Capture errno before it can be clobbered, warn when no UDP address is valid, and give the reboot test timing headroom

esphome/components/async_tcp/async_tcp_socket.cpp

@@ -43,11 +43,13 @@ bool AsyncClient::connect(const char *host, uint16_t port) {
   }
 
   if (socket_->setblocking(false) != 0) {
-    // A blocking connect()/read() would stall the whole loop
-    ESP_LOGE(TAG, "Failed to set nonblocking: errno %d", errno);
+    // Capture before the log and reset() below can clobber errno; a blocking
+    // connect()/read() would otherwise stall the whole loop
+    const int saved_errno = errno;
+    ESP_LOGE(TAG, "Failed to set nonblocking: errno %d", saved_errno);
     socket_.reset();
     if (error_cb_)
-      error_cb_(error_arg_, this, errno);
+      error_cb_(error_arg_, this, saved_errno);
     return false;
   }
 

esphome/components/udp/udp_component.cpp

@@ -19,6 +19,10 @@ void UDPComponent::setup() {
     }
     this->sockaddrs_.push_back(saddr);
   }
+  if (!this->addresses_.empty() && this->sockaddrs_.empty()) {
+    // Sending would be a silent no-op; surface the misconfiguration
+    this->status_set_warning(LOG_STR("no valid addresses"));
+  }
   // set up broadcast socket
   if (this->should_broadcast_) {
     this->broadcast_socket_ = socket::socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);

tests/integration/fixtures/api_reboot_timeout_after_authenticated_disconnect.yaml

@@ -2,6 +2,6 @@ esphome:
   name: api-reboot-test
 host:
 api:
-  reboot_timeout: 0.5s  # Very short timeout for fast testing
+  reboot_timeout: 2s  # Headroom to connect and authenticate a client first
 logger:
   level: DEBUG

tests/integration/test_api_reboot_timeout.py

@@ -59,6 +59,6 @@ async def test_api_reboot_timeout_after_authenticated_disconnect(
         async with api_client_connected() as client:
             await client.device_info()
         try:
-            await asyncio.wait_for(reboot_future, timeout=2.0)
+            await asyncio.wait_for(reboot_future, timeout=5.0)
         except TimeoutError:
             pytest.fail("Device did not reboot within expected timeout")