refactor(backend): clean up package re-exports, settings model properties, and unused signals

tests/test_local_settings_model.py

@@ -0,0 +1,61 @@
+import pytest
+
+from pygui.backend.data.local_settings import LocalSettings
+from pygui.backend.data.local_settings_model import LocalSettingsModel
+
+
+@pytest.fixture
+def shared_settings():
+    return LocalSettings()
+
+
+@pytest.fixture
+def model(qapp, tmp_path, shared_settings):
+    return LocalSettingsModel(shared_settings, tmp_path)
+
+
+def test_save_mutates_the_shared_instance_in_place(model, shared_settings):
+    # This is the bug candidate 1 fixes: DeviceController holds the same
+    # LocalSettings object, so a save here must be visible to it without
+    # a reload — no throwaway copy, no stale read until restart.
+    model.chamberId = "7"
+    model.waferReadTimeout = 45000
+    model.saveSettings()
+
+    assert shared_settings.chamber_id == "7"
+    assert shared_settings.wafer_read_timeout == 45000
+
+
+def test_save_persists_to_disk_and_reload_round_trips(tmp_path, qapp, shared_settings):
+    model = LocalSettingsModel(shared_settings, tmp_path)
+    model.chamberId = "9"
+    model.waferRetries = 3
+    model.saveSettings()
+
+    reloaded_settings = LocalSettings.read_settings(str(tmp_path))
+    other_model = LocalSettingsModel(reloaded_settings, tmp_path)
+    other_model.loadSettings()
+
+    assert other_model.chamberId == "9"
+    assert other_model.waferRetries == 3
+
+
+def test_revert_restores_last_saved_values(model):
+    model.chamberId = "2"
+    model.saveSettings()
+
+    model.chamberId = "unsaved-edit"
+    assert model.isDirty is True
+
+    model.revertChanges()
+    assert model.chamberId == "2"
+    assert model.isDirty is False
+
+
+def test_invalid_chamber_id_blocks_save(model, shared_settings):
+    shared_settings.chamber_id = "before"
+    model.chamberId = ""
+    model.saveSettings()
+
+    assert model.saveStatus.startswith("error:")
+    assert shared_settings.chamber_id == "before"  # unsaved, shared instance untouched