fix(tui): keep resumed live history current

tests/tui_gateway/test_protocol.py

@@ -496,6 +496,105 @@ def test_session_resume_reuses_existing_live_session(server, monkeypatch):
     assert created_sids == [first["result"]["session_id"]]
 
 
+def test_session_resume_live_payload_uses_current_history_with_ancestors(server, monkeypatch):
+    """Live resume should not reuse a stale ancestor-inclusive snapshot."""
+
+    target = "20260409_010101_child"
+    ancestor_history = [{"role": "user", "content": "ancestor"}]
+    current_history = [
+        {"role": "user", "content": "current"},
+        {"role": "assistant", "content": "current reply"},
+    ]
+
+    class _DB:
+        def get_session(self, _sid):
+            return {"id": target}
+
+        def get_session_by_title(self, _title):
+            return None
+
+        def reopen_session(self, _sid):
+            return None
+
+        def get_messages_as_conversation(self, _sid, include_ancestors=False):
+            if include_ancestors:
+                return ancestor_history + current_history
+            return list(current_history)
+
+    class _Worker:
+        def close(self):
+            pass
+
+    monkeypatch.setattr(server, "_get_db", lambda: _DB())
+    monkeypatch.setattr(
+        server,
+        "_make_agent",
+        lambda _sid, key, session_id=None: types.SimpleNamespace(
+            model="test/model", session_id=session_id or key
+        ),
+    )
+    monkeypatch.setattr(server, "_SlashWorker", lambda _key, _model: _Worker())
+    monkeypatch.setattr(
+        server,
+        "_start_notification_poller",
+        lambda _sid, _session: threading.Event(),
+    )
+    monkeypatch.setattr(server, "_notify_session_boundary", lambda *_args, **_kwargs: None)
+    monkeypatch.setattr(server, "_wire_callbacks", lambda _sid: None)
+    monkeypatch.setattr(server, "_emit", lambda *_args, **_kwargs: None)
+    monkeypatch.setattr(
+        server,
+        "_session_info",
+        lambda _agent, _session=None: {"model": "test/model"},
+    )
+
+    fake_approval = types.SimpleNamespace(
+        load_permanent_allowlist=lambda: None,
+        register_gateway_notify=lambda *_args, **_kwargs: None,
+    )
+
+    with patch.dict(sys.modules, {"tools.approval": fake_approval}):
+        first = server.handle_request(
+            {
+                "id": "first",
+                "method": "session.resume",
+                "params": {"session_id": target, "cols": 100},
+            }
+        )
+
+        assert "error" not in first
+        sid = first["result"]["session_id"]
+        assert first["result"]["messages"] == [
+            {"role": "user", "text": "ancestor"},
+            {"role": "user", "text": "current"},
+            {"role": "assistant", "text": "current reply"},
+        ]
+
+        with server._sessions[sid]["history_lock"]:
+            server._sessions[sid]["history"] = current_history + [
+                {"role": "user", "content": "new live turn"},
+                {"role": "assistant", "content": "new live reply"},
+            ]
+
+        second = server.handle_request(
+            {
+                "id": "second",
+                "method": "session.resume",
+                "params": {"session_id": target, "cols": 120},
+            }
+        )
+
+    assert "error" not in second
+    assert second["result"]["session_id"] == sid
+    assert second["result"]["messages"] == [
+        {"role": "user", "text": "ancestor"},
+        {"role": "user", "text": "current"},
+        {"role": "assistant", "text": "current reply"},
+        {"role": "user", "text": "new live turn"},
+        {"role": "assistant", "text": "new live reply"},
+    ]
+
+
 def test_make_agent_accepts_list_system_prompt(server, monkeypatch):
     captured = {}
 

tui_gateway/server.py

@@ -3016,6 +3016,9 @@ def _(rid, params: dict) -> dict:
             display_history = db.get_messages_as_conversation(
                 target, include_ancestors=True
             )
+            display_history_prefix = display_history[
+                : max(0, len(display_history) - len(history))
+            ]
             messages = _history_to_messages(display_history)
             tokens = _set_session_context(target)
             try:
@@ -3024,7 +3027,7 @@ def _(rid, params: dict) -> dict:
                 _clear_session_context(tokens)
             _init_session(sid, target, agent, history, cols=cols)
             if sid in _sessions:
-                _sessions[sid]["display_history"] = display_history
+                _sessions[sid]["display_history_prefix"] = display_history_prefix
         except Exception as e:
             return _err(rid, 5000, f"resume failed: {e}")
         session = _sessions.get(sid) or {}
@@ -3170,7 +3173,9 @@ def _live_session_payload(
             session["transport"] = transport
         if touch:
             session["last_active"] = time.time()
-        history = list(session.get("display_history") or session.get("history") or [])
+        history = list(session.get("display_history_prefix") or []) + list(
+            session.get("history") or []
+        )
         inflight = _inflight_snapshot(session)
         running = bool(session.get("running"))
     payload = {