[sntp] Merge multiple instances to fix crash and undefined behavior

.github/workflows/codeql.yml

@@ -58,7 +58,7 @@ jobs:
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@014f16e7ab1402f30e7c3329d33797e7948572db # v4.31.3
+        uses: github/codeql-action/init@0499de31b99561a6d14a36a5f662c2a54f91beee # v4.31.2
         with:
           languages: ${{ matrix.language }}
           build-mode: ${{ matrix.build-mode }}
@@ -86,6 +86,6 @@ jobs:
           exit 1
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@014f16e7ab1402f30e7c3329d33797e7948572db # v4.31.3
+        uses: github/codeql-action/analyze@0499de31b99561a6d14a36a5f662c2a54f91beee # v4.31.2
         with:
           category: "/language:${{matrix.language}}"

.pre-commit-config.yaml

@@ -11,7 +11,7 @@ ci:
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
     # Ruff version.
-    rev: v0.14.5
+    rev: v0.14.4
     hooks:
       # Run the linter.
       - id: ruff

esphome/components/api/user_services.h

@@ -51,14 +51,13 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
       return false;
     if (req.args.size() != sizeof...(Ts))
       return false;
-    this->execute_(req.args, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_(req.args, typename gens<sizeof...(Ts)>::type());
     return true;
   }
 
  protected:
   virtual void execute(Ts... x) = 0;
-  template<typename ArgsContainer, size_t... S>
-  void execute_(const ArgsContainer &args, std::index_sequence<S...> type) {
+  template<typename ArgsContainer, int... S> void execute_(const ArgsContainer &args, seq<S...> type) {
     this->execute((get_execute_arg_value<Ts>(args[S]))...);
   }
 
@@ -96,14 +95,13 @@ template<typename... Ts> class UserServiceDynamic : public UserServiceDescriptor
       return false;
     if (req.args.size() != sizeof...(Ts))
       return false;
-    this->execute_(req.args, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_(req.args, typename gens<sizeof...(Ts)>::type());
     return true;
   }
 
  protected:
   virtual void execute(Ts... x) = 0;
-  template<typename ArgsContainer, size_t... S>
-  void execute_(const ArgsContainer &args, std::index_sequence<S...> type) {
+  template<typename ArgsContainer, int... S> void execute_(const ArgsContainer &args, seq<S...> type) {
     this->execute((get_execute_arg_value<Ts>(args[S]))...);
   }
 

esphome/components/script/script.h

@@ -46,14 +46,14 @@ template<typename... Ts> class Script : public ScriptLogger, public Trigger<Ts..
 
   // execute this script using a tuple that contains the arguments
   void execute_tuple(const std::tuple<Ts...> &tuple) {
-    this->execute_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    this->execute_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
   // Internal function to give scripts readable names.
   void set_name(const LogString *name) { name_ = name; }
 
  protected:
-  template<size_t... S> void execute_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void execute_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->execute(std::get<S>(tuple)...);
   }
 
@@ -157,7 +157,7 @@ template<typename... Ts> class QueueingScript : public Script<Ts...>, public Com
       const size_t queue_capacity = static_cast<size_t>(this->max_runs_ - 1);
       auto tuple_ptr = std::move(this->var_queue_[this->queue_front_]);
       this->queue_front_ = (this->queue_front_ + 1) % queue_capacity;
-      this->trigger_tuple_(*tuple_ptr, std::make_index_sequence<sizeof...(Ts)>{});
+      this->trigger_tuple_(*tuple_ptr, typename gens<sizeof...(Ts)>::type());
     }
   }
 
@@ -174,7 +174,7 @@ template<typename... Ts> class QueueingScript : public Script<Ts...>, public Com
     }
   }
 
-  template<size_t... S> void trigger_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void trigger_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->trigger(std::get<S>(tuple)...);
   }
 
@@ -305,7 +305,7 @@ template<class C, typename... Ts> class ScriptWaitAction : public Action<Ts...>,
 
     while (!this->param_queue_.empty()) {
       auto &params = this->param_queue_.front();
-      this->play_next_tuple_(params, std::make_index_sequence<sizeof...(Ts)>{});
+      this->play_next_tuple_(params, typename gens<sizeof...(Ts)>::type());
       this->param_queue_.pop_front();
     }
     // Queue is now empty - disable loop until next play_complex
@@ -321,7 +321,7 @@ template<class C, typename... Ts> class ScriptWaitAction : public Action<Ts...>,
   }
 
  protected:
-  template<size_t... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play_next_(std::get<S>(tuple)...);
   }
 

esphome/components/sntp/time.py

@@ -1,9 +1,14 @@
+import logging
+
 import esphome.codegen as cg
 from esphome.components import time as time_
+from esphome.config_helpers import merge_config
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ID,
+    CONF_PLATFORM,
     CONF_SERVERS,
+    CONF_TIME,
     PLATFORM_BK72XX,
     PLATFORM_ESP32,
     PLATFORM_ESP8266,
@@ -12,13 +17,74 @@ from esphome.const import (
     PLATFORM_RTL87XX,
 )
 from esphome.core import CORE
+import esphome.final_validate as fv
+from esphome.types import ConfigType
+
+_LOGGER = logging.getLogger(__name__)
 
 DEPENDENCIES = ["network"]
+
+CONF_SNTP = "sntp"
+
 sntp_ns = cg.esphome_ns.namespace("sntp")
 SNTPComponent = sntp_ns.class_("SNTPComponent", time_.RealTimeClock)
 
 DEFAULT_SERVERS = ["0.pool.ntp.org", "1.pool.ntp.org", "2.pool.ntp.org"]
 
+
+def _sntp_final_validate(config: ConfigType) -> None:
+    """Merge multiple SNTP instances into one, similar to OTA merging behavior."""
+    full_conf = fv.full_config.get()
+    time_confs = full_conf.get(CONF_TIME, [])
+
+    sntp_configs: list[ConfigType] = []
+    other_time_configs: list[ConfigType] = []
+
+    for time_conf in time_confs:
+        if time_conf.get(CONF_PLATFORM) == CONF_SNTP:
+            sntp_configs.append(time_conf)
+        else:
+            other_time_configs.append(time_conf)
+
+    if len(sntp_configs) <= 1:
+        return
+
+    # Merge all SNTP configs into the first one
+    merged = sntp_configs[0]
+    for sntp_conf in sntp_configs[1:]:
+        # Validate that IDs are consistent if manually specified
+        if merged[CONF_ID].is_manual and sntp_conf[CONF_ID].is_manual:
+            raise cv.Invalid(
+                f"Found multiple SNTP configurations but {CONF_ID} is inconsistent"
+            )
+        merged = merge_config(merged, sntp_conf)
+
+    # Deduplicate servers while preserving order
+    servers = merged[CONF_SERVERS]
+    unique_servers = list(dict.fromkeys(servers))
+
+    # Warn if we're dropping servers due to 3-server limit
+    if len(unique_servers) > 3:
+        dropped = unique_servers[3:]
+        unique_servers = unique_servers[:3]
+        _LOGGER.warning(
+            "SNTP supports maximum 3 servers. Dropped excess server(s): %s",
+            dropped,
+        )
+
+    merged[CONF_SERVERS] = unique_servers
+
+    _LOGGER.warning(
+        "Found and merged %d SNTP time configurations into one instance",
+        len(sntp_configs),
+    )
+
+    # Replace time configs with merged SNTP + other time platforms
+    other_time_configs.append(merged)
+    full_conf[CONF_TIME] = other_time_configs
+    fv.full_config.set(full_conf)
+
+
 CONFIG_SCHEMA = cv.All(
     time_.TIME_SCHEMA.extend(
         {
@@ -40,6 +106,8 @@ CONFIG_SCHEMA = cv.All(
     ),
 )
 
+FINAL_VALIDATE_SCHEMA = _sntp_final_validate
+
 
 async def to_code(config):
     servers = config[CONF_SERVERS]

esphome/components/uart/__init__.py

@@ -1,4 +1,3 @@
-from logging import getLogger
 import math
 import re
 
@@ -36,8 +35,6 @@ from esphome.core import CORE, ID
 import esphome.final_validate as fv
 from esphome.yaml_util import make_data_base
 
-_LOGGER = getLogger(__name__)
-
 CODEOWNERS = ["@esphome/core"]
 uart_ns = cg.esphome_ns.namespace("uart")
 UARTComponent = uart_ns.class_("UARTComponent")
@@ -133,21 +130,6 @@ def validate_host_config(config):
     return config
 
 
-def validate_rx_buffer_size(config):
-    if CORE.is_esp32:
-        # ESP32 UART hardware FIFO is 128 bytes (LP UART is 16 bytes, but we use 128 as safe minimum)
-        # rx_buffer_size must be greater than the hardware FIFO length
-        min_buffer_size = 128
-        if config[CONF_RX_BUFFER_SIZE] <= min_buffer_size:
-            _LOGGER.warning(
-                "UART rx_buffer_size (%d bytes) is too small and must be greater than the hardware "
-                "FIFO size (%d bytes). The buffer size will be automatically adjusted at runtime.",
-                config[CONF_RX_BUFFER_SIZE],
-                min_buffer_size,
-            )
-    return config
-
-
 def _uart_declare_type(value):
     if CORE.is_esp8266:
         return cv.declare_id(ESP8266UartComponent)(value)
@@ -265,7 +247,6 @@ CONFIG_SCHEMA = cv.All(
     ).extend(cv.COMPONENT_SCHEMA),
     cv.has_at_least_one_key(CONF_TX_PIN, CONF_RX_PIN, CONF_PORT),
     validate_host_config,
-    validate_rx_buffer_size,
 )
 
 

esphome/components/uart/uart_component_esp_idf.cpp

@@ -91,16 +91,6 @@ void IDFUARTComponent::setup() {
   this->uart_num_ = static_cast<uart_port_t>(next_uart_num++);
   this->lock_ = xSemaphoreCreateMutex();
 
-#if (SOC_UART_LP_NUM >= 1)
-  size_t fifo_len = ((this->uart_num_ < SOC_UART_HP_NUM) ? SOC_UART_FIFO_LEN : SOC_LP_UART_FIFO_LEN);
-#else
-  size_t fifo_len = SOC_UART_FIFO_LEN;
-#endif
-  if (this->rx_buffer_size_ <= fifo_len) {
-    ESP_LOGW(TAG, "rx_buffer_size is too small, must be greater than %zu", fifo_len);
-    this->rx_buffer_size_ = fifo_len * 2;
-  }
-
   xSemaphoreTake(this->lock_, portMAX_DELAY);
 
   this->load_settings(false);
@@ -247,12 +237,8 @@ void IDFUARTComponent::set_rx_timeout(size_t rx_timeout) {
 
 void IDFUARTComponent::write_array(const uint8_t *data, size_t len) {
   xSemaphoreTake(this->lock_, portMAX_DELAY);
-  int32_t write_len = uart_write_bytes(this->uart_num_, data, len);
+  uart_write_bytes(this->uart_num_, data, len);
   xSemaphoreGive(this->lock_);
-  if (write_len != (int32_t) len) {
-    ESP_LOGW(TAG, "uart_write_bytes failed: %d != %zu", write_len, len);
-    this->mark_failed();
-  }
 #ifdef USE_UART_DEBUGGER
   for (size_t i = 0; i < len; i++) {
     this->debug_callback_.call(UART_DIRECTION_TX, data[i]);
@@ -281,7 +267,6 @@ bool IDFUARTComponent::peek_byte(uint8_t *data) {
 
 bool IDFUARTComponent::read_array(uint8_t *data, size_t len) {
   size_t length_to_read = len;
-  int32_t read_len = 0;
   if (!this->check_read_timeout_(len))
     return false;
   xSemaphoreTake(this->lock_, portMAX_DELAY);
@@ -292,31 +277,25 @@ bool IDFUARTComponent::read_array(uint8_t *data, size_t len) {
     this->has_peek_ = false;
   }
   if (length_to_read > 0)
-    read_len = uart_read_bytes(this->uart_num_, data, length_to_read, 20 / portTICK_PERIOD_MS);
+    uart_read_bytes(this->uart_num_, data, length_to_read, 20 / portTICK_PERIOD_MS);
   xSemaphoreGive(this->lock_);
 #ifdef USE_UART_DEBUGGER
   for (size_t i = 0; i < len; i++) {
     this->debug_callback_.call(UART_DIRECTION_RX, data[i]);
   }
 #endif
-  return read_len == (int32_t) length_to_read;
+  return true;
 }
 
 int IDFUARTComponent::available() {
-  size_t available = 0;
-  esp_err_t err;
+  size_t available;
 
   xSemaphoreTake(this->lock_, portMAX_DELAY);
-  err = uart_get_buffered_data_len(this->uart_num_, &available);
+  uart_get_buffered_data_len(this->uart_num_, &available);
+  if (this->has_peek_)
+    available++;
   xSemaphoreGive(this->lock_);
 
-  if (err != ESP_OK) {
-    ESP_LOGW(TAG, "uart_get_buffered_data_len failed: %s", esp_err_to_name(err));
-    this->mark_failed();
-  }
-  if (this->has_peek_) {
-    available++;
-  }
   return available;
 }
 

esphome/components/wifi/__init__.py

@@ -12,6 +12,7 @@ from esphome.components.network import (
 from esphome.components.psram import is_guaranteed as psram_is_guaranteed
 from esphome.config_helpers import filter_source_files_from_platform
 import esphome.config_validation as cv
+from esphome.config_validation import only_with_esp_idf
 from esphome.const import (
     CONF_AP,
     CONF_BSSID,
@@ -351,7 +352,7 @@ CONFIG_SCHEMA = cv.All(
                 single=True
             ),
             cv.Optional(CONF_USE_PSRAM): cv.All(
-                cv.only_on_esp32, cv.requires_component("psram"), cv.boolean
+                only_with_esp_idf, cv.requires_component("psram"), cv.boolean
             ),
         }
     ),

esphome/core/automation.h

@@ -11,26 +11,10 @@
 
 namespace esphome {
 
-// C++20 std::index_sequence is now used for tuple unpacking
-// Legacy seq<>/gens<> pattern deprecated but kept for backwards compatibility
 // https://stackoverflow.com/questions/7858817/unpacking-a-tuple-to-call-a-matching-function-pointer/7858971#7858971
-// Remove before 2026.6.0
-// NOLINTBEGIN(readability-identifier-naming)
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-#endif
-
-template<int...> struct ESPDEPRECATED("Use std::index_sequence instead. Removed in 2026.6.0", "2025.12.0") seq {};
-template<int N, int... S>
-struct ESPDEPRECATED("Use std::make_index_sequence instead. Removed in 2026.6.0", "2025.12.0") gens
-    : gens<N - 1, N - 1, S...> {};
-template<int... S> struct gens<0, S...> { using type = seq<S...>; };
-
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic pop
-#endif
-// NOLINTEND(readability-identifier-naming)
+template<int...> struct seq {};                                       // NOLINT
+template<int N, int... S> struct gens : gens<N - 1, N - 1, S...> {};  // NOLINT
+template<int... S> struct gens<0, S...> { using type = seq<S...>; };  // NOLINT
 
 #define TEMPLATABLE_VALUE_(type, name) \
  protected: \
@@ -168,11 +152,11 @@ template<typename... Ts> class Condition {
 
   /// Call check with a tuple of values as parameter.
   bool check_tuple(const std::tuple<Ts...> &tuple) {
-    return this->check_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    return this->check_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
  protected:
-  template<size_t... S> bool check_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> bool check_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     return this->check(std::get<S>(tuple)...);
   }
 };
@@ -247,11 +231,11 @@ template<typename... Ts> class Action {
       }
     }
   }
-  template<size_t... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_next_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play_next_(std::get<S>(tuple)...);
   }
   void play_next_tuple_(const std::tuple<Ts...> &tuple) {
-    this->play_next_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
+    this->play_next_tuple_(tuple, typename gens<sizeof...(Ts)>::type());
   }
 
   virtual void stop() {}
@@ -293,9 +277,7 @@ template<typename... Ts> class ActionList {
     if (this->actions_begin_ != nullptr)
       this->actions_begin_->play_complex(x...);
   }
-  void play_tuple(const std::tuple<Ts...> &tuple) {
-    this->play_tuple_(tuple, std::make_index_sequence<sizeof...(Ts)>{});
-  }
+  void play_tuple(const std::tuple<Ts...> &tuple) { this->play_tuple_(tuple, typename gens<sizeof...(Ts)>::type()); }
   void stop() {
     if (this->actions_begin_ != nullptr)
       this->actions_begin_->stop_complex();
@@ -316,7 +298,7 @@ template<typename... Ts> class ActionList {
   }
 
  protected:
-  template<size_t... S> void play_tuple_(const std::tuple<Ts...> &tuple, std::index_sequence<S...> /*unused*/) {
+  template<int... S> void play_tuple_(const std::tuple<Ts...> &tuple, seq<S...> /*unused*/) {
     this->play(std::get<S>(tuple)...);
   }
 

requirements_test.txt

@@ -1,6 +1,6 @@
 pylint==4.0.3
 flake8==7.3.0  # also change in .pre-commit-config.yaml when updating
-ruff==0.14.5  # also change in .pre-commit-config.yaml when updating
+ruff==0.14.4  # also change in .pre-commit-config.yaml when updating
 pyupgrade==3.21.1  # also change in .pre-commit-config.yaml when updating
 pre-commit
 

tests/component_tests/sntp/__init__.py

@@ -0,0 +1 @@
+"""Tests for SNTP component."""

tests/component_tests/sntp/config/sntp_test.yaml

@@ -0,0 +1,22 @@
+esphome:
+  name: sntp-test
+
+esp32:
+  board: esp32dev
+  framework:
+    type: esp-idf
+
+wifi:
+  ssid: "testssid"
+  password: "testpassword"
+
+# Test multiple SNTP instances that should be merged
+time:
+  - platform: sntp
+    servers:
+      - 192.168.1.1
+      - pool.ntp.org
+  - platform: sntp
+    servers:
+      - pool.ntp.org
+      - 192.168.1.2

tests/component_tests/sntp/test_init.py

@@ -0,0 +1,238 @@
+"""Tests for SNTP time configuration validation."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+import pytest
+
+from esphome import config_validation as cv
+from esphome.components.sntp.time import CONF_SNTP, _sntp_final_validate
+from esphome.const import CONF_ID, CONF_PLATFORM, CONF_SERVERS, CONF_TIME
+from esphome.core import ID
+import esphome.final_validate as fv
+
+
+@pytest.mark.parametrize(
+    ("time_configs", "expected_count", "expected_servers", "warning_messages"),
+    [
+        pytest.param(
+            [
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.1", "pool.ntp.org"],
+                }
+            ],
+            1,
+            ["192.168.1.1", "pool.ntp.org"],
+            [],
+            id="single_instance_no_merge",
+        ),
+        pytest.param(
+            [
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_1", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.1", "pool.ntp.org"],
+                },
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_2", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.2"],
+                },
+            ],
+            1,
+            ["192.168.1.1", "pool.ntp.org", "192.168.1.2"],
+            ["Found and merged 2 SNTP time configurations into one instance"],
+            id="two_instances_merged",
+        ),
+        pytest.param(
+            [
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_1", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.1", "pool.ntp.org"],
+                },
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_2", is_manual=False),
+                    CONF_SERVERS: ["pool.ntp.org", "192.168.1.2"],
+                },
+            ],
+            1,
+            ["192.168.1.1", "pool.ntp.org", "192.168.1.2"],
+            ["Found and merged 2 SNTP time configurations into one instance"],
+            id="deduplication_preserves_order",
+        ),
+        pytest.param(
+            [
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_1", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.1", "pool.ntp.org"],
+                },
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_2", is_manual=False),
+                    CONF_SERVERS: ["192.168.1.2", "pool2.ntp.org"],
+                },
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_3", is_manual=False),
+                    CONF_SERVERS: ["pool3.ntp.org"],
+                },
+            ],
+            1,
+            ["192.168.1.1", "pool.ntp.org", "192.168.1.2"],
+            [
+                "SNTP supports maximum 3 servers. Dropped excess server(s): ['pool2.ntp.org', 'pool3.ntp.org']",
+                "Found and merged 3 SNTP time configurations into one instance",
+            ],
+            id="three_instances_drops_excess_servers",
+        ),
+        pytest.param(
+            [
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_1", is_manual=False),
+                    CONF_SERVERS: [
+                        "192.168.1.1",
+                        "pool.ntp.org",
+                        "pool.ntp.org",
+                        "192.168.1.1",
+                    ],
+                },
+                {
+                    CONF_PLATFORM: CONF_SNTP,
+                    CONF_ID: ID("sntp_time_2", is_manual=False),
+                    CONF_SERVERS: ["pool.ntp.org", "192.168.1.2"],
+                },
+            ],
+            1,
+            ["192.168.1.1", "pool.ntp.org", "192.168.1.2"],
+            ["Found and merged 2 SNTP time configurations into one instance"],
+            id="deduplication_multiple_duplicates",
+        ),
+    ],
+)
+def test_sntp_instance_merging(
+    time_configs: list[dict[str, Any]],
+    expected_count: int,
+    expected_servers: list[str],
+    warning_messages: list[str],
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Test SNTP instance merging behavior."""
+    # Create a mock full config with time configs
+    full_conf = {CONF_TIME: time_configs.copy()}
+
+    # Set the context var
+    token = fv.full_config.set(full_conf)
+    try:
+        with caplog.at_level(logging.WARNING):
+            _sntp_final_validate({})
+
+        # Get the updated config
+        updated_conf = fv.full_config.get()
+
+        # Check if merging occurred
+        if len(time_configs) > 1:
+            # Verify only one SNTP instance remains
+            sntp_instances = [
+                tc
+                for tc in updated_conf[CONF_TIME]
+                if tc.get(CONF_PLATFORM) == CONF_SNTP
+            ]
+            assert len(sntp_instances) == expected_count
+
+            # Verify server list
+            assert sntp_instances[0][CONF_SERVERS] == expected_servers
+
+            # Verify warnings
+            for expected_msg in warning_messages:
+                assert any(
+                    expected_msg in record.message for record in caplog.records
+                ), f"Expected warning message '{expected_msg}' not found in log"
+        else:
+            # Single instance should not trigger merging or warnings
+            assert len(caplog.records) == 0
+            # Config should be unchanged
+            assert updated_conf[CONF_TIME] == time_configs
+    finally:
+        fv.full_config.reset(token)
+
+
+def test_sntp_inconsistent_manual_ids() -> None:
+    """Test that inconsistent manual IDs raise an error."""
+    # Create configs with manual IDs that are inconsistent
+    time_configs = [
+        {
+            CONF_PLATFORM: CONF_SNTP,
+            CONF_ID: ID("sntp_time_1", is_manual=True),
+            CONF_SERVERS: ["192.168.1.1"],
+        },
+        {
+            CONF_PLATFORM: CONF_SNTP,
+            CONF_ID: ID("sntp_time_2", is_manual=True),
+            CONF_SERVERS: ["192.168.1.2"],
+        },
+    ]
+
+    full_conf = {CONF_TIME: time_configs}
+
+    token = fv.full_config.set(full_conf)
+    try:
+        with pytest.raises(
+            cv.Invalid,
+            match="Found multiple SNTP configurations but id is inconsistent",
+        ):
+            _sntp_final_validate({})
+    finally:
+        fv.full_config.reset(token)
+
+
+def test_sntp_with_other_time_platforms(caplog: pytest.LogCaptureFixture) -> None:
+    """Test that SNTP merging doesn't affect other time platforms."""
+    time_configs = [
+        {
+            CONF_PLATFORM: CONF_SNTP,
+            CONF_ID: ID("sntp_time_1", is_manual=False),
+            CONF_SERVERS: ["192.168.1.1"],
+        },
+        {
+            CONF_PLATFORM: "homeassistant",
+            CONF_ID: ID("homeassistant_time", is_manual=False),
+        },
+        {
+            CONF_PLATFORM: CONF_SNTP,
+            CONF_ID: ID("sntp_time_2", is_manual=False),
+            CONF_SERVERS: ["192.168.1.2"],
+        },
+    ]
+
+    full_conf = {CONF_TIME: time_configs.copy()}
+
+    token = fv.full_config.set(full_conf)
+    try:
+        with caplog.at_level(logging.WARNING):
+            _sntp_final_validate({})
+
+        updated_conf = fv.full_config.get()
+
+        # Should have 2 time platforms: 1 merged SNTP + 1 homeassistant
+        assert len(updated_conf[CONF_TIME]) == 2
+
+        # Find the platforms
+        platforms = {tc[CONF_PLATFORM] for tc in updated_conf[CONF_TIME]}
+        assert platforms == {CONF_SNTP, "homeassistant"}
+
+        # Verify SNTP was merged
+        sntp_instances = [
+            tc for tc in updated_conf[CONF_TIME] if tc[CONF_PLATFORM] == CONF_SNTP
+        ]
+        assert len(sntp_instances) == 1
+        assert sntp_instances[0][CONF_SERVERS] == ["192.168.1.1", "192.168.1.2"]
+    finally:
+        fv.full_config.reset(token)