diff --git a/libs/partners/xai/langchain_xai/chat_models.py b/libs/partners/xai/langchain_xai/chat_models.py
index 22701217153f9..d2de07c20ff04 100644
--- a/libs/partners/xai/langchain_xai/chat_models.py
+++ b/libs/partners/xai/langchain_xai/chat_models.py
@@ -529,6 +529,9 @@ def _create_chat_result(
     ) -> ChatResult:
         rtn = super()._create_chat_result(response, generation_info)
 
+        for generation in rtn.generations:
+            generation.message.response_metadata["model_provider"] = "xai"
+
         if not isinstance(response, openai.BaseModel):
             return rtn
 
@@ -555,6 +558,10 @@ def _convert_chunk_to_generation_chunk(
             default_chunk_class,
             base_generation_info,
         )
+
+        if generation_chunk:
+            generation_chunk.message.response_metadata["model_provider"] = "xai"
+
         if (choices := chunk.get("choices")) and generation_chunk:
             top = choices[0]
             if isinstance(generation_chunk.message, AIMessageChunk) and (
diff --git a/libs/partners/xai/tests/integration_tests/test_chat_models.py b/libs/partners/xai/tests/integration_tests/test_chat_models.py
new file mode 100644
index 0000000000000..049f51e59bc70
--- /dev/null
+++ b/libs/partners/xai/tests/integration_tests/test_chat_models.py
@@ -0,0 +1,96 @@
+"""Integration tests for ChatXAI specific features."""
+
+from __future__ import annotations
+
+from typing import Literal
+
+import pytest
+from langchain_core.messages import AIMessage, AIMessageChunk, BaseMessageChunk
+
+from langchain_xai import ChatXAI
+
+MODEL_NAME = "grok-4-fast-reasoning"
+
+
+@pytest.mark.parametrize("output_version", ["", "v1"])
+def test_reasoning(output_version: Literal["", "v1"]) -> None:
+    """Test reasoning features.
+
+    Note: `grok-4` does not return `reasoning_content`, but may optionally return
+    encrypted reasoning content if `use_encrypted_content` is set to True.
+    """
+    # Test reasoning effort
+    if output_version:
+        chat_model = ChatXAI(
+            model="grok-3-mini",
+            reasoning_effort="low",
+            output_version=output_version,
+        )
+    else:
+        chat_model = ChatXAI(
+            model="grok-3-mini",
+            reasoning_effort="low",
+        )
+    input_message = "What is 3^3?"
+    response = chat_model.invoke(input_message)
+    assert response.content
+    assert response.additional_kwargs["reasoning_content"]
+
+    # Test streaming
+    full: BaseMessageChunk | None = None
+    for chunk in chat_model.stream(input_message):
+        full = chunk if full is None else full + chunk
+    assert isinstance(full, AIMessageChunk)
+    assert full.additional_kwargs["reasoning_content"]
+
+    # Check that we can access reasoning content blocks
+    assert response.content_blocks
+    reasoning_content = (
+        block for block in response.content_blocks if block["type"] == "reasoning"
+    )
+    assert len(list(reasoning_content)) >= 1
+
+    # Test that passing message with reasoning back in works
+    follow_up_message = "Based on your reasoning, what is 4^4?"
+    followup = chat_model.invoke([input_message, response, follow_up_message])
+    assert followup.content
+    assert followup.additional_kwargs["reasoning_content"]
+    followup_reasoning = (
+        block for block in followup.content_blocks if block["type"] == "reasoning"
+    )
+    assert len(list(followup_reasoning)) >= 1
+
+    # Test passing in a ReasoningContentBlock
+    response_metadata = {"model_provider": "xai"}
+    if output_version:
+        response_metadata["output_version"] = output_version
+    msg_w_reasoning = AIMessage(
+        content_blocks=response.content_blocks,
+        response_metadata=response_metadata,
+    )
+    followup_2 = chat_model.invoke(
+        [msg_w_reasoning, "Based on your reasoning, what is 5^5?"]
+    )
+    assert followup_2.content
+    assert followup_2.additional_kwargs["reasoning_content"]
+
+
+def test_web_search() -> None:
+    llm = ChatXAI(
+        model=MODEL_NAME,
+        search_parameters={"mode": "on", "max_search_results": 3},
+    )
+
+    # Test invoke
+    response = llm.invoke("Provide me a digest of world news in the last 24 hours.")
+    assert response.content
+    assert response.additional_kwargs["citations"]
+    assert len(response.additional_kwargs["citations"]) <= 3
+
+    # Test streaming
+    full = None
+    for chunk in llm.stream("Provide me a digest of world news in the last 24 hours."):
+        full = chunk if full is None else full + chunk
+    assert isinstance(full, AIMessageChunk)
+    assert full.additional_kwargs["citations"]
+    assert len(full.additional_kwargs["citations"]) <= 3
diff --git a/libs/partners/xai/tests/integration_tests/test_chat_models_standard.py b/libs/partners/xai/tests/integration_tests/test_chat_models_standard.py
index dada7d5c4bcd5..9b7871d6ac26f 100644
--- a/libs/partners/xai/tests/integration_tests/test_chat_models_standard.py
+++ b/libs/partners/xai/tests/integration_tests/test_chat_models_standard.py
@@ -4,26 +4,25 @@
 
 from typing import TYPE_CHECKING
 
-from langchain_core.messages import AIMessageChunk, BaseMessageChunk
+import pytest
+from langchain_core.messages import AIMessage
 from langchain_core.rate_limiters import InMemoryRateLimiter
 from langchain_tests.integration_tests import (  # type: ignore[import-not-found]
     ChatModelIntegrationTests,  # type: ignore[import-not-found]
 )
+from typing_extensions import override
 
 from langchain_xai import ChatXAI
 
 if TYPE_CHECKING:
     from langchain_core.language_models import BaseChatModel
 
-# Initialize the rate limiter in global scope, so it can be re-used
-# across tests.
+# Initialize the rate limiter in global scope, so it can be re-used across tests
 rate_limiter = InMemoryRateLimiter(
     requests_per_second=0.5,
 )
 
-
-# Not using Grok 4 since it doesn't support reasoning params (effort) or returns
-# reasoning content.
+MODEL_NAME = "grok-4-fast-reasoning"
 
 
 class TestXAIStandard(ChatModelIntegrationTests):
@@ -33,48 +32,28 @@ def chat_model_class(self) -> type[BaseChatModel]:
 
     @property
     def chat_model_params(self) -> dict:
-        # TODO: bump to test new Grok once they implement other features
         return {
-            "model": "grok-3",
+            "model": MODEL_NAME,
             "rate_limiter": rate_limiter,
             "stream_usage": True,
         }
 
-
-def test_reasoning_content() -> None:
-    """Test reasoning content."""
-    chat_model = ChatXAI(
-        model="grok-3-mini",
-        reasoning_effort="low",
-    )
-    response = chat_model.invoke("What is 3^3?")
-    assert response.content
-    assert response.additional_kwargs["reasoning_content"]
-
-    # Test streaming
-    full: BaseMessageChunk | None = None
-    for chunk in chat_model.stream("What is 3^3?"):
-        full = chunk if full is None else full + chunk
-    assert isinstance(full, AIMessageChunk)
-    assert full.additional_kwargs["reasoning_content"]
-
-
-def test_web_search() -> None:
-    llm = ChatXAI(
-        model="grok-3",
-        search_parameters={"mode": "auto", "max_search_results": 3},
+    @pytest.mark.xfail(
+        reason="Default model does not support stop sequences, using grok-3 instead"
     )
-
-    # Test invoke
-    response = llm.invoke("Provide me a digest of world news in the last 24 hours.")
-    assert response.content
-    assert response.additional_kwargs["citations"]
-    assert len(response.additional_kwargs["citations"]) <= 3
-
-    # Test streaming
-    full = None
-    for chunk in llm.stream("Provide me a digest of world news in the last 24 hours."):
-        full = chunk if full is None else full + chunk
-    assert isinstance(full, AIMessageChunk)
-    assert full.additional_kwargs["citations"]
-    assert len(full.additional_kwargs["citations"]) <= 3
+    @override
+    def test_stop_sequence(self, model: BaseChatModel) -> None:
+        """Override to use `grok-3` which supports stop sequences."""
+        params = {**self.chat_model_params, "model": "grok-3"}
+
+        grok3_model = ChatXAI(**params)
+
+        result = grok3_model.invoke("hi", stop=["you"])
+        assert isinstance(result, AIMessage)
+
+        custom_model = ChatXAI(
+            **params,
+            stop_sequences=["you"],
+        )
+        result = custom_model.invoke("hi")
+        assert isinstance(result, AIMessage)
diff --git a/libs/partners/xai/tests/unit_tests/__snapshots__/test_chat_models_standard.ambr b/libs/partners/xai/tests/unit_tests/__snapshots__/test_chat_models_standard.ambr
index 4cd1261555c90..6f1cd18c2e2dc 100644
--- a/libs/partners/xai/tests/unit_tests/__snapshots__/test_chat_models_standard.ambr
+++ b/libs/partners/xai/tests/unit_tests/__snapshots__/test_chat_models_standard.ambr
@@ -9,7 +9,7 @@
     'kwargs': dict({
       'max_retries': 2,
       'max_tokens': 100,
-      'model_name': 'grok-beta',
+      'model_name': 'grok-4',
       'request_timeout': 60.0,
       'stop': list([
       ]),
diff --git a/libs/partners/xai/tests/unit_tests/test_chat_models_standard.py b/libs/partners/xai/tests/unit_tests/test_chat_models_standard.py
index 7c9a947a913ed..7224655db79ed 100644
--- a/libs/partners/xai/tests/unit_tests/test_chat_models_standard.py
+++ b/libs/partners/xai/tests/unit_tests/test_chat_models_standard.py
@@ -7,6 +7,8 @@
 
 from langchain_xai import ChatXAI
 
+MODEL_NAME = "grok-4"
+
 
 class TestXAIStandard(ChatModelUnitTests):
     @property
@@ -15,7 +17,7 @@ def chat_model_class(self) -> type[BaseChatModel]:
 
     @property
     def chat_model_params(self) -> dict:
-        return {"model": "grok-beta"}
+        return {"model": MODEL_NAME}
 
     @property
     def init_from_env_params(self) -> tuple[dict, dict, dict]:
@@ -24,7 +26,7 @@ def init_from_env_params(self) -> tuple[dict, dict, dict]:
                 "XAI_API_KEY": "api_key",
             },
             {
-                "model": "grok-beta",
+                "model": MODEL_NAME,
             },
             {
                 "xai_api_key": "api_key",
diff --git a/libs/partners/xai/uv.lock b/libs/partners/xai/uv.lock
index 0e0024f50f844..ac0ffb5c3bc01 100644
--- a/libs/partners/xai/uv.lock
+++ b/libs/partners/xai/uv.lock
@@ -621,7 +621,7 @@ wheels = [
 
 [[package]]
 name = "langchain-core"
-version = "1.0.0a8"
+version = "1.0.0rc2"
 source = { editable = "../../core" }
 dependencies = [
     { name = "jsonpatch" },
@@ -699,6 +699,7 @@ dev = [{ name = "langchain-core", editable = "../../core" }]
 lint = [{ name = "ruff", specifier = ">=0.13.1,<0.14.0" }]
 test = [
     { name = "freezegun", specifier = ">=1.2.2,<2.0.0" },
+    { name = "langchain", editable = "../../langchain_v1" },
     { name = "langchain-core", editable = "../../core" },
     { name = "langchain-tests", editable = "../../standard-tests" },
     { name = "numpy", marker = "python_full_version < '3.13'", specifier = ">=1.26.4" },
@@ -728,7 +729,7 @@ typing = [
 
 [[package]]
 name = "langchain-tests"
-version = "1.0.0a2"
+version = "1.0.0rc1"
 source = { editable = "../../standard-tests" }
 dependencies = [
     { name = "httpx" },