[web_server] Add name_id to SSE for entity ID format migration

esphome/components/http_request/ota/ota_http_request.cpp

@@ -82,7 +82,7 @@ uint8_t OtaHttpRequestComponent::do_ota_() {
   uint32_t last_progress = 0;
   uint32_t update_start_time = millis();
   md5::MD5Digest md5_receive;
-  char md5_receive_str[33];
+  std::unique_ptr<char[]> md5_receive_str(new char[33]);
 
   if (this->md5_expected_.empty() && !this->http_get_md5_()) {
     return OTA_MD5_INVALID;
@@ -176,14 +176,14 @@ uint8_t OtaHttpRequestComponent::do_ota_() {
 
   // verify MD5 is as expected and act accordingly
   md5_receive.calculate();
-  md5_receive.get_hex(md5_receive_str);
-  this->md5_computed_ = md5_receive_str;
+  md5_receive.get_hex(md5_receive_str.get());
+  this->md5_computed_ = md5_receive_str.get();
   if (strncmp(this->md5_computed_.c_str(), this->md5_expected_.c_str(), MD5_SIZE) != 0) {
     ESP_LOGE(TAG, "MD5 computed: %s - Aborting due to MD5 mismatch", this->md5_computed_.c_str());
     this->cleanup_(std::move(backend), container);
     return ota::OTA_RESPONSE_ERROR_MD5_MISMATCH;
   } else {
-    backend->set_update_md5(md5_receive_str);
+    backend->set_update_md5(md5_receive_str.get());
   }
 
   container->end();

esphome/components/mhz19/mhz19.cpp

@@ -155,9 +155,6 @@ void MHZ19Component::dump_config() {
     case MHZ19_DETECTION_RANGE_0_10000PPM:
       range_str = "0 to 10000ppm";
       break;
-    default:
-      range_str = "default";
-      break;
   }
   ESP_LOGCONFIG(TAG, "  Detection range: %s", range_str);
 }

esphome/components/web_server/web_server.cpp

@@ -531,7 +531,19 @@ static void set_json_id(JsonObject &root, EntityBase *obj, const char *prefix, J
   memcpy(p, name.c_str(), name_len);
   p[name_len] = '\0';
 
-  root[ESPHOME_F("id")] = id_buf;
+  // name_id: new format {prefix}/{device?}/{name} - frontend should prefer this
+  // Remove in 2026.8.0 when id switches to new format permanently
+  root[ESPHOME_F("name_id")] = id_buf;
+
+  // id: old format {prefix}-{object_id} for backward compatibility
+  // Will switch to new format in 2026.8.0
+  char legacy_buf[ESPHOME_DOMAIN_MAX_LEN + 1 + OBJECT_ID_MAX_LEN];
+  char *lp = legacy_buf;
+  memcpy(lp, prefix, prefix_len);
+  lp += prefix_len;
+  *lp++ = '-';
+  obj->write_object_id_to(lp, sizeof(legacy_buf) - (lp - legacy_buf));
+  root[ESPHOME_F("id")] = legacy_buf;
 
   if (start_config == DETAIL_ALL) {
     root[ESPHOME_F("domain")] = prefix;