Added log handling for failed phone connection to the gateway

gateway-plugin/http_server.py

@@ -483,12 +483,18 @@ class HttpServer:
         # Register BEFORE the replay so a frame appended in between is
         # fanned out to us (and de-duped by cursor below) instead of lost.
         self._add_sub(sub)
+        reason = "eof"
         try:
             handler.send_response(200)
             handler.send_header("Content-Type", "text/event-stream")
             handler.send_header("Cache-Control", "no-cache")
             handler.send_header("X-Accel-Buffering", "no")
             handler.end_headers()
+            # INFO (not DEBUG like the per-request log): the stream
+            # lifecycle is the primary "is the device connected?" signal
+            # for debugging flaky links — a gap here is invisible at the
+            # gateway's default log level.
+            logger.info("android: SSE stream opened: %s (cursor=%d)", device_id, cursor)
             # 1. Catch-up from the outbox (id = cursor; the envelope also
             #    carries the cursor for the app's push dedupe).
             max_cursor = cursor
@@ -515,6 +521,7 @@ class HttpServer:
                     self._write_raw(handler, ": hb\n\n")
                     continue
                 if item is _STOP:
+                    reason = "stopped"
                     break
                 c, data = item
                 if c is not None and c <= max_cursor:
@@ -523,8 +530,9 @@ class HttpServer:
         except (BrokenPipeError, ConnectionResetError, OSError):
             # Client went away mid-stream: normal (the app reconnects with
             # Last-Event-ID and catches up from the outbox).
-            pass
+            reason = "client-gone"
         finally:
+            logger.info("android: SSE stream closed: %s (%s)", device_id, reason)
             self._remove_sub(sub)
 
     @staticmethod