Allow local template overrides in the site directory

closes #13

tests/unit/test_site.py

@@ -78,9 +78,29 @@ def test_clean_removes_output_directory(make_site):
     assert not site.output_path.exists()
 
 
-def test_resolve_template_path_raises_for_missing_template():
+def test_resolve_template_path_raises_for_missing_template(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text("name: test\ntemplate: does-not-exist\n")
+
     with pytest.raises(ConfigError, match="not found"):
-        Site.resolve_template_path("does-not-exist")
+        Site(path)
+
+
+def test_resolve_template_path_prefers_local_override(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text("name: test\ntemplate: plain\n")
+    local = path / "templates" / "plain"
+    local.mkdir(parents=True)
+
+    assert Site(path).template_path == local
+
+
+def test_resolve_template_path_falls_back_to_builtin(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text("name: test\ntemplate: plain\n")
+
+    assert Site(path).template_path.name == "plain"
+    assert not Site(path).template_path.is_relative_to(path)
 
 
 def test_home_url(site_dir):