dependsOn(RootProject(...)) crashes on IntelliJ import when depending on a non-IntelliJ SBT project

[teeckoo]

sbt-idea-plugin: dependsOn(RootProject(...)) crashes on IntelliJ import and excludes external projects from packaging

Problem

When an IntelliJ plugin project uses dependsOn(RootProject(...)) to depend on a normal SBT project, two errors occur during IntelliJ import:

1. NoSuchElementException in topoSortRefs — projectMap(root) crashes when the root is an external ProjectRef not in the map
2. RuntimeUndefined for intellijExtraRuntimePluginsInTests — settings aggregation via ScopeFilter(inDependencies(ThisProject)) reaches external projects that don't have sbt-idea-plugin enabled

Additionally, even after working around the crashes, external projects are excluded from the packaging graph — their class files and library dependencies are never included in the plugin artifact. This forces users to:

• Use packageFileMappings with explicit JARs — which prevents source-level debugging (IntelliJ can't map JAR classes back to source files)
• Manually pull libraryDependencies from each dependent project

Expected behavior

dependsOn(RootProject(...)) should work the same way it does in normal SBT projects:

• IntelliJ import should succeed without crashes
• External project class files should be included in the plugin artifact automatically
• External project library dependencies should be resolved and included automatically
• packageArtifactDynamic should enable source-level debugging across module boundaries, including external project sources

Steps to reproduce

1. Clone https://github.com/collaboncode/minimal-ij-plugin-setup
2. cd main-ij-plugin && sbt compile — succeeds
3. Open main-ij-plugin in IntelliJ as an SBT project — crashes

Minimal example

minimal-ij-plugin-setup/
├── non-ij-sbt-module/          # Normal SBT project with Greeter.scala
└── main-ij-plugin/             # IntelliJ plugin with dependsOn(RootProject(...))
    └── build.sbt               # dependsOn(RootProject(file("../non-ij-sbt-module")))

// main-ij-plugin/build.sbt
lazy val myLibrary = RootProject(file("../non-ij-sbt-module"))

lazy val myPlugin = project.in(file("."))
  .enablePlugins(SbtIdeaPlugin)
  .dependsOn(myLibrary)

Error 1: NoSuchElementException

java.util.NoSuchElementException: key not found:
  ProjectRef(file:.../non-ij-sbt-module/,non-ij-sbt-module)
    at org.jetbrains.sbtidea.structure.sbtImpl.SbtProjectStructureExtractorBase.topoSortRefs

Error 2: RuntimeUndefined

sbt.internal.util.Init$RuntimeUndefined: References to undefined settings at runtime.
ScopedKey(Scope(Select(ProjectRef(file:.../non-ij-sbt-module/,non-ij-sbt-module)), Zero, Zero, Zero),
  intellijExtraRuntimePluginsInTests)

Versions

• sbt: 1.11.7
• sbt-idea-plugin: 5.1.0
• Scala: 3.7.4
• IntelliJ build: 253.31033.53 (IdeaCommunity)

[unkarjedy]

Sorry for the late reply, I was on a vacation.
Is this PR still actual?

[teeckoo]

Hi Dmitrii Naumenko (@unkarjedy), welcome back 👋 — no worries about the delay.

Yes, still actual. The branch is now on two commits:

---

• Commit 1 — crash fix. Handles the NoSuchElementException in topoSortRefs and the RuntimeUndefined for intellijExtraRuntimePluginsInTests. Restores
  dependsOn(RootProject(...)) imports on its own.

---

• Commit 2 — packaging enhancement. Collects external-project packaging data via standard SBT keys (no plugin needed in the external project) and applies the
  root's packageLibraryMappings as a global filter. Removes the need for manual packageFileMappings / libraryDependencies pulls, and enables source-level
  debugging via packageArtifactDynamic.

---

Tests green ✅ (5 new core + 7 new packaging + existing suites). Running in production in two of our IntelliJ plugins against a locally-published 5.1.1-SNAPSHOT.

If you'd prefer to merge the crash fix first and review the packaging change separately, happy to split commit 2 into its own PR — just let me know.