ESP-NOW: STA interface, notify browser on send failure

- Activate STA interface before ESP-NOW to fix ESP_ERR_ESPNOW_IF
- Notify browser on send failure: WebSocket sends error JSON; preset API returns 503
- Use exceptions for failure (not return value) to avoid false errors when send succeeds
- presets.js: handle server error messages in WebSocket onmessage

Made-with: Cursor

src/controllers/preset.py

@@ -179,14 +179,20 @@ async def send_presets(request, session):
             batch = test_batch
             last_msg = test_msg
         else:
-            await send_chunk(batch)
+            try:
+                await send_chunk(batch)
+            except Exception:
+                return json.dumps({"error": "ESP-NOW send failed"}), 503, {'Content-Type': 'application/json'}
             await asyncio.sleep_ms(SEND_DELAY_MS)
             messages_sent += 1
             batch = {name: preset_obj}
             last_msg = build_message(presets=batch, save=save_flag, default=default_id)
 
     if batch:
-        await send_chunk(batch)
+        try:
+            await send_chunk(batch)
+        except Exception:
+            return json.dumps({"error": "ESP-NOW send failed"}), 503, {'Content-Type': 'application/json'}
         await asyncio.sleep_ms(SEND_DELAY_MS)
         messages_sent += 1
 

src/main.py

@@ -99,7 +99,13 @@ async def main(port=80):
                     print("WS received raw:", data)
 
                 # Forward raw JSON payload over ESPNow to configured peers
-                await esp.send(data)
+                try:
+                    await esp.send(data)
+                except Exception:
+                    try:
+                        await ws.send(json.dumps({"error": "ESP-NOW send failed"}))
+                    except Exception:
+                        pass
             else:
                 break
 

src/models/espnow.py

@@ -1,3 +1,5 @@
+import network
+
 import aioespnow
 
 
@@ -20,11 +22,17 @@ class ESPNow:
         if getattr(self, "_initialized", False):
             return
 
-        # Initialize ESPNow once (no disk persistence)
+        # ESP-NOW requires a WiFi interface to be active (STA or AP). Activate STA
+        # so ESP-NOW has an interface to use; we don't need to connect to an AP.
+        try:
+            sta = network.WLAN(network.STA_IF)
+            sta.active(True)
+        except Exception as e:
+            print("ESPNow: STA active failed:", e)
+
         self._esp = aioespnow.AIOESPNow()
         self._esp.active(True)
 
-   
         try:
             self._esp.add_peer(b"\xff\xff\xff\xff\xff\xff")
         except Exception:
@@ -56,6 +64,6 @@ class ESPNow:
         try:
             await self._esp.asend(b"\xff\xff\xff\xff\xff\xff", payload)
         except Exception as e:
-            # Log send failures but don't crash the app
             print("ESPNow.send error:", e)
+            raise
 

src/static/presets.js

@@ -25,6 +25,18 @@ const getEspnowSocket = () => {
     espnowPendingMessages = [];
   };
 
+  espnowSocket.onmessage = (event) => {
+    try {
+      const data = JSON.parse(event.data);
+      if (data && data.error) {
+        console.error('ESP-NOW:', data.error);
+        alert('ESP-NOW send failed. ' + (data.error === 'ESP-NOW send failed' ? 'Check device WiFi/interface.' : data.error));
+      }
+    } catch (_) {
+      // Ignore non-JSON or non-error messages
+    }
+  };
+
   espnowSocket.onclose = () => {
     espnowSocketReady = false;
     espnowSocket = null;