feat(tui): unify session history and context

tests/webui/test_session_context.py

@@ -0,0 +1,56 @@
+from nanobot.session import Session
+from nanobot.utils.helpers import estimate_message_tokens
+from nanobot.webui.session_context import session_context_payload
+
+
+def test_session_context_separates_archive_progress_from_replay() -> None:
+    messages = [
+        {"role": "user", "content": "old question"},
+        {"role": "assistant", "content": "old answer"},
+        {"role": "user", "content": "recent question"},
+        {"role": "assistant", "content": "recent answer"},
+    ]
+    session = Session(
+        key="websocket:context",
+        messages=messages,
+        last_consolidated=2,
+        metadata={
+            "_last_summary": {
+                "text": "The archived conversation settled the old question.",
+                "last_active": "2026-08-13T10:00:00Z",
+            }
+        },
+    )
+
+    replay = session.get_history(max_messages=0, include_runtime_context=False)
+    replay_tokens = sum(estimate_message_tokens(message) for message in replay)
+    summary_tokens = estimate_message_tokens(
+        {"role": "system", "content": "The archived conversation settled the old question."}
+    )
+    payload = session_context_payload(session)
+
+    assert payload == {
+        "schema_version": 1,
+        "session_key": "websocket:context",
+        "total_messages": 4,
+        "archived_messages": 2,
+        "replay_messages": len(replay),
+        "estimated_replay_tokens": replay_tokens,
+        "estimated_summary_tokens": summary_tokens,
+        "estimated_session_tokens": replay_tokens + summary_tokens,
+        "archived_summary": "The archived conversation settled the old question.",
+        "archived_summary_at": "2026-08-13T10:00:00Z",
+    }
+
+
+def test_session_context_tolerates_untrusted_summary_metadata() -> None:
+    session = Session(
+        key="websocket:context",
+        messages=[{"role": "user", "content": "hello"}],
+        metadata={"_last_summary": "invalid"},
+    )
+
+    payload = session_context_payload(session)
+
+    assert payload["archived_summary"] is None
+    assert payload["archived_summary_at"] is None