feat(hot-reload): Add HotModule dataclass and HotReloader registry

src/hot_reloader.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+from dataclasses import dataclass, field
+from typing import Any
+import copy
+import traceback
+
+@dataclass
+class HotModule:
+    name: str
+    file_path: str
+    state_keys: list[str] = field(default_factory=list)
+    delegation_targets: list[str] = field(default_factory=list)
+
+class HotReloader:
+    HOT_MODULES: dict[str, HotModule] = {}
+    last_error: str | None = None
+    is_error_state: bool = False
+
+    @classmethod
+    def register(cls, module: HotModule) -> None:
+        if module.name in cls.HOT_MODULES:
+            raise ValueError(f"Module {module.name} already registered")
+        cls.HOT_MODULES[module.name] = module
+
+    @classmethod
+    def capture_state(cls, app: Any, state_keys: list[str]) -> dict[str, Any]:
+        return {key: copy.deepcopy(getattr(app, key, None)) for key in state_keys if hasattr(app, key)}
+
+    @classmethod
+    def restore_state(cls, app: Any, state: dict[str, Any]) -> None:
+        for key, value in state.items():
+            setattr(app, key, value)

tests/test_hot_reloader.py

@@ -0,0 +1,35 @@
+from __future__ import annotations
+import pytest
+from src.hot_reloader import HotModule, HotReloader
+
+def test_hot_module_dataclass_fields():
+    hm = HotModule(
+        name="test_module",
+        file_path="/path/to/test_module.py",
+        state_keys=["attr1", "attr2"],
+        delegation_targets=["method_a", "method_b"],
+    )
+    assert hm.name == "test_module"
+    assert hm.file_path == "/path/to/test_module.py"
+    assert hm.state_keys == ["attr1", "attr2"]
+    assert hm.delegation_targets == ["method_a", "method_b"]
+
+def test_hot_reloader_register_and_get():
+    HotReloader.HOT_MODULES.clear()
+    hm = HotModule(name="test_mod", file_path="/fake/path.py", state_keys=[], delegation_targets=[])
+    HotReloader.register(hm)
+    assert "test_mod" in HotReloader.HOT_MODULES
+    assert HotReloader.HOT_MODULES["test_mod"] is hm
+
+def test_hot_reloader_register_duplicate_raises():
+    HotReloader.HOT_MODULES.clear()
+    hm1 = HotModule(name="dup", file_path="/a.py", state_keys=[], delegation_targets=[])
+    HotReloader.register(hm1)
+    with pytest.raises(ValueError, match="already registered"):
+        HotReloader.register(hm1)
+
+def test_hot_reloader_is_error_state():
+    HotReloader.HOT_MODULES.clear()
+    HotReloader.last_error = None
+    HotReloader.is_error_state = False
+    assert HotReloader.is_error_state is False