Window Insets support for Compose for Web

[Konstantin (terrakok)]

Added support for system window insets on Web. Compose scenes can now render edge-to-edge while respecting the safe area and the keyboard, exposing everything through the standard WindowInsets APIs (WindowInsets.safeDrawing, WindowInsets.ime, etc.).

compressO-Recording.2026-07-07.at.15-33-34.mp4

New experimental API

A new configuration flag on ComposeViewportConfiguration:

ComposeViewport(configure = { enableBrowserWindowInsets = true }) {
    // content that reacts to WindowInsets.safeDrawing, WindowInsets.ime, ...
}

• Defaults to false, so existing behavior is unchanged. When enabled, the scene reads safe area insets and tracks IME geometry, and reports them through the standard WindowInsets APIs.
• Requires the page to opt in to edge-to-edge rendering via the viewport meta tag:

  <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover" />
  

Without viewport-fit=cover the browser applies safe area padding automatically and all env(safe-area-inset-*) variables return 0px, so insets would always be zero. If the flag is enabled but the meta tag is missing, a warning is logged to the console.

Fixes https://youtrack.jetbrains.com/issue/CMP-10141

Testing

Added new web tests

Release Notes

Features - Web

• Added experimental support for system window insets on Web.

[ApoloApps]

I would still prefer to introduce the PlatformEmbeddingStrategy interface with FullPageStrategy and EmbeddedStrategy implementations (as per the youtrack issue). Much of what is explained in the enableBrowserWindowInsets KDoc can be easily understood with this API. PlatformEmbeddingStrategy can be used for other non-insets related APIs that might need different implementation in these modes

[Oleksandr Karpovich (eymar)]

introduce the PlatformEmbeddingStrategy interface with FullPageStrategy and EmbeddedStrategy implementations

As I understood your idea, FullPageStrategy would take care of configuring the index.html / styles for apps taking the entire viewport? Sort of simplification?
I think it's worth its a separate PR to simplify the API review process.