bindgen: works

crates/brk_bindgen/src/generators/rust/client.rs

@@ -534,7 +534,11 @@ pub fn generate_pattern_structs(
 
         writeln!(output, "}}\n").unwrap();
 
-        // Generate impl block with constructor for ALL patterns
+        // Skip constructor for non-parameterizable patterns (inlined at tree level)
+        if !metadata.is_parameterizable(&pattern.name) {
+            continue;
+        }
+
         let impl_generic = if pattern.is_generic {
             "<T: DeserializeOwned>"
         } else {

crates/brk_bindgen/src/generators/rust/tree.rs

@@ -99,15 +99,11 @@ fn generate_tree_node(
         } else {
             // Pattern type - use ::new() constructor
             let pattern = metadata.find_pattern(&child.field.rust_type);
-            if pattern.is_some_and(|p| p.is_templated()) {
-                // Templated pattern: pass base and disc
-                let disc = child
-                    .base_result
-                    .field_parts
-                    .values()
-                    .filter(|v| !v.is_empty())
-                    .min_by_key(|v| v.len())
-                    .cloned()
+            if let Some(pat) = pattern
+                && pat.is_templated()
+            {
+                let disc = pat
+                    .extract_disc_from_instance(&child.base_result.field_parts)
                     .unwrap_or_default();
                 writeln!(
                     output,