Add detached source lookup to results and errors

internal/engine/diagnostic.go

@@ -50,6 +50,16 @@ func (e *LoadError) Sources() []SourceInfo {
 	return cloneSourceInfos(e.sources)
 }
 
+// Source returns a detached record from the source evidence retained before
+// loading failed. IDs are local to the failed load. Empty or unknown IDs return
+// false.
+func (e *LoadError) Source(id string) (SourceInfo, bool) {
+	if e == nil {
+		return SourceInfo{}, false
+	}
+	return lookupSourceInfo(e.sources, id)
+}
+
 // WriteDiagnostics writes diagnostics in canonical order. It escapes terminal
 // control characters and propagates writer errors, including short writes.
 func WriteDiagnostics(output io.Writer, diagnostics []Diagnostic) error {

internal/engine/load.go

@@ -119,6 +119,16 @@ func (r *Inspection) Sources() []SourceInfo {
 	return cloneSourceInfos(r.sources)
 }
 
+// Source returns a detached record for an acquired source in this load. IDs are
+// local to the load; the lookup does not reacquire the source or access the
+// filesystem. Empty or unknown IDs return false.
+func (r *Inspection) Source(id string) (SourceInfo, bool) {
+	if r == nil {
+		return SourceInfo{}, false
+	}
+	return lookupSourceInfo(r.sources, id)
+}
+
 // SourceContext returns a passive filesystem view for an acquired source.
 // Unknown IDs and sources without a filesystem context return false.
 func (r *Inspection) SourceContext(id string) (ResourceContext, bool) {

internal/engine/records.go

@@ -92,7 +92,7 @@ const (
 	CodeDecodeUnknownField Code = "decode.unknown_field"
 	CodeDecodeArrayLength  Code = "decode.array_length"
 
-	CodeOptionsInvalid     Code = "options.invalid"
+	CodeOptionsInvalid Code = "options.invalid"
 
 	CodeImportDisabled      Code = "import.disabled"
 	CodeImportInvalid       Code = "import.invalid"
@@ -345,6 +345,18 @@ func cloneSourceInfo(source SourceInfo) SourceInfo {
 	return source
 }
 
+func lookupSourceInfo(sources []SourceInfo, id string) (SourceInfo, bool) {
+	if id == "" {
+		return SourceInfo{}, false
+	}
+	for _, source := range sources {
+		if source.ID == id {
+			return cloneSourceInfo(source), true
+		}
+	}
+	return SourceInfo{}, false
+}
+
 func cloneSourceVersionCheck(value *SourceVersionCheck) *SourceVersionCheck {
 	if value == nil {
 		return nil