test: restore AGENT_CONFIGS in-place to prevent dict reference leaks

Author: kennedy-whytech

tests/test_presets.py

@@ -3140,7 +3140,8 @@ def test_register_commands_substitutes_core_template_for_wrap_strategy(self, pro
                 project_dir / "preset", project_dir
             )
         finally:
-            CommandRegistrar.AGENT_CONFIGS = original
+            CommandRegistrar.AGENT_CONFIGS.clear()
+            CommandRegistrar.AGENT_CONFIGS.update(original)
 
         written = (agent_dir / "speckit.specify.md").read_text()
         assert "{CORE_TEMPLATE}" not in written
@@ -3296,7 +3297,8 @@ def test_register_commands_inherits_scripts_from_core(self, project_dir):
                 project_dir,
             )
         finally:
-            CommandRegistrar.AGENT_CONFIGS = original
+            CommandRegistrar.AGENT_CONFIGS.clear()
+            CommandRegistrar.AGENT_CONFIGS.update(original)
 
         written = (agent_dir / "speckit.specify.md").read_text()
         assert "{CORE_TEMPLATE}" not in written
@@ -3344,7 +3346,8 @@ def test_register_commands_toml_resolves_inherited_scripts(self, project_dir):
                 project_dir,
             )
         finally:
-            CommandRegistrar.AGENT_CONFIGS = original
+            CommandRegistrar.AGENT_CONFIGS.clear()
+            CommandRegistrar.AGENT_CONFIGS.update(original)
 
         written = (toml_dir / "speckit.specify.toml").read_text()
         assert "{CORE_TEMPLATE}" not in written