feat: implement conversation state management and persistence, enhance sidebar UI

tests/test_conversation_manager.py

@@ -0,0 +1,34 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+
+from conversation_manager import ConversationManager
+
+
+def test_conversation_manager_persists_history(tmp_path: Path) -> None:
+    manager = ConversationManager(storage_dir=tmp_path, conversation_id="test")
+    manager.append_message("user", "Hello there!")
+    manager.append_message("assistant", "General Kenobi.")
+
+    conversation_file = tmp_path / "test.json"
+    assert conversation_file.exists()
+
+    data = json.loads(conversation_file.read_text(encoding="utf-8"))
+    assert len(data["messages"]) == 2
+    assert data["messages"][0]["content"] == "Hello there!"
+
+    reloaded = ConversationManager(storage_dir=tmp_path, conversation_id="test")
+    assert [msg["content"] for msg in reloaded.messages] == [
+        "Hello there!",
+        "General Kenobi.",
+    ]
+
+
+def test_conversation_manager_rejects_invalid_role(tmp_path: Path) -> None:
+    manager = ConversationManager(storage_dir=tmp_path, conversation_id="invalid")
+
+    with pytest.raises(ValueError):
+        manager.append_message("narrator", "This should fail.")