[wifi] Free scan results memory after connection (saves up to 1.2KB RAM) (#11205)

esphome/components/wifi/__init__.py

@@ -447,6 +447,8 @@ async def to_code(config):
             var.get_disconnect_trigger(), [], on_disconnect_config
         )
 
+    CORE.add_job(final_step)
+
 
 @automation.register_condition("wifi.connected", WiFiConnectedCondition, cv.Schema({}))
 async def wifi_connected_to_code(config, condition_id, template_arg, args):
@@ -468,6 +470,28 @@ async def wifi_disable_to_code(config, action_id, template_arg, args):
     return cg.new_Pvariable(action_id, template_arg)
 
 
+KEEP_SCAN_RESULTS_KEY = "wifi_keep_scan_results"
+
+
+def request_wifi_scan_results():
+    """Request that WiFi scan results be kept in memory after connection.
+
+    Components that need access to scan results after WiFi is connected should
+    call this function during their code generation. This prevents the WiFi component from
+    freeing scan result memory after successful connection.
+    """
+    CORE.data[KEEP_SCAN_RESULTS_KEY] = True
+
+
+@coroutine_with_priority(CoroPriority.FINAL)
+async def final_step():
+    """Final code generation step to configure scan result retention."""
+    if CORE.data.get(KEEP_SCAN_RESULTS_KEY, False):
+        cg.add(
+            cg.RawExpression("wifi::global_wifi_component->set_keep_scan_results(true)")
+        )
+
+
 @automation.register_action(
     "wifi.configure",
     WiFiConfigureAction,

esphome/components/wifi/wifi_component.cpp

@@ -713,6 +713,12 @@ void WiFiComponent::check_connecting_finished() {
     this->state_ = WIFI_COMPONENT_STATE_STA_CONNECTED;
     this->num_retried_ = 0;
 
+    // Free scan results memory unless a component needs them
+    if (!this->keep_scan_results_) {
+      this->scan_result_.clear();
+      this->scan_result_.shrink_to_fit();
+    }
+
     if (this->fast_connect_) {
       this->save_fast_connect_settings_();
     }

esphome/components/wifi/wifi_component.h

@@ -316,6 +316,7 @@ class WiFiComponent : public Component {
   int8_t wifi_rssi();
 
   void set_enable_on_boot(bool enable_on_boot) { this->enable_on_boot_ = enable_on_boot; }
+  void set_keep_scan_results(bool keep_scan_results) { this->keep_scan_results_ = keep_scan_results; }
 
   Trigger<> *get_connect_trigger() const { return this->connect_trigger_; };
   Trigger<> *get_disconnect_trigger() const { return this->disconnect_trigger_; };
@@ -424,6 +425,7 @@ class WiFiComponent : public Component {
 #endif
   bool enable_on_boot_;
   bool got_ipv4_address_{false};
+  bool keep_scan_results_{false};
 
   // Pointers at the end (naturally aligned)
   Trigger<> *connect_trigger_{new Trigger<>()};

esphome/components/wifi_info/text_sensor.py

@@ -1,5 +1,5 @@
 import esphome.codegen as cg
-from esphome.components import text_sensor
+from esphome.components import text_sensor, wifi
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_BSSID,
@@ -77,7 +77,9 @@ async def to_code(config):
     await setup_conf(config, CONF_SSID)
     await setup_conf(config, CONF_BSSID)
     await setup_conf(config, CONF_MAC_ADDRESS)
+    if CONF_SCAN_RESULTS in config:
         await setup_conf(config, CONF_SCAN_RESULTS)
+        wifi.request_wifi_scan_results()
     await setup_conf(config, CONF_DNS_ADDRESS)
     if conf := config.get(CONF_IP_ADDRESS):
         wifi_info = await text_sensor.new_text_sensor(config[CONF_IP_ADDRESS])