feat: support shared-workspace file flow for matrix

tests/adapter/matrix/test_converter.py

@@ -53,6 +53,24 @@ def content_file_event():
     )
 
 
+def source_only_content_file_event():
+    return SimpleNamespace(
+        sender="@a:m.org",
+        body="doc.pdf",
+        event_id="$e5",
+        msgtype=None,
+        replyto_event_id=None,
+        source={
+            "content": {
+                "msgtype": "m.file",
+                "body": "source-only.pdf",
+                "url": "mxc://x/source-only",
+                "info": {"mimetype": "application/pdf"},
+            }
+        },
+    )
+
+
 def test_plain_text_to_incoming_message():
     result = from_room_event(text_event("Hello"), room_id="!r:m.org", chat_id="C1")
     assert isinstance(result, IncomingMessage)
@@ -147,5 +165,15 @@ def test_attachment_falls_back_to_content_payload():
     assert a.mime_type == "application/pdf"
 
 
+def test_attachment_falls_back_to_source_content_payload():
+    result = from_room_event(source_only_content_file_event(), room_id="!r:m.org", chat_id="C1")
+    assert isinstance(result, IncomingMessage)
+    a = result.attachments[0]
+    assert a.type == "document"
+    assert a.url == "mxc://x/source-only"
+    assert a.filename == "source-only.pdf"
+    assert a.mime_type == "application/pdf"
+
+
 def test_converter_module_does_not_expose_reaction_callbacks():
     assert not hasattr(converter, "from_reaction")