fix(presets): reject duplicate provides.templates name+type entries

src/specify_cli/presets/__init__.py

@@ -409,6 +409,7 @@ def _validate(self):
             raise PresetValidationError(
                 "Preset must provide at least one template"
             )
+        seen_name_types: set[tuple[str, str]] = set()
         for tmpl in templates:
             if not isinstance(tmpl, dict):
                 raise PresetValidationError(
@@ -438,6 +439,20 @@ def _validate(self):
                     f"must be one of {sorted(VALID_PRESET_TEMPLATE_TYPES)}"
                 )
 
+            # PresetResolver._manifest_declared_template returns the first
+            # 'provides.templates' entry matching a given (name, type) pair, so
+            # a later duplicate would be silently unreachable while still being
+            # counted by PresetManifest.templates. Reject at validation time
+            # instead, mirroring the sibling fix for ExtensionManifest's
+            # provides.templates/scripts (#4016).
+            name_type = (tmpl["name"], tmpl["type"])
+            if name_type in seen_name_types:
+                raise PresetValidationError(
+                    f"Duplicate template name '{tmpl['name']}' of type "
+                    f"'{tmpl['type']}' in 'provides.templates'"
+                )
+            seen_name_types.add(name_type)
+
             # Validate file path safety: must be relative, no parent traversal
             file_path = tmpl["file"]
             normalized = os.path.normpath(file_path)

tests/test_presets.py

@@ -500,6 +500,41 @@ def test_multiple_templates(self, temp_dir, valid_pack_data):
         manifest = PresetManifest(manifest_path)
         assert len(manifest.templates) == 4
 
+    def test_duplicate_template_name_and_type_raises_validation_error(
+        self, temp_dir, valid_pack_data
+    ):
+        """A later entry with the same (name, type) pair must be rejected.
+
+        ``PresetResolver._manifest_declared_template`` returns the FIRST
+        'provides.templates' entry matching a given (name, type) pair, so a
+        later duplicate would be silently unreachable while still being
+        counted by ``PresetManifest.templates`` -- mirroring the sibling bug
+        fixed for ``ExtensionManifest``'s provides.templates/scripts (#4016).
+        """
+        valid_pack_data["provides"]["templates"] = [
+            {"type": "command", "name": "specify", "file": "commands/specify-v1.md"},
+            {"type": "command", "name": "specify", "file": "commands/specify-v2.md"},
+        ]
+        manifest_path = temp_dir / "preset.yml"
+        with open(manifest_path, 'w') as f:
+            yaml.dump(valid_pack_data, f)
+        with pytest.raises(PresetValidationError, match="Duplicate template name"):
+            PresetManifest(manifest_path)
+
+    def test_same_name_different_type_templates_allowed(
+        self, temp_dir, valid_pack_data
+    ):
+        """The same name may recur across different template types."""
+        valid_pack_data["provides"]["templates"] = [
+            {"type": "template", "name": "specify", "file": "templates/specify.md"},
+            {"type": "command", "name": "specify", "file": "commands/specify.md"},
+        ]
+        manifest_path = temp_dir / "preset.yml"
+        with open(manifest_path, 'w') as f:
+            yaml.dump(valid_pack_data, f)
+        manifest = PresetManifest(manifest_path)
+        assert len(manifest.templates) == 2
+
 
 # ===== PresetRegistry Tests =====