Bound external result file reads

internal/adapters/scriptorium/subprocess.go

@@ -12,6 +12,9 @@ import (
 	"gitea.maximumdirect.net/eric/narratio/internal/fileops"
 )
 
+// MaxOutputFileBytes bounds one Scriptorium artifact result.
+const MaxOutputFileBytes int64 = 64 * 1024 * 1024
+
 // SubprocessRunner invokes Scriptorium through its public CLI.
 type SubprocessRunner struct{}
 
@@ -326,14 +329,11 @@ func writeInvocationConfig(path string, payload invocationPayload) error {
 }
 
 func validateNonEmptyOutput(path string) error {
-	info, err := os.Stat(path)
+	data, err := fileops.ReadRegularFile(path, MaxOutputFileBytes)
 	if err != nil {
-		return fmt.Errorf("stat file: %w", err)
+		return fmt.Errorf("scriptorium artifact output exceeds or cannot be read within %d-byte limit: %w", MaxOutputFileBytes, err)
 	}
-	if info.IsDir() {
-		return fmt.Errorf("path is a directory")
-	}
-	if info.Size() <= 0 {
+	if len(data) == 0 {
 		return fmt.Errorf("file is empty")
 	}
 	return nil