Notable Changes in IntelliJ Platform and Plugins API 2025.*

Several write actions now run on background threads instead of EDT:

• VFS refresh

• document commit (PSI reparsing)

• document saving on frame deactivation

API changes and additions:

• Dispatchers.UI — new coroutine dispatcher for the UI thread that does not acquire write-intent lock; use it for pure UI operations that do not need the read/write lock protection (as opposed to Dispatchers.EDT, which acquires write-intent lock for legacy model access).

• backgroundWriteAction() and readAndBackgroundWriteAction() — stabilized suspending functions for executing write actions on a background thread.

• Editor model data (document, caret, selection, folding) no longer requires a read lock when accessed on EDT.

• Tests relying on spinning the AWT event queue to wait for write actions may hang; use PlatformTestUtil.dispatchAllInvocationEventsInIdeEventQueue() which is adapted to await background write actions.

IdeProductMode (experimental) allows plugins to determine the current application mode at runtime:

• IdeProductMode.isBackend — the IDE runs as a remote development backend host

• IdeProductMode.isFrontend — the IDE runs as a frontend (JetBrains Client) connected to a remote host

• IdeProductMode.isMonolith — the IDE runs as a standard local (monolith) instance

Use this API to implement mode-specific behavior, e.g., to skip UI-related functionality when running as a backend.

New LSP capabilities are supported, all enabled by default and controllable via LspServerDescriptor.lspCustomization:

• Server Initiated Progress ($/progress)

• Highlight Usages In File (textDocument/documentHighlight)

• Go To Symbol (workspace/symbol)

• File Structure, Breadcrumbs, and Sticky Lines (textDocument/documentSymbol)

• Parameter Info (textDocument/signatureHelp)

See Supported Features for the full list.

The Islands theme is now the default UI theme. Custom themes must be updated to support it. See Supporting Islands Theme for migration steps including setting the parent theme, adapting background colors, border colors, and selected tab colors.

The Search Everywhere architecture has been redesigned to support remote development by separating data/logic from UI presentation, enabling results to be serialized and transmitted across process boundaries. New API components:

• SeItemsProvider replaces SearchEverywhereContributor as the main interface for providing search results. It can run on both backend and frontend and returns items with serializable presentation data.

• SeItemsProviderFactory is the new extension point for registering result sources.

• SeTab and SeTabFactory represent frontend-only tab abstractions for the Search Everywhere dialog.

• SeLegacyItemPresentationProvider provides a temporary adapter for migrating existing SearchEverywhereContributor implementations.

Existing plugins continue working in local (monolith) environments via adapters. The new API is enabled by default in remote development. Migration is recommended now; the old API will be deprecated in 2026.2. See also blog post for details.

Language Server Protocol (LSP) and Template Languages APIs no longer require a paid subscription in IntelliJ IDEA. While the LSP implementation is not part of the Community Edition, it will still remain enabled in IntelliJ IDEA even without an active paid subscription. Although closed-source, the LSP implementation will remain fully available for third-party plugins free of charge. See LSP Plugin Setup for the updated setup.

Several APIs are stabilized and one is deprecated:

• runBlockingCancellable(), currentThreadCoroutineScope(), and coroutineToIndicator() are promoted to stable.

• blockingContext() is now a no-op and deprecated (IJPL-445). The platform manages thread contexts automatically; remove all usages.

• Threads blocked on read/write lock acquisition now react to cancellation and throw CancellationException instead of proceeding.

SwingUtilities.invokeLater() and SwingUtilities.invokeAndWait() no longer automatically wrap their callbacks in the Write-Intent lock (IJPL-149317). Code accessing the PSI/VFS model inside these callbacks must now use an explicit read or write action. Pure UI-only operations require no changes. Similarly, coroutines launched on Dispatchers.Main no longer acquire the Write-Intent lock (IJPL-178581). Use Dispatchers.EDT to preserve the previous behavior, or move model access to Dispatchers.Default with an explicit readAction/writeAction. edtWriteAction() is introduced as a stable, explicitly named alternative to writeAction() for write actions that must run on EDT.

Methods marked with @Unmodifiable now really return unmodifiable collections (only in internal /test mode for now).