update: K2 mode is default

Author: sarahhaggarty

docs/topics/k2-compiler-migration-guide.md

@@ -17,9 +17,8 @@ The new architecture and enriched data structure enables the K2 compiler to prov
 * **Easier introduction of syntactic sugar for new language features**. In the future, you'll be able to use more concise,
   readable code when new features are introduced.
 * **Faster compilation times**. Compilation times can be [significantly faster](#performance-improvements).
-* **Enhanced IDE performance**. If you enable K2 mode in IntelliJ IDEA, then IntelliJ IDEA will use the K2 compiler
-  frontend to analyze your Kotlin code, bringing stability and performance improvements. For more information,
-  see [Support in IDEs](#support-in-ides).
+* **Enhanced IDE performance**. Starting with 2025.1, IntelliJ IDEA uses K2 mode to analyze your Kotlin code, increasing
+ stability and providing performance improvements. For more information, see [Support in IDEs](#support-in-ides).
 
 This guide:
 
@@ -556,29 +555,28 @@ For more information on what is possible with build reports, see [Build reports]
 
 ## Support in IDEs
 
-By default, both IntelliJ IDEA and Android Studio 2024.1 use the previous compiler for code analysis, code completion,
-highlighting, and other IDE-related features. This is to ensure performance and stability while we work on integrating 
-the new Kotlin K2 compiler.
+K2 mode in IntelliJ IDEA and Android Studio uses the K2 compiler to improve code analysis, code completion, and highlighting.
 
-If you'd like to try using the same features with the new Kotlin K2 compiler, support is available from IntelliJ IDEA and 
-Android Studio 2024.1. To enable K2 mode:
+Starting with IntelliJ IDEA 2025.1, K2 mode is [enabled by default](https://blog.jetbrains.com/idea/2025/04/k2-mode-in-intellij-idea-2025-1-current-state-and-faq/).
 
-1. In your IDE, go to **Settings** | **Languages & Frameworks** | **Kotlin**.
+In Android Studio, you can enable K2 mode starting with 2024.1 by following these steps:
+
+1. Go to **Settings** | **Languages & Frameworks** | **Kotlin**.
 2. Select the **Enable K2 mode** option.
 
-Learn more about K2 mode in our [blog](https://blog.jetbrains.com/idea/2024/11/k2-mode-becomes-stable/).
+### Previous IDE behavior {initial-collapse-state="collapsed" collapsible="true"}
+
+If you want to go back to the previous IDE behavior, you can disable K2 mode:
+
+1. Go to **Settings** | **Languages & Frameworks** | **Kotlin**.
+2. Deselect the **Enable K2 mode** option.
 
 > We plan to introduce [Stable](components-stability.md#stability-levels-explained) language features after Kotlin 2.1.0.
-> Until then, you can continue to use the previous compiler for code analysis, and you won't encounter any code highlighting
+> Until then, you can continue to use the previous IDE features for code analysis, and you won't encounter any code highlighting
 > issues due to unrecognized language features.
 >
 {style="note"}
 
-It's important to note that regardless of which compiler you use for code analysis in your IDE, the compiler used
-by your build system is **independent** and configured separately in your build script. If you [upgrade your Kotlin version
-to Kotlin 2.0.0 in your build scripts](#how-to-enable-the-kotlin-k2-compiler), the new K2 compiler will be used by default
-by your build system only.
-
 ## Try the Kotlin K2 compiler in the Kotlin Playground
 
 The Kotlin Playground supports Kotlin 2.0.0 and later releases. [Check it out!](https://pl.kotl.in/czuoQprce)

docs/topics/releases.md

@@ -73,16 +73,19 @@ If you are migrating to the new language release, Kotlin plugin's migration tool
 
 ## IDE support
 
-Even with the release of the K2 compiler, IntelliJ IDEA and Android Studio still use the previous compiler by default 
-for code analysis, code completion, highlighting, and other IDE-related features.
+Kotlin has full out-of-the-box support in [IntelliJ IDEA](https://www.jetbrains.com/idea/download/) and
+[Android Studio](https://developer.android.com/kotlin/get-started) with an official Kotlin plugin developed by JetBrains.
 
-Starting from 2024.1, IntelliJ IDEA can use the new K2 compiler to analyze your code with its K2 mode.
-To enable it, go to **Settings** | **Languages & Frameworks** | **Kotlin** and select the **Enable K2 mode** option.
+K2 mode in IntelliJ IDEA and Android Studio uses the K2 compiler to improve code analysis, code completion, and highlighting.
 
-![Enable K2 mode](k2-mode.png){width=200}
+Starting with IntelliJ IDEA 2025.1, K2 mode is [enabled by default](https://blog.jetbrains.com/idea/2025/04/k2-mode-in-intellij-idea-2025-1-current-state-and-faq/).
 
-After enabling K2 mode, you may notice differences in IDE analysis due to changes in compiler behavior.
-Learn how the new K2 compiler differs from the previous one in the [migration guide](k2-compiler-migration-guide.md).
+In Android Studio, you can enable K2 mode starting with 2024.1 by following these steps:
+
+1. Go to **Settings** | **Languages & Frameworks** | **Kotlin**.
+2. Select the **Enable K2 mode** option.
+
+Learn more about K2 mode in [our blog](https://blog.jetbrains.com/idea/2025/04/k2-mode-in-intellij-idea-2025-1-current-state-and-faq/).
 
 ## Kotlin release compatibility