fix: complete HM42 monochrome image planes

tests/test_client.py

@@ -7,10 +7,11 @@ from ppclock.client import PPClient
 
 
 class FakeTransport:
-    def __init__(self):
+    def __init__(self, firmware_revision=None):
         self.epd_writes = []
         self.rxtx_writes = []
         self.address = "AA:BB:CC:DD:EE:FF"
+        self.firmware_revision = firmware_revision
 
     async def __aenter__(self):
         return self
@@ -78,6 +79,33 @@ class TestCommands:
         assert client._t.rxtx_writes[0] == bytes([0xEA, 0x00])
         assert len(client._t.epd_writes) == 63 + 63 + 1
 
+    @pytest.mark.asyncio
+    async def test_upload_mono_non_hm42_sends_one_plane(self):
+        from PIL import Image
+        client = PPClient(FakeTransport("PP_da14585_4.2"))
+        result = await client.upload_image(
+            Image.new("RGB", (400, 300), "white"), slot=1,
+            algo="none", mono=True,
+        )
+        assert result["bytes_bw"] == 15000
+        assert result["bytes_red"] == 0
+        assert len(client._t.epd_writes) == 63 + 1
+
+    @pytest.mark.asyncio
+    async def test_upload_mono_hm42_appends_empty_red_plane(self):
+        from PIL import Image
+        client = PPClient(FakeTransport("HM42_AIO_V1.0.9"))
+        result = await client.upload_image(
+            Image.new("RGB", (400, 300), "white"), slot=1,
+            algo="none", mono=True,
+        )
+        assert result["bytes_bw"] == 15000
+        assert result["bytes_red"] == 15000
+        assert len(client._t.epd_writes) == 63 + 63 + 1
+        first_red = client._t.epd_writes[63]
+        assert first_red[:4] == bytes.fromhex("03000000")
+        assert set(first_red[4:]) == {0}
+
     @pytest.mark.asyncio
     async def test_render_template(self, client):
         result = await client.render_template("custom", {"text": "你好"})