diff --git a/routes/history_routes.py b/routes/history_routes.py
index bcadeee..9dbfd4b 100644
--- a/routes/history_routes.py
+++ b/routes/history_routes.py
@@ -544,7 +544,7 @@ def setup_history_routes(session_manager) -> APIRouter:
             # Build text to summarize
             convo_text = "\n".join(
                 f"{(m.role if isinstance(m, ChatMessage) else m.get('role', '')).upper()}: "
-                f"{(m.content if isinstance(m, ChatMessage) else m.get('content', ''))[:2000]}"
+                f"{((m.content if isinstance(m, ChatMessage) else m.get('content')) or '')[:2000]}"
                 for m in older
             )
 
diff --git a/tests/test_history_compact_tool_calls.py b/tests/test_history_compact_tool_calls.py
new file mode 100644
index 0000000..99a6b34
--- /dev/null
+++ b/tests/test_history_compact_tool_calls.py
@@ -0,0 +1,145 @@
+from types import SimpleNamespace
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+from core.models import ChatMessage
+import routes.history_routes as history_routes
+
+
+class _FakeQuery:
+    def __init__(self, rows=None, first_row=None):
+        self._rows = rows or []
+        self._first_row = first_row
+
+    def filter(self, *args, **kwargs):
+        return self
+
+    def order_by(self, *args, **kwargs):
+        return self
+
+    def all(self):
+        return self._rows
+
+    def first(self):
+        return self._first_row
+
+
+class _FakeDb:
+    def __init__(self):
+        self.added = []
+        self.deleted = []
+        self.session_row = SimpleNamespace(message_count=0, updated_at=None)
+
+    def query(self, model):
+        if model is history_routes.DbSession:
+            return _FakeQuery(first_row=self.session_row)
+        return _FakeQuery(rows=[])
+
+    def add(self, row):
+        self.added.append(row)
+
+    def delete(self, row):
+        self.deleted.append(row)
+
+    def commit(self):
+        pass
+
+    def close(self):
+        pass
+
+
+class _FakeSessionManager:
+    def __init__(self, session):
+        self.session = session
+        self.saved = False
+
+    def get_session(self, session_id):
+        if session_id != self.session.id:
+            raise KeyError(session_id)
+        return self.session
+
+    def save_sessions(self):
+        self.saved = True
+
+
+class _FakeSession:
+    id = "session-1"
+    name = "Tool session"
+    endpoint_url = "http://example.test/v1"
+    model = "test-model"
+    headers = {}
+
+    def __init__(self, history):
+        self.history = history
+        self.message_count = len(history)
+
+    def get_context_messages(self):
+        return [
+            msg.to_dict() if isinstance(msg, ChatMessage) else msg
+            for msg in self.history
+        ]
+
+
+def _compact_prompt_for(monkeypatch, history):
+    captured = {}
+
+    async def fake_llm_call_async(endpoint_url, model, messages, **kwargs):
+        captured["messages"] = messages
+        return "Summary text"
+
+    monkeypatch.setattr(history_routes, "_verify_session_owner", lambda request, session_id: None)
+    monkeypatch.setattr(history_routes, "SessionLocal", lambda: _FakeDb())
+
+    import src.endpoint_resolver as endpoint_resolver
+    import src.llm_core as llm_core
+    import src.model_context as model_context
+
+    monkeypatch.setattr(endpoint_resolver, "resolve_endpoint", lambda kind: (None, None, {}))
+    monkeypatch.setattr(llm_core, "llm_call_async", fake_llm_call_async)
+    monkeypatch.setattr(model_context, "estimate_tokens", lambda messages: 100)
+    monkeypatch.setattr(model_context, "get_context_length", lambda endpoint_url, model: 1000)
+
+    session = _FakeSession(history)
+    manager = _FakeSessionManager(session)
+    app = FastAPI()
+    app.include_router(history_routes.setup_history_routes(manager))
+
+    response = TestClient(app).post("/api/session/session-1/compact")
+
+    assert response.status_code == 200
+    assert response.json()["status"] == "ok"
+    assert manager.saved is True
+    return captured["messages"][1]["content"]
+
+
+def test_manual_compact_tolerates_chatmessage_with_none_content(monkeypatch):
+    compact_prompt = _compact_prompt_for(
+        monkeypatch,
+        [
+            ChatMessage(role="user", content="start"),
+            ChatMessage(role="assistant", content=None),
+            ChatMessage(role="tool", content="tool result"),
+            ChatMessage(role="assistant", content="done"),
+            ChatMessage(role="user", content="next"),
+            ChatMessage(role="assistant", content="final"),
+        ],
+    )
+    assert "ASSISTANT: None" not in compact_prompt
+    assert "ASSISTANT: " in compact_prompt
+
+
+def test_manual_compact_tolerates_dict_message_with_none_content(monkeypatch):
+    compact_prompt = _compact_prompt_for(
+        monkeypatch,
+        [
+            {"role": "user", "content": "start"},
+            {"role": "assistant", "content": None},
+            ChatMessage(role="tool", content="tool result"),
+            ChatMessage(role="assistant", content="done"),
+            ChatMessage(role="user", content="next"),
+            ChatMessage(role="assistant", content="final"),
+        ],
+    )
+    assert "ASSISTANT: None" not in compact_prompt
+    assert "ASSISTANT: " in compact_prompt