDataSource, ToolInvocationPresentation, ToolProgress } from '../languageModelToolsService.js';
++import { InternalEditToolId } from './toolIds.js';
++
++export { ExtensionEditToolId, InternalEditToolId } from './toolIds.js';
+ 
+-export const ExtensionEditToolId = 'vscode_editFile';
+-export const InternalEditToolId = 'vscode_editFile_internal';
+ export const EditToolData: IToolData = {
+ 	id: InternalEditToolId,
+ 	displayName: '', // not used
+diff --git a/src/vs/workbench/contrib/chat/common/tools/builtinTools/toolIds.ts b/src/vs/workbench/contrib/chat/common/tools/builtinTools/toolIds.ts
+new file mode 100644
+index 00000000..91daae1f
+--- /dev/null
++++ b/src/vs/workbench/contrib/chat/common/tools/builtinTools/toolIds.ts
+@@ -0,0 +1,9 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++// Kept in a dependency-free module so that the extension host can use them without loading the tools
++export const ExtensionEditToolId = 'vscode_editFile';
++export const InternalEditToolId = 'vscode_editFile_internal';
++export const InternalFetchWebPageToolId = 'vscode_fetchWebPage_internal';
+diff --git a/src/vs/workbench/contrib/chat/common/tools/builtinTools/tools.ts b/src/vs/workbench/contrib/chat/common/tools/builtinTools/tools.ts
+index 4a711c40..bec1c893 100644
+--- a/src/vs/workbench/contrib/chat/common/tools/builtinTools/tools.ts
++++ b/src/vs/workbench/contrib/chat/common/tools/builtinTools/tools.ts
+@@ -104,4 +104,4 @@ export class BuiltinToolsContribution extends Disposable implements IWorkbenchCo
+ 	}
+ }
+ 
+-export const InternalFetchWebPageToolId = 'vscode_fetchWebPage_internal';
++export { InternalFetchWebPageToolId } from './toolIds.js';
+diff --git a/src/vs/workbench/contrib/scm/browser/scm.contribution.ts b/src/vs/workbench/contrib/scm/browser/scm.contribution.ts
+index 6ee2a32c..a5cba418 100644
+--- a/src/vs/workbench/contrib/scm/browser/scm.contribution.ts
++++ b/src/vs/workbench/contrib/scm/browser/scm.contribution.ts
+@@ -40,7 +40,7 @@ import { SCMAccessibilityHelp } from './scmAccessibilityHelp.js';
+ import { EditorContextKeys } from '../../../../editor/common/editorContextKeys.js';
+ import { SCMHistoryItemContextContribution } from './scmHistoryChatContext.js';
+ import { ChatContextKeys } from '../../chat/common/actions/chatContextKeys.js';
+-import { CHAT_SETUP_SUPPORT_ANONYMOUS_ACTION_ID } from '../../chat/browser/actions/chatActions.js';
++import { CHAT_SETUP_SUPPORT_ANONYMOUS_ACTION_ID } from '../../chat/browser/actions/chatConstants.js';
+ import { SCMInputContextKeys } from './scmInput.js';
+ import product from '../../../../platform/product/common/product.js';
+ 
+diff --git a/src/vs/workbench/contrib/scm/browser/scmInput.ts b/src/vs/workbench/contrib/scm/browser/scmInput.ts
+index 63642985..66846d74 100644
+--- a/src/vs/workbench/contrib/scm/browser/scmInput.ts
++++ b/src/vs/workbench/contrib/scm/browser/scmInput.ts
+@@ -70,7 +70,7 @@ import { IAccessibilityService } from '../../../../platform/accessibility/common
+ import { AccessibilityCommandId } from '../../accessibility/common/accessibilityCommands.js';
+ import { ChatContextKeys } from '../../chat/common/actions/chatContextKeys.js';
+ import product from '../../../../platform/product/common/product.js';
+-import { CHAT_SETUP_SUPPORT_ANONYMOUS_ACTION_ID } from '../../chat/browser/actions/chatActions.js';
++import { CHAT_SETUP_SUPPORT_ANONYMOUS_ACTION_ID } from '../../chat/browser/actions/chatConstants.js';
+ 
+ export const SCMInputContextKeys = {
+ 	SCMInputHasValidationMessage: new RawContextKey<boolean>('scmInputHasValidationMessage', false),
+diff --git a/src/vs/workbench/contrib/search/browser/searchTreeModel/searchResult.ts b/src/vs/workbench/contrib/search/browser/searchTreeModel/searchResult.ts
+index c55c9aa6..7cba78cd 100644
+--- a/src/vs/workbench/contrib/search/browser/searchTreeModel/searchResult.ts
++++ b/src/vs/workbench/contrib/search/browser/searchTreeModel/searchResult.ts
+@@ -10,7 +10,7 @@ import { ITextModel } from '../../../../../editor/common/model.js';
+ import { IModelService } from '../../../../../editor/common/services/model.js';
+ import { IInstantiationService } from '../../../../../platform/instantiation/common/instantiation.js';
+ import { IProgress, IProgressStep } from '../../../../../platform/progress/common/progress.js';
+-import { NotebookEditorWidget } from '../../../notebook/browser/notebookEditorWidget.js';
++import type { NotebookEditorWidget } from '../../../notebook/browser/notebookEditorWidget.js';
+ import { INotebookEditorService } from '../../../notebook/browser/services/notebookEditorService.js';
+ import { IAITextQuery, IFileMatch, ISearchComplete, ITextQuery, QueryType } from '../../../../services/search/common/search.js';
+ import { arrayContainsElementOrParent, IChangeEvent, ISearchTreeFileMatch, ISearchTreeFolderMatch, IPlainTextSearchHeading, ISearchModel, ISearchResult, isSearchTreeFileMatch, isSearchTreeFolderMatch, isSearchTreeFolderMatchNoRoot, isSearchTreeFolderMatchWithResource, isSearchTreeMatch, isTextSearchHeading, ITextSearchHeading, mergeSearchResultEvents, RenderableMatch, SEARCH_RESULT_PREFIX } from './searchTreeCommon.js';
+@@ -48,9 +48,9 @@ export class SearchResultImpl extends Disposable implements ISearchResult {
+ 		this._register(this.modelService.onModelAdded(model => this.onModelAdded(model)));
+ 
+ 		this._register(this.notebookEditorService.onDidAddNotebookEditor(widget => {
+-			if (widget instanceof NotebookEditorWidget) {
+-				this.onDidAddNotebookEditorWidget(<NotebookEditorWidget>widget);
+-			}
++			// Only NotebookEditorWidget registers itself with the notebook editor service, so a type-only cast is
++			// enough here and avoids a runtime dependency on the whole notebook editor implementation
++			this.onDidAddNotebookEditorWidget(<NotebookEditorWidget>widget);
+ 		}));
+ 
+ 		this._id = SEARCH_RESULT_PREFIX + Date.now().toString();
+diff --git a/src/vs/workbench/contrib/search/browser/searchView.ts b/src/vs/workbench/contrib/search/browser/searchView.ts
+index cd44270e..9f200dd3 100644
+--- a/src/vs/workbench/contrib/search/browser/searchView.ts
++++ b/src/vs/workbench/contrib/search/browser/searchView.ts
+@@ -55,7 +55,8 @@ import { IViewPaneOptions, ViewPane } from '../../../browser/parts/views/viewPan
+ import { IEditorPane } from '../../../common/editor.js';
+ import { Memento } from '../../../common/memento.js';
+ import { IViewDescriptorService } from '../../../common/views.js';
+-import { NotebookEditor } from '../../notebook/browser/notebookEditor.js';
++import type { NotebookEditor } from '../../notebook/browser/notebookEditor.js';
++import { NOTEBOOK_EDITOR_ID } from '../../notebook/common/notebookCommon.js';
+ import { ExcludePatternInputWidget, IncludePatternInputWidget } from './patternInputWidget.js';
+ import { IFindInFilesArgs } from './searchActionsBase.js';
+ import { searchDetailsIcon } from './searchIcons.js';
+@@ -2269,13 +2270,15 @@ export class SearchView extends ViewPane {
+ 			return;
+ 		}
+ 
+-		if (editor instanceof NotebookEditor) {
++		// Checking the editor id rather than using `instanceof` avoids a runtime dependency on the notebook editor
++		if (editor?.getId() === NOTEBOOK_EDITOR_ID) {
++			const notebookEditor = editor as NotebookEditor;
+ 			const elemParent = element.parent() as INotebookFileInstanceMatch;
+ 			if (isSearchTreeMatch(element)) {
+ 				if (isIMatchInNotebook(element)) {
+ 					element.parent().showMatch(element);
+ 				} else {
+-					const editorWidget = editor.getControl();
++					const editorWidget = notebookEditor.getControl();
+ 					if (editorWidget) {
+ 						// Ensure that the editor widget is binded. If if is, then this should return immediately.
+ 						// Otherwise, it will bind the widget.
+diff --git a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
+index 129e228a..6c4ba470 100644
+--- a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
++++ b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
+@@ -85,7 +85,7 @@ import { IPathService } from '../../../services/path/common/pathService.js';
+ import { IPreferencesService } from '../../../services/preferences/common/preferences.js';
+ import { IRemoteAgentService } from '../../../services/remote/common/remoteAgentService.js';
+ import { IViewsService } from '../../../services/views/common/viewsService.js';
+-import { CHAT_OPEN_ACTION_ID } from '../../chat/browser/actions/chatActions.js';
++import { CHAT_OPEN_ACTION_ID } from '../../chat/browser/actions/chatConstants.js';
+ import { IChatAgentService } from '../../chat/common/participants/chatAgents.js';
+ import { IChatService } from '../../chat/common/chatService/chatService.js';
+ import { configureTaskIcon, isWorkspaceFolder, ITaskQuickPickEntry, QUICKOPEN_DETAIL_CONFIG, QUICKOPEN_SKIP_CONFIG, TaskQuickPick } from './taskQuickPick.js';
+diff --git a/src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts b/src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts
+index 0294c9fa..a7edf1ca 100644
+--- a/src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts
++++ b/src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts
+@@ -29,7 +29,7 @@ import { MarkdownString } from '../../../../../base/common/htmlContent.js';
+ import { IChatContextPickService } from '../../../chat/browser/attachments/chatContextPickService.js';
+ import { IChatWidgetService } from '../../../chat/browser/chat.js';
+ import { IInstantiationService } from '../../../../../platform/instantiation/common/instantiation.js';
+-import { TerminalContext } from '../../../chat/browser/actions/chatContext.js';
++import type { TerminalContext } from '../../../chat/browser/actions/chatContext.js';
+ import { getTerminalUri, parseTerminalUri } from '../terminalUri.js';
+ import { URI } from '../../../../../base/common/uri.js';
+ import { ChatAgentLocation } from '../../../chat/common/constants.js';
+@@ -547,6 +547,8 @@ export class DecorationAddon extends Disposable implements ITerminalAddon, IDeco
+ 				let terminalContext: TerminalContext | undefined;
+ 				if (this._resource) {
+ 					const parsedUri = parseTerminalUri(this._resource);
++					// Loaded lazily: the chat context implementation is only needed once a command is attached to chat
++					const { TerminalContext } = await import('../../../chat/browser/actions/chatContext.js');
+ 					terminalContext = this._instantiationService.createInstance(TerminalContext, getTerminalUri(parsedUri.workspaceId, parsedUri.instanceId!, undefined, command.id));
+ 				}
+ 
+diff --git a/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcome.ts b/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcome.ts
+index e31e406c..3ef69f71 100644
+--- a/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcome.ts
++++ b/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcome.ts
+@@ -42,7 +42,7 @@ import { ACTION_ID_NEW_CHAT } from '../../chat/browser/actions/chatActions.js';
+ import { IAgentSessionsService } from '../../chat/browser/agentSessions/agentSessionsService.js';
+ import { AgentSessionProviders, AgentSessionTarget } from '../../chat/browser/agentSessions/agentSessions.js';
+ import { IAgentSession } from '../../chat/browser/agentSessions/agentSessionsModel.js';
+-import { AgentSessionsWelcomeEditorOptions, AgentSessionsWelcomeInput, AgentSessionsWelcomeWorkspaceKind } from './agentSessionsWelcomeInput.js';
++import { AgentSessionsWelcomeEditorOptions, AgentSessionsWelcomeInput, AgentSessionsWelcomeWorkspaceKind, agentSessionsWelcomeCommandId } from './agentSessionsWelcomeInput.js';
+ import { IChatService } from '../../chat/common/chatService/chatService.js';
+ import { IChatModel } from '../../chat/common/model/chatModel.js';
+ import { ChatViewId, IChatWidgetService, ISessionTypePickerDelegate, IWorkspacePickerDelegate, IWorkspacePickerItem } from '../../chat/browser/chat.js';
+@@ -129,7 +129,7 @@ type AgentSessionsWelcomeActionEvent = {
+ export class AgentSessionsWelcomePage extends EditorPane {
+ 
+ 	static readonly ID = 'agentSessionsWelcomePage';
+-	static readonly COMMAND_ID = 'workbench.action.openAgentSessionsWelcome';
++	static readonly COMMAND_ID = agentSessionsWelcomeCommandId;
+ 
+ 	private container!: HTMLElement;
+ 	private contentContainer!: HTMLElement;
+diff --git a/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcomeInput.ts b/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcomeInput.ts
+index 4057dedf..de88c08b 100644
+--- a/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcomeInput.ts
++++ b/src/vs/workbench/contrib/welcomeAgentSessions/browser/agentSessionsWelcomeInput.ts
+@@ -11,6 +11,7 @@ import { IUntypedEditorInput } from '../../../common/editor.js';
+ import { IEditorOptions } from '../../../../platform/editor/common/editor.js';
+ 
+ export const agentSessionsWelcomeInputTypeId = 'workbench.editors.agentSessionsWelcomeInput';
++export const agentSessionsWelcomeCommandId = 'workbench.action.openAgentSessionsWelcome';
+ export type AgentSessionsWelcomeInitiator = 'startup' | 'command';
+ export type AgentSessionsWelcomeWorkspaceKind = 'empty' | 'folder' | 'workspace';
+ 
+diff --git a/src/vs/workbench/contrib/welcomeGettingStarted/browser/gettingStarted.contribution.ts b/src/vs/workbench/contrib/welcomeGettingStarted/browser/gettingStarted.contribution.ts
+index f90937e6..0b9fb3a1 100644
+--- a/src/vs/workbench/contrib/welcomeGettingStarted/browser/gettingStarted.contribution.ts
++++ b/src/vs/workbench/contrib/welcomeGettingStarted/browser/gettingStarted.contribution.ts
+@@ -32,7 +32,7 @@ import { Categories } from '../../../../platform/action/common/actionCommonCateg
+ import { DisposableStore } from '../../../../base/common/lifecycle.js';
+ import { AccessibleViewRegistry } from '../../../../platform/accessibility/browser/accessibleViewRegistry.js';
+ import { GettingStartedAccessibleView } from './gettingStartedAccessibleView.js';
+-import { AgentSessionsWelcomePage } from '../../welcomeAgentSessions/browser/agentSessionsWelcome.js';
++import { agentSessionsWelcomeCommandId } from '../../welcomeAgentSessions/browser/agentSessionsWelcomeInput.js';
+ import { IChatEntitlementService } from '../../../services/chat/common/chatEntitlementService.js';
+ import './gettingStartedService._contribution.js';
+ 
+@@ -72,7 +72,7 @@ registerAction2(class extends Action2 {
+ 
+ 		// If no specific walkthrough is requested and agent sessions welcome is preferred, open that instead
+ 		if (!walkthroughID && !chatEntitlementService.sentiment.hidden && configurationService.getValue<string>('workbench.startupEditor') === 'agentSessionsWelcomePage') {
+-			commandService.executeCommand(AgentSessionsWelcomePage.COMMAND_ID);
++			commandService.executeCommand(agentSessionsWelcomeCommandId);
+ 			return;
+ 		} else {
+ 			if (walkthroughID) {
+-- 
+2.39.5 (Apple Git-154)
+
diff --git a/vscode-patches/0110-refactor-split-extension-host-contribution-per-featu.patch b/vscode-patches/0110-refactor-split-extension-host-contribution-per-featu.patch
new file mode 100644
index 00000000..014efee7
--- /dev/null
+++ b/vscode-patches/0110-refactor-split-extension-host-contribution-per-featu.patch
@@ -0,0 +1,286 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Brian Jenkins <brianjenkins94@gmail.com>
+Date: Mon, 28 Sep 2026 00:30:27 -0400
+Subject: [PATCH] refactor: split extension host contribution per feature
+
+extensionHost.contribution still imports everything, but the chat, notebook
+and mcp mainThread participants now live in their own files next to an
+extensionHost.base.contribution, so they can be loaded only when needed.
+
+Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
+---
+ .../extensionHost.base.contribution.ts        |  90 +++++++++++++++
+ .../extensionHost.chat.contribution.ts        |  16 +++
+ .../api/browser/extensionHost.contribution.ts | 105 +-----------------
+ .../browser/extensionHost.mcp.contribution.ts |   7 ++
+ .../extensionHost.notebook.contribution.ts    |  11 ++
+ 5 files changed, 128 insertions(+), 101 deletions(-)
+ create mode 100644 src/vs/workbench/api/browser/extensionHost.base.contribution.ts
+ create mode 100644 src/vs/workbench/api/browser/extensionHost.chat.contribution.ts
+ create mode 100644 src/vs/workbench/api/browser/extensionHost.mcp.contribution.ts
+ create mode 100644 src/vs/workbench/api/browser/extensionHost.notebook.contribution.ts
+
+diff --git a/src/vs/workbench/api/browser/extensionHost.base.contribution.ts b/src/vs/workbench/api/browser/extensionHost.base.contribution.ts
+new file mode 100644
+index 00000000..bb2c5531
+--- /dev/null
++++ b/src/vs/workbench/api/browser/extensionHost.base.contribution.ts
+@@ -0,0 +1,90 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++
++// --- other interested parties
++import '../common/jsonValidationExtensionPoint.js';
++import '../../services/themes/common/colorExtensionPoint.js';
++import '../../services/themes/common/iconExtensionPoint.js';
++import '../../services/themes/common/tokenClassificationExtensionPoint.js';
++import '../../contrib/codeEditor/common/languageConfigurationExtensionPoint.js';
++import './statusBarExtensionPoint.js';
++import '../../services/themes/browser/cssExtensionPoint.js';
++
++// --- mainThread participants
++import './mainThreadAgentEditorComments.js';
++import './mainThreadLocalization.js';
++import './mainThreadBulkEdits.js';
++import './mainThreadEmbeddings.js';
++import './mainThreadCodeInsets.js';
++import './mainThreadCLICommands.js';
++import './mainThreadClipboard.js';
++import './mainThreadCommands.js';
++import './mainThreadConfiguration.js';
++import './mainThreadConsole.js';
++import './mainThreadDebugService.js';
++import './mainThreadDecorations.js';
++import './mainThreadDiagnostics.js';
++import './mainThreadDialogs.js';
++import './mainThreadDocumentContentProviders.js';
++import './mainThreadDocuments.js';
++import './mainThreadDocumentsAndEditors.js';
++import './mainThreadEditor.js';
++import './mainThreadEditors.js';
++import './mainThreadEditorTabs.js';
++import './mainThreadErrors.js';
++import './mainThreadExtensionService.js';
++import './mainThreadFileSystem.js';
++import './mainThreadFileSystemEventService.js';
++import './mainThreadLanguageFeatures.js';
++import './mainThreadLanguages.js';
++import './mainThreadLogService.js';
++import './mainThreadMessageService.js';
++import './mainThreadManagedSockets.js';
++import './mainThreadBrowserTunnelProxy.js';
++import './mainThreadOutputService.js';
++import './mainThreadProgress.js';
++import './mainThreadQuickDiff.js';
++import './mainThreadDocumentDiff.js';
++import './mainThreadQuickOpen.js';
++import './mainThreadRemoteConnectionData.js';
++import './mainThreadSaveParticipant.js';
++import './mainThreadSpeech.js';
++import './mainThreadEditSessionIdentityParticipant.js';
++import './mainThreadSCM.js';
++import './mainThreadSearch.js';
++import './mainThreadStatusBar.js';
++import './mainThreadStorage.js';
++import './mainThreadTelemetry.js';
++import './mainThreadTerminalService.js';
++import './mainThreadTerminalShellIntegration.js';
++import './mainThreadTheming.js';
++import './mainThreadTreeViews.js';
++import './mainThreadDownloadService.js';
++import './mainThreadUrls.js';
++import './mainThreadUriOpeners.js';
++import './mainThreadWindow.js';
++import './mainThreadPower.js';
++import './mainThreadWebviewManager.js';
++import './mainThreadWorkspace.js';
++import './mainThreadComments.js';
++import './mainThreadInteractive.js';
++import './mainThreadTask.js';
++import './mainThreadLabelService.js';
++import './mainThreadTunnelService.js';
++import './mainThreadAuthentication.js';
++import './mainThreadTimeline.js';
++import './mainThreadTesting.js';
++import './mainThreadSecretState.js';
++import './mainThreadShare.js';
++import './mainThreadProfileContentHandlers.js';
++import './mainThreadAiRelatedInformation.js';
++import './mainThreadAiEmbeddingVector.js';
++import './mainThreadAiSettingsSearch.js';
++import './mainThreadChatOutputRenderer.js';
++import './mainThreadDataChannels.js';
++import './mainThreadMeteredConnection.js';
++import './mainThreadGitExtensionService.js';
++import './mainThreadBrowsers.js';
+diff --git a/src/vs/workbench/api/browser/extensionHost.chat.contribution.ts b/src/vs/workbench/api/browser/extensionHost.chat.contribution.ts
+new file mode 100644
+index 00000000..c319d415
+--- /dev/null
++++ b/src/vs/workbench/api/browser/extensionHost.chat.contribution.ts
+@@ -0,0 +1,16 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++// Chat and language model mainThread participants, split out of extensionHost.contribution so they can be loaded separately
++import './mainThreadLanguageModels.js';
++import './mainThreadChatAgents2.js';
++import './mainThreadChatCodeMapper.js';
++import './mainThreadLanguageModelTools.js';
++import './mainThreadChatContext.js';
++import './mainThreadChatDebug.js';
++import './mainThreadChatStatus.js';
++import './mainThreadChatQuota.js';
++import './mainThreadChatInputNotification.js';
++import './mainThreadChatSessions.js';
+diff --git a/src/vs/workbench/api/browser/extensionHost.contribution.ts b/src/vs/workbench/api/browser/extensionHost.contribution.ts
+index 82aee03d..93e9b81f 100644
+--- a/src/vs/workbench/api/browser/extensionHost.contribution.ts
++++ b/src/vs/workbench/api/browser/extensionHost.contribution.ts
+@@ -3,104 +3,7 @@
+  *  Licensed under the MIT License. See License.txt in the project root for license information.
+  *--------------------------------------------------------------------------------------------*/
+ 
+-
+-// --- other interested parties
+-import '../common/jsonValidationExtensionPoint.js';
+-import '../../services/themes/common/colorExtensionPoint.js';
+-import '../../services/themes/common/iconExtensionPoint.js';
+-import '../../services/themes/common/tokenClassificationExtensionPoint.js';
+-import '../../contrib/codeEditor/common/languageConfigurationExtensionPoint.js';
+-import './statusBarExtensionPoint.js';
+-import '../../services/themes/browser/cssExtensionPoint.js';
+-
+-// --- mainThread participants
+-import './mainThreadAgentEditorComments.js';
+-import './mainThreadLocalization.js';
+-import './mainThreadBulkEdits.js';
+-import './mainThreadLanguageModels.js';
+-import './mainThreadChatAgents2.js';
+-import './mainThreadChatCodeMapper.js';
+-import './mainThreadLanguageModelTools.js';
+-import './mainThreadEmbeddings.js';
+-import './mainThreadCodeInsets.js';
+-import './mainThreadCLICommands.js';
+-import './mainThreadClipboard.js';
+-import './mainThreadCommands.js';
+-import './mainThreadConfiguration.js';
+-import './mainThreadConsole.js';
+-import './mainThreadDebugService.js';
+-import './mainThreadDecorations.js';
+-import './mainThreadDiagnostics.js';
+-import './mainThreadDialogs.js';
+-import './mainThreadDocumentContentProviders.js';
+-import './mainThreadDocuments.js';
+-import './mainThreadDocumentsAndEditors.js';
+-import './mainThreadEditor.js';
+-import './mainThreadEditors.js';
+-import './mainThreadEditorTabs.js';
+-import './mainThreadErrors.js';
+-import './mainThreadExtensionService.js';
+-import './mainThreadFileSystem.js';
+-import './mainThreadFileSystemEventService.js';
+-import './mainThreadLanguageFeatures.js';
+-import './mainThreadLanguages.js';
+-import './mainThreadLogService.js';
+-import './mainThreadMessageService.js';
+-import './mainThreadManagedSockets.js';
+-import './mainThreadBrowserTunnelProxy.js';
+-import './mainThreadOutputService.js';
+-import './mainThreadProgress.js';
+-import './mainThreadQuickDiff.js';
+-import './mainThreadDocumentDiff.js';
+-import './mainThreadQuickOpen.js';
+-import './mainThreadRemoteConnectionData.js';
+-import './mainThreadSaveParticipant.js';
+-import './mainThreadSpeech.js';
+-import './mainThreadEditSessionIdentityParticipant.js';
+-import './mainThreadSCM.js';
+-import './mainThreadSearch.js';
+-import './mainThreadStatusBar.js';
+-import './mainThreadStorage.js';
+-import './mainThreadTelemetry.js';
+-import './mainThreadTerminalService.js';
+-import './mainThreadTerminalShellIntegration.js';
+-import './mainThreadTheming.js';
+-import './mainThreadTreeViews.js';
+-import './mainThreadDownloadService.js';
+-import './mainThreadUrls.js';
+-import './mainThreadUriOpeners.js';
+-import './mainThreadWindow.js';
+-import './mainThreadPower.js';
+-import './mainThreadWebviewManager.js';
+-import './mainThreadWorkspace.js';
+-import './mainThreadComments.js';
+-import './mainThreadNotebook.js';
+-import './mainThreadNotebookKernels.js';
+-import './mainThreadNotebookDocumentsAndEditors.js';
+-import './mainThreadNotebookRenderers.js';
+-import './mainThreadNotebookSaveParticipant.js';
+-import './mainThreadInteractive.js';
+-import './mainThreadTask.js';
+-import './mainThreadLabelService.js';
+-import './mainThreadTunnelService.js';
+-import './mainThreadAuthentication.js';
+-import './mainThreadTimeline.js';
+-import './mainThreadTesting.js';
+-import './mainThreadSecretState.js';
+-import './mainThreadShare.js';
+-import './mainThreadProfileContentHandlers.js';
+-import './mainThreadAiRelatedInformation.js';
+-import './mainThreadAiEmbeddingVector.js';
+-import './mainThreadAiSettingsSearch.js';
+-import './mainThreadMcp.js';
+-import './mainThreadChatContext.js';
+-import './mainThreadChatDebug.js';
+-import './mainThreadChatStatus.js';
+-import './mainThreadChatQuota.js';
+-import './mainThreadChatInputNotification.js';
+-import './mainThreadChatOutputRenderer.js';
+-import './mainThreadChatSessions.js';
+-import './mainThreadDataChannels.js';
+-import './mainThreadMeteredConnection.js';
+-import './mainThreadGitExtensionService.js';
+-import './mainThreadBrowsers.js';
++import './extensionHost.base.contribution.js';
++import './extensionHost.chat.contribution.js';
++import './extensionHost.notebook.contribution.js';
++import './extensionHost.mcp.contribution.js';
+diff --git a/src/vs/workbench/api/browser/extensionHost.mcp.contribution.ts b/src/vs/workbench/api/browser/extensionHost.mcp.contribution.ts
+new file mode 100644
+index 00000000..570c524a
+--- /dev/null
++++ b/src/vs/workbench/api/browser/extensionHost.mcp.contribution.ts
+@@ -0,0 +1,7 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++// MCP mainThread participants, split out of extensionHost.contribution so they can be loaded separately
++import './mainThreadMcp.js';
+diff --git a/src/vs/workbench/api/browser/extensionHost.notebook.contribution.ts b/src/vs/workbench/api/browser/extensionHost.notebook.contribution.ts
+new file mode 100644
+index 00000000..ff2f3cc2
+--- /dev/null
++++ b/src/vs/workbench/api/browser/extensionHost.notebook.contribution.ts
+@@ -0,0 +1,11 @@
++/*---------------------------------------------------------------------------------------------
++ *  Copyright (c) Microsoft Corporation. All rights reserved.
++ *  Licensed under the MIT License. See License.txt in the project root for license information.
++ *--------------------------------------------------------------------------------------------*/
++
++// Notebook mainThread participants, split out of extensionHost.contribution so they can be loaded separately
++import './mainThreadNotebook.js';
++import './mainThreadNotebookKernels.js';
++import './mainThreadNotebookDocumentsAndEditors.js';
++import './mainThreadNotebookRenderers.js';
++import './mainThreadNotebookSaveParticipant.js';
+-- 
+2.39.5 (Apple Git-154)
+