There also isn’t tag/sources posted for the latest EAPs (https://github.com/JetBrains/intellij-community/tags) - this is painful, we have these tags for example for IDEA:
no breaking changes in public APIs in 2026.1 EAP yet
We’ve seem to have found breaking changes in 2026.x/261/ (seems to be in 261.19799) in the intellij-elixir plugin (https://github.com/KronicDeth/intellij-elixir) plugin.
e: file:///home/runner/work/intellij-elixir/intellij-elixir/src/org/elixir_lang/folding/Builder.kt:260:75 Argument type mismatch: actual type is 'String?', but 'String' was expected.
This commit adds @NotNull for result and parameter which is only source-incompatible with Kotlin code that passes null there, while fully binary-compatible and will not break existing plugin versions.