0103 writes a card, 0104 asks for the list, 0108 a2=7 opens the reader

Caught on the charger's own command topic while a card was removed and
added back in the Anker app. Enrolling at the charger is three MQTT
messages and no REST call: open the reader, take the UID the tap
publishes, write it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

API Server/internal/plugins/builtin/ankersolix/mqttcards_test.go

@@ -122,3 +122,33 @@ func TestCardReadWithoutACard(t *testing.T) {
 		t.Errorf("rfidCardRead = %v, want it absent", values["rfidCardRead"])
 	}
 }
+
+// The two writes the Anker app sent, caught on the charger's own command topic:
+// the same card removed and then added back, the action the only difference.
+func TestDecodeCardWriteCommands(t *testing.T) {
+	for _, tc := range []struct {
+		name, hex string
+		action    float64
+	}{
+		{"delete", "ff091f0003000f0103a10122a2020102a3020101a4080404dfe672151a901f", 2},
+		{"add", "ff091f0003000f0103a10122a2020101a3020101a4080404dfe672151a901c", 1},
+	} {
+		data, err := hex.DecodeString(tc.hex)
+		if err != nil {
+			t.Fatal(err)
+		}
+		msgType, values, err := decodeFrame(data)
+		if err != nil {
+			t.Fatalf("%s: decodeFrame: %v", tc.name, err)
+		}
+		if msgType != msgEVCardWrite {
+			t.Fatalf("%s: msgType = %q, want %q", tc.name, msgType, msgEVCardWrite)
+		}
+		if got, _ := values["cardWriteAction"].(float64); got != tc.action {
+			t.Errorf("%s: cardWriteAction = %v, want %v", tc.name, values["cardWriteAction"], tc.action)
+		}
+		if got := values["cardWritten"]; got != "04DFE672151A90" {
+			t.Errorf("%s: cardWritten = %v, want the UID", tc.name, got)
+		}
+	}
+}

API Server/internal/plugins/builtin/ankersolix/mqttframe.go

@@ -92,6 +92,20 @@ const (
 	// from the account: the same address get_ocpp_info reports, and the source
 	// number that view leaves as a bare integer.
 	msgEVOcppInfo = "0911"
+	// The three commands the app sends about cards, all captured from its own
+	// traffic on the charger's command topic. The pattern is the connector's
+	// everywhere: a command 01xx is answered by the data frame 09xx.
+	//
+	//	0103  write one card:  a2 = 1 add, 2 delete; a4 = the UID  -> 0903, then 0904
+	//	0104  ask for the list                                     -> 0904
+	//	0111  ask which OCPP backend                               -> 0911
+	//
+	// The fourth is not its own message: opening the reader is the power-mode
+	// command with powerModeReadCard, which is answered by 0908.
+	msgEVCardWrite   = "0103"
+	msgEVCardListReq = "0104"
+	msgEVOcppInfoReq = "0111"
+
 	// The reader, reporting a card held against it. Captured during an
 	// enrol-at-the-charger: the frame arrives the moment the card is tapped,
 	// carrying the UID, and the charger publishes its updated card list a second
@@ -99,7 +113,14 @@ const (
 	// closes with nothing tapped, which is what makes the UID field the event.
 	msgEVCardRead = "0908"
 
-	// powerModeRestart is the only value the power-mode command is known to take.
+	// powerModeReadCard opens the card reader for a tap: the app sends the
+	// power-mode command with this value and the charger answers 0908 — with the
+	// UID if a card was held against it inside the twenty seconds, and without one
+	// if the window closed empty. Captured from the app on an A5191; the same 7
+	// comes back in the answer.
+	powerModeReadCard uint8 = 7
+
+	// powerModeRestart is the only other value the power-mode command is known to take.
 	// The map documents 5 and nothing else, so nothing else is sent.
 	powerModeRestart uint8 = 5
 )
@@ -232,6 +253,13 @@ var evCardRead = map[byte]mqttField{
 	0xa3: {name: "rfidCardRead"},
 }
 
+// evCardWrite names the write the app sends. a3 was 1 on both the add and the
+// delete, so it keeps its own key rather than a guessed name.
+var evCardWrite = map[byte]mqttField{
+	0xa2: {name: "cardWriteAction"}, // 1 add, 2 delete
+	0xa4: {name: "cardWritten"},
+}
+
 // evOcppInfo names the charger's own view of its OCPP backend.
 var evOcppInfo = map[byte]mqttField{
 	0xa2: {name: "ocppBackendName"},
@@ -244,9 +272,10 @@ var evOcppInfo = map[byte]mqttField{
 // settings report: evMessages is what stamps the timestamp a control command
 // waits on, and a card list is not an acknowledgement of anything.
 var evInfoMessages = map[string]map[byte]mqttField{
-	msgEVCards:    evCards,
-	msgEVOcppInfo: evOcppInfo,
-	msgEVCardRead: evCardRead,
+	msgEVCards:     evCards,
+	msgEVOcppInfo:  evOcppInfo,
+	msgEVCardRead:  evCardRead,
+	msgEVCardWrite: evCardWrite,
 }
 
 // evMessages selects a field map by message type. A type absent from here is one