diff --git a/custom_components/ha_text_ai/__init__.py b/custom_components/ha_text_ai/__init__.py
index d5e6d3e..5782a57 100644
--- a/custom_components/ha_text_ai/__init__.py
+++ b/custom_components/ha_text_ai/__init__.py
@@ -9,7 +9,7 @@ The HA Text AI integration.
 from __future__ import annotations
 
 import logging
-from typing import Any, Dict
+from typing import Any
 
 import asyncio
 
@@ -20,12 +20,11 @@ from homeassistant.const import CONF_API_KEY, CONF_NAME
 from homeassistant.core import HomeAssistant, ServiceCall, SupportsResponse
 from homeassistant.exceptions import ConfigEntryNotReady, HomeAssistantError
 from homeassistant.helpers import config_validation as cv
-from homeassistant.helpers import aiohttp_client
 from homeassistant.util import dt as dt_util
 
 from .coordinator import HATextAICoordinator
 from .api_client import APIClient
-from .utils import normalize_name, safe_log_data, validate_endpoint
+from .utils import create_pinned_session, normalize_name, safe_log_data, validate_endpoint
 from .providers import get_default_endpoint, get_default_model, build_auth_headers
 from .const import (
     DOMAIN,
@@ -110,7 +109,7 @@ def get_coordinator_by_instance(hass: HomeAssistant, instance: str) -> HATextAIC
 
     raise HomeAssistantError(f"Instance {instance} not found")
 
-async def async_setup(hass: HomeAssistant, config: Dict[str, Any]) -> bool:
+async def async_setup(hass: HomeAssistant, config: dict[str, Any]) -> bool:
     """Set up the Home Assistant Text AI component."""
     # Initialize domain data storage
     hass.data.setdefault(DOMAIN, {})
@@ -274,22 +273,26 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
             _LOGGER.error("API provider not specified")
             raise ConfigEntryNotReady("API provider is required")
 
-        session = aiohttp_client.async_get_clientsession(hass)
-
         model = config.get(CONF_MODEL, get_default_model(api_provider))
         raw_endpoint = config.get(CONF_API_ENDPOINT, get_default_endpoint(api_provider))
         allow_local = config.get(CONF_ALLOW_LOCAL_NETWORK, DEFAULT_ALLOW_LOCAL_NETWORK)
         if allow_local:
-            _LOGGER.warning(
+            _LOGGER.info(
                 "Local network mode enabled for endpoint %s — "
-                "SSRF protection disabled, API credentials may be sent without TLS",
+                "SSRF protection relaxed for self-hosted proxies",
                 raw_endpoint,
             )
         try:
-            endpoint = await validate_endpoint(hass, raw_endpoint, allow_local=allow_local)
+            endpoint, resolved_ips = await validate_endpoint(
+                hass, raw_endpoint, allow_local=allow_local
+            )
         except ValueError as err:
             _LOGGER.error("Invalid API endpoint: %s", err)
             raise ConfigEntryNotReady(f"Invalid API endpoint: {err}") from err
+
+        # Pinned session closes DNS-rebinding TOCTOU and isolates cookies
+        # from other integrations sharing the same endpoint hostname.
+        session = create_pinned_session(hass, endpoint, resolved_ips)
         # API key can now be updated via options
         api_key = config.get(CONF_API_KEY, entry.data.get(CONF_API_KEY))
         instance_name = entry.data.get(CONF_NAME, entry.entry_id)
@@ -363,7 +366,6 @@ async def async_update_options(hass: HomeAssistant, entry: ConfigEntry) -> None:
     _LOGGER.info("Options updated for %s, reloading integration", entry.title)
     await hass.config_entries.async_reload(entry.entry_id)
 
-
 async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
     """Unload a config entry."""
     try:
diff --git a/custom_components/ha_text_ai/api_client.py b/custom_components/ha_text_ai/api_client.py
index 9f266a5..dbc5737 100644
--- a/custom_components/ha_text_ai/api_client.py
+++ b/custom_components/ha_text_ai/api_client.py
@@ -8,9 +8,11 @@ API Client for HA Text AI.
 """
 from __future__ import annotations
 
-import logging
 import asyncio
-from typing import Any, Dict, List, Optional
+import json
+import logging
+import re
+from typing import Any
 from aiohttp import ClientSession, ClientTimeout
 
 from homeassistant.exceptions import HomeAssistantError
@@ -29,7 +31,6 @@ from .const import (
 
 _LOGGER = logging.getLogger(__name__)
 
-
 class APIClient:
     """API Client for OpenAI and Anthropic."""
 
@@ -37,11 +38,11 @@ class APIClient:
         self,
         session: ClientSession,
         endpoint: str,
-        headers: Dict[str, str],
+        headers: dict[str, str],
         api_provider: str,
         model: str,
         api_timeout: int = DEFAULT_API_TIMEOUT,
-        api_key: Optional[str] = None,
+        api_key: str | None = None,
     ) -> None:
         """Initialize API client."""
         self.session = session
@@ -89,8 +90,8 @@ class APIClient:
     async def _make_request(
         self,
         url: str,
-        payload: Dict[str, Any],
-    ) -> Dict[str, Any]:
+        payload: dict[str, Any],
+    ) -> dict[str, Any]:
         """Make API request with retry logic for transient errors only.
 
         Retries on:
@@ -174,7 +175,7 @@ class APIClient:
         raise HomeAssistantError("API request failed after all retries")
 
     @staticmethod
-    def _parse_retry_after(value: Optional[str]) -> Optional[float]:
+    def _parse_retry_after(value: str | None) -> float | None:
         """Parse Retry-After header (seconds). Caps at 60s to avoid long stalls."""
         if not value:
             return None
@@ -189,13 +190,13 @@ class APIClient:
     async def create(
         self,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Create completion using appropriate API."""
         try:
             self._validate_parameters(temperature, max_tokens)
@@ -224,43 +225,60 @@ class APIClient:
             _LOGGER.error("API request failed: %s", str(e))
             raise HomeAssistantError(f"API request failed: {str(e)}") from e
 
-    @staticmethod
-    def _is_openai_reasoning_model(model: str) -> bool:
-        """Detect OpenAI reasoning models (o-series and GPT-5 family).
+    # Non-reasoning variants whose names otherwise overlap with the
+    # reasoning prefix set (e.g. "gpt-5-chat-latest" is classic chat).
+    _OPENAI_NON_REASONING_PATTERNS: tuple[str, ...] = ("gpt-5-chat",)
+    _OPENAI_REASONING_REGEX = re.compile(
+        r"^(?:o\d+|gpt-[5-9](?:\.\d+)?)(?:[-_].*)?$"
+    )
+
+    @classmethod
+    def _is_openai_reasoning_model(cls, model: str) -> bool:
+        """Detect OpenAI reasoning models (o-series and GPT-5+ family).
 
         Reasoning models require max_completion_tokens (not max_tokens),
         do not accept custom temperature, and use "developer" role instead
-        of "system". Cutoff: models released 2025-09 and later are all
-        reasoning-by-default (o3, o4-mini, gpt-5, gpt-5-mini, gpt-5-nano).
+        of "system". Uses a regex so future o5/gpt-6 releases are caught
+        without code change. Explicitly excludes chat-variants
+        (e.g. gpt-5-chat-latest) which are classic chat models.
         """
         if not model:
             return False
-        m = model.lower().lstrip()
-        # Match bare model names and dated variants (o3-2025-04-16 etc.)
-        return (
-            m.startswith(("o1", "o3", "o4-mini", "o4"))
-            or m.startswith(("gpt-5", "gpt5"))
-        )
+        m = model.strip().lower()
+        # OpenRouter-style "openai/o3" prefix — strip provider namespace.
+        if "/" in m:
+            m = m.rsplit("/", 1)[-1]
+        for non_reasoning in cls._OPENAI_NON_REASONING_PATTERNS:
+            if m.startswith(non_reasoning):
+                return False
+        return bool(cls._OPENAI_REASONING_REGEX.match(m))
 
     @staticmethod
     def _convert_system_to_developer(
-        messages: List[Dict[str, str]],
-    ) -> List[Dict[str, str]]:
+        messages: list[dict[str, str]],
+    ) -> list[dict[str, str]]:
         """Rename role "system" to "developer" for OpenAI reasoning models."""
         return [
             {**m, "role": "developer"} if m.get("role") == "system" else m
             for m in messages
         ]
 
-    @staticmethod
+    # Matches /no_think only as a standalone soft-switch token (word-bounded),
+    # not when users discuss the concept ("discuss /no_think semantics").
+    _NO_THINK_TOKEN_RE = re.compile(r"(?:^|\s)/no_think(?:\s|$)")
+
+    @classmethod
     def _apply_no_think_tag(
-        messages: List[Dict[str, str]],
-    ) -> List[Dict[str, str]]:
+        cls,
+        messages: list[dict[str, str]],
+    ) -> list[dict[str, str]]:
         """Append Qwen-style /no_think soft switch to the last user message.
 
         Why: Qwen3 reasoning models treat "/no_think" in the last user turn as a
         request to skip thinking. Non-Qwen models ignore the trailing token
         harmlessly, so this is safe to apply to all OpenAI-compatible backends.
+        Uses word-boundary regex for dedup so that user content mentioning
+        "/no_think" mid-sentence isn't mistaken for an existing soft switch.
         """
         if not messages:
             return messages
@@ -268,8 +286,8 @@ class APIClient:
         for i in range(len(patched) - 1, -1, -1):
             if patched[i].get("role") == "user":
                 content = patched[i].get("content", "")
-                if "/no_think" not in content:
-                    patched[i]["content"] = f"{content} /no_think".strip()
+                if not cls._NO_THINK_TOKEN_RE.search(content):
+                    patched[i]["content"] = f"{content.rstrip()} /no_think".lstrip()
                 break
         return patched
 
@@ -285,7 +303,6 @@ class APIClient:
         """
         if not text or "<think>" not in text:
             return text
-        import re
         pattern = re.compile(r"<think>.*?</think>", flags=re.DOTALL)
         cleaned = text
         # Iterative pass: each iteration peels one layer of nested tags.
@@ -303,14 +320,13 @@ class APIClient:
 
     @staticmethod
     def _apply_structured_output(
-        payload: Dict[str, Any],
+        payload: dict[str, Any],
         structured_output: bool,
-        json_schema: Optional[str],
+        json_schema: str | None,
     ) -> None:
         """Apply OpenAI-compatible structured output to payload in-place."""
         if not (structured_output and json_schema):
             return
-        import json
         try:
             schema = json.loads(json_schema)
             payload["response_format"] = {
@@ -328,16 +344,28 @@ class APIClient:
     async def _create_deepseek_completion(
         self,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
-    ) -> Dict[str, Any]:
-        """Create completion using DeepSeek API."""
+    ) -> dict[str, Any]:
+        """Create completion using DeepSeek API.
+
+        DeepSeek-reasoner (R1) is a reasoning model: it ignores /no_think
+        (thinking is always on by design) and emits reasoning_content as a
+        separate field alongside content. We skip the no_think append for
+        this model and preserve reasoning_content in the response payload
+        so it's available for logging/debug.
+        """
         url = f"{self.endpoint}/chat/completions"
-        final_messages = self._apply_no_think_tag(messages) if disable_thinking else messages
+        is_reasoner = "reasoner" in model.lower()
+        final_messages = (
+            self._apply_no_think_tag(messages)
+            if (disable_thinking and not is_reasoner)
+            else messages
+        )
         payload = {
             "model": model,
             "messages": final_messages,
@@ -348,13 +376,18 @@ class APIClient:
         self._apply_structured_output(payload, structured_output, json_schema)
 
         data = await self._make_request(url, payload)
-        content = data["choices"][0]["message"]["content"]
-        if disable_thinking:
+        message = data["choices"][0]["message"]
+        content = message.get("content", "")
+        reasoning = message.get("reasoning_content")
+        if disable_thinking and not is_reasoner:
             content = self._strip_think_blocks(content)
         return {
             "choices": [
                 {
-                    "message": {"content": content},
+                    "message": {
+                        "content": content,
+                        **({"reasoning_content": reasoning} if reasoning else {}),
+                    },
                 }
             ],
             "usage": {
@@ -367,13 +400,13 @@ class APIClient:
     async def _create_openai_completion(
         self,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Create completion using OpenAI API.
 
         Reasoning models (o-series, gpt-5 family) require a different payload
@@ -388,13 +421,16 @@ class APIClient:
 
         if is_reasoning:
             prepared_messages = self._convert_system_to_developer(messages)
-            payload: Dict[str, Any] = {
+            payload: dict[str, Any] = {
                 "model": model,
                 "messages": prepared_messages,
                 "max_completion_tokens": max_tokens,
             }
             if disable_thinking:
-                payload["reasoning_effort"] = "low"
+                # gpt-5+ supports "minimal" (cheapest, lowest-CoT). o-series
+                # rejects "minimal" and accepts low/medium/high — fall back to "low".
+                effort = "minimal" if model.lower().startswith(("gpt-5", "gpt5")) else "low"
+                payload["reasoning_effort"] = effort
         else:
             prepared_messages = (
                 self._apply_no_think_tag(messages) if disable_thinking else messages
@@ -429,13 +465,13 @@ class APIClient:
     async def _create_anthropic_completion(
         self,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Create completion using Anthropic API."""
         url = f"{self.endpoint}/v1/messages"
 
@@ -455,10 +491,9 @@ class APIClient:
         # schema strings (built from templates/webhook data) could otherwise
         # break out of the JSON fence and rewrite the system instruction.
         if structured_output and json_schema:
-            import json as _json
             try:
-                _json.loads(json_schema)
-            except _json.JSONDecodeError as err:
+                json.loads(json_schema)
+            except json.JSONDecodeError as err:
                 _LOGGER.warning(
                     "Anthropic: invalid JSON schema, ignoring structured_output: %s", err
                 )
@@ -489,10 +524,14 @@ class APIClient:
             payload["system"] = system_prompt
 
         data = await self._make_request(url, payload)
-        # Anthropic returns text in "content" array; extended thinking arrives
-        # as a separate thinking-type block (not <think> tags), so no strip
-        # is required. Extended thinking is opt-in — we simply never request it.
-        content = data["content"][0]["text"]
+        # Anthropic returns an array of content blocks; if extended thinking
+        # is ever enabled the first block may be type="thinking". Find the
+        # first text-type block instead of hardcoding index [0].
+        content = ""
+        for block in data.get("content", []):
+            if block.get("type") == "text":
+                content = block.get("text", "")
+                break
         return {
             "choices": [
                 {
@@ -509,13 +548,13 @@ class APIClient:
     async def _create_gemini_completion(
         self,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Create completion using Gemini API with google-genai library.
 
         Args:
@@ -566,7 +605,6 @@ class APIClient:
             parsed_schema = None
             if structured_output and json_schema:
                 try:
-                    import json
                     parsed_schema = json.loads(json_schema)
                     _LOGGER.debug("Gemini structured output enabled with schema")
                 except json.JSONDecodeError as e:
@@ -589,10 +627,14 @@ class APIClient:
                     config.response_mime_type = "application/json"
                     config.response_schema = parsed_schema
 
-                # Disable thinking for Gemini 2.5+ models (ignored by 2.0 and earlier)
+                # Disable thinking for Gemini 2.5+ models. Flash variants accept
+                # thinking_budget=0 (fully off); Pro variants reject 0 and require
+                # at least 128 tokens of thinking. 2.0 and earlier ignore the field.
                 if disable_thinking:
+                    m_lower = model.lower()
+                    budget = 128 if "2.5-pro" in m_lower else 0
                     try:
-                        config.thinking_config = types.ThinkingConfig(thinking_budget=0)
+                        config.thinking_config = types.ThinkingConfig(thinking_budget=budget)
                     except (AttributeError, TypeError) as err:
                         _LOGGER.debug(
                             "ThinkingConfig not supported by this google-genai version: %s", err
@@ -685,10 +727,12 @@ class APIClient:
 
         except ImportError as e:
             _LOGGER.error("Google Gemini library not installed: %s", e)
-            raise HomeAssistantError("Missing dependency: google-genai. Please install it.")
+            raise HomeAssistantError(
+                "Missing dependency: google-genai. Please install it."
+            ) from e
         except Exception as e:
             _LOGGER.error("Gemini API error: %s", e)
-            raise HomeAssistantError("Gemini API request failed")
+            raise HomeAssistantError(f"Gemini API request failed: {e}") from e
 
     async def shutdown(self) -> None:
         """Shutdown API client."""
diff --git a/custom_components/ha_text_ai/config_flow.py b/custom_components/ha_text_ai/config_flow.py
index c744c36..7eca6ca 100644
--- a/custom_components/ha_text_ai/config_flow.py
+++ b/custom_components/ha_text_ai/config_flow.py
@@ -9,14 +9,13 @@ Config flow for HA text AI integration.
 from __future__ import annotations
 
 import logging
-from typing import Any, Dict, Optional
+from typing import Any
 
 import voluptuous as vol
 from homeassistant import config_entries
 from homeassistant.const import CONF_API_KEY, CONF_NAME
 from homeassistant.core import callback
 from homeassistant.config_entries import ConfigFlowResult
-from homeassistant.helpers.aiohttp_client import async_get_clientsession
 from homeassistant.helpers import selector
 
 from .const import (
@@ -61,13 +60,17 @@ from .const import (
 )
 from homeassistant.util import dt as dt_util
 
-from .utils import normalize_name, safe_log_data, validate_endpoint
+from .utils import (
+    create_pinned_session,
+    normalize_name,
+    safe_log_data,
+    validate_endpoint,
+)
 from .providers import get_default_endpoint, get_default_model, build_auth_headers
 
 _LOGGER = logging.getLogger(__name__)
 
-
-def _build_parameter_schema(data: Dict[str, Any]) -> dict:
+def _build_parameter_schema(data: dict[str, Any]) -> dict:
     """Build shared parameter schema fields used by both ConfigFlow and OptionsFlow."""
     return {
         vol.Optional(
@@ -100,7 +103,6 @@ def _build_parameter_schema(data: Dict[str, Any]) -> dict:
         ): bool,
     }
 
-
 class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
     """Handle a config flow for HA text AI."""
 
@@ -112,7 +114,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         self._data = {}
         self._provider = None
 
-    async def async_step_user(self, user_input: Optional[Dict[str, Any]] = None) -> ConfigFlowResult:
+    async def async_step_user(self, user_input: dict[str, Any] | None = None) -> ConfigFlowResult:
         """Handle the initial step."""
         if user_input is None:
             return self.async_show_form(
@@ -131,7 +133,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         return await self.async_step_provider()
 
     def _build_provider_schema(
-        self, data: Optional[Dict[str, Any]] = None
+        self, data: dict[str, Any] | None = None
     ) -> vol.Schema:
         """Build provider configuration schema with optional defaults from data."""
         defaults = data or {}
@@ -150,7 +152,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         schema_dict.update(_build_parameter_schema(defaults))
         return vol.Schema(schema_dict)
 
-    async def async_step_provider(self, user_input: Optional[Dict[str, Any]] = None) -> ConfigFlowResult:
+    async def async_step_provider(self, user_input: dict[str, Any] | None = None) -> ConfigFlowResult:
         """Handle provider configuration step."""
         self._errors = {}
 
@@ -229,7 +231,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
         return normalized
 
-    async def _async_validate_api(self, user_input: Dict[str, Any]) -> bool:
+    async def _async_validate_api(self, user_input: dict[str, Any]) -> bool:
         """Validate API connection using provider registry."""
         try:
             if CONF_API_KEY not in user_input:
@@ -239,7 +241,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
 
             try:
                 allow_local = user_input.get(CONF_ALLOW_LOCAL_NETWORK, DEFAULT_ALLOW_LOCAL_NETWORK)
-                endpoint = await validate_endpoint(
+                endpoint, resolved_ips = await validate_endpoint(
                     self.hass, user_input[CONF_API_ENDPOINT], allow_local=allow_local
                 )
             except ValueError as err:
@@ -253,7 +255,9 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
                     return False
                 return True
 
-            session = async_get_clientsession(self.hass)
+            # Pinned session ensures the reachability check goes to the same
+            # IP that will later be used by api_client (no DNS rebinding).
+            session = create_pinned_session(self.hass, endpoint, resolved_ips)
             headers = build_auth_headers(self._provider, user_input[CONF_API_KEY])
 
             from .providers import get_provider_config
@@ -274,7 +278,7 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
             self._errors["base"] = "cannot_connect"
             return False
 
-    async def _create_entry(self, user_input: Dict[str, Any]) -> ConfigFlowResult:
+    async def _create_entry(self, user_input: dict[str, Any]) -> ConfigFlowResult:
         """Create the config entry with unique_id deduplication."""
         instance_name = user_input[CONF_NAME]
         normalized_name = normalize_name(instance_name)
@@ -314,7 +318,6 @@ class HATextAIConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         """Get the options flow for this handler."""
         return OptionsFlowHandler()
 
-
 class OptionsFlowHandler(config_entries.OptionsFlow):
     """Handle options flow."""
 
@@ -326,7 +329,9 @@ class OptionsFlowHandler(config_entries.OptionsFlow):
                 return False
 
             try:
-                endpoint = await validate_endpoint(self.hass, endpoint, allow_local=allow_local)
+                endpoint, resolved_ips = await validate_endpoint(
+                    self.hass, endpoint, allow_local=allow_local
+                )
             except ValueError as err:
                 _LOGGER.error("Endpoint validation failed: %s", err)
                 self._errors["base"] = "cannot_connect"
@@ -335,7 +340,7 @@ class OptionsFlowHandler(config_entries.OptionsFlow):
             if provider == API_PROVIDER_GEMINI:
                 return True
 
-            session = async_get_clientsession(self.hass)
+            session = create_pinned_session(self.hass, endpoint, resolved_ips)
             headers = build_auth_headers(provider, api_key)
 
             from .providers import get_provider_config
@@ -356,11 +361,11 @@ class OptionsFlowHandler(config_entries.OptionsFlow):
             self._errors["base"] = "cannot_connect"
             return False
 
-    async def async_step_init(self, user_input: Optional[Dict[str, Any]] = None) -> ConfigFlowResult:
+    async def async_step_init(self, user_input: dict[str, Any] | None = None) -> ConfigFlowResult:
         """Handle provider selection step."""
         if not hasattr(self, "_errors"):
             self._errors: dict[str, str] = {}
-            self._selected_provider: Optional[str] = None
+            self._selected_provider: str | None = None
         current_data = {**self.config_entry.data, **self.config_entry.options}
         current_provider = current_data.get(CONF_API_PROVIDER, API_PROVIDER_OPENAI)
 
@@ -386,7 +391,7 @@ class OptionsFlowHandler(config_entries.OptionsFlow):
             }
         )
 
-    async def async_step_settings(self, user_input: Optional[Dict[str, Any]] = None) -> ConfigFlowResult:
+    async def async_step_settings(self, user_input: dict[str, Any] | None = None) -> ConfigFlowResult:
         """Handle settings configuration step."""
         self._errors = {}
         current_data = {**self.config_entry.data, **self.config_entry.options}
@@ -477,8 +482,8 @@ class OptionsFlowHandler(config_entries.OptionsFlow):
     def _get_settings_schema(
         self,
         provider: str,
-        current_data: Dict[str, Any],
-        user_input: Optional[Dict[str, Any]],
+        current_data: dict[str, Any],
+        user_input: dict[str, Any] | None,
         default_endpoint: str,
         default_model: str,
     ) -> vol.Schema:
diff --git a/custom_components/ha_text_ai/const.py b/custom_components/ha_text_ai/const.py
index 97f08ba..f3ab014 100644
--- a/custom_components/ha_text_ai/const.py
+++ b/custom_components/ha_text_ai/const.py
@@ -29,7 +29,7 @@ API_PROVIDERS: Final = [
     API_PROVIDER_GEMINI
 ]
 
-VERSION: Final = "2.5.0"
+VERSION: Final = "2.5.1"
 
 # Default endpoints
 DEFAULT_OPENAI_ENDPOINT: Final = "https://api.openai.com/v1"
diff --git a/custom_components/ha_text_ai/coordinator.py b/custom_components/ha_text_ai/coordinator.py
index 104d08a..a6b5132 100644
--- a/custom_components/ha_text_ai/coordinator.py
+++ b/custom_components/ha_text_ai/coordinator.py
@@ -12,7 +12,7 @@ import asyncio
 import logging
 import os
 from datetime import timedelta
-from typing import Any, Dict, List, Optional
+from typing import Any
 
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.core import HomeAssistant
@@ -40,7 +40,6 @@ from .utils import normalize_name
 
 _LOGGER = logging.getLogger(__name__)
 
-
 class HATextAICoordinator(DataUpdateCoordinator):
     """Home Assistant Text AI Conversation Coordinator."""
 
@@ -101,9 +100,9 @@ class HATextAICoordinator(DataUpdateCoordinator):
         self._is_rate_limited = False
         self._is_maintenance = False
         self.endpoint_status = "ready"
-        self._system_prompt: Optional[str] = None
+        self._system_prompt: str | None = None
 
-        self._last_response: Dict[str, Any] = {
+        self._last_response: dict[str, Any] = {
             "timestamp": dt_util.utcnow().isoformat(),
             "question": "",
             "response": "",
@@ -132,7 +131,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
     # Convenience accessors for backward compatibility
     # ------------------------------------------------------------------
     @property
-    def _conversation_history(self) -> List[Dict[str, Any]]:
+    def _conversation_history(self) -> list[dict[str, Any]]:
         return self._history.conversation_history
 
     @property
@@ -155,12 +154,12 @@ class HATextAICoordinator(DataUpdateCoordinator):
     # Last response
     # ------------------------------------------------------------------
     @property
-    def last_response(self) -> Dict[str, Any]:
+    def last_response(self) -> dict[str, Any]:
         """Get the last response."""
         return self._last_response
 
     @last_response.setter
-    def last_response(self, value: Dict[str, Any]) -> None:
+    def last_response(self, value: dict[str, Any]) -> None:
         self._last_response = value
 
     # ------------------------------------------------------------------
@@ -173,7 +172,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
         except Exception as err:
             _LOGGER.error("Error updating HA state for %s: %s", self.instance_name, err)
 
-    async def _async_update_data(self) -> Dict[str, Any]:
+    async def _async_update_data(self) -> dict[str, Any]:
         """Update coordinator data."""
         try:
             current_state = self._get_current_state()
@@ -209,14 +208,14 @@ class HATextAICoordinator(DataUpdateCoordinator):
     async def async_ask_question(
         self,
         question: str,
-        model: Optional[str] = None,
-        temperature: Optional[float] = None,
-        max_tokens: Optional[int] = None,
-        system_prompt: Optional[str] = None,
-        context_messages: Optional[int] = None,
+        model: str | None = None,
+        temperature: float | None = None,
+        max_tokens: int | None = None,
+        system_prompt: str | None = None,
+        context_messages: int | None = None,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
-        disable_thinking: Optional[bool] = None,
+        json_schema: str | None = None,
+        disable_thinking: bool | None = None,
     ) -> dict:
         """Process question with context management."""
         if self.client is None:
@@ -279,11 +278,11 @@ class HATextAICoordinator(DataUpdateCoordinator):
         self,
         question: str,
         model: str,
-        messages: List[Dict[str, str]],
+        messages: list[dict[str, str]],
         temperature: float,
         max_tokens: int,
         structured_output: bool = False,
-        json_schema: Optional[str] = None,
+        json_schema: str | None = None,
         disable_thinking: bool = False,
     ) -> dict:
         """Send request to AI provider and return structured response.
@@ -348,12 +347,12 @@ class HATextAICoordinator(DataUpdateCoordinator):
 
     async def async_get_history(
         self,
-        limit: Optional[int] = None,
-        filter_model: Optional[str] = None,
-        start_date: Optional[str] = None,
+        limit: int | None = None,
+        filter_model: str | None = None,
+        start_date: str | None = None,
         include_metadata: bool = False,
         sort_order: str = "newest",
-    ) -> List[Dict[str, Any]]:
+    ) -> list[dict[str, Any]]:
         """Get conversation history with optional filtering."""
         return await self._history.async_get_history(
             limit=limit,
@@ -383,7 +382,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
             return STATE_ERROR
         return STATE_READY
 
-    def _get_safe_initial_state(self) -> Dict[str, Any]:
+    def _get_safe_initial_state(self) -> dict[str, Any]:
         return {
             "state": STATE_ERROR,
             "metrics": {},
@@ -403,7 +402,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
             "normalized_name": self.normalized_name,
         }
 
-    def _get_sanitized_last_response(self) -> Dict[str, Any]:
+    def _get_sanitized_last_response(self) -> dict[str, Any]:
         """Get sanitized version of last response with truncation."""
         response = self.last_response.copy()
 
@@ -422,7 +421,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
     def _calculate_uptime(self) -> float:
         return (dt_util.utcnow() - self._start_time).total_seconds()
 
-    def _get_truncated_system_prompt(self) -> Optional[str]:
+    def _get_truncated_system_prompt(self) -> str | None:
         if not self._system_prompt:
             return None
         if len(self._system_prompt) <= 4096:
@@ -430,7 +429,7 @@ class HATextAICoordinator(DataUpdateCoordinator):
         return self._system_prompt[:4096] + TRUNCATION_INDICATOR
 
     @staticmethod
-    def _validate_update_data(data: Dict[str, Any]) -> None:
+    def _validate_update_data(data: dict[str, Any]) -> None:
         for key in ("state", "metrics", "last_response"):
             if key not in data:
                 raise ValueError(f"Missing required key: {key}")
diff --git a/custom_components/ha_text_ai/history.py b/custom_components/ha_text_ai/history.py
index cd440d7..303f5a1 100644
--- a/custom_components/ha_text_ai/history.py
+++ b/custom_components/ha_text_ai/history.py
@@ -14,7 +14,7 @@ import os
 import shutil
 import traceback
 from datetime import datetime
-from typing import Any, Dict, List, Optional
+from typing import Any
 
 import aiofiles
 
@@ -34,7 +34,6 @@ MAX_ARCHIVE_FILES = 3
 
 _LOGGER = logging.getLogger(__name__)
 
-
 class AsyncFileHandler:
     """Async context manager for file operations."""
 
@@ -49,7 +48,6 @@ class AsyncFileHandler:
     async def __aexit__(self, exc_type, exc_val, exc_tb):
         await self.file.close()
 
-
 def _assert_not_symlink(path: str) -> None:
     """Refuse to operate on a path that resolves to a symlink.
 
@@ -61,7 +59,6 @@ def _assert_not_symlink(path: str) -> None:
     if os.path.islink(path):
         raise OSError(f"Refusing to operate on symlink: {path}")
 
-
 class HistoryManager:
     """Manages conversation history for an instance."""
 
@@ -84,10 +81,10 @@ class HistoryManager:
             history_dir, f"{normalized_name}_history.json"
         )
         self._max_history_file_size = MAX_HISTORY_FILE_SIZE
-        self._conversation_history: List[Dict[str, Any]] = []
+        self._conversation_history: list[dict[str, Any]] = []
 
     @property
-    def conversation_history(self) -> List[Dict[str, Any]]:
+    def conversation_history(self) -> list[dict[str, Any]]:
         return self._conversation_history
 
     @property
@@ -388,13 +385,13 @@ class HistoryManager:
 
     async def async_get_history(
         self,
-        limit: Optional[int] = None,
-        filter_model: Optional[str] = None,
-        start_date: Optional[str] = None,
+        limit: int | None = None,
+        filter_model: str | None = None,
+        start_date: str | None = None,
         include_metadata: bool = False,
         sort_order: str = "newest",
         default_model: str = "",
-    ) -> List[Dict[str, Any]]:
+    ) -> list[dict[str, Any]]:
         """Get conversation history with optional filtering and sorting."""
         try:
             history = self._conversation_history.copy()
@@ -425,8 +422,11 @@ class HistoryManager:
             else:
                 history.sort(key=lambda x: x.get("timestamp", ""), reverse=True)
 
+            # Clamp limit to ABSOLUTE_MAX_HISTORY_SIZE to prevent pathological
+            # caller requests from producing multi-MB service payloads.
             if limit and limit > 0:
-                history = history[:limit]
+                effective_limit = min(int(limit), ABSOLUTE_MAX_HISTORY_SIZE)
+                history = history[:effective_limit]
 
             if include_metadata:
                 enriched = []
@@ -447,7 +447,7 @@ class HistoryManager:
             _LOGGER.error("Error getting history: %s", e)
             return []
 
-    def get_limited_history(self, max_display: int = 5) -> Dict[str, Any]:
+    def get_limited_history(self, max_display: int = 5) -> dict[str, Any]:
         """Get limited conversation history for sensor attributes.
 
         Returns last `max_display` entries with truncated text for HA state.
diff --git a/custom_components/ha_text_ai/manifest.json b/custom_components/ha_text_ai/manifest.json
index 92e6698..e6ec8bf 100644
--- a/custom_components/ha_text_ai/manifest.json
+++ b/custom_components/ha_text_ai/manifest.json
@@ -15,5 +15,5 @@
     "google-genai>=1.16.0,<2.0.0"
   ],
   "single_config_entry": false,
-  "version": "2.5.0"
+  "version": "2.5.1"
 }
diff --git a/custom_components/ha_text_ai/metrics.py b/custom_components/ha_text_ai/metrics.py
index 6369ef8..bad17f6 100644
--- a/custom_components/ha_text_ai/metrics.py
+++ b/custom_components/ha_text_ai/metrics.py
@@ -13,7 +13,7 @@ import logging
 import os
 import re
 import traceback
-from typing import Any, Dict
+from typing import Any
 
 from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import HomeAssistantError
@@ -21,7 +21,7 @@ from homeassistant.util import dt as dt_util
 
 _LOGGER = logging.getLogger(__name__)
 
-DEFAULT_METRICS: Dict[str, Any] = {
+DEFAULT_METRICS: dict[str, Any] = {
     "total_tokens": 0,
     "prompt_tokens": 0,
     "completion_tokens": 0,
@@ -33,7 +33,6 @@ DEFAULT_METRICS: Dict[str, Any] = {
     "min_latency": 0,
 }
 
-
 class MetricsManager:
     """Manages performance metrics for an instance."""
 
@@ -46,10 +45,10 @@ class MetricsManager:
         self.hass = hass
         self.instance_name = instance_name
         self._metrics_file = metrics_file
-        self._performance_metrics: Dict[str, Any] = DEFAULT_METRICS.copy()
+        self._performance_metrics: dict[str, Any] = DEFAULT_METRICS.copy()
 
     @property
-    def metrics(self) -> Dict[str, Any]:
+    def metrics(self) -> dict[str, Any]:
         return self._performance_metrics
 
     async def async_initialize(self) -> None:
@@ -57,7 +56,7 @@ class MetricsManager:
         loaded = await self._load_metrics()
         self._performance_metrics = loaded or DEFAULT_METRICS.copy()
 
-    async def _load_metrics(self) -> Dict[str, Any] | None:
+    async def _load_metrics(self) -> dict[str, Any] | None:
         try:
             exists = await self.hass.async_add_executor_job(
                 os.path.exists, self._metrics_file
@@ -108,7 +107,7 @@ class MetricsManager:
 
         await self._save_metrics()
 
-    async def get_current_metrics(self) -> Dict[str, Any]:
+    async def get_current_metrics(self) -> dict[str, Any]:
         """Get current performance metrics."""
         return self._performance_metrics.copy()
 
@@ -116,7 +115,7 @@ class MetricsManager:
         self,
         error: Exception,
         model: str,
-    ) -> Dict[str, Any]:
+    ) -> dict[str, Any]:
         """Record an error in metrics and return error details."""
         self._performance_metrics["total_errors"] += 1
         self._performance_metrics["failed_requests"] += 1
@@ -146,7 +145,7 @@ class MetricsManager:
         if len(error_msg) > 256:
             error_msg = error_msg[:256] + "..."
 
-        error_details: Dict[str, Any] = {
+        error_details: dict[str, Any] = {
             "timestamp": dt_util.utcnow().isoformat(),
             "model": model,
             "instance": self.instance_name,
diff --git a/custom_components/ha_text_ai/providers.py b/custom_components/ha_text_ai/providers.py
index 1e5f959..8ad6030 100644
--- a/custom_components/ha_text_ai/providers.py
+++ b/custom_components/ha_text_ai/providers.py
@@ -62,7 +62,6 @@ PROVIDER_REGISTRY: dict[str, dict[str, Any]] = {
     },
 }
 
-
 def get_provider_config(provider: str) -> dict[str, Any]:
     """Get full provider configuration.
 
@@ -73,17 +72,14 @@ def get_provider_config(provider: str) -> dict[str, Any]:
         raise ValueError(f"Unknown API provider: {provider}")
     return PROVIDER_REGISTRY[provider]
 
-
 def get_default_endpoint(provider: str) -> str:
     """Get default API endpoint for a provider."""
     return get_provider_config(provider)["default_endpoint"]
 
-
 def get_default_model(provider: str) -> str:
     """Get default model for a provider."""
     return get_provider_config(provider)["default_model"]
 
-
 def build_auth_headers(provider: str, api_key: str) -> dict[str, str]:
     """Build authentication headers for a provider."""
     config = get_provider_config(provider)
diff --git a/custom_components/ha_text_ai/sensor.py b/custom_components/ha_text_ai/sensor.py
index 20c50c6..45c357b 100644
--- a/custom_components/ha_text_ai/sensor.py
+++ b/custom_components/ha_text_ai/sensor.py
@@ -10,7 +10,7 @@ from __future__ import annotations
 
 import logging
 import math
-from typing import Any, Dict
+from typing import Any
 from homeassistant.components.sensor import (
     SensorEntity,
     SensorEntityDescription,
@@ -79,7 +79,6 @@ _LOGGER = logging.getLogger(__name__)
 _ATTR_TEXT_LIMIT = 2048
 _ATTR_PROMPT_LIMIT = 512
 
-
 async def async_setup_entry(
     hass: HomeAssistant,
     entry: ConfigEntry,
@@ -185,7 +184,7 @@ class HATextAISensor(CoordinatorEntity, SensorEntity):
                 return None
         return value
 
-    def _sanitize_attributes(self, attributes: Dict[str, Any]) -> Dict[str, Any]:
+    def _sanitize_attributes(self, attributes: dict[str, Any]) -> dict[str, Any]:
         """Sanitize all attributes for JSON serialization."""
         sanitized = {
             key: self._sanitize_value(value)
@@ -231,7 +230,7 @@ class HATextAISensor(CoordinatorEntity, SensorEntity):
         return ENTITY_ICON
 
     @property
-    def extra_state_attributes(self) -> Dict[str, Any]:
+    def extra_state_attributes(self) -> dict[str, Any]:
         """Return entity specific state attributes."""
         if not self.coordinator.data:
             return {}
diff --git a/custom_components/ha_text_ai/utils.py b/custom_components/ha_text_ai/utils.py
index 1e6d106..1965aec 100644
--- a/custom_components/ha_text_ai/utils.py
+++ b/custom_components/ha_text_ai/utils.py
@@ -8,14 +8,22 @@ Utility functions for HA Text AI integration.
 """
 from __future__ import annotations
 
+import hashlib
 import ipaddress
+import logging
 import socket
 from typing import Any
 from urllib.parse import urlparse
 
+import aiohttp
+from aiohttp.abc import AbstractResolver
+from aiohttp.resolver import DefaultResolver
+
 from homeassistant.const import CONF_API_KEY
 from homeassistant.core import HomeAssistant
+from homeassistant.helpers.aiohttp_client import async_create_clientsession
 
+_LOGGER = logging.getLogger(__name__)
 
 def normalize_name(name: str) -> str:
     """Normalize name to conform to HA naming convention using underscores.
@@ -27,12 +35,10 @@ def normalize_name(name: str) -> str:
     normalized = ''.join(c if c.isalnum() or c == '_' else '_' for c in name)
     normalized = '_'.join(filter(None, normalized.split('_'))).lower()
     if not normalized:
-        import hashlib
         digest = hashlib.sha256(name.encode("utf-8", errors="replace")).hexdigest()[:8]
         normalized = f"instance_{digest}"
     return normalized
 
-
 def safe_log_data(
     data: dict[str, Any],
     sensitive_keys: tuple[str, ...] = (CONF_API_KEY,),
@@ -40,11 +46,9 @@ def safe_log_data(
     """Filter sensitive keys from data for safe logging."""
     return {k: "***" if k in sensitive_keys else v for k, v in data.items()}
 
-
 class _RestrictedIPError(ValueError):
     """Raised when an IP address is in a restricted range."""
 
-
 def _check_ip_restricted(addr: ipaddress.IPv4Address | ipaddress.IPv6Address) -> bool:
     """Check if an IP address is in a restricted range."""
     return (
@@ -56,14 +60,136 @@ def _check_ip_restricted(addr: ipaddress.IPv4Address | ipaddress.IPv6Address) ->
         or addr.is_unspecified
     )
 
+def _is_cloud_metadata_or_unsafe(
+    addr: ipaddress.IPv4Address | ipaddress.IPv6Address,
+) -> bool:
+    """Block link-local and cloud instance-metadata addresses.
 
-async def validate_endpoint(hass: HomeAssistant, endpoint: str, *, allow_local: bool = False) -> str:
-    """Validate API endpoint URL for security.
+    These must be blocked even in allow_local_network mode:
+    - IPv4 link-local (169.254.0.0/16) covers AWS/GCP/Azure IMDS 169.254.169.254.
+    - IPv6 link-local (fe80::/10).
+    - Multicast and unspecified addresses.
+    Without this check, a self-hosted HA running on a cloud VM could be
+    tricked into exfiltrating cloud credentials via IMDS.
+    """
+    return addr.is_multicast or addr.is_unspecified or addr.is_link_local
+
+class _PinnedResolver(AbstractResolver):
+    """aiohttp resolver that returns pre-validated IPs for a single hostname.
+
+    Why: prevents DNS-rebinding attacks. After validate_endpoint has
+    confirmed the hostname resolves to a safe IP, we pin that IP in the
+    resolver used by the aiohttp session. aiohttp then skips its own
+    DNS lookup on each request and uses the pinned IP, closing the
+    TOCTOU gap between validation and actual HTTP call.
+    """
+
+    def __init__(
+        self,
+        pinned: dict[str, list[tuple[str, int]]],
+        fallback: AbstractResolver | None = None,
+    ) -> None:
+        self._pinned = pinned
+        self._fallback = fallback or DefaultResolver()
+
+    async def resolve(
+        self,
+        host: str,
+        port: int = 0,
+        family: int = socket.AF_INET,
+    ) -> list[dict[str, Any]]:
+        entries = self._pinned.get(host.lower())
+        if entries is None:
+            return await self._fallback.resolve(host, port, family)
+        return [
+            {
+                "hostname": host,
+                "host": ip,
+                "port": port or default_port,
+                "family": _family_for(ip),
+                "proto": 0,
+                "flags": 0,
+            }
+            for ip, default_port in entries
+        ]
+
+    async def close(self) -> None:
+        await self._fallback.close()
+
+def _family_for(ip: str) -> int:
+    """Return AF_INET or AF_INET6 based on the IP literal."""
+    try:
+        return socket.AF_INET6 if ":" in ip else socket.AF_INET
+    except Exception:
+        return socket.AF_INET
+
+async def resolve_hostname_ips(
+    hass: HomeAssistant,
+    hostname: str,
+) -> list[str]:
+    """Resolve hostname to all its IPs via the event-loop-safe executor.
+
+    Returns a list of IP strings (may contain both IPv4 and IPv6).
+    Raises ValueError on resolution failure.
+    """
+    try:
+        addrinfos = await hass.async_add_executor_job(
+            socket.getaddrinfo, hostname, None
+        )
+    except socket.gaierror as err:
+        raise ValueError(f"Cannot resolve hostname: {hostname}") from err
+    ips = []
+    seen: set[str] = set()
+    for _family, _type, _proto, _canonname, sockaddr in addrinfos:
+        ip = sockaddr[0]
+        if ip not in seen:
+            seen.add(ip)
+            ips.append(ip)
+    if not ips:
+        raise ValueError(f"No IPs for hostname: {hostname}")
+    return ips
+
+def create_pinned_session(
+    hass: HomeAssistant,
+    endpoint: str,
+    resolved_ips: list[str],
+) -> aiohttp.ClientSession:
+    """Create an isolated aiohttp session with pinned DNS and no cookie jar.
+
+    Addresses two issues at once:
+    - DNS rebinding: aiohttp will reuse the pinned IPs from validate_endpoint
+      rather than re-resolving the hostname on each request.
+    - Cookie pollution: DummyCookieJar prevents cookies from leaking between
+      this integration and other HA components sharing the same domain.
+    """
+    parsed = urlparse(endpoint)
+    hostname = (parsed.hostname or "").lower()
+    port = parsed.port or (443 if parsed.scheme == "https" else 80)
+    pinned: dict[str, list[tuple[str, int]]] = {
+        hostname: [(ip, port) for ip in resolved_ips]
+    }
+    connector = aiohttp.TCPConnector(resolver=_PinnedResolver(pinned))
+    return async_create_clientsession(
+        hass,
+        cookie_jar=aiohttp.DummyCookieJar(),
+        connector=connector,
+    )
+
+async def validate_endpoint(
+    hass: HomeAssistant,
+    endpoint: str,
+    *,
+    allow_local: bool = False,
+) -> tuple[str, list[str]]:
+    """Validate API endpoint URL for security and pin resolved IPs.
 
     Ensures HTTPS-only and blocks private/reserved IP ranges (SSRF protection).
     When allow_local is True, permits private IPs and HTTP scheme for self-hosted proxies.
     Uses async DNS resolution to avoid blocking the event loop.
-    Returns the validated endpoint stripped of trailing slashes.
+
+    Returns: (validated_endpoint_without_trailing_slash, resolved_ips).
+    The resolved IPs are intended for pinning in aiohttp resolver via
+    create_pinned_session(), closing the DNS-rebinding TOCTOU gap.
 
     Raises:
         ValueError: If the endpoint fails validation.
@@ -81,54 +207,47 @@ async def validate_endpoint(hass: HomeAssistant, endpoint: str, *, allow_local:
     if not hostname:
         raise ValueError("Invalid endpoint URL: no hostname")
 
-    if allow_local:
-        # Even in local mode, block multicast and unspecified addresses
+    resolved_ips: list[str] = []
+
+    # Collect and check all resolved IPs (or IP literal directly).
+    def _collect(ips: list[str]) -> None:
+        for ip in ips:
+            if ip not in resolved_ips:
+                resolved_ips.append(ip)
+
+    try:
+        addr = ipaddress.ip_address(hostname)
         _is_ip_literal = True
-        try:
-            addr = ipaddress.ip_address(hostname)
-        except ValueError:
-            _is_ip_literal = False
+    except ValueError:
+        addr = None
+        _is_ip_literal = False
 
-        if _is_ip_literal:
-            if addr.is_multicast or addr.is_unspecified:
-                raise ValueError("Multicast and unspecified addresses are not allowed")
-        else:
-            # Not an IP literal — resolve and check
-            try:
-                addrinfos = await hass.async_add_executor_job(
-                    socket.getaddrinfo, hostname, None
-                )
-                for family, _type, _proto, _canonname, sockaddr in addrinfos:
-                    resolved = ipaddress.ip_address(sockaddr[0])
-                    if resolved.is_multicast or resolved.is_unspecified:
-                        raise ValueError(
-                            "Hostname resolves to multicast/unspecified address"
-                        )
-            except socket.gaierror as err:
-                raise ValueError(f"Cannot resolve hostname: {hostname}") from err
+    if _is_ip_literal:
+        _collect([hostname])
     else:
-        # Full SSRF protection — block private/reserved IPs
         try:
-            addr = ipaddress.ip_address(hostname)
-            if _check_ip_restricted(addr):
-                raise _RestrictedIPError("Private/reserved IP addresses are not allowed")
-        except _RestrictedIPError:
-            raise
-        except ValueError:
-            # Not an IP literal — resolve hostname and check all resolved IPs
-            # to prevent DNS rebinding attacks
-            try:
-                addrinfos = await hass.async_add_executor_job(
-                    socket.getaddrinfo, hostname, None
-                )
-                for family, _type, _proto, _canonname, sockaddr in addrinfos:
-                    ip_str = sockaddr[0]
-                    resolved_addr = ipaddress.ip_address(ip_str)
-                    if _check_ip_restricted(resolved_addr):
-                        raise ValueError(
-                            "Hostname resolves to a restricted IP range"
-                        )
-            except socket.gaierror as err:
-                raise ValueError(f"Cannot resolve hostname: {hostname}") from err
+            addrinfos = await hass.async_add_executor_job(
+                socket.getaddrinfo, hostname, None
+            )
+        except socket.gaierror as err:
+            raise ValueError(f"Cannot resolve hostname: {hostname}") from err
+        _collect([sockaddr[0] for (*_, sockaddr) in addrinfos])
 
-    return endpoint.rstrip("/")
+    if not resolved_ips:
+        raise ValueError(f"No IPs resolved for hostname: {hostname}")
+
+    # Validate each resolved IP against the selected policy.
+    for ip_str in resolved_ips:
+        ip_obj = ipaddress.ip_address(ip_str)
+        if allow_local:
+            if _is_cloud_metadata_or_unsafe(ip_obj):
+                raise ValueError(
+                    "Link-local/metadata/multicast addresses are not allowed"
+                )
+        else:
+            if _check_ip_restricted(ip_obj):
+                raise _RestrictedIPError(
+                    "Private/reserved IP addresses are not allowed"
+                )
+
+    return endpoint.rstrip("/"), resolved_ips