fix: use conversational message for zero products

Changes "Found 0 products..." to "No products matched your requirements."
for a more natural user experience.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: bokelley

src/adcp/types/base.py

@@ -37,8 +37,8 @@ def decorator(func: MessageFormatter) -> MessageFormatter:
 @_register_response_message("GetProductsResponse")
 def _get_products_message(self: Any) -> str:
     products = getattr(self, "products", None)
-    if products is None:
-        return "No products found."
+    if products is None or len(products) == 0:
+        return "No products matched your requirements."
     count = len(products)
     return f"Found {count} {_pluralize(count, 'product')} matching your requirements."
 

tests/test_response_str.py

@@ -52,9 +52,9 @@ def test_multiple_products(self):
         assert str(response) == "Found 3 products matching your requirements."
 
     def test_zero_products(self):
-        """Zero products uses plural form."""
+        """Zero products uses conversational message."""
         response = GetProductsResponse.model_construct(products=[])
-        assert str(response) == "Found 0 products matching your requirements."
+        assert str(response) == "No products matched your requirements."
 
 
 class TestListCreativeFormatsResponseStr: