feat: pass scalac options to presentation compiler

[warcholjakub]

Fixes false diagnostics when using capture checking or other compiler flags set via //> using option or scalacOptions.

[Copilot]

Pull request overview

This PR propagates user-specified scalacOptions (from Scala CLI directives and sbt scalacOptions) into the Metals presentation compiler configuration to reduce incorrect/false diagnostics.

Changes:

• Add extraction/filtering of “PC-relevant” scalac flags from Scala CLI directives and sbt config.
• Extend Metals configuration models/plumbing to carry scalacOptions end-to-end (client → metals-runner → presentation compiler).
• Add unit tests for option extraction/filtering for both Scala CLI and sbt inputs.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
scala-cli-runner/src/test/scala/org/scastie/scalacli/ScalaCliScalacOptionsTest.scala	Adds tests for extracting PC-relevant options from Scala CLI directives.
sbt-runner/src/test/scala/org/scastie/sbt/SbtScalacOptionsTest.scala	Adds tests for extracting/filtering PC-relevant options from sbt scalacOptions.
metals-runner/src/main/scala/org/scastie/metals/PresentationCompilers.scala	Passes extracted scalacOptions into newInstance when creating presentation compilers.
metals-runner/src/main/scala/org/scastie/metals/MetalsDispatcher.scala	Threads configuration.scalacOptions into presentation compiler creation.
client/src/main/scala/org/scastie/client/scalacli/ScalaCliUtils.scala	Extends parse result to include extracted Scala CLI PC scalac options.
client/src/main/scala/org/scastie/client/components/editor/MetalsClient.scala	Includes scalacOptions in ScastieMetalsOptions sent to Metals backend.
client/src/main/scala/org/scastie/client/components/editor/InteractiveProvider.scala	Stores/passes scalac options; triggers Metals reconfigure when options change.
client/src/main/scala/org/scastie/client/components/editor/CodeEditor.scala	Adds pcScalacOptions prop for Metals configuration.
client/src/main/scala/org/scastie/client/components/MainPanel.scala	Wires pcScalacOptions into CodeEditor (currently only for sbt inputs).
api/src/main/scala/org/scastie/api/Inputs.scala	Adds PC-relevant filtering and option extraction helpers for sbt + Scala CLI inputs.
api/src/main/scala/org/scastie/api/ApiModels.scala	Extends ScastieMetalsOptions API model with scalacOptions.

Comments suppressed due to low confidence (1)

api/src/main/scala/org/scastie/api/ApiModels.scala:78

• ScastieMetalsOptions added a new field but still uses Circe deriveDecoder. Circe’s generic derivation doesn’t populate missing fields from Scala default args, so older clients that omit scalacOptions will fail decoding. To keep backward compatibility, consider making scalacOptions an Option[List[String]] (mapping None to Nil), or provide a custom decoder that treats a missing scalacOptions field as Nil.

case class ScastieMetalsOptions(dependencies: Set[ScalaDependency], scalaTarget: ScalaTarget, scalacOptions: List[String] = Nil)

object ScastieMetalsOptions {
  implicit val scastieMetalsOptionsEncoder: Encoder[ScastieMetalsOptions] = deriveEncoder[ScastieMetalsOptions]
  implicit val scastieMetalsOptionsDecoder: Decoder[ScastieMetalsOptions] = deriveDecoder[ScastieMetalsOptions]
}

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