feat(webui): add temporary chat mode

tests/session/test_session_cache.py

@@ -1,7 +1,7 @@
 import gc
 import weakref
 
-from nanobot.session.manager import SESSION_CACHE_MAX_SIZE, SessionManager
+from nanobot.session.manager import FILE_MAX_MESSAGES, SESSION_CACHE_MAX_SIZE, SessionManager
 
 
 def _bounded_manager(tmp_path, limit: int) -> SessionManager:
@@ -73,3 +73,38 @@ def test_flush_all_includes_live_sessions_outside_strong_cache(tmp_path, monkeyp
 
     assert manager.flush_all() == 2
     assert set(saved) == {("test:active", True), ("test:other", True)}
+
+
+def test_transient_session_never_reaches_storage(tmp_path) -> None:
+    manager = SessionManager(tmp_path)
+    session = manager.get_or_create_transient("websocket:temporary-test")
+    session.add_message("user", "secret")
+
+    manager.save(session, fsync=True)
+
+    assert manager.flush_all() == 0
+    assert manager.read_session_file(session.key) is None
+    assert list(manager.sessions_dir.glob("*.jsonl")) == []
+
+
+def test_transient_session_history_is_bounded_in_memory(tmp_path) -> None:
+    manager = SessionManager(tmp_path)
+    session = manager.get_or_create_transient("websocket:temporary-bounded")
+    for index in range(FILE_MAX_MESSAGES + 2):
+        session.add_message("user", f"message {index}")
+
+    manager.save(session)
+
+    assert len(session.messages) <= FILE_MAX_MESSAGES
+    assert session.messages[-1]["content"] == f"message {FILE_MAX_MESSAGES + 1}"
+    assert manager.read_session_file(session.key) is None
+
+
+def test_discard_transient_session_forgets_live_history(tmp_path) -> None:
+    manager = SessionManager(tmp_path)
+    session = manager.get_or_create_transient("websocket:temporary-test")
+    session.add_message("user", "secret")
+
+    assert manager.discard_transient(session.key) is True
+    assert manager.get_cached(session.key) is None
+    assert manager.discard_transient(session.key) is False