feat(macros): preserve user function as standalone item in codegen

Refactor #[chain], #[renderer], #[help], and #[completion] macros to
keep
the original user function as a named item instead of inlining its body.
Trait method implementations now call the original function by name,
injecting resources from the application context.

This improves debugging (stack traces reference user function names),
error messages, and macro expansion clarity.

1 files changed, 25 insertions, 14 deletions

diff --git a/mingling_macros/src/attr/completion.rs b/mingling_macros/src/attr/completion.rs
index e917d7d..3ced091 100644
--- a/mingling_macros/src/attr/completion.rs
+++ b/mingling_macros/src/attr/completion.rs
@@ -47,11 +47,8 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
 
     // Extract the first param pattern and type for the ctx parameter
     let first_arg = &inputs[0];
-    let (ctx_pat, _ctx_type) = match first_arg {
-        FnArg::Typed(PatType { pat, ty, .. }) => {
-            let param_pat = (**pat).clone();
-            (param_pat, (**ty).clone())
-        }
+    let _ctx_type = match first_arg {
+        FnArg::Typed(PatType { ty, .. }) => (**ty).clone(),
         FnArg::Receiver(_) => {
             return syn::Error::new(
                 first_arg.span(),
@@ -61,6 +58,7 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
             .into();
         }
     };
+    let fixed_ctx: Pat = syn::parse_quote!(ctx);
 
     // Extract resources from params 2 through N, skipping ctx
     let resources = match extract_resources_from_args(sig, 1) {
@@ -70,7 +68,6 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
 
     // Get the function body
     let fn_body = &input_fn.block;
-    let fn_body_stmts = &fn_body.stmts;
 
     // Get function attributes excluding the completion attribute
     let mut fn_attrs = input_fn.attrs.clone();
@@ -96,12 +93,26 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
     // Generate immutable resource bindings
     let immut_resource_stmts = generate_immut_resource_bindings(resources.iter(), &program_type);
 
-    // Build the comp method body with resource injection
-    // Use modify_res for mutable resources same pattern as renderer.rs
-    let wrapped_body = if mut_resources.is_empty() {
-        quote! { #(#fn_body_stmts)* }
+    // Build the call to the original function with resource arguments injected
+    let resource_args: Vec<_> = resources
+        .iter()
+        .map(|res| {
+            let var_name = &res.var_name;
+            quote! { #var_name }
+        })
+        .collect();
+
+    let fn_call = if has_resources {
+        quote! { #fn_name(#fixed_ctx, #(#resource_args),*) }
+    } else {
+        quote! { #fn_name(#fixed_ctx) }
+    };
+
+    // Wrap the function call with modify_res for mutable resources
+    let inner_call = if mut_resources.is_empty() {
+        fn_call
     } else {
-        let mut wrapped = quote! { #(#fn_body_stmts)* };
+        let mut wrapped = fn_call;
         for res in mut_resources.iter().rev() {
             let var_name = &res.var_name;
             let inner_type = &res.inner_type;
@@ -117,10 +128,10 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
     let comp_body = if has_resources {
         quote! {
             #(#immut_resource_stmts)*
-            #wrapped_body
+            #inner_call
         }
     } else {
-        quote! { #(#fn_body_stmts)* }
+        quote! { #inner_call }
     };
 
     // Generate the struct and implementation
@@ -135,7 +146,7 @@ pub(crate) fn completion_attr(attr: TokenStream, item: TokenStream) -> TokenStre
         impl ::mingling::Completion for #struct_name {
             type Previous = #previous_type_path;
 
-            fn comp(#ctx_pat: &::mingling::ShellContext) #output {
+            fn comp(#fixed_ctx: &::mingling::ShellContext) #output {
                 #comp_body
             }
         }