diff --git a/fusion_plating/fusion_plating/__init__.py b/fusion_plating/fusion_plating/__init__.py
index bd8e7014..e27b75b8 100644
--- a/fusion_plating/fusion_plating/__init__.py
+++ b/fusion_plating/fusion_plating/__init__.py
@@ -155,7 +155,7 @@ def _create_template_from_node(env, node, seen):
 
     tpl = env['fp.step.template'].create(vals)
     if kind:
-        tpl._seed_default_inputs()
+        tpl.action_seed_default_inputs()
 
 
 def _seed_minimal_library(env):
@@ -180,7 +180,7 @@ def _seed_minimal_library(env):
     ]
     for name, kind in minimal:
         tpl = Tpl.create({'name': name, 'default_kind': kind})
-        tpl._seed_default_inputs()
+        tpl.action_seed_default_inputs()
     _logger.info(
         'Fusion Plating: seeded minimal step library (%s entries)',
         len(minimal),
diff --git a/fusion_plating/fusion_plating/models/fp_step_template.py b/fusion_plating/fusion_plating/models/fp_step_template.py
index a0d3a25c..25189410 100644
--- a/fusion_plating/fusion_plating/models/fp_step_template.py
+++ b/fusion_plating/fusion_plating/models/fp_step_template.py
@@ -198,9 +198,13 @@ class FpStepTemplate(models.Model):
         'gating': [],
     }
 
-    def _seed_default_inputs(self):
+    def action_seed_default_inputs(self):
         """Seed input_template_ids based on default_kind. Idempotent —
-        only adds inputs whose names don't already exist on this template."""
+        only adds inputs whose names don't already exist on this template.
+
+        Public method (Odoo 19 requires non-underscore-prefixed names
+        for methods called from a view button).
+        """
         Input = self.env['fp.step.template.input']
         for tpl in self:
             if not tpl.default_kind:
diff --git a/fusion_plating/fusion_plating/views/fp_step_template_views.xml b/fusion_plating/fusion_plating/views/fp_step_template_views.xml
index edb3df5a..9af2dd93 100644
--- a/fusion_plating/fusion_plating/views/fp_step_template_views.xml
+++ b/fusion_plating/fusion_plating/views/fp_step_template_views.xml
@@ -30,7 +30,7 @@
         <field name="arch" type="xml">
             <form string="Step Library Template">
                 <header>
-                    <button name="_seed_default_inputs" type="object"
+                    <button name="action_seed_default_inputs" type="object"
                             string="Seed Default Inputs" class="btn-secondary"
                             invisible="not default_kind"/>
                 </header>