bugfix: skip Scala CLI auto-start outside workspace folders

[russwyte]

Summary

• Fixes #8736: fallback no longer auto-starts Scala CLI (or runs presentation-compiler load) when textDocument/didOpen targets a path outside the LSP workspace folder(s).
• Short-circuits out-of-workspace didOpen in FallbackMetalsLspService, clears stale diagnostics, and gates auto-start via ScalaCliAutoStart.
• WorkspaceLspService passes both Scala and non-Scala folder roots into the check. Empty folder list keeps legacy auto-start (standalone / no-folder sessions). Manual metals.scala-cli-start is unchanged.

Motivation

Some editors (notably Cursor) can send didOpen for Scala files outside the configured workspace. Metals treated those as orphans and started a Scala CLI BSP per file, flooding Problems and spawning many processes even with no open tabs.

Test plan

• unit/testOnly tests.ScalaCliAutoStartSuite (membership policy: in/out, siblings, empty folders, non-Scala/Java, scripts, worksheets/sbt, multi-folder, prefix lookalikes, lexical symlink cases)
• unit/testOnly tests.OutOfWorkspaceScalaCliLspSuite (LSP: outside/sibling skip; empty folders still auto-start; outside .sc / non-Scala / repeated outsiders)
• Reviewers: confirm manual Scala CLI start still works for intentional out-of-workspace files (ScalaCliSuite / StartScalaCliServer)

[coderabbitai]

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📝 Walkthrough

Walkthrough

Scala CLI fallback auto-start now checks Scala file type and workspace-folder containment. Workspace folders are supplied dynamically to the fallback service, which skips out-of-workspace startup while retaining in-workspace orphan behavior. Unit and LSP tests cover these decisions.

Changes

Workspace-aware Scala CLI auto-start

Layer / File(s)	Summary
Scala CLI auto-start policy and unit coverage metals/src/main/scala/scala/meta/internal/metals/scalacli/ScalaCliAutoStart.scala, tests/unit/src/test/scala/tests/ScalaCliAutoStartSuite.scala	Adds workspace-aware auto-start decisions requiring Scala file types and workspace containment, while preserving empty-workspace behavior and covering nested folders, siblings, scripts, non-Scala files, and symlinks.
Fallback service integration metals/src/main/scala/scala/meta/internal/metals/FallbackMetalsLspService.scala, metals/src/main/scala/scala/meta/internal/metals/WorkspaceLspService.scala	Aggregates workspace folders, passes them to the fallback service, clears diagnostics for out-of-workspace documents, and gates Scala CLI startup for eligible paths.
LSP regression coverage and CI registration tests/unit/src/test/scala/tests/OutOfWorkspaceScalaCliLspSuite.scala, project/TestGroups.scala	Tests out-of-workspace, sibling, script, multiple-file, non-Scala, and empty-workspace didOpen behavior, and adds the suites to CI test sharding.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant LSPClient
  participant WorkspaceLspService
  participant FallbackMetalsLspService
  participant ScalaCliAutoStart
  LSPClient->>WorkspaceLspService: didOpen document
  WorkspaceLspService->>FallbackMetalsLspService: handle document path
  FallbackMetalsLspService->>ScalaCliAutoStart: check workspace and file type
  alt outside workspace
    ScalaCliAutoStart-->>FallbackMetalsLspService: skip startup
    FallbackMetalsLspService-->>LSPClient: clear diagnostics
  else eligible path
    ScalaCliAutoStart-->>FallbackMetalsLspService: allow startup
    FallbackMetalsLspService->>FallbackMetalsLspService: start/import Scala CLI and run load()
  end

Loading

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes implement the requested workspace-folder gating for out-of-workspace didOpen paths and preserve in-workspace and empty-workspace behavior.
Out of Scope Changes check	✅ Passed	The added helper, tests, and test-group wiring all support the workspace auto-start fix and do not introduce unrelated scope.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: preventing Scala CLI auto-start outside workspace folders.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@tests/unit/src/test/scala/tests/OutOfWorkspaceScalaCliLspSuite.scala`:
- Around line 43-52: The fixed 500 ms delays do not synchronize assertions with
fallback import completion. In
tests/unit/src/test/scala/tests/OutOfWorkspaceScalaCliLspSuite.scala#L43-L52 and
`#L81-L87`, replace each Thread.sleep-based wait with awaiting the fallback-import
task or the existing test-harness idle hook before performing the Scala CLI
server/path assertions.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 3da690e7-235c-4cb8-8c22-d6ddfe3afcf7

📥 Commits

Reviewing files that changed from the base of the PR and between 0116337 and 547856b.

📒 Files selected for processing (5)

• metals/src/main/scala/scala/meta/internal/metals/FallbackMetalsLspService.scala
• metals/src/main/scala/scala/meta/internal/metals/WorkspaceLspService.scala
• metals/src/main/scala/scala/meta/internal/metals/scalacli/ScalaCliAutoStart.scala
• tests/unit/src/test/scala/tests/OutOfWorkspaceScalaCliLspSuite.scala
• tests/unit/src/test/scala/tests/ScalaCliAutoStartSuite.scala

[russwyte]

Opened a parallel port to main-v2 for the 2.0 milestones: https://github.com/scalameta/metals/pull/$(gh pr list --repo scalameta/metals --head russwyte:bugfix/no-scala-cli-outside-workspace-v2 --json number --jq '.[0].number')

[russwyte]

Parallel port to main-v2 for the 2.0 milestones: #8738