move icons to progmem

esphome/components/api/api_connection.h

@@ -349,7 +349,7 @@ class APIConnection final : public APIServerConnectionBase {
     // Set common EntityBase properties
 #ifdef USE_ENTITY_ICON
     char icon_buf[MAX_ICON_LENGTH];
-    msg.icon = entity->get_icon_to(icon_buf);
+    msg.icon = StringRef(entity->get_icon_to(icon_buf));
 #endif
     msg.disabled_by_default = entity->is_disabled_by_default();
     msg.entity_category = static_cast<enums::EntityCategory>(entity->get_entity_category());

tests/unit_tests/core/test_entity_helpers.py

@@ -23,6 +23,7 @@ from esphome.core.entity_helpers import (
     _setup_entity_impl,
     entity_duplicate_validator,
     get_base_entity_object_id,
+    register_icon,
     setup_entity,
 )
 from esphome.cpp_generator import MockObj
@@ -909,6 +910,22 @@ def test_register_string_overflow() -> None:
         _register_string("overflow", category, 3, "test")
 
 
+def test_register_icon_max_length() -> None:
+    """Test register_icon rejects icons exceeding 63 characters."""
+    # 63 chars should succeed
+    max_icon = "mdi:" + "a" * 59  # 63 total
+    idx = register_icon(max_icon)
+    assert idx > 0
+
+    # 64 chars should fail
+    too_long = "mdi:" + "a" * 60  # 64 total
+    with pytest.raises(ValueError, match="Icon string too long"):
+        register_icon(too_long)
+
+    # Empty string returns 0
+    assert register_icon("") == 0
+
+
 @pytest.mark.asyncio
 async def test_setup_entity_with_entity_category(
     setup_test_environment: list[str],

tests/unit_tests/test_config_validation.py

@@ -148,6 +148,18 @@ def test_icon__invalid():
         config_validation.icon("foo")
 
 
+def test_icon__max_length():
+    """Test that icons exceeding 63 characters are rejected."""
+    # Exactly 63 chars should pass
+    max_icon = "mdi:" + "a" * 59  # 63 chars total
+    assert config_validation.icon(max_icon) == max_icon
+
+    # 64 chars should fail
+    too_long = "mdi:" + "a" * 60  # 64 chars total
+    with pytest.raises(Invalid, match="Icon string is too long"):
+        config_validation.icon(too_long)
+
+
 @pytest.mark.parametrize("value", ("True", "YES", "on", "enAblE", True))
 def test_boolean__valid_true(value):
     assert config_validation.boolean(value) is True