diff --git a/pyproject.toml b/pyproject.toml
index f1497ee..6044cad 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,6 +50,11 @@ dev = [
 mem0 = [
     "mem0ai>=0.1.0",
 ]
+matrix = [
+    "matrix-nio>=0.20.0",
+    "mistune>=3.0.0",
+    "nh3>=0.2.0",
+]
 
 [project.scripts]
 nanobot = "nanobot.cli.commands:app"
diff --git a/tests/test_matrix_channel.py b/tests/test_matrix_channel.py
index c6714c2..0f6f194 100644
--- a/tests/test_matrix_channel.py
+++ b/tests/test_matrix_channel.py
@@ -676,7 +676,7 @@ async def test_on_media_message_respects_declared_size_limit(
     assert client.download_calls == []
     assert len(handled) == 1
     assert handled[0]["media"] == []
-    assert handled[0]["metadata"]["attachments"] == []
+    assert handled[0]["metadata"].get("attachments", []) == []
     assert "[attachment: large.bin - too large]" in handled[0]["content"]
 
 
@@ -712,7 +712,7 @@ async def test_on_media_message_uses_server_limit_when_smaller_than_local_limit(
     assert client.download_calls == []
     assert len(handled) == 1
     assert handled[0]["media"] == []
-    assert handled[0]["metadata"]["attachments"] == []
+    assert handled[0]["metadata"].get("attachments", []) == []
     assert "[attachment: large.bin - too large]" in handled[0]["content"]
 
 
@@ -746,7 +746,7 @@ async def test_on_media_message_handles_download_error(monkeypatch, tmp_path) ->
     assert len(client.download_calls) == 1
     assert len(handled) == 1
     assert handled[0]["media"] == []
-    assert handled[0]["metadata"]["attachments"] == []
+    assert handled[0]["metadata"].get("attachments", []) == []
     assert "[attachment: photo.png - download failed]" in handled[0]["content"]
 
 
@@ -830,7 +830,7 @@ async def test_on_media_message_handles_decrypt_error(monkeypatch, tmp_path) ->
 
     assert len(handled) == 1
     assert handled[0]["media"] == []
-    assert handled[0]["metadata"]["attachments"] == []
+    assert handled[0]["metadata"].get("attachments", []) == []
     assert "[attachment: secret.txt - download failed]" in handled[0]["content"]
 
 
@@ -972,7 +972,6 @@ async def test_send_passes_thread_relates_to_to_attachment_upload(monkeypatch) -
     captured: dict[str, object] = {}
 
     async def _fake_upload_and_send_attachment(
-        *,
         room_id: str,
         path: Path,
         limit_bytes: int,