Standardize unimplemented API failures

tools/generate_surface.py

@@ -128,7 +128,7 @@ def render_type(name: str, kind: str, arity: int, csharp_name: str, indent: str)
     declaration = f"pub struct {rust_name}{params}" + (";" if not marker else f"{marker};")
     return [
         f"{indent}/// `{kind}` shim for C# `{csharp_name}`; members remain intentionally unimplemented.",
-        f"{indent}#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]",
+        f"{indent}#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]",
         f"{indent}{declaration}",
         f"{indent}impl{('<' + ', '.join(f'T{i}' for i in range(arity)) + '>') if arity else ''} {rust_name}{('<' + ', '.join(f'T{i}' for i in range(arity)) + '>') if arity else ''} {{",
         f"{indent}    pub const CSHARP_NAME: &'static str = \"{csharp_name}\";",