Interpret command flag aliases in the parser

internal/commandmeta/metadata.go

@@ -41,6 +41,12 @@ type Flag struct {
 	Required bool
 }
 
+// FlagAlias maps one option spelling to a canonical flag spelling.
+type FlagAlias struct {
+	Source string
+	Target string
+}
+
 // Failure is a neutral parsing or presentation failure.
 type Failure struct {
 	Message string
@@ -53,14 +59,16 @@ type Result struct {
 	Path          []string
 	HelpRequested bool
 	FlagValues    [][]string
+	FlagSpellings [][]string
 	Operands      []string
 	Failure       *Failure
 }
 
 // ParseOptions makes parser context and streams explicit.
 type ParseOptions struct {
-	Context context.Context
-	In      io.Reader
-	Out     io.Writer
-	Err     io.Writer
+	Context     context.Context
+	In          io.Reader
+	Out         io.Writer
+	Err         io.Writer
+	FlagAliases []FlagAlias
 }