fix(send_message): deliver Matrix media via adapter

Matrix media delivery was silently dropped by send_message because Matrix
wasn't wired into the native adapter-backed media path. Only Telegram,
Discord, and Weixin had native media support.

Adds _send_matrix_via_adapter() which creates a MatrixAdapter instance,
connects, sends text + media via the adapter's native upload methods
(send_document, send_image_file, send_video, send_voice), then disconnects.

Also fixes a stale URL-encoding assertion in test_send_message_missing_platforms
that broke after PR #10151 added quote() to room IDs.

Cherry-picked from PR #10486 by helix4u.

tests/tools/test_send_message_missing_platforms.py

@@ -123,7 +123,7 @@ class TestSendMatrix:
         session.put.assert_called_once()
         call_kwargs = session.put.call_args
         url = call_kwargs[0][0]
-        assert url.startswith("https://matrix.example.com/_matrix/client/v3/rooms/!room:example.com/send/m.room.message/")
+        assert url.startswith("https://matrix.example.com/_matrix/client/v3/rooms/%21room%3Aexample.com/send/m.room.message/")
         assert call_kwargs[1]["headers"]["Authorization"] == "Bearer syt_tok"
         payload = call_kwargs[1]["json"]
         assert payload["msgtype"] == "m.text"

tests/tools/test_send_message_tool.py

@@ -12,6 +12,7 @@ from gateway.config import Platform
 from tools.send_message_tool import (
     _parse_target_ref,
     _send_discord,
+    _send_matrix_via_adapter,
     _send_telegram,
     _send_to_platform,
     send_message_tool,
@@ -594,6 +595,84 @@ class TestSendToPlatformChunking:
         assert all(call == [] for call in sent_calls[:-1])
         assert sent_calls[-1] == media
 
+    def test_matrix_media_uses_native_adapter_helper(self):
+
+        doc_path = Path("/tmp/test-send-message-matrix.pdf")
+        doc_path.write_bytes(b"%PDF-1.4 test")
+
+        try:
+            helper = AsyncMock(return_value={"success": True, "platform": "matrix", "chat_id": "!room:example.com", "message_id": "$evt"})
+            with patch("tools.send_message_tool._send_matrix_via_adapter", helper):
+                result = asyncio.run(
+                    _send_to_platform(
+                        Platform.MATRIX,
+                        SimpleNamespace(enabled=True, token="tok", extra={"homeserver": "https://matrix.example.com"}),
+                        "!room:example.com",
+                        "here you go",
+                        media_files=[(str(doc_path), False)],
+                    )
+                )
+
+            assert result["success"] is True
+            helper.assert_awaited_once()
+            call = helper.await_args
+            assert call.args[1] == "!room:example.com"
+            assert call.args[2] == "here you go"
+            assert call.kwargs["media_files"] == [(str(doc_path), False)]
+        finally:
+            doc_path.unlink(missing_ok=True)
+
+    def test_send_matrix_via_adapter_sends_document(self, tmp_path):
+        file_path = tmp_path / "report.pdf"
+        file_path.write_bytes(b"%PDF-1.4 test")
+
+        calls = []
+
+        class FakeAdapter:
+            def __init__(self, _config):
+                self.connected = False
+
+            async def connect(self):
+                self.connected = True
+                calls.append(("connect",))
+                return True
+
+            async def send(self, chat_id, message, metadata=None):
+                calls.append(("send", chat_id, message, metadata))
+                return SimpleNamespace(success=True, message_id="$text")
+
+            async def send_document(self, chat_id, file_path, metadata=None):
+                calls.append(("send_document", chat_id, file_path, metadata))
+                return SimpleNamespace(success=True, message_id="$file")
+
+            async def disconnect(self):
+                calls.append(("disconnect",))
+
+        fake_module = SimpleNamespace(MatrixAdapter=FakeAdapter)
+
+        with patch.dict(sys.modules, {"gateway.platforms.matrix": fake_module}):
+            result = asyncio.run(
+                _send_matrix_via_adapter(
+                    SimpleNamespace(enabled=True, token="tok", extra={"homeserver": "https://matrix.example.com"}),
+                    "!room:example.com",
+                    "report attached",
+                    media_files=[(str(file_path), False)],
+                )
+            )
+
+        assert result == {
+            "success": True,
+            "platform": "matrix",
+            "chat_id": "!room:example.com",
+            "message_id": "$file",
+        }
+        assert calls == [
+            ("connect",),
+            ("send", "!room:example.com", "report attached", None),
+            ("send_document", "!room:example.com", str(file_path), None),
+            ("disconnect",),
+        ]
+
 
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 # HTML auto-detection in Telegram send