Reuse validated filesystem facts through acquisition

internal/engine/acquisition.go

@@ -178,9 +178,11 @@ func acquireInput(request inputAcquisitionRequest, policy acquisitionPolicy, sta
 			input.document = versionProcessing.payload
 		}
 		if request.input.filesystem != nil && (selectedSource.kind == sourceNone || !activeOverlay(request.ordinaryOverlay)) {
-			if diagnostic := validateFilesystemContext(selectedSource, request.input.filesystem, parsed); diagnostic != nil {
+			resolved, diagnostic := validateFilesystemContext(selectedSource, request.input.filesystem, parsed, tier.hostToken)
+			if diagnostic != nil {
 				return input, []Diagnostic{*diagnostic}
 			}
+			input.resolvedFilesystem = &resolved
 		}
 	}
 	if !request.input.imports && input.document != nil {

internal/engine/filesystem.go

@@ -7,73 +7,33 @@ import (
 	"strings"
 )
 
-func validateFilesystemContext(source Source, context *FilesystemContext, main parsedSource) *Diagnostic {
-	if source.kind == sourceNone && context.FS == nil {
-		return validateAbsentHostFilesystemContext(context)
-	}
-	if nativeContext(source, context) {
-		resolved, diagnostic := resolveNativeFilesystemContext(source, context)
-		if diagnostic != nil {
-			return diagnostic
-		}
-		return validateResolvedFilesystemDirectories(resolved)
-	}
-	resolved, diagnostic := resolveHostFilesystemContext(source, context, main, nil)
+func validateFilesystemContext(source Source, context *FilesystemContext, main parsedSource, hostToken *namespaceToken) (resolvedFilesystemContext, *Diagnostic) {
+	resolved, diagnostic := resolveFilesystemContext(source, context, main, hostToken)
 	if diagnostic != nil {
-		return diagnostic
+		// Keep absent-input validation's existing diagnostic while sharing
+		// root/base derivation with overlay and resource-context handling.
+		if source.kind == sourceNone && context.FS == nil && diagnostic.Code == CodeImportOutsideRoot {
+			diagnostic.Message = "import base must stay inside the configuration root"
+		}
+		return resolvedFilesystemContext{}, diagnostic
 	}
 	if diagnostic := validateResolvedFilesystemDirectories(resolved); diagnostic != nil {
-		return diagnostic
+		return resolvedFilesystemContext{}, diagnostic
+	}
+	if resolved.native != nil {
+		return resolved, nil
 	}
 	root, err := os.OpenRoot(resolved.rootPath)
 	if err != nil {
 		value := globFilesystemDiagnostic(err, "configuration root could not be opened", Location{})
 		value.Primary = nil
-		return &value
+		return resolvedFilesystemContext{}, &value
 	}
 	if err := root.Close(); err != nil {
 		value := importDiagnostic(CodeImportRead, "configuration root could not be closed", nil)
-		return &value
+		return resolvedFilesystemContext{}, &value
 	}
-	return nil
-}
-
-func validateAbsentHostFilesystemContext(context *FilesystemContext) *Diagnostic {
-	rootPath, err := canonicalExistingPath(context.Root)
-	if err != nil {
-		value := importDiagnostic(CodeImportInvalid, "configuration root could not be canonicalized", nil)
-		return &value
-	}
-	basePath := rootPath
-	if context.BaseDir != "" {
-		basePath, err = canonicalExistingPath(context.BaseDir)
-		if err != nil {
-			value := importDiagnostic(CodeImportInvalid, "import base directory could not be canonicalized", nil)
-			return &value
-		}
-	}
-	if !containedPath(rootPath, basePath) {
-		value := importDiagnostic(CodeImportOutsideRoot, "import base must stay inside the configuration root", nil)
-		return &value
-	}
-	for _, candidate := range []string{rootPath, basePath} {
-		info, err := os.Stat(candidate)
-		if err != nil || !info.IsDir() {
-			value := importDiagnostic(CodeImportInvalid, "configuration root and import base must be directories", nil)
-			return &value
-		}
-	}
-	root, err := os.OpenRoot(rootPath)
-	if err != nil {
-		value := globFilesystemDiagnostic(err, "configuration root could not be opened", Location{})
-		value.Primary = nil
-		return &value
-	}
-	if err := root.Close(); err != nil {
-		value := importDiagnostic(CodeImportRead, "configuration root could not be closed", nil)
-		return &value
-	}
-	return nil
+	return resolved, nil
 }
 
 func filesystemOptionDiagnostics(source Source, context *FilesystemContext) []Diagnostic {

internal/engine/selected_overlay.go

@@ -43,7 +43,6 @@ func resolveOrdinaryOverlayFilesystem(source Source, context *FilesystemContext,
 			value := optionDiagnostic(CodeOptionsInvalid, "NoSource overlays require explicit filesystem context")
 			return resolvedFilesystemContext{}, &value
 		}
-		return resolveAbsentFilesystemContext(context)
 	}
 	if existing != nil {
 		return *existing, nil