Update ROADMAP.md

Author: martinbonnin

ROADMAP.md

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 # 🔮 Apollo Kotlin Roadmap
 
-**Last updated: 2025-06-02**
+**Last updated: 2025-06-12**
 
 For up to date release notes, refer to the project [Changelog](https://github.com/apollographql/apollo-kotlin/blob/main/CHANGELOG.md).
 
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 All active feature development is now being done for `5.x` releases on the `main` branch.  Critical bugfixes and security patches will land in version 4 on the `release-4.x` branch.
 
+v5 focuses on removing deprecated symbols to keep the codebase clean as well as incremental additions:
+* GraphQL spec tracking: support for [default values coercion](https://github.com/graphql/graphql-spec/pull/793/), [schema coordinates](https://github.com/graphql/graphql-spec/pull/794/), [fragment arguments](https://github.com/graphql/graphql-spec/pull/1081), [`@stream`](https://github.com/graphql/graphql-spec/pull/742), ...
+* Testing improvements: [data builders in the test source set](https://github.com/apollographql/apollo-kotlin/issues/5257), [strict mode](https://github.com/apollographql/apollo-kotlin/issues/3344), ...
+* More KMP targets: linux, wasm
+* ...
+
+The scope will be refined as the release date approaches. There should overall be no big bang. We aim for ABI compatibility for all symbols except those that were deprecated in v4 (and have been removed), `@ApolloExperimental` symbols and artifacts used at build time (`apollo-gradle-plugin`, `apollo-compiler`, `apollo-tooling`).
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+With `apollo-kotlin` being more and more stable, most of the work is now happening in [Apollo Galaxy repos](https://www.apollographql.com/docs/kotlin/advanced/galaxy), most notably the [normalized cache](https://github.com/apollographql/apollo-kotlin-normalized-cache). 
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 ## Jetpack Compose extensions 
 
 [Jetpack Compose](https://developer.android.com/jetpack/compose) is a declarative UI framework for building Android UIs written in Kotlin.  We are experimenting with a few different approaches for supporting Compose in the Apollo Kotlin library.  Our 3.8.0 release introduced an experimental API for use with Compose but gathered little feedback. We're planning to revisit this with more ambitious goals in terms of fragments colocation, error boundaries and more generally integration with the UI framework.