Isolate source directive processing

docs/roadmap/implementation.md

@@ -685,6 +685,15 @@ destinations, selected overlays, and NoSource preserve callback counts, order,
 warnings, safe diagnostics, and retained declaration locations.
 Focused check: `go test ./internal/engine -run 'SourceVersion|Version|Directive|Destination'`.
 
+Status: **complete** (first part of F02). Prior completed commits: `2736ddf`,
+`deb9aa5`, `ae3408a`, `ea27f17`, `08a8c25`, `877c497`, `8aba43d`, `7bf2f0c`,
+`0f9ecf1`, `119b42c`, `247a12b`, `4fcff5f`, `12d350a`, `08f2a8f`, `826062a`,
+`e4a5ecb`, `3122e2f`, `6f6130f`, `4fd3bee`, and `4bf940c`. Validation passed:
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./internal/engine -run 'SourceVersion|Version|Directive|Destination' -count=1`,
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./internal/engine -count=1`,
+`env GOTOOLCHAIN=local GOPROXY=off GOTELEMETRY=off go test ./... -count=1`,
+and `git diff --check`.
+
 ## Stage 22 — Isolate Standalone Placement And Acquisition Completion
 
 Finding: second part of **F02**.

internal/engine/acquisition.go

@@ -39,7 +39,6 @@ func acquireInput(request inputAcquisitionRequest, policy acquisitionPolicy, sta
 	versionState := state.versionState
 	visited := tier.visited
 	hostToken := tier.hostToken
-	role := request.role
 	sourceID := "source-" + strconv.Itoa(accounting.sources+1)
 	selectedSource := source
 	if source.kind == sourceSearch {
@@ -98,67 +97,10 @@ func acquireInput(request inputAcquisitionRequest, policy acquisitionPolicy, sta
 			return input, directiveDiagnostics
 		}
 	}
-	var versionProcessing *sourceVersionProcessingResult
+	request.directiveContext = directiveContext
-	if directiveContext == rootDirectiveContextSource {
+	versionProcessing, diagnostics := processAcquiredInputVersion(parsed, request, versionState)
-		var sourceID string
+	if len(diagnostics) != 0 {
-		if parsed.source != nil {
+		return input, diagnostics
-			sourceID = parsed.source.ID
-		}
-		var processed sourceVersionProcessingResult
-		var failures []Diagnostic
-		if versionState != nil {
-			processed, failures = versionState.processWithDirectiveContext(parsed.document, role, destination, sourceID, request.input.placementMode, directiveContext)
-		} else {
-			processed = processSourceVersionWithDirectiveContext(parsed.document, request.protectionRule, role, destination, sourceVersionModeDefault, directiveContext)
-			failures = processed.diagnostics
-		}
-		if len(failures) != 0 {
-			return input, failures
-		}
-		versionProcessing = &processed
-		if role == sourceVersionMain && versionState != nil {
-			versionState.mainProcessing = &processed
-		}
-	} else if directiveContext == rootDirectiveContextLayered {
-		extracted, failures := extractRootDirectives(parsed.document, rootDirectiveContextLayered)
-		if len(failures) != 0 {
-			return input, failures
-		}
-		processed := sourceVersionProcessingResult{
-			payload: extracted.body, imports: extracted.imports, sequences: extracted.sequences,
-			directiveContext: rootDirectiveContextLayered,
-		}
-		if versionState != nil && versionState.mode != sourceVersionModeDefault {
-			var sourceID string
-			if parsed.source != nil {
-				sourceID = parsed.source.ID
-			}
-			versionProcessed, versionFailures := versionState.process(extracted.body, role, destination, sourceID, request.input.placementMode)
-			if len(versionFailures) != 0 {
-				return input, versionFailures
-			}
-			versionProcessed.imports = extracted.imports
-			versionProcessed.sequences = append(cloneSequenceDeclarations(extracted.sequences), versionProcessed.sequences...)
-			versionProcessed.directiveContext = rootDirectiveContextLayered
-			processed = versionProcessed
-			if role == sourceVersionMain {
-				versionState.mainProcessing = &processed
-			}
-		}
-		versionProcessing = &processed
-	} else if versionState != nil && versionState.mode != sourceVersionModeDefault {
-		var sourceID string
-		if parsed.source != nil {
-			sourceID = parsed.source.ID
-		}
-		processed, failures := versionState.process(parsed.document, role, destination, sourceID, request.input.placementMode)
-		if len(failures) != 0 {
-			return input, failures
-		}
-		versionProcessing = &processed
-		if role == sourceVersionMain {
-			versionState.mainProcessing = &processed
-		}
 	}
 	request.input.source = selectedSource
 	if request.input.imports && selectedSource.kind != sourceNone {
@@ -235,6 +177,85 @@ func acquireInput(request inputAcquisitionRequest, policy acquisitionPolicy, sta
 	return input, nil
 }
 
+func processAcquiredInputVersion(parsed parsedSource, request inputAcquisitionRequest, state *sourceVersionState) (*sourceVersionProcessingResult, []Diagnostic) {
+	sourceID := ""
+	if parsed.source != nil {
+		sourceID = parsed.source.ID
+	}
+
+	var result sourceVersionProcessingResult
+	hasResult := false
+	updateMainProcessing := false
+	switch request.directiveContext {
+	case rootDirectiveContextSource:
+		if state != nil {
+			processed, diagnostics := state.processWithDirectiveContext(
+				parsed.document, request.role, request.input.destination, sourceID,
+				request.input.placementMode, request.directiveContext,
+			)
+			if len(diagnostics) != 0 {
+				return nil, diagnostics
+			}
+			result = processed
+			updateMainProcessing = request.role == sourceVersionMain
+		} else {
+			result = processSourceVersionWithDirectiveContext(
+				parsed.document, request.protectionRule, request.role,
+				request.input.destination, sourceVersionModeDefault, request.directiveContext,
+			)
+			if len(result.diagnostics) != 0 {
+				return nil, result.diagnostics
+			}
+		}
+		hasResult = true
+	case rootDirectiveContextLayered:
+		extracted, diagnostics := extractRootDirectives(parsed.document, request.directiveContext)
+		if len(diagnostics) != 0 {
+			return nil, diagnostics
+		}
+		result = sourceVersionProcessingResult{
+			payload: extracted.body, imports: extracted.imports, sequences: extracted.sequences,
+			directiveContext: request.directiveContext,
+		}
+		hasResult = true
+		if state != nil && state.mode != sourceVersionModeDefault {
+			processed, diagnostics := state.process(
+				extracted.body, request.role, request.input.destination,
+				sourceID, request.input.placementMode,
+			)
+			if len(diagnostics) != 0 {
+				return nil, diagnostics
+			}
+			processed.imports = extracted.imports
+			processed.sequences = append(cloneSequenceDeclarations(extracted.sequences), processed.sequences...)
+			processed.directiveContext = request.directiveContext
+			result = processed
+			updateMainProcessing = request.role == sourceVersionMain
+		}
+	default:
+		if state != nil && state.mode != sourceVersionModeDefault {
+			processed, diagnostics := state.process(
+				parsed.document, request.role, request.input.destination,
+				sourceID, request.input.placementMode,
+			)
+			if len(diagnostics) != 0 {
+				return nil, diagnostics
+			}
+			result = processed
+			hasResult = true
+			updateMainProcessing = request.role == sourceVersionMain
+		}
+	}
+	if !hasResult {
+		return nil, nil
+	}
+	if updateMainProcessing {
+		completed := result
+		state.mainProcessing = &completed
+	}
+	return &result, nil
+}
+
 func registerAcquiredSource(source Source, context *FilesystemContext, info *SourceInfo, visited map[resourceIdentity]importRoute, hostToken *namespaceToken) *Diagnostic {
 	if visited == nil || info == nil || info.Path == "" {
 		return nil