[core] Partially revert "Hash entity keys from the raw name to fix collisions" (#18361)

esphome/components/api/api_connection.cpp

@@ -448,7 +448,7 @@ void APIConnection::on_disconnect_response() {
 uint16_t APIConnection::fill_and_encode_entity_state(EntityBase *entity, StateResponseProtoMessage &msg,
                                                      CalculateSizeFn size_fn, MessageEncodeFn encode_fn,
                                                      APIConnection *conn, uint32_t remaining_size) {
-  msg.key = entity->get_entity_key();
+  msg.key = entity->get_object_id_hash();
 #ifdef USE_DEVICES
   msg.device_id = entity->get_device_id();
 #endif
@@ -459,7 +459,7 @@ uint16_t APIConnection::fill_and_encode_entity_info(EntityBase *entity, InfoResp
                                                     CalculateSizeFn size_fn, MessageEncodeFn encode_fn,
                                                     APIConnection *conn, uint32_t remaining_size) {
   // Set common fields that are shared by all entity types
-  msg.key = entity->get_entity_key();
+  msg.key = entity->get_object_id_hash();
 
   if (entity->has_own_name()) {
     msg.name = entity->get_name();
@@ -1149,7 +1149,7 @@ void APIConnection::try_send_camera_image_() {
     bool done = this->image_reader_->available() == to_send;
 
     CameraImageResponse msg;
-    msg.key = camera::Camera::instance()->get_entity_key();
+    msg.key = camera::Camera::instance()->get_object_id_hash();
     msg.set_data(this->image_reader_->peek_data_buffer(), to_send);
     msg.done = done;
 #ifdef USE_DEVICES

esphome/components/infrared/infrared.cpp

@@ -154,8 +154,12 @@ bool Infrared::on_receive(remote_base::RemoteReceiveData data) {
   // Forward received IR data to API server
 #if defined(USE_API) && defined(USE_IR_RF)
   if (api::global_api_server != nullptr) {
-    api::global_api_server->send_infrared_rf_receive_event(this->get_device_id_or_zero(), this->get_entity_key(),
+#ifdef USE_DEVICES
-                                                           &data.get_raw_data());
+    uint32_t device_id = this->get_device_id();
+#else
+    uint32_t device_id = 0;
+#endif
+    api::global_api_server->send_infrared_rf_receive_event(device_id, this->get_object_id_hash(), &data.get_raw_data());
   }
 #endif
   return false;  // Don't consume the event, allow other listeners to process it

esphome/components/mqtt/__init__.py

@@ -63,7 +63,6 @@ from esphome.const import (
     PlatformFramework,
 )
 from esphome.core import CORE, CoroPriority, coroutine_with_priority
-from esphome.core.entity_helpers import ObjectIdEntity, validate_no_object_id_conflicts
 from esphome.types import ConfigType
 
 DEPENDENCIES = ["network"]
@@ -333,68 +332,6 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-# Platforms whose MQTT components subscribe to an object_id-derived command topic.
-# Keep in sync with the platforms extending cv.MQTT_COMMAND_COMPONENT_SCHEMA, plus
-# text, whose MQTT component subscribes a command topic that cannot be overridden.
-_COMMAND_TOPIC_PLATFORMS = frozenset(
-    {
-        "alarm_control_panel",
-        "button",
-        "climate",
-        "cover",
-        "datetime",
-        "fan",
-        "light",
-        "lock",
-        "number",
-        "select",
-        "switch",
-        "text",
-        "update",
-        "valve",
-    }
-)
-
-
-# Platforms whose MQTT components derive extra sub-topics (position/command,
-# mode/command, speed/command, ...) from the object_id, each with its own config
-# key; custom state and command topics cannot exempt them from conflicting.
-_SUB_TOPIC_PLATFORMS = frozenset({"climate", "cover", "fan", "valve"})
-
-
-def _topics_conflict(entities: list[ObjectIdEntity], config: ConfigType) -> bool:
-    """Check whether more than one entity actually uses an object_id-derived topic.
-
-    An empty topic_prefix disables default topics entirely, custom state and
-    command topics avoid the default topics, and disabling discovery (globally
-    or per entity) avoids the discovery config topic.
-    """
-    if config[CONF_TOPIC_PREFIX]:
-        platform = entities[0].platform
-        if platform in _SUB_TOPIC_PLATFORMS:
-            return True
-        if sum(CONF_STATE_TOPIC not in entity.config for entity in entities) > 1:
-            return True
-        if (
-            platform in _COMMAND_TOPIC_PLATFORMS
-            and sum(CONF_COMMAND_TOPIC not in entity.config for entity in entities) > 1
-        ):
-            return True
-    if not config[CONF_DISCOVERY]:
-        return False
-    discovery_entities = sum(
-        entity.config.get(CONF_DISCOVERY, True) for entity in entities
-    )
-    return discovery_entities > 1
-
-
-FINAL_VALIDATE_SCHEMA = validate_no_object_id_conflicts(
-    "mqtt builds default topics and discovery topics from the entity object_id, "
-    "which is the name converted to ASCII",
-    conflict_filter=_topics_conflict,
-)
-
-
 def exp_mqtt_message(config):
     if config is None:
         return cg.optional(cg.TemplateArguments(MQTTMessage))

esphome/components/prometheus/__init__.py

@@ -3,7 +3,6 @@ from esphome.components import web_server_base
 from esphome.components.web_server_base import CONF_WEB_SERVER_BASE_ID
 import esphome.config_validation as cv
 from esphome.const import CONF_ID, CONF_INCLUDE_INTERNAL, CONF_NAME, CONF_RELABEL
-from esphome.core.entity_helpers import validate_no_object_id_conflicts
 from esphome.cpp_types import EntityBase
 
 AUTO_LOAD = ["web_server_base"]
@@ -36,11 +35,6 @@ CONFIG_SCHEMA = cv.Schema(
     },
 ).extend(cv.COMPONENT_SCHEMA)
 
-FINAL_VALIDATE_SCHEMA = validate_no_object_id_conflicts(
-    "prometheus builds metric labels from the entity object_id, "
-    "which is the name converted to ASCII"
-)
-
 
 async def to_code(config):
     paren = await cg.get_variable(config[CONF_WEB_SERVER_BASE_ID])

esphome/components/radio_frequency/radio_frequency.cpp

@@ -99,8 +99,12 @@ bool RadioFrequency::on_receive(remote_base::RemoteReceiveData data) {
   // Forward received RF data to API server
 #if defined(USE_API) && defined(USE_RADIO_FREQUENCY)
   if (api::global_api_server != nullptr) {
-    api::global_api_server->send_infrared_rf_receive_event(this->get_device_id_or_zero(), this->get_entity_key(),
+#ifdef USE_DEVICES
-                                                           &data.get_raw_data());
+    uint32_t device_id = this->get_device_id();
+#else
+    uint32_t device_id = 0;
+#endif
+    api::global_api_server->send_infrared_rf_receive_event(device_id, this->get_object_id_hash(), &data.get_raw_data());
   }
 #endif
   return false;  // Don't consume the event, allow other listeners to process it

esphome/components/template/text/template_text.cpp

@@ -20,14 +20,18 @@ void TemplateText::setup() {
 
   // Need std::string for pref_->setup() to fill from flash
   std::string value{this->initial_value_ != nullptr ? this->initial_value_ : ""};
-  uint32_t extra = 0;
+  // For future hash migration: use migrate_entity_preference_() with:
-  extra += this->traits.get_min_length() << 2;
+  //   old_key = get_preference_hash() + extra
-  extra += this->traits.get_max_length() << 4;
+  //   new_key = get_preference_hash_v2() + extra
-  extra += fnv1_hash(this->traits.get_pattern_c_str()) << 6;
+  // See: https://github.com/esphome/backlog/issues/85
-  // TextSaver::setup() picks the key for the platform and migrates old data once
+#pragma GCC diagnostic push
-  uint32_t key = this->preference_key_base_() + extra;
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-  uint32_t old_key = this->old_preference_key_base_() + extra;
+  uint32_t key = this->get_preference_hash();
-  this->pref_->setup(key, old_key, value);
+#pragma GCC diagnostic pop
+  key += this->traits.get_min_length() << 2;
+  key += this->traits.get_max_length() << 4;
+  key += fnv1_hash(this->traits.get_pattern_c_str()) << 6;
+  this->pref_->setup(key, value);
   if (!value.empty())
     this->publish_state(value);
 }

esphome/components/template/text/template_text.h

@@ -14,9 +14,7 @@ class TemplateTextSaverBase {
  public:
   virtual bool save(const std::string &value) { return true; }
 
-  /// old_id is the pre-2026.8.0 preference key; data stored under it is moved to id once.
+  virtual void setup(uint32_t id, std::string &value) {}
-  /// See: https://github.com/esphome/backlog/issues/85
-  virtual void setup(uint32_t id, uint32_t old_id, std::string &value) {}
 
  protected:
   ESPPreferenceObject pref_;
@@ -47,16 +45,11 @@ template<uint8_t SZ> class TextSaver : public TemplateTextSaverBase {
 
   // Make the preference object.  Fill the provided location with the saved data
   // If it is available, else leave it alone
-  void setup(uint32_t id, uint32_t old_id, std::string &value) override {
+  void setup(uint32_t id, std::string &value) override {
-    char temp[SZ + 1];
-#ifdef USE_PREFERENCE_KEY_LOOKUP
     this->pref_ = global_preferences->make_preference<uint8_t[SZ + 1]>(id);
-    bool hasdata = migrate_preference(this->pref_, reinterpret_cast<uint8_t *>(temp), SZ + 1, old_id, id);
+
-#else
+    char temp[SZ + 1];
-    // Slot-based backends keep the old key; it is only a validity tag on a positional slot
-    this->pref_ = global_preferences->make_preference<uint8_t[SZ + 1]>(old_id);
     bool hasdata = this->pref_.load(&temp);
-#endif
 
     if (hasdata) {
       size_t len = static_cast<uint8_t>(temp[0]);

esphome/core/application.h

@@ -120,8 +120,8 @@ class Application {
 // NOLINTBEGIN(bugprone-macro-parentheses)
 #define ENTITY_TYPE_(type, singular, plural, count, upper) \
   void register_##singular(type *obj) { this->plural##_.push_back(obj); } \
-  void register_##singular(type *obj, const char *name, uint32_t entity_key, uint32_t entity_fields) { \
+  void register_##singular(type *obj, const char *name, uint32_t object_id_hash, uint32_t entity_fields) { \
-    obj->configure_entity_(name, entity_key, entity_fields); \
+    obj->configure_entity_(name, object_id_hash, entity_fields); \
     this->plural##_.push_back(obj); \
   }
 #define ENTITY_CONTROLLER_TYPE_(type, singular, plural, count, upper, callback) \
@@ -329,7 +329,7 @@ class Application {
 #define GET_ENTITY_METHOD(entity_type, entity_name, entities_member) \
   entity_type *get_##entity_name##_by_key(uint32_t key, uint32_t device_id, bool include_internal = false) { \
     for (auto *obj : this->entities_member##_) { \
-      if (obj->get_entity_key() == key && obj->get_device_id() == device_id && \
+      if (obj->get_object_id_hash() == key && obj->get_device_id() == device_id && \
           (include_internal || !obj->is_internal())) \
         return obj; \
     } \
@@ -340,7 +340,7 @@ class Application {
 #define GET_ENTITY_METHOD(entity_type, entity_name, entities_member) \
   entity_type *get_##entity_name##_by_key(uint32_t key, bool include_internal = false) { \
     for (auto *obj : this->entities_member##_) { \
-      if (obj->get_entity_key() == key && (include_internal || !obj->is_internal())) \
+      if (obj->get_object_id_hash() == key && (include_internal || !obj->is_internal())) \
         return obj; \
     } \
     return nullptr; \

esphome/core/entity_base.cpp

@@ -8,7 +8,7 @@ namespace esphome {
 
 static const char *const TAG = "entity_base";
 
-void EntityBase::configure_entity_(const char *name, uint32_t entity_key, uint32_t entity_fields) {
+void EntityBase::configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_fields) {
   this->name_ = StringRef(name);
   if (this->name_.empty()) {
 #ifdef USE_DEVICES
@@ -30,15 +30,15 @@ void EntityBase::configure_entity_(const char *name, uint32_t entity_key, uint32
       }
     }
     this->flags_.has_own_name = false;
-    // Dynamic name - must calculate key at runtime
+    // Dynamic name - must calculate hash at runtime
-    this->calc_entity_key_();
+    this->calc_object_id_();
   } else {
     this->flags_.has_own_name = true;
-    // Static name - use pre-computed key if provided
+    // Static name - use pre-computed hash if provided
-    if (entity_key != 0) {
+    if (object_id_hash != 0) {
-      this->entity_key_ = entity_key;
+      this->object_id_hash_ = object_id_hash;
     } else {
-      this->calc_entity_key_();
+      this->calc_object_id_();
     }
   }
   // Unpack entity string table indices and flags from entity_fields.
@@ -147,15 +147,9 @@ std::string EntityBase::get_icon() const {
 }
 #endif  // !USE_ESP8266
 
-// Calculate the entity key directly from the raw name (no transformations)
+// Calculate Object ID Hash directly from name using snake_case + sanitize
-void EntityBase::calc_entity_key_() { this->entity_key_ = fnv1_hash_bytes(this->name_.c_str(), this->name_.size()); }
+void EntityBase::calc_object_id_() {
-
+  this->object_id_hash_ = fnv1_hash_object_id(this->name_.c_str(), this->name_.size());
-// Reconstruct the OLD (pre-2026.8.0) object_id-based hash for preference key compatibility.
-// Named entities historically used the hash pre-computed by Python code generation, which
-// sanitized per UTF-8 code point; entities without their own name computed the hash at
-// runtime per byte. See https://github.com/esphome/backlog/issues/85
-uint32_t EntityBase::calc_old_object_id_hash_() const {
-  return fnv1_hash_object_id(this->name_.c_str(), this->name_.size(), this->flags_.has_own_name);
 }
 
 size_t EntityBase::write_object_id_to(char *buf, size_t buf_size) const {
@@ -173,22 +167,16 @@ StringRef EntityBase::get_object_id_to(std::span<char, OBJECT_ID_MAX_LEN> buf) c
 }
 
 ESPPreferenceObject EntityBase::make_entity_preference_(size_t size, uint32_t version) {
-  // The old key hashed the sanitized object_id, so multiple entity names could collide on
+  // The key hashes the sanitized object_id, so multiple entity names can collide on one
-  // one key and overwrite each other's stored preferences; the new key hashes the raw name.
+  // key and overwrite each other's stored preferences ("Living Room" and "living_room",
-  // See: https://github.com/esphome/backlog/issues/85
+  // or two UTF-8 names that both sanitize to underscores). Keys hashed from the raw name
-  uint32_t old_key = this->old_preference_key_base_() ^ version;
+  // fix this, but they change the entity key API clients track, which the Home Assistant
-#ifdef USE_PREFERENCE_KEY_LOOKUP
+  // esphome integration cannot handle yet. See: https://github.com/esphome/backlog/issues/85
-  uint32_t new_key = this->preference_key_base_() ^ version;
+#pragma GCC diagnostic push
-  auto pref = global_preferences->make_preference(size, new_key);
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-  // All in-tree entity preferences fit the stack buffer, so migration never hits the heap
+  uint32_t key = this->get_preference_hash() ^ version;
-  SmallBufferWithHeapFallback<64> buffer(size);
+#pragma GCC diagnostic pop
-  migrate_preference(pref, buffer.get(), size, old_key, new_key);
+  return global_preferences->make_preference(size, key);
-  return pref;
-#else
-  // Slot-based backends keep the old key: it is only a validity tag on a positional slot,
-  // so collisions cannot corrupt data there and keeping it preserves stored state.
-  return global_preferences->make_preference(size, old_key);
-#endif
 }
 
 #ifdef USE_ENTITY_ICON

esphome/core/entity_base.h

@@ -73,17 +73,8 @@ class EntityBase {
   // Get whether this Entity has its own name or it should use the device friendly_name.
   bool has_own_name() const { return this->flags_.has_own_name; }
 
-  // Get the unique key of this Entity: FNV-1 hash of the raw entity name.
+  // Get the unique Object ID of this Entity
-  // This is the key sent to API clients and used to route entity state.
+  uint32_t get_object_id_hash() const { return this->object_id_hash_; }
-  uint32_t get_entity_key() const { return this->entity_key_; }
-
-  /// Returns the LEGACY object_id hash, unchanged from previous releases, so existing
-  /// callers keep getting stable values (for example preference keys). This is no longer
-  /// the key sent to API clients; that is get_entity_key().
-  ESPDEPRECATED("Use get_entity_key() for the entity key sent to API clients, or "
-                "make_entity_preference<T>() for preference storage. Will be removed in 2027.1.0.",
-                "2026.8.0")
-  uint32_t get_object_id_hash() const { return this->calc_old_object_id_hash_(); }
 
   /// Get object_id with zero heap allocation
   /// For static case: returns StringRef to internal storage (buffer unused)
@@ -190,23 +181,39 @@ class EntityBase {
   // Set has_state - for components that need to manually set this
   void set_has_state(bool state) { this->flags_.has_state = state; }
 
-  /// Get this entity's device id, or 0 when devices are not compiled in (main device).
+  /**
-  uint32_t get_device_id_or_zero() const {
+   * @brief Get a unique hash for storing preferences/settings for this entity.
-#ifdef USE_DEVICES
+   *
-    return this->get_device_id();
+   * This method returns a hash that uniquely identifies the entity for the purpose of
-#else
+   * storing preferences (such as calibration, state, etc.). Unlike get_object_id_hash(),
-    return 0;
+   * this hash also incorporates the device_id (if devices are enabled), ensuring uniqueness
-#endif
+   * across multiple devices that may have entities with the same object_id.
-  }
+   *
-
+   * Use this method when storing or retrieving preferences/settings that should be unique
-  /// Get the LEGACY preference key: FNV-1 hash of the sanitized object_id, XOR device_id.
+   * per device-entity pair. Use get_object_id_hash() when you need a hash that identifies
-  /// Intentionally keeps the old algorithm so external callers that store preferences under
+   * the entity regardless of the device it belongs to.
-  /// this key keep stable keys; make_entity_preference() migrates to the new raw-name key,
+   *
-  /// this method never will.
+   * For backward compatibility, if device_id is 0 (the main device), the hash is unchanged
+   * from previous versions, so existing single-device configurations will continue to work.
+   *
+   * @return uint32_t The unique hash for preferences, including device_id if available.
+   * @deprecated Use make_entity_preference<T>() instead, or preferences won't be migrated.
+   * See https://github.com/esphome/backlog/issues/85
+   */
   ESPDEPRECATED("Use make_entity_preference<T>() instead, or preferences won't be migrated. "
                 "See https://github.com/esphome/backlog/issues/85. Will be removed in 2027.1.0.",
-                "2026.8.0")
+                "2026.7.0")
-  uint32_t get_preference_hash() { return this->old_preference_key_base_(); }
+  uint32_t get_preference_hash() {
+#ifdef USE_DEVICES
+    // Combine object_id_hash with device_id to ensure uniqueness across devices
+    // Note: device_id is 0 for the main device, so XORing with 0 preserves the original hash
+    // This ensures backward compatibility for existing single-device configurations
+    return this->get_object_id_hash() ^ this->get_device_id();
+#else
+    // Without devices, just use object_id_hash as before
+    return this->get_object_id_hash();
+#endif
+  }
 
   /// Create a preference object for storing this entity's state/settings.
   /// @tparam T The type of data to store (must be trivially copyable)
@@ -223,9 +230,9 @@ class EntityBase {
   // before push_back, so codegen can emit a single combined call per entity.
   friend class Application;
 
-  /// Combined entity setup from codegen: set name, entity key, entity string indices, and flags.
+  /// Combined entity setup from codegen: set name, object_id hash, entity string indices, and flags.
   /// Bit layout of entity_fields is defined by the ENTITY_FIELD_*_SHIFT constants above.
-  void configure_entity_(const char *name, uint32_t entity_key, uint32_t entity_fields);
+  void configure_entity_(const char *name, uint32_t object_id_hash, uint32_t entity_fields);
 
 #ifdef USE_DEVICES
   // Codegen-only setter — only accessible from setup() via friend declaration.
@@ -233,24 +240,13 @@ class EntityBase {
 #endif
 
   /// Non-template helper for make_entity_preference() to avoid code bloat.
-  /// Migrates preferences from the old sanitized-object_id key to the raw-name key
+  /// When the preference hash algorithm changes, migration logic goes here.
-  /// on key-lookup platforms. See: https://github.com/esphome/backlog/issues/85
   ESPPreferenceObject make_entity_preference_(size_t size, uint32_t version);
 
-  void calc_entity_key_();
+  void calc_object_id_();
-
-  /// Reconstruct the OLD (pre-2026.8.0) sanitized-object_id hash for preference keys.
-  uint32_t calc_old_object_id_hash_() const;
-
-  /// Preference key base for this entity: raw-name entity key XOR device_id.
-  uint32_t preference_key_base_() const { return this->entity_key_ ^ this->get_device_id_or_zero(); }
-
-  /// Legacy preference key base: sanitized-object_id hash XOR device_id.
-  /// Note: device_id is 0 for the main device, so XORing with 0 preserves the original hash.
-  uint32_t old_preference_key_base_() const { return this->calc_old_object_id_hash_() ^ this->get_device_id_or_zero(); }
 
   StringRef name_;
-  uint32_t entity_key_{};
+  uint32_t object_id_hash_{};
 #ifdef USE_DEVICES
   Device *device_{};
 #endif

esphome/core/entity_helpers.py

@@ -25,86 +25,25 @@ from esphome.core.config import (
 from esphome.cpp_generator import MockObj, RawStatement, add, get_variable
 from esphome.cpp_types import App
 import esphome.final_validate as fv
-from esphome.helpers import cpp_string_escape, fnv1_hash_name, sanitize, snake_case
+from esphome.helpers import (
+    cpp_string_escape,
+    fnv1_hash,
+    fnv1_hash_object_id,
+    sanitize,
+    snake_case,
+)
 from esphome.types import ConfigType, EntityMetadata
 
 _LOGGER = logging.getLogger(__name__)
 
 DOMAIN = "entity_string_pool"
 
-_OBJECT_ID_DOMAIN = "entity_object_ids"
-
-
-@dataclass
-class ObjectIdEntity:
-    """An entity tracked by the sanitized object_id its name resolves to."""
-
-    name: str
-    platform: str
-    config: ConfigType
-
-
-def _get_object_id_registry() -> dict[tuple[str, str, str], list[ObjectIdEntity]]:
-    """(device_id, platform, sanitized object_id) -> entities resolving to it."""
-    return CORE.data.setdefault(_OBJECT_ID_DOMAIN, {})
-
-
-def validate_no_object_id_conflicts(
-    reason: str,
-    conflict_filter: Callable[[list[ObjectIdEntity], ConfigType], bool] | None = None,
-) -> Callable[[ConfigType], ConfigType]:
-    """Create a final-validate step that rejects entities with colliding object_ids.
-
-    Entity keys are hashed from the raw name, so names that only differ in characters
-    lost during sanitizing (for example two UTF-8 names) validate fine in general.
-    Components that still address entities by the sanitized object_id string must
-    reject those configs until they are migrated to raw names.
-
-    Args:
-        reason: One sentence stating what the component builds from the object_id,
-            e.g. "mqtt builds default topics from the entity object_id"
-        conflict_filter: Optional predicate receiving the colliding entities and the
-            component config; return False when the component is not affected
-
-    Returns:
-        A validator function for use as (or within) FINAL_VALIDATE_SCHEMA
-    """
-
-    def validator(config: ConfigType) -> ConfigType:
-        # Skip in testing_mode, which is used for grouped component testing
-        if CORE.testing_mode:
-            return config
-        conflicts = {
-            key: entities
-            for key, entities in _get_object_id_registry().items()
-            if len(entities) > 1
-            and (conflict_filter is None or conflict_filter(entities, config))
-        }
-        if not conflicts:
-            return config
-        lines = [f"{reason}, so these entities would conflict:"]
-        lines.extend(
-            f"  - {platform} entities "
-            + ", ".join(f"'{e.name}'" for e in entities)
-            + (f" on device '{device_id}'" if device_id else "")
-            + f" share the object_id '{object_id}'"
-            for (device_id, platform, object_id), entities in conflicts.items()
-        )
-        lines.append(
-            "To fix: Add unique ASCII characters (e.g., '1', '2', or 'A', 'B') "
-            "to distinguish the names"
-        )
-        raise cv.Invalid("\n".join(lines))
-
-    return validator
-
-
 # Private config keys for storing registered string indices
 _KEY_DC_IDX = "_entity_dc_idx"
 _KEY_UOM_IDX = "_entity_uom_idx"
 _KEY_ICON_IDX = "_entity_icon_idx"
 _KEY_ENTITY_NAME = "_entity_name"
-_KEY_ENTITY_KEY = "_entity_key"
+_KEY_OBJECT_ID_HASH = "_entity_object_id_hash"
 
 # Bit layout for entity_fields in configure_entity_().
 # Keep in sync with ENTITY_FIELD_*_SHIFT constants in esphome/core/entity_base.h
@@ -367,7 +306,7 @@ def finalize_entity_strings(var: MockObj, config: ConfigType) -> None:
     standalone ``var->configure_entity_(name, hash, packed)``.
     """
     entity_name = config[_KEY_ENTITY_NAME]
-    entity_key = config[_KEY_ENTITY_KEY]
+    object_id_hash = config[_KEY_OBJECT_ID_HASH]
     dc_idx = config.get(_KEY_DC_IDX, 0)
     uom_idx = config.get(_KEY_UOM_IDX, 0)
     icon_idx = config.get(_KEY_ICON_IDX, 0)
@@ -387,30 +326,57 @@ def finalize_entity_strings(var: MockObj, config: ConfigType) -> None:
     register_method = config.get(_KEY_REGISTER_METHOD)
     if register_method is not None:
         expr = getattr(App, f"register_{register_method}")(
-            var, entity_name, entity_key, packed
+            var, entity_name, object_id_hash, packed
         )
     else:
-        expr = var.configure_entity_(entity_name, entity_key, packed)
+        expr = var.configure_entity_(entity_name, object_id_hash, packed)
     if comment:
         add(RawStatement(f"{expr};  // {comment}"))
     else:
         add(expr)
 
 
-def get_base_entity_name(
+def get_base_entity_object_id(
     name: str, friendly_name: str | None, device_name: str | None = None
 ) -> str:
-    """Return the base name whose hash becomes this entity's key on the device.
+    """Calculate the base object ID for an entity that will be set via set_object_id().
 
-    Follows the name selection in C++ EntityBase::configure_entity_() (entity_base.cpp):
+    This function calculates what object_id_c_str_ should be set to in C++.
-    entity name, then sub-device name, then friendly name, then the device name.
 
-    This is a config-time approximation for duplicate checking: when
+    The C++ EntityBase::write_object_id_to() (entity_base.cpp) works as:
-    name_add_mac_suffix is enabled the device appends the MAC suffix at runtime,
+    - If !has_own_name && is_name_add_mac_suffix_enabled():
-    which is unknown here and identical for every entity on the device, so
+        return str_sanitize(str_snake_case(App.get_friendly_name()))  // Dynamic
-    ignoring it cannot change whether two entities collide with each other.
+    - Else:
+        return object_id_c_str_ ?? ""  // What we set via set_object_id()
+
+    Since we're calculating what to pass to set_object_id(), we always need to
+    generate the object_id the same way, regardless of name_add_mac_suffix setting.
+
+    Args:
+        name: The entity name (empty string if no name)
+        friendly_name: The friendly name from CORE.friendly_name
+        device_name: The device name if entity is on a sub-device
+
+    Returns:
+        The base object ID to use for duplicate checking and to pass to set_object_id()
     """
-    return name or device_name or friendly_name or CORE.name
+
+    if name:
+        # Entity has its own name (has_own_name will be true)
+        base_str = name
+    elif device_name:
+        # Entity has empty name and is on a sub-device
+        # C++ EntityBase::set_name() uses device->get_name() when device is set
+        base_str = device_name
+    elif friendly_name:
+        # Entity has empty name (has_own_name will be false)
+        # C++ uses App.get_friendly_name() which returns friendly_name or device name
+        base_str = friendly_name
+    else:
+        # Fallback to device name
+        base_str = CORE.name
+
+    return sanitize(snake_case(base_str))
 
 
 def setup_entity(var_or_platform, config=None, platform=None):
@@ -469,15 +435,15 @@ async def _setup_entity_impl(var: MockObj, config: ConfigType, platform: str) ->
         device: MockObj = await get_variable(device_id_obj)
         add(var.set_device_(device))
 
-    # Pre-compute entity name and entity key for configure_entity_()
+    # Pre-compute entity name and object_id hash for configure_entity_()
     # which is emitted later by finalize_entity_strings().
-    # For named entities: pre-compute the key from the raw entity name
+    # For named entities: pre-compute hash from entity name
-    # For empty-name entities: pass 0, C++ calculates the key at runtime from
+    # For empty-name entities: pass 0, C++ calculates hash at runtime from
-    # device name, friendly_name, or app name
+    # device name, friendly_name, or app name (bug-for-bug compatibility)
     entity_name = config[CONF_NAME]
-    entity_key = fnv1_hash_name(entity_name) if entity_name else 0
+    object_id_hash = fnv1_hash_object_id(entity_name) if entity_name else 0
     config[_KEY_ENTITY_NAME] = entity_name
-    config[_KEY_ENTITY_KEY] = entity_key
+    config[_KEY_OBJECT_ID_HASH] = object_id_hash
     # Store flags for packing into configure_entity_()
     config[_KEY_DISABLED_BY_DEFAULT] = int(config[CONF_DISABLED_BY_DEFAULT])
     if CONF_INTERNAL in config:
@@ -590,13 +556,16 @@ def entity_duplicate_validator(platform: str) -> Callable[[ConfigType], ConfigTy
             # Use the device ID string directly for uniqueness
             device_id = device_id_obj.id
 
-        # Hash the same raw name the device hashes into the entity key at runtime.
+        # Calculate what object_id will actually be used
-        # This handles empty names correctly by using device/friendly names.
+        # This handles empty names correctly by using device/friendly names
-        base_name = get_base_entity_name(entity_name, CORE.friendly_name, device_name)
+        name_key = get_base_entity_object_id(
-        name_hash = fnv1_hash_name(base_name)
+            entity_name, CORE.friendly_name, device_name
+        )
 
-        # Check for duplicates: two entities on the same device and platform must not
+        # Check for duplicates by the FNV-1 hash of the object_id, which is the entity
-        # share an entity key, since the key is what routes state to API clients
+        # key that routes state to API clients. This rejects names that sanitize to the
+        # same object_id, and also two different object_ids whose 32-bit hashes collide.
+        name_hash = fnv1_hash(name_key)
         unique_key = (device_id, platform, name_hash)
         if unique_key in CORE.unique_ids:
             # Get the existing entity metadata
@@ -621,14 +590,26 @@ def entity_duplicate_validator(platform: str) -> Callable[[ConfigType], ConfigTy
             if existing_component != "unknown":
                 conflict_msg += f" from component '{existing_component}'"
 
-            # Different names can only clash here through a genuine hash collision
+            # Distinguish names that sanitize to the same object_id from a genuine
+            # 32-bit hash collision between two different object_ids
             collision_msg = ""
             if entity_name != existing_name:
-                collision_msg = (
+                existing_object_id = get_base_entity_object_id(
-                    f"\n  The names '{entity_name}' and '{existing_name}' produce the"
+                    existing_name, CORE.friendly_name, existing_device or None
-                    f"\n  same entity key hash ({name_hash:#010x})."
-                    "\n  To fix: Rename one of the entities"
                 )
+                if existing_object_id == name_key:
+                    collision_msg = (
+                        f"\n  Original names: '{entity_name}' and '{existing_name}'"
+                        f"\n  Both convert to ASCII ID: '{name_key}'"
+                        "\n  To fix: Add unique ASCII characters (e.g., '1', '2', or 'A', 'B')"
+                        "\n          to distinguish them"
+                    )
+                else:
+                    collision_msg = (
+                        f"\n  The object_ids '{name_key}' and '{existing_object_id}'"
+                        f"\n  produce the same entity key hash ({name_hash:#010x})."
+                        "\n  To fix: Rename one of the entities"
+                    )
 
             # Skip duplicate entity name validation when testing_mode is enabled
             # This flag is used for grouped component testing
@@ -640,19 +621,6 @@ def entity_duplicate_validator(platform: str) -> Callable[[ConfigType], ConfigTy
                     f"{collision_msg}"
                 )
 
-        # Components that still address entities by the sanitized object_id reject
-        # colliding names in final validation via validate_no_object_id_conflicts(),
-        # so track every entity by the object_id its name resolves to. Scoped per
-        # device and platform to match the strictness configs had before entity keys
-        # moved to raw names: same-named entities on different sub-devices were
-        # already accepted then, internal entities were already skipped (above), and
-        # overlaps between platforms that share an MQTT component type (sensor and
-        # text_sensor both publish under "sensor") were already possible.
-        object_id = sanitize(snake_case(base_name))
-        _get_object_id_registry().setdefault(
-            (device_id, platform, object_id), []
-        ).append(ObjectIdEntity(base_name, platform, config))
-
         # Store metadata about this entity
         entity_metadata: EntityMetadata = {
             "name": entity_name,

esphome/core/helpers.h

@@ -809,19 +809,6 @@ constexpr uint32_t FNV1_OFFSET_BASIS = 2166136261UL;
 /// FNV-1 32-bit prime
 constexpr uint32_t FNV1_PRIME = 16777619UL;
 
-/// Calculate a FNV-1 hash over raw bytes with an explicit length. Unlike fnv1_hash(const char *),
-/// each byte is hashed as an unsigned value, so results are platform-independent for bytes >= 0x80.
-/// IMPORTANT: Must match Python fnv1_hash_name() in esphome/helpers.py, which hashes the UTF-8
-/// encoded bytes of the name. Used to compute entity keys from raw names.
-inline uint32_t fnv1_hash_bytes(const char *str, size_t len) {
-  uint32_t hash = FNV1_OFFSET_BASIS;
-  for (size_t i = 0; i < len; i++) {
-    hash *= FNV1_PRIME;
-    hash ^= static_cast<uint8_t>(str[i]);
-  }
-  return hash;
-}
-
 /// Extend a FNV-1 hash with an integer (hashes each byte).
 template<std::integral T> constexpr uint32_t fnv1_hash_extend(uint32_t hash, T value) {
   using UnsignedT = std::make_unsigned_t<T>;
@@ -1026,20 +1013,12 @@ template<size_t N> inline char *str_sanitize_to(char (&buffer)[N], const char *s
 // str_sanitize moved to alloc_helpers.h - remove this comment before 2026.11.0
 
 /// Calculate FNV-1 hash of a string while applying snake_case + sanitize transformations.
-/// This is the LEGACY entity hash, kept only to reconstruct preference keys that existing
+/// This computes object_id hashes directly from names without creating an intermediate buffer.
-/// devices already have stored; see https://github.com/esphome/backlog/issues/85.
+/// IMPORTANT: Must match Python fnv1_hash_object_id() in esphome/helpers.py.
-/// With per_code_point set, UTF-8 continuation bytes are skipped so each multi-byte character
+/// If you modify this function, update the Python version and tests in both places.
-/// contributes one underscore — this matches Python fnv1_hash_object_id() in esphome/helpers.py,
+inline uint32_t fnv1_hash_object_id(const char *str, size_t len) {
-/// which produced the hash for named entities. The per-byte form (default) matches the old
-/// runtime hash for entities without their own name. Do not change either behavior.
-/// Known limitation: Python's lower() is Unicode aware, so the rare code points it maps to a
-/// different number of characters or to ASCII (e.g. 'İ', the Kelvin sign) reconstruct wrong;
-/// such names skip migration once and fall back to their defaults.
-inline uint32_t fnv1_hash_object_id(const char *str, size_t len, bool per_code_point = false) {
   uint32_t hash = FNV1_OFFSET_BASIS;
   for (size_t i = 0; i < len; i++) {
-    if (per_code_point && (static_cast<uint8_t>(str[i]) & 0xC0) == 0x80)
-      continue;  // UTF-8 continuation byte, already counted via its lead byte
     hash *= FNV1_PRIME;
     // Apply snake_case (space->underscore, uppercase->lowercase) then sanitize
     hash ^= static_cast<uint8_t>(to_sanitized_char(to_snake_case_char(str[i])));

esphome/core/preference_backend.h

@@ -24,9 +24,10 @@
 #endif
 
 // Key-lookup preference backends find stored data by key; their platforms add the
-// USE_PREFERENCE_KEY_LOOKUP define from Python codegen, which enables preference key
+// USE_PREFERENCE_KEY_LOOKUP define from Python codegen, which enables one-shot reads
-// migration. Slot-based backends (ESP8266, RP2040) instead allocate a storage slot for
+// of stored data by key (the primitive preference key migrations need). Slot-based
-// every make_preference() call and use the key only as a validity tag on that slot;
+// backends (ESP8266, RP2040) instead allocate a storage slot for every
+// make_preference() call and use the key only as a validity tag on that slot;
 // migration is not possible there, and key collisions cannot corrupt data.
 
 namespace esphome {
@@ -104,10 +105,9 @@ concept PreferencesContract = requires(T prefs, size_t len, uint32_t type, bool
 };
 
 // Key-lookup platforms additionally provide load_from_key(), a one-shot read
-// of a stored preference by key that migrate_preference() relies on; see the
+// of a stored preference by key; see the key-lookup note at the top of this
-// key-lookup note at the top of this file. Not part of PreferencesContract,
+// file. Not part of PreferencesContract, so it is asserted in preferences.h
-// so it is asserted in preferences.h only where USE_PREFERENCE_KEY_LOOKUP
+// only where USE_PREFERENCE_KEY_LOOKUP is set.
-// is set.
 template<typename T>
 concept PreferencesKeyLookupContract = requires(T prefs, uint32_t type, uint8_t *data, size_t len) {
   { prefs.load_from_key(type, data, len) } -> std::same_as<bool>;

esphome/core/preferences.cpp

@@ -1,25 +0,0 @@
-#include "esphome/core/preferences.h"
-#include "esphome/core/log.h"
-#include <cinttypes>
-
-namespace esphome {
-
-#ifdef USE_PREFERENCE_KEY_LOOKUP
-static const char *const TAG = "preferences";
-
-bool migrate_preference(ESPPreferenceObject &new_pref, uint8_t *scratch, size_t size, uint32_t old_key,
-                        uint32_t new_key) {
-  if (new_pref.load(scratch, size))
-    return true;  // Current data present - never overwrite newer data with the old copy
-  // One-shot read by key: no backend is allocated for the old key, so boots with
-  // nothing to migrate (for example fresh installs) cost no heap
-  if (old_key == new_key || !global_preferences->load_from_key(old_key, scratch, size))
-    return false;  // No data stored under the old key, nothing to migrate
-  if (!new_pref.save(scratch, size)) {
-    ESP_LOGW(TAG, "Pref migration %" PRIx32 " -> %" PRIx32 " failed", old_key, new_key);
-  }
-  return true;
-}
-#endif  // USE_PREFERENCE_KEY_LOOKUP
-
-}  // namespace esphome

esphome/core/preferences.h

@@ -56,17 +56,5 @@ namespace esphome {
 static_assert(PreferencesKeyLookupContract<ESPPreferences>,
               "This platform emits USE_PREFERENCE_KEY_LOOKUP but its preferences manager does not provide "
               "load_from_key() (esphome/core/preference_backend.h)");
-
-/// Copy preference data stored under old_key into new_pref (created for new_key) if the keys
-/// differ and new_pref has no data yet. scratch must hold at least size bytes.
-/// Returns true when scratch holds the entity's current data (loaded or just migrated).
-/// The old entry is intentionally left in place so a firmware downgrade still finds its data.
-/// If saving under the new key fails, callers that consume scratch (like TextSaver) still get
-/// valid data for this boot, callers that reload from the preference fall back to their
-/// defaults, and the migration simply runs again on the next boot.
-/// Only available on key-lookup preference backends; slot-based backends keep their old
-/// keys instead. See: https://github.com/esphome/backlog/issues/85
-bool migrate_preference(ESPPreferenceObject &new_pref, uint8_t *scratch, size_t size, uint32_t old_key,
-                        uint32_t new_key);
 }  // namespace esphome
 #endif  // USE_PREFERENCE_KEY_LOOKUP

esphome/helpers.py

@@ -91,13 +91,8 @@ def fnv1a_32bit_hash(string: str) -> int:
 def fnv1_hash_object_id(name: str) -> int:
     """Compute FNV-1 hash of name with snake_case + sanitize transformations.
 
-    IMPORTANT: Must produce same result as C++ fnv1_hash_object_id() in helpers.h
+    IMPORTANT: Must produce same result as C++ fnv1_hash_object_id() in helpers.h.
-    with per_code_point set. This is the OLD entity hash; it computes preference
+    If you modify this function, update the C++ version and tests in both places.
-    keys that existing devices already have stored (see
-    https://github.com/esphome/backlog/issues/85) and is also still used for live
-    keys derived from config IDs (see the motion component's calibration key).
-    Note: lower() here is Unicode aware while the C++ reconstruction is not; see
-    the known limitation note on the C++ function.
     """
     return fnv1_hash(sanitize(snake_case(name)))
 
@@ -105,9 +100,9 @@ def fnv1_hash_object_id(name: str) -> int:
 def fnv1_hash_name(name: str) -> int:
     """Compute FNV-1 hash of the raw entity name (UTF-8 bytes, no transformations).
 
-    IMPORTANT: Must produce same result as C++ fnv1_hash_bytes() in helpers.h,
+    2026.8 beta firmware stored preferences under keys derived from this hash;
-    which hashes the name bytes as stored on the device.
+    a future key migration must reconstruct those keys to recover that data
-    Used for pre-computing entity keys at code generation time.
+    (see https://github.com/esphome/backlog/issues/85).
     """
     return _fnv1_hash(name.encode("utf-8"))
 

tests/integration/entity_utils.py

@@ -8,7 +8,7 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING
 
-from esphome.helpers import fnv1_hash_name, sanitize, snake_case
+from esphome.helpers import fnv1_hash_object_id, sanitize, snake_case
 
 if TYPE_CHECKING:
     from aioesphomeapi import DeviceInfo, EntityInfo
@@ -25,16 +25,15 @@ def infer_name_add_mac_suffix(device_info: DeviceInfo) -> bool:
     return device_info.name.endswith(f"-{mac_suffix}")
 
 
-def _resolve_entity_name(
+def _get_name_for_object_id(
     entity: EntityInfo,
     device_info: DeviceInfo,
     device_id_to_name: dict[int, str],
 ) -> str:
-    """Resolve the effective name for an entity.
+    """Get the name used for object_id computation.
 
     This is the algorithm that aioesphomeapi will use to determine which
-    name to use for computing object_id client-side from API data; the same
+    name to use for computing object_id client-side from API data.
-    name is what the device hashes into the entity key.
 
     Args:
         entity: The entity to get name for
@@ -73,27 +72,27 @@ def compute_entity_object_id(
     Returns:
         The computed object_id string
     """
-    name = _resolve_entity_name(entity, device_info, device_id_to_name)
+    name_for_id = _get_name_for_object_id(entity, device_info, device_id_to_name)
-    return compute_object_id(name)
+    return compute_object_id(name_for_id)
 
 
-def compute_entity_key(
+def compute_entity_hash(
     entity: EntityInfo,
     device_info: DeviceInfo,
     device_id_to_name: dict[int, str],
 ) -> int:
-    """Compute expected entity key for an entity.
+    """Compute expected object_id hash for an entity.
 
     Args:
-        entity: The entity to compute the key for
+        entity: The entity to compute hash for
         device_info: Device info from the API
         device_id_to_name: Mapping of device_id to device name for sub-devices
 
     Returns:
-        The computed FNV-1 hash of the raw name
+        The computed FNV-1 hash
     """
-    name = _resolve_entity_name(entity, device_info, device_id_to_name)
+    name_for_id = _get_name_for_object_id(entity, device_info, device_id_to_name)
-    return fnv1_hash_name(name)
+    return fnv1_hash_object_id(name_for_id)
 
 
 def verify_entity_object_id(
@@ -119,7 +118,7 @@ def verify_entity_object_id(
         f"expected '{expected_object_id}', got '{entity.object_id}'"
     )
 
-    expected_hash = compute_entity_key(entity, device_info, device_id_to_name)
+    expected_hash = compute_entity_hash(entity, device_info, device_id_to_name)
     assert entity.key == expected_hash, (
         f"hash mismatch for entity '{entity.name}': "
         f"expected {expected_hash:#x}, got {entity.key:#x}"

tests/integration/fixtures/fnv1_hash_object_id.yaml

@@ -71,38 +71,6 @@ esphome:
           ESP_LOGE("FNV1_OID", "empty FAILED: 0x%08x != 0x811c9dc5", hash_empty);
         }
 
-        // Raw name hash: matches Python fnv1_hash_name("My Sensor Name")
-        uint32_t hash_raw = esphome::fnv1_hash_bytes("My Sensor Name", 14);
-        if (hash_raw == 0x8cec6fb0) {
-          ESP_LOGI("FNV1_OID", "raw PASSED");
-        } else {
-          ESP_LOGE("FNV1_OID", "raw FAILED: 0x%08x != 0x8cec6fb0", hash_raw);
-        }
-
-        // Raw name hash over UTF-8 bytes: matches Python fnv1_hash_name("Température")
-        uint32_t hash_raw_utf8 = esphome::fnv1_hash_bytes("Temp\xc3\xa9rature", 12);
-        if (hash_raw_utf8 == 0x531a74aa) {
-          ESP_LOGI("FNV1_OID", "raw_utf8 PASSED");
-        } else {
-          ESP_LOGE("FNV1_OID", "raw_utf8 FAILED: 0x%08x != 0x531a74aa", hash_raw_utf8);
-        }
-
-        // Old-key UTF-8 variant: matches Python fnv1_hash_object_id("Température")
-        uint32_t hash_old_utf8 = esphome::fnv1_hash_object_id("Temp\xc3\xa9rature", 12, true);
-        if (hash_old_utf8 == 0x965698f3) {
-          ESP_LOGI("FNV1_OID", "old_utf8 PASSED");
-        } else {
-          ESP_LOGE("FNV1_OID", "old_utf8 FAILED: 0x%08x != 0x965698f3", hash_old_utf8);
-        }
-
-        // Old-key UTF-8 variant with multi-byte only name: Python fnv1_hash_object_id("温度")
-        uint32_t hash_old_cjk = esphome::fnv1_hash_object_id("\xe6\xb8\xa9\xe5\xba\xa6", 6, true);
-        if (hash_old_cjk == 0x3276cb9f) {
-          ESP_LOGI("FNV1_OID", "old_cjk PASSED");
-        } else {
-          ESP_LOGE("FNV1_OID", "old_cjk FAILED: 0x%08x != 0x3276cb9f", hash_old_cjk);
-        }
-
 host:
 api:
 logger:

tests/integration/fixtures/multi_device_preferences.yaml

@@ -156,17 +156,10 @@ button:
           ESP_LOGI("test", "Device A Mode: %s", id(mode_device_a).current_option().c_str());
           ESP_LOGI("test", "Device B Mode: %s", id(mode_device_b).current_option().c_str());
           ESP_LOGI("test", "Main Mode: %s", id(mode_main).current_option().c_str());
-          // Log preference key bases for entities that actually store preferences.
+          // Log preference hashes for entities that actually store preferences
-          // This is the key base make_entity_preference() uses: entity key XOR device id.
+          ESP_LOGI("test", "Device A Switch Pref Hash: %u", id(light_device_a).get_preference_hash());
-          ESP_LOGI("test", "Device A Switch Pref Hash: %u",
+          ESP_LOGI("test", "Device B Switch Pref Hash: %u", id(light_device_b).get_preference_hash());
-                   id(light_device_a).get_entity_key() ^ id(light_device_a).get_device_id_or_zero());
+          ESP_LOGI("test", "Main Switch Pref Hash: %u", id(light_main).get_preference_hash());
-          ESP_LOGI("test", "Device B Switch Pref Hash: %u",
+          ESP_LOGI("test", "Device A Number Pref Hash: %u", id(setpoint_device_a).get_preference_hash());
-                   id(light_device_b).get_entity_key() ^ id(light_device_b).get_device_id_or_zero());
+          ESP_LOGI("test", "Device B Number Pref Hash: %u", id(setpoint_device_b).get_preference_hash());
-          ESP_LOGI("test", "Main Switch Pref Hash: %u",
+          ESP_LOGI("test", "Main Number Pref Hash: %u", id(setpoint_main).get_preference_hash());
-                   id(light_main).get_entity_key() ^ id(light_main).get_device_id_or_zero());
-          ESP_LOGI("test", "Device A Number Pref Hash: %u",
-                   id(setpoint_device_a).get_entity_key() ^ id(setpoint_device_a).get_device_id_or_zero());
-          ESP_LOGI("test", "Device B Number Pref Hash: %u",
-                   id(setpoint_device_b).get_entity_key() ^ id(setpoint_device_b).get_device_id_or_zero());
-          ESP_LOGI("test", "Main Number Pref Hash: %u",
-                   id(setpoint_main).get_entity_key() ^ id(setpoint_main).get_device_id_or_zero());

tests/integration/fixtures/preference_key_migration.yaml

@@ -1,35 +0,0 @@
-esphome:
-  name: host-pref-key-migration
-
-host:
-api:
-logger:
-
-switch:
-  - platform: template
-    id: test_switch_restore
-    name: Test Switch
-    optimistic: true
-    restore_mode: RESTORE_DEFAULT_OFF
-
-number:
-  - platform: template
-    id: test_number_restore
-    name: Test Number
-    optimistic: true
-    restore_value: true
-    initial_value: 1.0
-    min_value: 0
-    max_value: 100
-    step: 0.5
-
-text:
-  - platform: template
-    id: test_text_restore
-    name: Test Text
-    mode: text
-    optimistic: true
-    restore_value: true
-    initial_value: fallback
-    min_length: 0
-    max_length: 20

tests/integration/host_prefs.py

@@ -25,25 +25,15 @@ def clear_host_prefs(device_name: str) -> None:
     host_prefs_path(device_name).unlink(missing_ok=True)
 
 
-def write_host_prefs(device_name: str, entries: dict[int, bytes]) -> Path:
-    """Write preference entries, replacing the file's contents.
-
-    Returns the path that was written.
-    """
-    payload = b""
-    for key, data in entries.items():
-        if len(data) > 255:
-            raise ValueError(f"Preference data too long: {len(data)} bytes (max 255)")
-        payload += struct.pack("<IB", key, len(data)) + data
-    path = host_prefs_path(device_name)
-    path.parent.mkdir(parents=True, exist_ok=True)
-    path.write_bytes(payload)
-    return path
-
-
 def write_host_pref(device_name: str, key: int, data: bytes) -> Path:
     """Write a single preference entry, replacing the file's contents.
 
     Returns the path that was written.
     """
-    return write_host_prefs(device_name, {key: data})
+    if len(data) > 255:
+        raise ValueError(f"Preference data too long: {len(data)} bytes (max 255)")
+    path = host_prefs_path(device_name)
+    path.parent.mkdir(parents=True, exist_ok=True)
+    payload = struct.pack("<IB", key, len(data)) + data
+    path.write_bytes(payload)
+    return path

tests/integration/test_fnv1_hash_object_id.py

@@ -37,10 +37,6 @@ async def test_fnv1_hash_object_id(
         "special",
         "complex",
         "empty",
-        "raw",
-        "raw_utf8",
-        "old_utf8",
-        "old_cjk",
     }
 
     def on_log_line(line: str) -> None:

tests/integration/test_object_id_api_verification.py

@@ -2,8 +2,8 @@
 
 This test verifies a three-way match between:
 1. C++ object_id generation (get_object_id_to using to_sanitized_char/to_snake_case_char)
-2. C++ entity key generation (fnv1_hash of the raw name in helpers.h)
+2. C++ hash generation (fnv1_hash_object_id in helpers.h)
-3. Python computation (sanitize/snake_case and fnv1_hash_name in helpers.py)
+3. Python computation (sanitize/snake_case in helpers.py, fnv1_hash_object_id)
 
 The API response contains C++ computed values, so verifying API == Python
 implicitly verifies C++ == Python == API for both object_id and hash.
@@ -25,7 +25,7 @@ from __future__ import annotations
 
 import pytest
 
-from esphome.helpers import fnv1_hash_name
+from esphome.helpers import fnv1_hash_object_id
 
 from .entity_utils import compute_object_id, verify_all_entities
 from .types import APIClientConnectedFactory, RunCompiledFunction
@@ -123,7 +123,7 @@ async def test_object_id_api_verification(
             )
 
             # Verify hash can be computed from the name
-            hash_from_name = fnv1_hash_name(entity_name)
+            hash_from_name = fnv1_hash_object_id(entity_name)
             assert hash_from_name == entity.key, (
                 f"Entity '{entity_name}': hash mismatch. "
                 f"Python hash {hash_from_name:#x}, API key {entity.key:#x}"
@@ -164,7 +164,7 @@ async def test_object_id_api_verification(
             )
 
             # Verify hash matches
-            expected_hash = fnv1_hash_name(expected_name)
+            expected_hash = fnv1_hash_object_id(expected_name)
             assert entity.key == expected_hash, (
                 f"Empty-name entity (device_id={entity.device_id}): hash mismatch. "
                 f"API key: {entity.key:#x}, expected: {expected_hash:#x}"

tests/integration/test_object_id_friendly_name_no_mac_suffix.py

@@ -11,7 +11,7 @@ from __future__ import annotations
 
 import pytest
 
-from esphome.helpers import fnv1_hash_name
+from esphome.helpers import fnv1_hash_object_id
 
 from .entity_utils import (
     compute_object_id,
@@ -62,7 +62,7 @@ async def test_object_id_friendly_name_no_mac_suffix(
         )
 
         # Hash should match friendly_name
-        expected_hash = fnv1_hash_name("My Friendly Device")
+        expected_hash = fnv1_hash_object_id("My Friendly Device")
         assert entity.key == expected_hash, (
             f"Expected hash {expected_hash:#x}, got {entity.key:#x}"
         )

tests/integration/test_object_id_no_friendly_name.py

@@ -17,7 +17,7 @@ from __future__ import annotations
 
 import pytest
 
-from esphome.helpers import fnv1_hash_name
+from esphome.helpers import fnv1_hash_object_id
 
 from .entity_utils import compute_object_id, verify_all_entities
 from .types import APIClientConnectedFactory, RunCompiledFunction
@@ -96,7 +96,7 @@ async def test_object_id_no_friendly_name_no_mac_suffix(
     OLD behavior:
     - is_object_id_dynamic_() returned false (mac suffix not enabled)
     - Used object_id_c_str_ which was pre-computed in Python
-    - Python used get_base_entity_name() with fallback to CORE.name
+    - Python used get_base_entity_object_id() with fallback to CORE.name
 
     Result: object_id = sanitize(snake_case(device_name))
     """
@@ -126,7 +126,7 @@ async def test_object_id_no_friendly_name_no_mac_suffix(
         )
 
         # Hash should match device name
-        expected_hash = fnv1_hash_name("test-device")
+        expected_hash = fnv1_hash_object_id("test-device")
         assert entity.key == expected_hash, (
             f"Expected hash {expected_hash:#x}, got {entity.key:#x}"
         )

tests/integration/test_preference_key_migration.py

@@ -1,165 +0,0 @@
-"""Integration test for entity preference key migration.
-
-Entity keys are now the FNV-1 hash of the raw name instead of the sanitized
-object_id (https://github.com/esphome/backlog/issues/85). On key-lookup
-preference backends, make_entity_preference() must move data stored under the
-old key to the new key, so devices keep their restored state after upgrading.
-
-This test seeds the host preferences file the way a pre-migration firmware
-would have written it and verifies:
-1. Data stored under the OLD key is restored (migration happened, no data loss)
-2. Data already stored under the NEW key is never overwritten by old data
-"""
-
-from __future__ import annotations
-
-import socket
-import struct
-
-from aioesphomeapi import (
-    NumberInfo,
-    NumberState,
-    SwitchInfo,
-    SwitchState,
-    TextInfo,
-    TextState,
-)
-import pytest
-
-from esphome.helpers import fnv1_hash, fnv1_hash_name, fnv1_hash_object_id
-
-from .conftest import run_binary_and_wait_for_port, wait_and_connect_api_client
-from .host_prefs import clear_host_prefs, write_host_prefs
-from .state_utils import InitialStateHelper, require_entity
-from .types import CompileFunction, ConfigWriter
-
-DEVICE_NAME = "host-pref-key-migration"
-
-# The pre-migration preference key was the sanitized object_id hash; the new
-# key is the raw-name hash. All entities are on the main device (device_id 0)
-# and their preferences use no version salt, so the key is just the hash.
-SWITCH_OLD_KEY = fnv1_hash_object_id("Test Switch")
-SWITCH_NEW_KEY = fnv1_hash_name("Test Switch")
-NUMBER_OLD_KEY = fnv1_hash_object_id("Test Number")
-NUMBER_NEW_KEY = fnv1_hash_name("Test Number")
-
-# template_text salts its key with the length limits and pattern hash; this must
-# match TemplateText::setup() in template_text.cpp (min_length 0, max_length 20,
-# no pattern configured)
-TEXT_KEY_EXTRA = (0 << 2) + (20 << 4) + (fnv1_hash("") << 6)
-TEXT_OLD_KEY = (fnv1_hash_object_id("Test Text") + TEXT_KEY_EXTRA) & 0xFFFFFFFF
-TEXT_NEW_KEY = (fnv1_hash_name("Test Text") + TEXT_KEY_EXTRA) & 0xFFFFFFFF
-
-# TextSaver<20> stores a length-prefixed buffer of max_length + 1 bytes
-TEXT_MAX_LENGTH = 20
-
-
-def text_pref_payload(value: str) -> bytes:
-    """Build the length-prefixed buffer TextSaver stores for a value."""
-    data = value.encode("utf-8")
-    assert len(data) <= TEXT_MAX_LENGTH
-    return bytes([len(data)]) + data + b"\x00" * (TEXT_MAX_LENGTH - len(data))
-
-
-@pytest.mark.asyncio
-async def test_preference_key_migration(
-    yaml_config: str,
-    write_yaml_config: ConfigWriter,
-    compile_esphome: CompileFunction,
-    reserved_tcp_port: tuple[int, socket.socket],
-) -> None:
-    """Test that preferences stored under the old key survive the upgrade."""
-    port, port_socket = reserved_tcp_port
-
-    assert SWITCH_OLD_KEY != SWITCH_NEW_KEY
-    assert NUMBER_OLD_KEY != NUMBER_NEW_KEY
-    assert TEXT_OLD_KEY != TEXT_NEW_KEY
-
-    # Write and compile once
-    config_path = await write_yaml_config(yaml_config)
-    binary_path = await compile_esphome(config_path)
-
-    # Release the reserved port so the binary can bind to it
-    port_socket.close()
-
-    async def boot_and_get_initial_states() -> tuple[
-        SwitchState, NumberState, TextState
-    ]:
-        """Boot the binary and return the restored entity states."""
-        async with (
-            run_binary_and_wait_for_port(binary_path, "127.0.0.1", port),
-            wait_and_connect_api_client(port=port) as client,
-        ):
-            device_info = await client.device_info()
-            assert device_info.name == DEVICE_NAME
-
-            entities, _ = await client.list_entities_services()
-            switch_entity = require_entity(
-                entities, "test_switch", SwitchInfo, "Test Switch"
-            )
-            number_entity = require_entity(
-                entities, "test_number", NumberInfo, "Test Number"
-            )
-            text_entity = require_entity(entities, "test_text", TextInfo, "Test Text")
-
-            initial_state_helper = InitialStateHelper(entities)
-            client.subscribe_states(
-                initial_state_helper.on_state_wrapper(lambda s: None)
-            )
-            await initial_state_helper.wait_for_initial_states()
-
-            switch_state = initial_state_helper.initial_states[switch_entity.key]
-            number_state = initial_state_helper.initial_states[number_entity.key]
-            text_state = initial_state_helper.initial_states[text_entity.key]
-            assert isinstance(switch_state, SwitchState)
-            assert isinstance(number_state, NumberState)
-            assert isinstance(text_state, TextState)
-            return switch_state, number_state, text_state
-
-    try:
-        # --- Run 1: only OLD keys present, as written by pre-migration firmware.
-        # The restored states prove the data was migrated to the new keys.
-        write_host_prefs(
-            DEVICE_NAME,
-            {
-                SWITCH_OLD_KEY: b"\x01",  # bool: switch was ON
-                NUMBER_OLD_KEY: struct.pack("<f", 42.5),
-                TEXT_OLD_KEY: text_pref_payload("hello"),
-            },
-        )
-        switch_state, number_state, text_state = await boot_and_get_initial_states()
-        assert switch_state.state is True, (
-            "Switch state stored under the old preference key was lost"
-        )
-        assert number_state.state == 42.5, (
-            "Number value stored under the old preference key was lost"
-        )
-        assert text_state.state == "hello", (
-            "Text value stored under the old preference key was lost"
-        )
-
-        # --- Run 2: both keys present with different values. The NEW key holds
-        # the current data and must win; stale old-key data must never clobber it.
-        write_host_prefs(
-            DEVICE_NAME,
-            {
-                SWITCH_OLD_KEY: b"\x00",  # stale: OFF
-                SWITCH_NEW_KEY: b"\x01",  # current: ON
-                NUMBER_OLD_KEY: struct.pack("<f", 42.5),  # stale
-                NUMBER_NEW_KEY: struct.pack("<f", 13.5),  # current
-                TEXT_OLD_KEY: text_pref_payload("hello"),  # stale
-                TEXT_NEW_KEY: text_pref_payload("world"),  # current
-            },
-        )
-        switch_state, number_state, text_state = await boot_and_get_initial_states()
-        assert switch_state.state is True, (
-            "Stale old-key data overwrote the current new-key switch state"
-        )
-        assert number_state.state == 13.5, (
-            "Stale old-key data overwrote the current new-key number value"
-        )
-        assert text_state.state == "world", (
-            "Stale old-key data overwrote the current new-key text value"
-        )
-    finally:
-        clear_host_prefs(DEVICE_NAME)

tests/unit_tests/components/mqtt/test_object_id_conflicts.py

@@ -1,239 +0,0 @@
-"""Tests for the MQTT object_id conflict filter.
-
-MQTT still builds default topics and discovery topics from the sanitized
-object_id, so entity names that only differ in characters lost during
-sanitizing conflict there; _topics_conflict() exempts entities that never
-use an object_id-derived topic. See https://github.com/esphome/backlog/issues/85
-"""
-
-from pathlib import Path
-
-import pytest
-
-from esphome.components.mqtt import (
-    _COMMAND_TOPIC_PLATFORMS,
-    _SUB_TOPIC_PLATFORMS,
-    _topics_conflict,
-)
-from esphome.config_validation import Invalid
-from esphome.const import (
-    CONF_COMMAND_TOPIC,
-    CONF_DISCOVERY,
-    CONF_NAME,
-    CONF_STATE_TOPIC,
-    CONF_TOPIC_PREFIX,
-)
-from esphome.core import CORE
-from esphome.core.entity_helpers import (
-    entity_duplicate_validator,
-    validate_no_object_id_conflicts,
-)
-
-COMPONENTS_DIR = Path(__file__).parents[4] / "esphome" / "components"
-
-REASON = "mqtt builds default topics from the entity object_id"
-
-
-# MQTT infrastructure sources, not entity components
-_NON_ENTITY_MQTT_SOURCES = {"mqtt_client", "mqtt_component"}
-# The date, time and datetime MQTT components all belong to the datetime platform
-_DATETIME_STEMS = {"date", "time", "datetime"}
-
-
-def test_command_topic_platforms_in_sync() -> None:
-    """Verify _COMMAND_TOPIC_PLATFORMS matches the MQTT components that subscribe.
-
-    Drift silently reintroduces shared subscribe topics, so this derives the set
-    from the C++ components that actually call subscribe(); that also catches
-    platforms like text that subscribe a command topic without exposing a
-    command_topic key in their schema.
-    """
-    expected: set[str] = set()
-    for path in (COMPONENTS_DIR / "mqtt").glob("mqtt_*.cpp"):
-        if path.stem in _NON_ENTITY_MQTT_SOURCES:
-            continue
-        if "this->subscribe" not in path.read_text(encoding="utf-8"):
-            continue
-        stem = path.stem.removeprefix("mqtt_")
-        expected.add("datetime" if stem in _DATETIME_STEMS else stem)
-    assert expected == _COMMAND_TOPIC_PLATFORMS
-
-
-def test_sub_topic_platforms_in_sync() -> None:
-    """Verify _SUB_TOPIC_PLATFORMS matches the MQTT components with sub-topics.
-
-    Platforms whose MQTT headers use MQTT_COMPONENT_CUSTOM_TOPIC derive extra
-    topics such as position/command from the object_id.
-    """
-    expected = {
-        path.stem.removeprefix("mqtt_")
-        for path in (COMPONENTS_DIR / "mqtt").glob("mqtt_*.h")
-        if path.stem != "mqtt_component"
-        and "MQTT_COMPONENT_CUSTOM_TOPIC" in path.read_text(encoding="utf-8")
-    }
-    assert expected == _SUB_TOPIC_PLATFORMS
-
-
-def test_conflict_filter_exempts_custom_topics() -> None:
-    """Test that custom state topics with discovery off avoid the conflict."""
-    validator = entity_duplicate_validator("sensor")
-    # Both entities have custom state topics and discovery disabled per entity,
-    # so no object_id-derived MQTT topic is used
-    validator(
-        {
-            CONF_NAME: "Датчик открытия",
-            CONF_STATE_TOPIC: "custom/topic/a",
-            CONF_DISCOVERY: False,
-        }
-    )
-    validator(
-        {
-            CONF_NAME: "Датчик закрытия",
-            CONF_STATE_TOPIC: "custom/topic/b",
-            CONF_DISCOVERY: False,
-        }
-    )
-
-    component_validator = validate_no_object_id_conflicts(
-        REASON, conflict_filter=_topics_conflict
-    )
-    config: dict = {CONF_DISCOVERY: True, CONF_TOPIC_PREFIX: "test-device"}
-    assert component_validator(config) is config
-
-    # Without the filter the same conflicts are fatal
-    with pytest.raises(Invalid, match=r"mqtt builds default topics"):
-        validate_no_object_id_conflicts(REASON)({})
-
-
-def test_conflict_on_default_command_topic() -> None:
-    """Test that commandable platforms conflict through their default command topic.
-
-    Custom state topics with discovery off are not enough for platforms that also
-    subscribe to an object_id-derived command topic.
-    """
-    validator = entity_duplicate_validator("switch")
-    validator(
-        {
-            CONF_NAME: "Датчик открытия",
-            CONF_STATE_TOPIC: "custom/topic/a",
-            CONF_DISCOVERY: False,
-        }
-    )
-    validator(
-        {
-            CONF_NAME: "Датчик закрытия",
-            CONF_STATE_TOPIC: "custom/topic/b",
-            CONF_DISCOVERY: False,
-        }
-    )
-
-    component_validator = validate_no_object_id_conflicts(
-        REASON, conflict_filter=_topics_conflict
-    )
-    mqtt_config: dict = {CONF_DISCOVERY: True, CONF_TOPIC_PREFIX: "test-device"}
-    # Both switches share the default command topic: rejected
-    with pytest.raises(Invalid, match=r"mqtt builds default topics"):
-        component_validator(mqtt_config)
-
-    # With custom command topics as well, nothing derives from the object_id
-    CORE.reset()
-    validator = entity_duplicate_validator("switch")
-    validator(
-        {
-            CONF_NAME: "Датчик открытия",
-            CONF_STATE_TOPIC: "custom/topic/a",
-            CONF_COMMAND_TOPIC: "custom/cmd/a",
-            CONF_DISCOVERY: False,
-        }
-    )
-    validator(
-        {
-            CONF_NAME: "Датчик закрытия",
-            CONF_STATE_TOPIC: "custom/topic/b",
-            CONF_COMMAND_TOPIC: "custom/cmd/b",
-            CONF_DISCOVERY: False,
-        }
-    )
-    assert component_validator(mqtt_config) is mqtt_config
-
-
-def test_conflict_on_sub_topic_platforms() -> None:
-    """Test that platforms with extra object_id sub-topics always conflict.
-
-    Covers derive topics like position/command from the object_id through their
-    own config keys, so custom state and command topics cannot exempt them.
-    """
-    validator = entity_duplicate_validator("cover")
-    validator(
-        {
-            CONF_NAME: "Датчик открытия",
-            CONF_STATE_TOPIC: "custom/topic/a",
-            CONF_COMMAND_TOPIC: "custom/cmd/a",
-            CONF_DISCOVERY: False,
-        }
-    )
-    validator(
-        {
-            CONF_NAME: "Датчик закрытия",
-            CONF_STATE_TOPIC: "custom/topic/b",
-            CONF_COMMAND_TOPIC: "custom/cmd/b",
-            CONF_DISCOVERY: False,
-        }
-    )
-
-    component_validator = validate_no_object_id_conflicts(
-        REASON, conflict_filter=_topics_conflict
-    )
-    with pytest.raises(Invalid, match=r"mqtt builds default topics"):
-        component_validator({CONF_DISCOVERY: True, CONF_TOPIC_PREFIX: "test-device"})
-
-
-def test_no_conflict_on_disjoint_default_topics() -> None:
-    """Test that entities whose default topics are disjoint do not conflict.
-
-    One entity uses only the default command topic and the other only the default
-    state topic, so they never share a topic.
-    """
-    validator = entity_duplicate_validator("switch")
-    validator(
-        {
-            CONF_NAME: "Датчик открытия",
-            CONF_STATE_TOPIC: "custom/topic/a",
-            CONF_DISCOVERY: False,
-        }
-    )
-    validator(
-        {
-            CONF_NAME: "Датчик закрытия",
-            CONF_COMMAND_TOPIC: "custom/cmd/b",
-            CONF_DISCOVERY: False,
-        }
-    )
-
-    component_validator = validate_no_object_id_conflicts(
-        REASON, conflict_filter=_topics_conflict
-    )
-    config: dict = {CONF_DISCOVERY: True, CONF_TOPIC_PREFIX: "test-device"}
-    assert component_validator(config) is config
-
-
-def test_no_conflict_on_empty_topic_prefix() -> None:
-    """Test that an empty topic_prefix disables the default topic conflict.
-
-    With topic_prefix set to null no default topics exist at runtime, so entities
-    without custom state topics cannot conflict; only discovery still matters.
-    """
-    validator = entity_duplicate_validator("sensor")
-    validator({CONF_NAME: "Датчик открытия"})
-    validator({CONF_NAME: "Датчик закрытия"})
-
-    component_validator = validate_no_object_id_conflicts(
-        REASON, conflict_filter=_topics_conflict
-    )
-    # No default topics and no discovery: valid
-    config: dict = {CONF_DISCOVERY: False, CONF_TOPIC_PREFIX: ""}
-    assert component_validator(config) is config
-
-    # Discovery still uses object_id-derived config topics: rejected
-    with pytest.raises(Invalid, match=r"mqtt builds default topics"):
-        component_validator({CONF_DISCOVERY: True, CONF_TOPIC_PREFIX: ""})

tests/unit_tests/core/test_entity_helpers.py

@@ -1,4 +1,4 @@
-"""Tests for entity helpers: name selection, entity key hashing, duplicate checks."""
+"""Test get_base_entity_object_id function matches C++ behavior."""
 
 from collections.abc import Callable, Generator
 from pathlib import Path
@@ -25,17 +25,16 @@ from esphome.core.entity_helpers import (
     _setup_entity_impl,
     entity_duplicate_validator,
     finalize_entity_strings,
-    get_base_entity_name,
+    get_base_entity_object_id,
     register_device_class,
     register_icon,
     register_unit_of_measurement,
     setup_device_class,
     setup_entity,
     setup_unit_of_measurement,
-    validate_no_object_id_conflicts,
 )
 from esphome.cpp_generator import MockObj
-from esphome.helpers import fnv1_hash_name, sanitize, snake_case
+from esphome.helpers import fnv1_hash, sanitize, snake_case
 
 from .common import load_config_from_fixture
 
@@ -58,26 +57,206 @@ def restore_core_state() -> Generator[None, None, None]:
     CORE.friendly_name = original_friendly_name
 
 
-def test_get_base_entity_name_priority_order() -> None:
+def test_with_entity_name() -> None:
+    """Test when entity has its own name - should use entity name."""
+    # Simple name
+    assert get_base_entity_object_id("Temperature Sensor", None) == "temperature_sensor"
+    assert (
+        get_base_entity_object_id("Temperature Sensor", "Device Name")
+        == "temperature_sensor"
+    )
+    # Even with device name, entity name takes precedence
+    assert (
+        get_base_entity_object_id("Temperature Sensor", "Device Name", "Sub Device")
+        == "temperature_sensor"
+    )
+
+    # Name with special characters
+    assert (
+        get_base_entity_object_id("Temp!@#$%^&*()Sensor", None)
+        == "temp__________sensor"
+    )
+    assert get_base_entity_object_id("Temp-Sensor_123", None) == "temp-sensor_123"
+
+    # Already snake_case
+    assert get_base_entity_object_id("temperature_sensor", None) == "temperature_sensor"
+
+    # Mixed case
+    assert get_base_entity_object_id("TemperatureSensor", None) == "temperaturesensor"
+    assert get_base_entity_object_id("TEMPERATURE SENSOR", None) == "temperature_sensor"
+
+
+def test_empty_name_with_device_name() -> None:
+    """Test when entity has empty name and is on a sub-device - should use device name."""
+    # C++ behavior: when has_own_name is false and device is set, uses device->get_name()
+    assert (
+        get_base_entity_object_id("", "Friendly Device", "Sub Device 1")
+        == "sub_device_1"
+    )
+    assert (
+        get_base_entity_object_id("", "Kitchen Controller", "controller_1")
+        == "controller_1"
+    )
+    assert get_base_entity_object_id("", None, "Test-Device_123") == "test-device_123"
+
+
+def test_empty_name_with_friendly_name() -> None:
+    """Test when entity has empty name and no device - should use friendly name."""
+    # C++ behavior: when has_own_name is false, uses App.get_friendly_name()
+    assert get_base_entity_object_id("", "Friendly Device") == "friendly_device"
+    assert get_base_entity_object_id("", "Kitchen Controller") == "kitchen_controller"
+    assert get_base_entity_object_id("", "Test-Device_123") == "test-device_123"
+
+    # Special characters in friendly name
+    assert get_base_entity_object_id("", "Device!@#$%") == "device_____"
+
+
+def test_empty_name_no_friendly_name() -> None:
+    """Test when entity has empty name and no friendly name - should use device name."""
+    # Test with CORE.name set
+    CORE.name = "device-name"
+    assert get_base_entity_object_id("", None) == "device-name"
+
+    CORE.name = "Test Device"
+    assert get_base_entity_object_id("", None) == "test_device"
+
+
+def test_edge_cases() -> None:
+    """Test edge cases."""
+    # Only spaces
+    assert get_base_entity_object_id("   ", None) == "___"
+
+    # Unicode characters (should be replaced)
+    assert get_base_entity_object_id("Température", None) == "temp_rature"
+    assert get_base_entity_object_id("测试", None) == "__"
+
+    # Empty string with empty friendly name (empty friendly name is treated as None)
+    # Falls back to CORE.name
+    CORE.name = "device"
+    assert get_base_entity_object_id("", "") == "device"
+
+    # Very long name (should work fine)
+    long_name = "a" * 100 + " " + "b" * 100
+    expected = "a" * 100 + "_" + "b" * 100
+    assert get_base_entity_object_id(long_name, None) == expected
+
+
+@pytest.mark.parametrize(
+    ("name", "expected"),
+    [
+        ("Temperature Sensor", "temperature_sensor"),
+        ("Living Room Light", "living_room_light"),
+        ("Test-Device_123", "test-device_123"),
+        ("Special!@#Chars", "special___chars"),
+        ("UPPERCASE NAME", "uppercase_name"),
+        ("lowercase name", "lowercase_name"),
+        ("Mixed Case Name", "mixed_case_name"),
+        ("   Spaces   ", "___spaces___"),
+    ],
+)
+def test_matches_cpp_helpers(name: str, expected: str) -> None:
+    """Test that the logic matches using snake_case and sanitize directly."""
+    # For non-empty names, verify our function produces same result as direct snake_case + sanitize
+    assert get_base_entity_object_id(name, None) == sanitize(snake_case(name))
+    assert get_base_entity_object_id(name, None) == expected
+
+
+def test_empty_name_fallback() -> None:
+    """Test empty name handling which falls back to friendly_name or CORE.name."""
+    # Empty name is handled specially - it doesn't just use sanitize(snake_case(""))
+    # Instead it falls back to friendly_name or CORE.name
+    assert sanitize(snake_case("")) == ""  # Direct conversion gives empty string
+    # But our function returns a fallback
+    CORE.name = "device"
+    assert get_base_entity_object_id("", None) == "device"  # Uses device name
+
+
+def test_name_add_mac_suffix_behavior() -> None:
+    """Test behavior related to name_add_mac_suffix.
+
+    In C++, an entity's object_id is computed from its name_ via
+    write_object_id_to() (sanitized snake_case). When an entity has no name,
+    configure_entity_() sets name_ from the friendly name, with the MAC suffix
+    appended when name_add_mac_suffix is enabled. Our function always returns
+    the same result since we're calculating the base for duplicate tracking.
+    """
+    # The function should always return the same result regardless of
+    # name_add_mac_suffix setting, as we're calculating the base object_id
+    assert get_base_entity_object_id("", "Test Device") == "test_device"
+    assert get_base_entity_object_id("Entity Name", "Test Device") == "entity_name"
+
+
+def test_priority_order() -> None:
     """Test the priority order: entity name > device name > friendly name > CORE.name."""
     CORE.name = "core-device"
 
-    # 1. Entity name has highest priority and is used as-is, no transformations
+    # 1. Entity name has highest priority
     assert (
-        get_base_entity_name("Entity Name", "Friendly Name", "Device Name")
+        get_base_entity_object_id("Entity Name", "Friendly Name", "Device Name")
-        == "Entity Name"
+        == "entity_name"
     )
-    assert get_base_entity_name("Température", None) == "Température"
 
     # 2. Device name is next priority (when entity name is empty)
-    assert get_base_entity_name("", "Friendly Name", "Device Name") == "Device Name"
+    assert (
+        get_base_entity_object_id("", "Friendly Name", "Device Name") == "device_name"
+    )
 
     # 3. Friendly name is next (when entity and device names are empty)
-    assert get_base_entity_name("", "Friendly Name", None) == "Friendly Name"
+    assert get_base_entity_object_id("", "Friendly Name", None) == "friendly_name"
 
-    # 4. CORE.name is last resort; an empty friendly name falls through to it
+    # 4. CORE.name is last resort
-    assert get_base_entity_name("", None, None) == "core-device"
+    assert get_base_entity_object_id("", None, None) == "core-device"
-    assert get_base_entity_name("", "") == "core-device"
+
+
+@pytest.mark.parametrize(
+    ("name", "friendly_name", "device_name", "expected"),
+    [
+        # name, friendly_name, device_name, expected
+        ("Living Room Light", None, None, "living_room_light"),
+        ("", "Kitchen Controller", None, "kitchen_controller"),
+        (
+            "",
+            "ESP32 Device",
+            "controller_1",
+            "controller_1",
+        ),  # Device name takes precedence
+        ("GPIO2 Button", None, None, "gpio2_button"),
+        ("WiFi Signal", "My Device", None, "wifi_signal"),
+        ("", None, "esp32_node", "esp32_node"),
+        ("Front Door Sensor", "Home Assistant", "door_controller", "front_door_sensor"),
+    ],
+)
+def test_real_world_examples(
+    name: str, friendly_name: str | None, device_name: str | None, expected: str
+) -> None:
+    """Test real-world entity naming scenarios."""
+    result = get_base_entity_object_id(name, friendly_name, device_name)
+    assert result == expected
+
+
+def test_issue_6953_scenarios() -> None:
+    """Test specific scenarios from issue #6953."""
+    # Scenario 1: Multiple empty names on main device with name_add_mac_suffix
+    # The Python code calculates the base, C++ might append MAC suffix dynamically
+    CORE.name = "device-name"
+    CORE.friendly_name = "Friendly Device"
+
+    # All empty names should resolve to same base
+    assert get_base_entity_object_id("", CORE.friendly_name) == "friendly_device"
+    assert get_base_entity_object_id("", CORE.friendly_name) == "friendly_device"
+    assert get_base_entity_object_id("", CORE.friendly_name) == "friendly_device"
+
+    # Scenario 2: Empty names on sub-devices
+    assert (
+        get_base_entity_object_id("", "Main Device", "controller_1") == "controller_1"
+    )
+    assert (
+        get_base_entity_object_id("", "Main Device", "controller_2") == "controller_2"
+    )
+
+    # Scenario 3: xyz duplicates
+    assert get_base_entity_object_id("xyz", None) == "xyz"
+    assert get_base_entity_object_id("xyz", "Device") == "xyz"
 
 
 # Tests for setup_entity function
@@ -336,10 +515,9 @@ def test_entity_duplicate_validator() -> None:
     config1 = {CONF_NAME: "Temperature"}
     validated1 = validator(config1)
     assert validated1 == config1
-    temperature_key = ("", "sensor", fnv1_hash_name("Temperature"))
+    assert ("", "sensor", fnv1_hash("temperature")) in CORE.unique_ids
-    assert temperature_key in CORE.unique_ids
     # Check metadata was stored
-    metadata = CORE.unique_ids[temperature_key]
+    metadata = CORE.unique_ids[("", "sensor", fnv1_hash("temperature"))]
     assert metadata["name"] == "Temperature"
     assert metadata["platform"] == "sensor"
 
@@ -347,9 +525,8 @@ def test_entity_duplicate_validator() -> None:
     config2 = {CONF_NAME: "Humidity"}
     validated2 = validator(config2)
     assert validated2 == config2
-    humidity_key = ("", "sensor", fnv1_hash_name("Humidity"))
+    assert ("", "sensor", fnv1_hash("humidity")) in CORE.unique_ids
-    assert humidity_key in CORE.unique_ids
+    metadata2 = CORE.unique_ids[("", "sensor", fnv1_hash("humidity"))]
-    metadata2 = CORE.unique_ids[humidity_key]
     assert metadata2["name"] == "Humidity"
 
     # Duplicate entity should fail
@@ -360,6 +537,34 @@ def test_entity_duplicate_validator() -> None:
         validator(config3)
 
 
+def test_entity_duplicate_validator_hash_collision() -> None:
+    """Test that two different object_ids with the same FNV-1 hash are rejected."""
+    # Brute-forced FNV-1 32-bit collision pair; both object_ids hash to 0xe95747e4
+    name_a = "Sensor aooxzi"
+    name_b = "Sensor baraia"
+    object_id_a = sanitize(snake_case(name_a))
+    object_id_b = sanitize(snake_case(name_b))
+    assert object_id_a != object_id_b
+    assert fnv1_hash(object_id_a) == fnv1_hash(object_id_b)
+
+    validator = entity_duplicate_validator("sensor")
+
+    config1 = {CONF_NAME: name_a}
+    validated1 = validator(config1)
+    assert validated1 == config1
+
+    config2 = {CONF_NAME: name_b}
+    with pytest.raises(
+        Invalid,
+        match=re.compile(
+            r"Duplicate sensor entity with name 'Sensor baraia' found.*"
+            r"produce the same entity key hash \(0xe95747e4\)",
+            re.DOTALL,
+        ),
+    ):
+        validator(config2)
+
+
 def test_entity_duplicate_validator_with_devices() -> None:
     """Test entity_duplicate_validator with devices."""
     # Create validator for sensor platform
@@ -370,19 +575,18 @@ def test_entity_duplicate_validator_with_devices() -> None:
     device2 = ID("device2", type="Device")
 
     # Same name on different devices should pass
-    name_hash = fnv1_hash_name("Temperature")
     config1 = {CONF_NAME: "Temperature", CONF_DEVICE_ID: device1}
     validated1 = validator(config1)
     assert validated1 == config1
-    assert ("device1", "sensor", name_hash) in CORE.unique_ids
+    assert ("device1", "sensor", fnv1_hash("temperature")) in CORE.unique_ids
-    metadata1 = CORE.unique_ids[("device1", "sensor", name_hash)]
+    metadata1 = CORE.unique_ids[("device1", "sensor", fnv1_hash("temperature"))]
     assert metadata1["device_id"] == "device1"
 
     config2 = {CONF_NAME: "Temperature", CONF_DEVICE_ID: device2}
     validated2 = validator(config2)
     assert validated2 == config2
-    assert ("device2", "sensor", name_hash) in CORE.unique_ids
+    assert ("device2", "sensor", fnv1_hash("temperature")) in CORE.unique_ids
-    metadata2 = CORE.unique_ids[("device2", "sensor", name_hash)]
+    metadata2 = CORE.unique_ids[("device2", "sensor", fnv1_hash("temperature"))]
     assert metadata2["device_id"] == "device2"
 
     # Duplicate on same device should fail
@@ -434,33 +638,6 @@ def test_entity_different_platforms_yaml_validation(
     assert result is not None
 
 
-def test_object_id_conflict_mqtt_yaml_validation(
-    yaml_file: Callable[[str], str], capsys: pytest.CaptureFixture[str]
-) -> None:
-    """Test that names sanitizing to the same object_id fail when mqtt is configured."""
-    result = load_config_from_fixture(
-        yaml_file, "object_id_conflict_mqtt.yaml", FIXTURES_DIR
-    )
-    assert result is None
-
-    captured = capsys.readouterr()
-    assert (
-        "mqtt builds default topics and discovery topics from the entity object_id"
-        in captured.out
-    )
-
-
-def test_object_id_conflict_without_mqtt_yaml_validation(
-    yaml_file: Callable[[str], str],
-) -> None:
-    """Test that names sanitizing to the same object_id pass without mqtt/prometheus."""
-    result = load_config_from_fixture(
-        yaml_file, "object_id_conflict_no_mqtt.yaml", FIXTURES_DIR
-    )
-    # This should succeed
-    assert result is not None
-
-
 def test_entity_duplicate_validator_error_message() -> None:
     """Test that duplicate entity error messages include helpful metadata."""
     # Create validator for sensor platform
@@ -519,8 +696,7 @@ def test_entity_duplicate_validator_internal_entities() -> None:
     validated1 = validator(config1)
     assert validated1 == config1
     # New format includes device_id (empty string for main device)
-    temperature_key = ("", "sensor", fnv1_hash_name("Temperature"))
+    assert ("", "sensor", fnv1_hash("temperature")) in CORE.unique_ids
-    assert temperature_key in CORE.unique_ids
 
     # Internal entity with same name should pass (not added to unique_ids)
     config2 = {CONF_NAME: "Temperature", CONF_INTERNAL: True}
@@ -528,7 +704,9 @@ def test_entity_duplicate_validator_internal_entities() -> None:
     assert validated2 == config2
     # Internal entity should not be added to unique_ids
     # Count how many times the key appears (should still be 1)
-    count = sum(1 for k in CORE.unique_ids if k == temperature_key)
+    count = sum(
+        1 for k in CORE.unique_ids if k == ("", "sensor", fnv1_hash("temperature"))
+    )
     assert count == 1
 
     # Another internal entity with same name should also pass
@@ -536,7 +714,9 @@ def test_entity_duplicate_validator_internal_entities() -> None:
     validated3 = validator(config3)
     assert validated3 == config3
     # Still only one entry in unique_ids (from the non-internal entity)
-    count = sum(1 for k in CORE.unique_ids if k == temperature_key)
+    count = sum(
+        1 for k in CORE.unique_ids if k == ("", "sensor", fnv1_hash("temperature"))
+    )
     assert count == 1
 
     # Non-internal entity with same name should fail
@@ -564,148 +744,30 @@ def test_empty_or_null_device_id_on_entity() -> None:
 
 
 def test_entity_duplicate_validator_non_ascii_names() -> None:
-    """Test that distinct non-ASCII names no longer collide.
+    """Test that non-ASCII names show helpful error messages."""
-
-    These names used to be rejected because both sanitize to only underscores;
-    the entity key now hashes the raw name so they stay distinct.
-    """
     # Create validator for binary_sensor platform
     validator = entity_duplicate_validator("binary_sensor")
 
-    # Both Russian sensors should pass even though they sanitize identically
+    # First Russian sensor should pass
     config1 = {CONF_NAME: "Датчик открытия основного крана"}
     validated1 = validator(config1)
     assert validated1 == config1
 
+    # Second Russian sensor with different text but same ASCII conversion should fail
     config2 = {CONF_NAME: "Датчик закрытия основного крана"}
-    validated2 = validator(config2)
-    assert validated2 == config2
-
-    # An exact duplicate still fails
-    config3 = {CONF_NAME: "Датчик открытия основного крана"}
-    with pytest.raises(
-        Invalid,
-        match=r"Duplicate binary_sensor entity with name 'Датчик открытия основного крана' found",
-    ):
-        validator(config3)
-
-
-def test_entity_duplicate_validator_hash_collision() -> None:
-    """Test that two different names with the same FNV-1 hash are rejected."""
-    # Brute-forced FNV-1 32-bit collision pair; both hash to 0x0ee5ff7b
-    name_a = "Sensor m2CZ"
-    name_b = "Sensor qCaa"
-    assert name_a != name_b
-    assert fnv1_hash_name(name_a) == fnv1_hash_name(name_b)
-
-    validator = entity_duplicate_validator("sensor")
-
-    config1 = {CONF_NAME: name_a}
-    validated1 = validator(config1)
-    assert validated1 == config1
-
-    config2 = {CONF_NAME: name_b}
     with pytest.raises(
         Invalid,
         match=re.compile(
-            rf"Duplicate sensor entity with name '{name_b}' found.*"
+            r"Duplicate binary_sensor entity with name 'Датчик закрытия основного крана' found.*"
-            rf"The names '{name_b}' and '{name_a}' produce the.*"
+            r"Original names: 'Датчик закрытия основного крана' and 'Датчик открытия основного крана'.*"
-            r"same entity key hash \(0x0ee5ff7b\).*"
+            r"Both convert to ASCII ID: '_______________________________'.*"
-            r"To fix: Rename one of the entities",
+            r"To fix: Add unique ASCII characters \(e\.g\., '1', '2', or 'A', 'B'\)",
             re.DOTALL,
         ),
     ):
         validator(config2)
 
 
-def test_object_id_conflicts_rejected_by_component_validator() -> None:
-    """Test that object_id conflicts pass entity validation but fail for mqtt/prometheus."""
-    validator = entity_duplicate_validator("sensor")
-
-    # Both names validate fine in general (distinct raw names, distinct keys)
-    validator({CONF_NAME: "Датчик открытия"})
-    validator({CONF_NAME: "Датчик закрытия"})
-
-    # A component that addresses entities by object_id must reject the config
-    component_validator = validate_no_object_id_conflicts(
-        "mqtt builds default topics from the entity object_id"
-    )
-    with pytest.raises(
-        Invalid,
-        match=re.compile(
-            r"mqtt builds default topics from the entity object_id.*"
-            r"sensor entities 'Датчик открытия', 'Датчик закрытия' "
-            r"share the object_id '_______________'.*"
-            r"To fix: Add unique ASCII characters",
-            re.DOTALL,
-        ),
-    ):
-        component_validator({})
-
-
-def test_object_id_conflicts_skipped_in_testing_mode() -> None:
-    """Test that testing_mode skips the conflict check, as used for grouped testing."""
-    validator = entity_duplicate_validator("sensor")
-    validator({CONF_NAME: "Датчик открытия"})
-    validator({CONF_NAME: "Датчик закрытия"})
-
-    component_validator = validate_no_object_id_conflicts(
-        "mqtt builds default topics from the entity object_id"
-    )
-    CORE.testing_mode = True
-    try:
-        config: dict = {}
-        assert component_validator(config) is config
-    finally:
-        CORE.testing_mode = False
-
-
-def test_object_id_conflicts_none_recorded() -> None:
-    """Test that distinct object_ids produce no conflicts."""
-    validator = entity_duplicate_validator("sensor")
-    validator({CONF_NAME: "Temperature"})
-    validator({CONF_NAME: "Humidity"})
-
-    component_validator = validate_no_object_id_conflicts(
-        "mqtt builds default topics from the entity object_id"
-    )
-    config: dict = {}
-    assert component_validator(config) is config
-
-
-def test_object_id_conflicts_device_scoped() -> None:
-    """Test that the object_id conflict check is scoped per device.
-
-    Same-named entities on different sub-devices were accepted before entity keys
-    moved to raw names, so the check keeps that scope; conflicts within one device
-    are still reported with the device named in the message.
-    """
-    validator = entity_duplicate_validator("sensor")
-    validator({CONF_NAME: "Temperature", CONF_DEVICE_ID: ID("device1", type="Device")})
-    validator({CONF_NAME: "Temperature", CONF_DEVICE_ID: ID("device2", type="Device")})
-
-    component_validator = validate_no_object_id_conflicts(
-        "prometheus builds metric labels from the entity object_id"
-    )
-    config: dict = {}
-    assert component_validator(config) is config
-
-    # Two names sanitizing identically on the same sub-device still conflict
-    validator(
-        {CONF_NAME: "Датчик открытия", CONF_DEVICE_ID: ID("device1", type="Device")}
-    )
-    validator(
-        {CONF_NAME: "Датчик закрытия", CONF_DEVICE_ID: ID("device1", type="Device")}
-    )
-    with pytest.raises(
-        Invalid,
-        match=re.compile(
-            r"prometheus builds metric labels.*on device 'device1'", re.DOTALL
-        ),
-    ):
-        component_validator({})
-
-
 def test_entity_duplicate_validator_same_name_no_enhanced_message() -> None:
     """Test that identical names don't show the enhanced message."""
     # Create validator for sensor platform
@@ -763,7 +825,7 @@ async def test_setup_entity_empty_name_with_device(
 
     # For empty-name entities, Python stores hash 0 - C++ calculates hash at runtime
     assert config.get("_entity_name") == ""
-    assert config.get("_entity_key") == 0
+    assert config.get("_entity_object_id_hash") == 0
 
 
 @pytest.mark.asyncio
@@ -792,7 +854,7 @@ async def test_setup_entity_empty_name_with_mac_suffix(
 
     # For empty-name entities, Python stores hash 0 - C++ calculates hash at runtime
     assert config.get("_entity_name") == ""
-    assert config.get("_entity_key") == 0
+    assert config.get("_entity_object_id_hash") == 0
 
 
 @pytest.mark.asyncio
@@ -822,7 +884,7 @@ async def test_setup_entity_empty_name_with_mac_suffix_no_friendly_name(
 
     # For empty-name entities, Python stores hash 0 - C++ calculates hash at runtime
     assert config.get("_entity_name") == ""
-    assert config.get("_entity_key") == 0
+    assert config.get("_entity_object_id_hash") == 0
 
 
 @pytest.mark.asyncio
@@ -853,7 +915,7 @@ async def test_setup_entity_empty_name_no_mac_suffix_no_friendly_name(
 
     # For empty-name entities, Python stores hash 0 - C++ calculates hash at runtime
     assert config.get("_entity_name") == ""
-    assert config.get("_entity_key") == 0
+    assert config.get("_entity_object_id_hash") == 0
 
 
 def test_register_string_overflow() -> None:

tests/unit_tests/fixtures/core/entity_helpers/object_id_conflict_mqtt.yaml

@@ -1,22 +0,0 @@
-esphome:
-  name: test-object-id-conflict
-
-esp32:
-  board: esp32dev
-
-wifi:
-  ssid: MySSID
-  password: password1
-
-mqtt:
-  broker: test.mosquitto.org
-
-sensor:
-  # Distinct raw names are fine in general, but both sanitize to the same
-  # object_id, which MQTT still uses to build default topics - should fail
-  - platform: template
-    name: "Датчик открытия"
-    lambda: return 21.0;
-  - platform: template
-    name: "Датчик закрытия"
-    lambda: return 22.0;

tests/unit_tests/fixtures/core/entity_helpers/object_id_conflict_no_mqtt.yaml

@@ -1,15 +0,0 @@
-esphome:
-  name: test-object-id-ok
-
-esp32:
-  board: esp32dev
-
-sensor:
-  # Distinct raw names that sanitize to the same object_id are allowed when no
-  # component addresses entities by object_id (no mqtt or prometheus configured)
-  - platform: template
-    name: "Датчик открытия"
-    lambda: return 21.0;
-  - platform: template
-    name: "Датчик закрытия"
-    lambda: return 22.0;

tests/unit_tests/test_preference_hash_stability.py

@@ -5,11 +5,11 @@ users to lose stored preferences (calibration values, restore states, etc.) on
 firmware upgrades, or break entity state routing to API clients.
 
 Two algorithms are locked here (see https://github.com/esphome/backlog/issues/85):
-1. `fnv1_hash_object_id(name)` - the LEGACY hash (snake_case + sanitize, then FNV-1).
+1. `fnv1_hash_object_id(name)` - the object_id hash (snake_case + sanitize, then FNV-1).
-   Existing devices have preferences stored under keys derived from it; slot-based
+   The entity key sent to API clients and the base of every stored preference key.
-   backends (ESP8266, RP2040) keep using it, and key-lookup backends migrate FROM it.
+2. `fnv1_hash_name(name)` - FNV-1 over the raw UTF-8 name bytes. 2026.8 beta
-2. `fnv1_hash_name(name)` - the entity key (FNV-1 over the raw UTF-8 name bytes).
+   firmware stored preferences under keys derived from it; a future key migration
-   Sent to API clients and used as the preference key base on key-lookup backends.
+   must reconstruct those keys to recover that data.
 
 DO NOT CHANGE THE EXPECTED VALUES - if tests fail after modifying a hash algorithm,
 the change breaks backward compatibility and will cause data loss.
@@ -124,8 +124,9 @@ def test_entity_object_id_hash_stability(
     """Verify fnv1_hash_object_id produces stable hashes for entity names.
 
     CRITICAL: These expected values MUST NOT CHANGE. Existing devices have
-    preferences stored under keys derived from this legacy hash; changing it
+    preferences stored under keys derived from this hash, and it is the entity
-    breaks the old-to-new key migration and loses stored preferences.
+    key sent to API clients; changing it loses stored preferences and breaks
+    entity state routing.
     """
     actual = fnv1_hash_object_id(entity_name)
     assert actual == expected_object_id_hash, (
@@ -144,9 +145,8 @@ def compute_legacy_preference_key(
 ) -> int:
     """Compute the legacy preference key: (object_id_hash ^ device_id) ^ version.
 
-    This is the key existing devices have data stored under. Slot-based backends
+    This is the key EntityBase::make_entity_preference_() (entity_base.cpp)
-    (ESP8266, RP2040) still use it directly; key-lookup backends compute it as the
+    stores every entity preference under.
-    migration source in EntityBase::make_entity_preference_() (entity_base.cpp).
     """
     object_id_hash = fnv1_hash_object_id(entity_name)
     preference_hash = object_id_hash ^ device_id
@@ -179,8 +179,8 @@ def test_legacy_preference_key_computation(
 ) -> None:
     """Verify legacy preference key computation matches expected values.
 
-    This test ensures the formula doesn't change, which would break both slot-based
+    This test ensures the formula doesn't change, which would lose stored
-    preference storage and the migration source keys on key-lookup backends.
+    preferences on every platform.
     """
     actual_key = compute_legacy_preference_key(entity_name, version, device_id)
 
@@ -215,12 +215,12 @@ def test_legacy_preference_key_computation(
     ],
 )
 def test_entity_key_hash_stability(entity_name: str, expected_key: int) -> None:
-    """Verify fnv1_hash_name produces stable entity keys.
+    """Verify fnv1_hash_name produces stable raw-name hashes.
 
-    CRITICAL: These expected values MUST NOT CHANGE. The entity key is sent to
+    CRITICAL: These expected values MUST NOT CHANGE. 2026.8 beta firmware stored
-    API clients and is the new preference key base; changing the algorithm
+    preferences under keys derived from this hash; a future key migration must
-    would break state routing and lose stored preferences.
+    reconstruct those keys, and changing the algorithm would strand that data.
-    Must match C++ fnv1_hash_bytes() in esphome/core/helpers.h.
+    Matched C++ fnv1_hash_bytes() (2026.8 beta), which the unrevert restores.
     """
     actual = fnv1_hash_name(entity_name)
     assert actual == expected_key, (