diff --git a/gateway/run.py b/gateway/run.py
index 7b9622485..294e71287 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -7816,6 +7816,11 @@ class GatewayRunner:
                         # response, just without the typing indicator.
                         _adapter_supports_edit = getattr(_adapter, "SUPPORTS_MESSAGE_EDITING", True)
                         _effective_cursor = _scfg.cursor if _adapter_supports_edit else ""
+                        # Some Matrix clients render the streaming cursor
+                        # as a visible tofu/white-box artifact.  Keep
+                        # streaming text on Matrix, but suppress the cursor.
+                        if source.platform == Platform.MATRIX:
+                            _effective_cursor = ""
                         _consumer_cfg = StreamConsumerConfig(
                             edit_interval=_scfg.edit_interval,
                             buffer_threshold=_scfg.buffer_threshold,
diff --git a/tests/gateway/test_run_progress_topics.py b/tests/gateway/test_run_progress_topics.py
index c1dda60b5..7859edd74 100644
--- a/tests/gateway/test_run_progress_topics.py
+++ b/tests/gateway/test_run_progress_topics.py
@@ -378,6 +378,25 @@ class PreviewedResponseAgent:
         }
 
 
+class StreamingRefineAgent:
+    def __init__(self, **kwargs):
+        self.stream_delta_callback = kwargs.get("stream_delta_callback")
+        self.tools = []
+
+    def run_conversation(self, message, conversation_history=None, task_id=None):
+        if self.stream_delta_callback:
+            self.stream_delta_callback("Continuing to refine:")
+        time.sleep(0.1)
+        if self.stream_delta_callback:
+            self.stream_delta_callback(" Final answer.")
+        return {
+            "final_response": "Continuing to refine: Final answer.",
+            "response_previewed": True,
+            "messages": [],
+            "api_calls": 1,
+        }
+
+
 class QueuedCommentaryAgent:
     calls = 0
 
@@ -425,6 +444,10 @@ async def _run_with_agent(
     session_id,
     pending_text=None,
     config_data=None,
+    platform=Platform.TELEGRAM,
+    chat_id="-1001",
+    chat_type="group",
+    thread_id="17585",
 ):
     if config_data:
         import yaml
@@ -439,7 +462,7 @@ async def _run_with_agent(
     fake_run_agent.AIAgent = agent_cls
     monkeypatch.setitem(sys.modules, "run_agent", fake_run_agent)
 
-    adapter = ProgressCaptureAdapter()
+    adapter = ProgressCaptureAdapter(platform=platform)
     runner = _make_runner(adapter)
     gateway_run = importlib.import_module("gateway.run")
     if config_data and "streaming" in config_data:
@@ -447,12 +470,14 @@ async def _run_with_agent(
     monkeypatch.setattr(gateway_run, "_hermes_home", tmp_path)
     monkeypatch.setattr(gateway_run, "_resolve_runtime_agent_kwargs", lambda: {"api_key": "***"})
     source = SessionSource(
-        platform=Platform.TELEGRAM,
-        chat_id="-1001",
-        chat_type="group",
-        thread_id="17585",
+        platform=platform,
+        chat_id=chat_id,
+        chat_type=chat_type,
+        thread_id=thread_id,
     )
-    session_key = "agent:main:telegram:group:-1001:17585"
+    session_key = f"agent:main:{platform.value}:{chat_type}:{chat_id}"
+    if thread_id:
+        session_key = f"{session_key}:{thread_id}"
     if pending_text is not None:
         adapter._pending_messages[session_key] = MessageEvent(
             text=pending_text,
@@ -580,6 +605,30 @@ async def test_run_agent_previewed_final_marks_already_sent(monkeypatch, tmp_pat
     assert [call["content"] for call in adapter.sent] == ["You're welcome."]
 
 
+@pytest.mark.asyncio
+async def test_run_agent_matrix_streaming_omits_cursor(monkeypatch, tmp_path):
+    adapter, result = await _run_with_agent(
+        monkeypatch,
+        tmp_path,
+        StreamingRefineAgent,
+        session_id="sess-matrix-streaming",
+        config_data={
+            "display": {"tool_progress": "off", "interim_assistant_messages": False},
+            "streaming": {"enabled": True, "edit_interval": 0.01, "buffer_threshold": 1},
+        },
+        platform=Platform.MATRIX,
+        chat_id="!room:matrix.example.org",
+        chat_type="group",
+        thread_id="$thread",
+    )
+
+    assert result.get("already_sent") is True
+    all_text = [call["content"] for call in adapter.sent] + [call["content"] for call in adapter.edits]
+    assert all_text, "expected streamed Matrix content to be sent or edited"
+    assert all("▉" not in text for text in all_text)
+    assert any("Continuing to refine:" in text for text in all_text)
+
+
 @pytest.mark.asyncio
 async def test_run_agent_queued_message_does_not_treat_commentary_as_final(monkeypatch, tmp_path):
     QueuedCommentaryAgent.calls = 0