Support LSP quick fixes and intention actions on non-project files by implementing `DumbAware` on `LSPLazyCodeActionIntentionAction`

Summary

LSP4IJ already supports diagnostics, folding, code lenses, documentation, and document links on non-project files (files outside content roots) by marking their respective passes/providers as DumbAware (LSPDiagnosticsPassFactory, LSPFoldingRangeBuilder, LSPCodeLensProvider, LSPDocumentationTargetProvider, LSPDocumentLinkPass).

However, LSP quick fixes (LSPQuickFixIntentionAction) and intention actions (LSPIntentionAction0..19) do not work on non-project files because their base class LSPLazyCodeActionIntentionAction does not implement com.intellij.openapi.project.DumbAware.

Root Cause

In IntelliJ Platform, both the intention popup (Alt+Enter via ShowIntentionsPass#addAvailableFixesForGroups and ShowIntentionsPass#getRegisteredIntentionActions) and the hover tooltip quick-fix button (DaemonTooltipActionProviderKt#extractMostPriorityFixFromHighlightInfo / DaemonTooltipAction#execute -> findIntention) filter actions using DumbService#isUsableInCurrentContext(Object thing, VirtualFile file):

fun isUsableInCurrentContext(thing: Any, file: VirtualFile?) : Boolean {
  if (file == null || !file.isInLocalFileSystem) return isUsableInCurrentContext(thing)
  return (!isDumb && FileIndexFacade.getInstance(project).isIndexable(file)) || isDumbAware(thing, project is LightEditCompatible)
}

For a non-project file (a file outside the project's content roots/libraries), FileIndexFacade.getInstance(project).isIndexable(file) returns false even when the IDE is in Smart Mode (!isDumb == true).

Because (!isDumb && isIndexable(file)) evaluates to false, IntelliJ requires isDumbAware(thing) to be true:

• Prior to IntelliJ 2026.2 (IJPL-254242), extractMostPriorityFixFromHighlightInfo missed the isUsableInCurrentContext check, so LSP quick fixes were shown in hover tooltips on non-project files, but clicking them silently failed inside DaemonTooltipAction#execute -> findIntention (which called ShowIntentionsPass#getAvailableFixes -> isUsableInCurrentContext -> false).
• In newer IntelliJ builds where extractMostPriorityFixFromHighlightInfo also checks isUsableInCurrentContext, non-DumbAware quick fixes and intentions are completely hidden on non-project files in both tooltips and Alt+Enter.

Proposed Solution

1. Implement DumbAware on LSPLazyCodeActionIntentionAction:
   Since external language servers operate out-of-process and do not rely on IntelliJ's PSI indexes, LSPLazyCodeActionIntentionAction should implement DumbAware.

   • Note: For LSPIntentionAction0..19 registered via <intentionAction> in plugin.xml, IntelliJ wraps them in IntentionActionWrapper which implements IntentionActionDelegate (PossiblyDumbAware) and delegates isDumbAware() to DumbService.isDumbAware(getDelegate()). Thus, marking LSPLazyCodeActionIntentionAction as DumbAware automatically makes both LSPQuickFixIntentionAction and LSPIntentionAction0..19 dumb-aware.

2. Guard against actual project indexing in LSPLazyCodeActionIntentionAction#isAvailable:
   LSPIntentionAction#isAvailable already checks ProjectIndexingManager.canExecuteLSPFeature(file) != ExecuteLSPFeatureStatus.NOW to avoid triggering LSP requests while the project is actually indexing (scanning || dumbIndexing || DumbService.isDumb(project)). Moving this check up to LSPLazyCodeActionIntentionAction#isAvailable ensures that LSPQuickFixIntentionAction is also guarded during actual indexing while still returning true (ExecuteLSPFeatureStatus.NOW) for non-project files in Smart Mode:

// In com.redhat.devtools.lsp4ij.features.codeAction.LSPLazyCodeActionIntentionAction
public class LSPLazyCodeActionIntentionAction implements IntentionAction, DumbAware {
    ...
    @Override
    public boolean isAvailable(@NotNull Project project, Editor editor, PsiFile file) {
        if (ProjectIndexingManager.canExecuteLSPFeature(file) != ExecuteLSPFeatureStatus.NOW) {
            return false;
        }
        loadCodeActionIfNeeded();
        return isValidCodeAction(this.action);
    }

3. (Optional) Ensure write access for multi-file WorkspaceEdits on non-project files:
   For the currently active PsiFile, ShowIntentionActionsHandler#invokeIntention automatically calls FileModificationService.getInstance().preparePsiElementsForWrite(...) (triggering IntelliJ's standard "Non-Project Files Protection" unlock dialog before invoke() runs). However, if a WorkspaceEdit modifies secondary non-project files, LSPIJUtils#applyWorkspaceEdit should call FileModificationService.getInstance().prepareVirtualFilesForWrite(project, affectedFiles) (or ReadonlyStatusHandler.ensureFilesWritable(...)) before modifying documents.

Start in com.redhat.devtools.lsp4ij.features.codeAction.LSPLazyCodeActionIntentionAction and compare LSPIntentionAction#isAvailable with ProjectIndexingManager.canExecuteLSPFeature. Check how IntentionActionWrapper delegates DumbAware, then verify quick fixes and intention actions are available for non-project files in Smart Mode but not during indexing. Review LSPIJUtils#applyWorkspaceEdit and the mentioned FileModificationService behavior if addressing secondary-file writes.