1 files changed, 106 insertions, 10 deletions
diff --git a/mingling_macros/src/pack_err.rs b/mingling_macros/src/pack_err.rs
index 51bc656..8f147be 100644
--- a/mingling_macros/src/pack_err.rs
+++ b/mingling_macros/src/pack_err.rs
@@ -2,6 +2,8 @@ use proc_macro::TokenStream;
 use quote::quote;
 use syn::{Ident, Token, Type, parse_macro_input};
 
+use crate::get_global_set;
+
 /// Converts a PascalCase/UpperCamelCase identifier string to snake_case.
 ///
 /// Examples:
@@ -67,16 +69,12 @@ pub fn pack_err(input: TokenStream) -> TokenStream {
             let name_str = type_name.to_string();
             let snake_name = to_snake_case(&name_str);
 
-            #[cfg(not(feature = "general_renderer"))]
+            // Note: No longer derives Serialize under general_renderer.
+            // Use pack_err_structural for structured output support.
             let derive = quote! {
                 #[derive(::mingling::Groupped)]
             };
 
-            #[cfg(feature = "general_renderer")]
-            let derive = quote! {
-                #[derive(::mingling::Groupped, ::serde::Serialize)]
-            };
-
             let expanded = quote! {
                 #derive
                 pub struct #type_name {
@@ -104,18 +102,114 @@ pub fn pack_err(input: TokenStream) -> TokenStream {
             let name_str = type_name.to_string();
             let snake_name = to_snake_case(&name_str);
 
-            #[cfg(not(feature = "general_renderer"))]
+            // Note: No longer derives Serialize under general_renderer.
+            // Use pack_err_structural for structured output support.
             let derive = quote! {
                 #[derive(::mingling::Groupped)]
             };
 
-            #[cfg(feature = "general_renderer")]
-            let derive = quote! {
+            let expanded = quote! {
+                #derive
+                pub struct #type_name {
+                    /// The snake_case name of this error, automatically set at compile time.
+                    pub name: String,
+                    /// Additional context info for this error.
+                    pub info: #inner_type,
+                }
+
+                impl #type_name {
+                    /// Creates a new error with the given info.
+                    /// The `name` field is automatically set to the snake_case of the struct name.
+                    pub fn new(info: #inner_type) -> Self {
+                        Self {
+                            name: #snake_name.into(),
+                            info,
+                        }
+                    }
+                }
+
+                ::mingling::macros::register_type!(#type_name);
+            };
+
+            expanded.into()
+        }
+    }
+}
+
+/// `pack_err_structural!` — like `pack_err!` but also marks the type as
+/// supporting structured output via `StructuralData`.
+///
+/// # Syntax
+///
+/// ```rust,ignore
+/// pack_err_structural!(ErrorNotFound);
+/// pack_err_structural!(ErrorNotDir = PathBuf);
+/// ```
+///
+/// This is equivalent to:
+/// ```rust,ignore
+/// pack_err!(ErrorNotFound);
+/// impl ::mingling::__private::StructuralDataSealed for ErrorNotFound {}
+/// impl ::mingling::__private::StructuralData for ErrorNotFound {}
+/// ```
+#[cfg(feature = "general_renderer")]
+pub fn pack_err_structural(input: TokenStream) -> TokenStream {
+    let parsed = parse_macro_input!(input as PackErrInput);
+
+    let type_name = match &parsed {
+        PackErrInput::Simple { type_name } => type_name.clone(),
+        PackErrInput::Typed { type_name, .. } => type_name.clone(),
+    };
+
+    // Register in STRUCTURED_TYPES
+    let type_name_str = type_name.to_string();
+    get_global_set(&crate::STRUCTURED_TYPES)
+        .lock()
+        .unwrap()
+        .insert(type_name_str);
+
+    let structural_data = quote! {
+        impl ::mingling::__private::StructuralDataSealed for #type_name {}
+        impl ::mingling::__private::StructuralData for #type_name {}
+    };
+
+    // Generate the struct + impls (same as pack_err! but with Serialize derive + sealed)
+    match parsed {
+        PackErrInput::Simple { type_name } => {
+            let name_str = type_name.to_string();
+            let snake_name = to_snake_case(&name_str);
+
+            let expanded = quote! {
                 #[derive(::mingling::Groupped, ::serde::Serialize)]
+                pub struct #type_name {
+                    /// The snake_case name of this error, automatically set at compile time.
+                    pub name: String,
+                }
+
+                impl ::std::default::Default for #type_name {
+                    fn default() -> Self {
+                        Self {
+                            name: #snake_name.into(),
+                        }
+                    }
+                }
+
+                ::mingling::macros::register_type!(#type_name);
+
+                #structural_data
             };
 
+            expanded.into()
+        }
+        PackErrInput::Typed {
+            type_name,
+            inner_type,
+        } => {
+            let name_str = type_name.to_string();
+            let snake_name = to_snake_case(&name_str);
+
             let expanded = quote! {
-                #derive
+                #[derive(::mingling::Groupped, ::serde::Serialize)]
                 pub struct #type_name {
                     /// The snake_case name of this error, automatically set at compile time.
                     pub name: String,
@@ -135,6 +229,8 @@ pub fn pack_err(input: TokenStream) -> TokenStream {
                 }
 
                 ::mingling::macros::register_type!(#type_name);
+
+                #structural_data
             };
 
             expanded.into()