WiFiManager: stabilize root rendering and reduce page reallocations.

Keep root template state request-scoped so dynamic placeholders stay consistent during chunked renders, add reserve() coverage for non-streamed pages, and add compile/test coverage for the new root render lifecycle.

test/test_wifimanager/test_main.cpp

@@ -30,6 +30,8 @@ TestCase tests[] = {
     TEST_ENTRY(test_config_portal_multiple_start_stop),
     TEST_ENTRY(test_config_portal_already_active),
     TEST_ENTRY(test_get_config_portal_ssid),
+    TEST_ENTRY(test_root_render_menu_state_transitions),
+    TEST_ENTRY(test_root_render_snapshot_consistency),
     
     // Non-blocking tests
     TEST_ENTRY(test_nonblocking_process),

test/test_wifimanager/test_main.h

@@ -40,6 +40,8 @@ void test_stop_web_portal();
 void test_config_portal_multiple_start_stop();
 void test_config_portal_already_active();
 void test_get_config_portal_ssid();
+void test_root_render_menu_state_transitions();
+void test_root_render_snapshot_consistency();
 
 // Non-blocking tests
 void test_nonblocking_process();

test/test_wifimanager/tests/test_root_render_lifecycle.cpp

@@ -0,0 +1,64 @@
+#include <unity.h>
+#include <Arduino.h>
+#include <WiFiManager.h>
+#include <WiFiManagerHandlers.h>
+
+void test_root_render_menu_state_transitions() {
+    Serial.println("[TEST]   Testing root menu state transitions...");
+
+    WiFiManager wm;
+    WiFiManagerHandlers handlers(&wm);
+
+    String menuBefore;
+    handlers.getMenuOut(&menuBefore);
+    TEST_ASSERT_EQUAL(-1, menuBefore.indexOf("/close"));
+
+    wm.setConfigPortalTimeout(5);
+    wm.startConfigPortal("RootStateAP");
+    wm.process();
+    delay(100);
+
+    String menuActive;
+    handlers.getMenuOut(&menuActive);
+    TEST_ASSERT_NOT_EQUAL(-1, menuActive.indexOf("/close"));
+
+    wm.stopConfigPortal();
+    delay(100);
+
+    String menuAfter;
+    handlers.getMenuOut(&menuAfter);
+    TEST_ASSERT_EQUAL(-1, menuAfter.indexOf("/close"));
+
+    Serial.println("[TEST]   Root menu state transitions test completed successfully");
+}
+
+void test_root_render_snapshot_consistency() {
+    Serial.println("[TEST]   Testing root render snapshot consistency...");
+
+    WiFiManager wm;
+    WiFiManagerHandlers handlers(&wm);
+
+    wm.setConfigPortalTimeout(5);
+    wm.startConfigPortal("RootSnapshotAP");
+    wm.process();
+    delay(100);
+
+    String menuSnapshot1;
+    String statusSnapshot1;
+    handlers.getMenuOut(&menuSnapshot1);
+    handlers.reportStatus(statusSnapshot1);
+
+    String menuSnapshot2;
+    String statusSnapshot2;
+    handlers.getMenuOut(&menuSnapshot2);
+    handlers.reportStatus(statusSnapshot2);
+
+    TEST_ASSERT_GREATER_THAN(0, menuSnapshot1.length());
+    TEST_ASSERT_GREATER_THAN(0, statusSnapshot1.length());
+    TEST_ASSERT_EQUAL_STRING(menuSnapshot1.c_str(), menuSnapshot2.c_str());
+    TEST_ASSERT_EQUAL_STRING(statusSnapshot1.c_str(), statusSnapshot2.c_str());
+
+    wm.stopConfigPortal();
+
+    Serial.println("[TEST]   Root render snapshot consistency test completed successfully");
+}