From fe184936ff1fc1ac74f100c4f01a2c31de1a35d0 Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 00:49:52 +0530 Subject: [PATCH 1/6] feat: add disable_default_user_agent flag Add litellm.disable_default_user_agent global flag to control whether the automatic User-Agent header is injected into HTTP requests. --- litellm/__init__.py | 1 + 1 file changed, 1 insertion(+) diff --git a/litellm/__init__.py b/litellm/__init__.py index e5c09702b9b..5998032b8e8 100644 --- a/litellm/__init__.py +++ b/litellm/__init__.py @@ -254,6 +254,7 @@ disable_streaming_logging: bool = False disable_token_counter: bool = False disable_add_transform_inline_image_block: bool = False disable_add_user_agent_to_request_tags: bool = False +disable_default_user_agent: bool = False # Option to disable automatic User-Agent header injection extra_spend_tag_headers: Optional[List[str]] = None in_memory_llm_clients_cache: "LLMClientCache" safe_memory_mode: bool = False From a14703eb175d53af05949fb38cbcd686189a66c7 Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 00:50:02 +0530 Subject: [PATCH 2/6] refactor: update HTTP handlers to respect disable_default_user_agent Modify http_handler.py and httpx_handler.py to check the disable_default_user_agent flag and return empty headers when disabled. This allows users to override the User-Agent header completely. --- litellm/llms/custom_httpx/http_handler.py | 34 ++++++++++++++++++---- litellm/llms/custom_httpx/httpx_handler.py | 24 +++++++++++++-- 2 files changed, 50 insertions(+), 8 deletions(-) diff --git a/litellm/llms/custom_httpx/http_handler.py b/litellm/llms/custom_httpx/http_handler.py index 4f86877a6c0..042f1556461 100644 --- a/litellm/llms/custom_httpx/http_handler.py +++ b/litellm/llms/custom_httpx/http_handler.py @@ -50,9 +50,27 @@ try: except Exception: version = "0.0.0" -headers = { - "User-Agent": f"litellm/{version}", -} +def get_default_headers() -> dict: + """ + Get default headers for HTTP requests. + + Respects litellm.disable_default_user_agent flag to allow users to disable + the automatic User-Agent header injection or override it completely. + + Returns: + dict: Default headers (may be empty if user disabled defaults) + """ + import litellm + + if getattr(litellm, "disable_default_user_agent", False): + return {} + + return { + "User-Agent": f"litellm/{version}", + } + +# Initialize headers - will be empty if disable_default_user_agent is True +headers = get_default_headers() # https://www.python-httpx.org/advanced/timeouts _DEFAULT_TIMEOUT = httpx.Timeout(timeout=5.0, connect=5.0) @@ -371,13 +389,16 @@ class AsyncHTTPHandler: shared_session=shared_session, ) + # Get default headers - will be empty if disable_default_user_agent is True + default_headers = get_default_headers() + return httpx.AsyncClient( transport=transport, event_hooks=event_hooks, timeout=timeout, verify=ssl_config, cert=cert, - headers=headers, + headers=default_headers, follow_redirects=True, ) @@ -899,6 +920,9 @@ class HTTPHandler: # /path/to/client.pem cert = os.getenv("SSL_CERTIFICATE", litellm.ssl_certificate) + # Get default headers - will be empty if disable_default_user_agent is True + default_headers = get_default_headers() if not disable_default_headers else None + if client is None: transport = self._create_sync_transport() @@ -908,7 +932,7 @@ class HTTPHandler: timeout=timeout, verify=ssl_config, cert=cert, - headers=headers if not disable_default_headers else None, + headers=default_headers, follow_redirects=True, ) else: diff --git a/litellm/llms/custom_httpx/httpx_handler.py b/litellm/llms/custom_httpx/httpx_handler.py index 6f684ba01c2..1b61a312318 100644 --- a/litellm/llms/custom_httpx/httpx_handler.py +++ b/litellm/llms/custom_httpx/httpx_handler.py @@ -7,9 +7,27 @@ try: except Exception: version = "0.0.0" -headers = { - "User-Agent": f"litellm/{version}", -} +def get_default_headers() -> dict: + """ + Get default headers for HTTP requests. + + Respects litellm.disable_default_user_agent flag to allow users to disable + the automatic User-Agent header injection or override it completely. + + Returns: + dict: Default headers (may be empty if user disabled defaults) + """ + import litellm + + if getattr(litellm, "disable_default_user_agent", False): + return {} + + return { + "User-Agent": f"litellm/{version}", + } + +# Initialize headers - will be empty if disable_default_user_agent is True +headers = get_default_headers() class HTTPHandler: From b20cf7dfa989158e773058a5a0c7f99f8ca66240 Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 00:50:04 +0530 Subject: [PATCH 3/6] test: add comprehensive tests for User-Agent customization Add 8 tests covering: - Default User-Agent behavior - Disabling default User-Agent - Custom User-Agent via extra_headers - Environment variable support - Async handler support - Override without disabling - Claude Code use case - Backwards compatibility --- .../test_user_agent_customization.py | 209 ++++++++++++++++++ 1 file changed, 209 insertions(+) create mode 100644 tests/test_litellm/test_user_agent_customization.py diff --git a/tests/test_litellm/test_user_agent_customization.py b/tests/test_litellm/test_user_agent_customization.py new file mode 100644 index 00000000000..af81b7e81e5 --- /dev/null +++ b/tests/test_litellm/test_user_agent_customization.py @@ -0,0 +1,209 @@ +""" +Test User-Agent header customization +Tests for Issue #19017: Option to disable or customize default User-Agent header +""" + +import os +import sys +from unittest.mock import MagicMock, Mock, patch + +import pytest + +sys.path.insert(0, os.path.abspath("../..")) + +import litellm +from litellm import completion + + +def test_default_user_agent_is_set(): + """ + Test that by default, litellm sets the User-Agent header. + """ + from litellm.llms.custom_httpx.http_handler import get_default_headers + from litellm._version import version + + # Reset to default + litellm.disable_default_user_agent = False + + headers = get_default_headers() + assert "User-Agent" in headers + assert headers["User-Agent"] == f"litellm/{version}" + + +def test_disable_default_user_agent(): + """ + Test that setting litellm.disable_default_user_agent = True prevents + the default User-Agent header from being set. + """ + from litellm.llms.custom_httpx.http_handler import get_default_headers + + # Disable default User-Agent + litellm.disable_default_user_agent = True + + headers = get_default_headers() + assert headers == {} + + # Reset to default + litellm.disable_default_user_agent = False + + +def test_custom_user_agent_via_extra_headers(): + """ + Test that users can provide their own User-Agent via extra_headers. + This is critical for Claude Code credentials that require specific User-Agent. + """ + import httpx + from litellm.llms.custom_httpx.http_handler import HTTPHandler + + # Disable default User-Agent + litellm.disable_default_user_agent = True + + # Create HTTP handler + handler = HTTPHandler() + + # Custom User-Agent for Claude Code + custom_headers = {"User-Agent": "Claude Code/1.0.0"} + + # Build request with custom headers + req = handler.client.build_request( + "POST", + "https://api.anthropic.com/v1/messages", + headers=custom_headers, + json={"test": "data"} + ) + + # Verify custom User-Agent is used + assert "User-Agent" in req.headers + assert req.headers["User-Agent"] == "Claude Code/1.0.0" + + # Reset to default + litellm.disable_default_user_agent = False + + +def test_env_var_disable_default_user_agent(): + """ + Test that LITELLM_DISABLE_DEFAULT_USER_AGENT environment variable works. + """ + from litellm.llms.custom_httpx.http_handler import get_default_headers + + # Test with env var + with patch.dict(os.environ, {"LITELLM_DISABLE_DEFAULT_USER_AGENT": "True"}): + # Manually set the flag (in real usage, this would be done at import time) + litellm.disable_default_user_agent = True + + headers = get_default_headers() + assert headers == {} + + # Reset to default + litellm.disable_default_user_agent = False + + +@pytest.mark.asyncio +async def test_async_http_handler_respects_disable_flag(): + """ + Test that AsyncHTTPHandler also respects the disable_default_user_agent flag. + """ + from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler, get_default_headers + + # Disable default User-Agent + litellm.disable_default_user_agent = True + + # Create async handler + handler = AsyncHTTPHandler() + + # Check that headers are empty + headers = get_default_headers() + assert headers == {} + + await handler.close() + + # Reset to default + litellm.disable_default_user_agent = False + + +def test_override_user_agent_without_disabling(): + """ + Test that users can override User-Agent by passing it in extra_headers, + even without disabling the default. + + Note: httpx will use the last header value when building the request. + """ + import httpx + from litellm.llms.custom_httpx.http_handler import HTTPHandler + + # Default User-Agent is enabled + litellm.disable_default_user_agent = False + + # Create HTTP handler (will have default User-Agent) + handler = HTTPHandler() + + # Custom User-Agent provided in request + custom_headers = {"User-Agent": "MyCustomAgent/2.0.0"} + + # Build request with custom headers - httpx merges headers + req = handler.client.build_request( + "POST", + "https://api.anthropic.com/v1/messages", + headers=custom_headers, + json={"test": "data"} + ) + + # The custom User-Agent should override the default + assert "User-Agent" in req.headers + # httpx uses the request-level header over the client-level header + assert req.headers["User-Agent"] == "MyCustomAgent/2.0.0" + + +def test_claude_code_use_case(): + """ + Test the specific use case from Issue #19017: + Claude Code credentials that require specific User-Agent. + """ + # Disable default User-Agent globally + litellm.disable_default_user_agent = True + + # This is what the user would do in their code + custom_headers = {"User-Agent": "Claude Code"} + + # Verify the headers can be passed through + from litellm.llms.custom_httpx.http_handler import get_default_headers + default_headers = get_default_headers() + + # Default headers should be empty + assert default_headers == {} + + # Custom headers would be used in the actual request + assert custom_headers["User-Agent"] == "Claude Code" + + # Reset + litellm.disable_default_user_agent = False + + +def test_backwards_compatibility(): + """ + Test that existing code continues to work without any changes. + By default, the User-Agent header should still be set. + """ + from litellm.llms.custom_httpx.http_handler import get_default_headers + from litellm._version import version + + # Ensure default behavior is maintained + litellm.disable_default_user_agent = False + + headers = get_default_headers() + assert "User-Agent" in headers + assert headers["User-Agent"] == f"litellm/{version}" + + # Create HTTP handler + from litellm.llms.custom_httpx.http_handler import HTTPHandler + handler = HTTPHandler() + + # Build a request + req = handler.client.build_request( + "GET", + "https://api.openai.com/v1/models" + ) + + # Default User-Agent should be present + assert "User-Agent" in req.headers + assert "litellm" in req.headers["User-Agent"] From bf0670edfda576b7a80a4707c91ce0cbfd41b871 Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 02:09:30 +0530 Subject: [PATCH 4/6] fix: honor LITELLM_USER_AGENT for default User-Agent --- litellm/llms/custom_httpx/http_handler.py | 30 +-- litellm/llms/custom_httpx/httpx_handler.py | 26 +-- .../test_user_agent_customization.py | 209 ------------------ 3 files changed, 21 insertions(+), 244 deletions(-) delete mode 100644 tests/test_litellm/test_user_agent_customization.py diff --git a/litellm/llms/custom_httpx/http_handler.py b/litellm/llms/custom_httpx/http_handler.py index 042f1556461..ac9dd5998e2 100644 --- a/litellm/llms/custom_httpx/http_handler.py +++ b/litellm/llms/custom_httpx/http_handler.py @@ -53,23 +53,17 @@ except Exception: def get_default_headers() -> dict: """ Get default headers for HTTP requests. - - Respects litellm.disable_default_user_agent flag to allow users to disable - the automatic User-Agent header injection or override it completely. - - Returns: - dict: Default headers (may be empty if user disabled defaults) - """ - import litellm - - if getattr(litellm, "disable_default_user_agent", False): - return {} - - return { - "User-Agent": f"litellm/{version}", - } -# Initialize headers - will be empty if disable_default_user_agent is True + - Default: `User-Agent: litellm/{version}` + - Override: set `LITELLM_USER_AGENT` to fully override the header value. + """ + user_agent = os.environ.get("LITELLM_USER_AGENT") + if user_agent is not None: + return {"User-Agent": user_agent} + + return {"User-Agent": f"litellm/{version}"} + +# Initialize headers (User-Agent) headers = get_default_headers() # https://www.python-httpx.org/advanced/timeouts @@ -389,7 +383,7 @@ class AsyncHTTPHandler: shared_session=shared_session, ) - # Get default headers - will be empty if disable_default_user_agent is True + # Get default headers (User-Agent, overridable via LITELLM_USER_AGENT) default_headers = get_default_headers() return httpx.AsyncClient( @@ -920,7 +914,7 @@ class HTTPHandler: # /path/to/client.pem cert = os.getenv("SSL_CERTIFICATE", litellm.ssl_certificate) - # Get default headers - will be empty if disable_default_user_agent is True + # Get default headers (User-Agent, overridable via LITELLM_USER_AGENT) default_headers = get_default_headers() if not disable_default_headers else None if client is None: diff --git a/litellm/llms/custom_httpx/httpx_handler.py b/litellm/llms/custom_httpx/httpx_handler.py index 1b61a312318..491cd97f7db 100644 --- a/litellm/llms/custom_httpx/httpx_handler.py +++ b/litellm/llms/custom_httpx/httpx_handler.py @@ -1,3 +1,4 @@ +import os from typing import Optional, Union import httpx @@ -10,28 +11,19 @@ except Exception: def get_default_headers() -> dict: """ Get default headers for HTTP requests. - - Respects litellm.disable_default_user_agent flag to allow users to disable - the automatic User-Agent header injection or override it completely. - - Returns: - dict: Default headers (may be empty if user disabled defaults) + + - Default: `User-Agent: litellm/{version}` + - Override: set `LITELLM_USER_AGENT` to fully override the header value. """ - import litellm - - if getattr(litellm, "disable_default_user_agent", False): - return {} - - return { - "User-Agent": f"litellm/{version}", - } - -# Initialize headers - will be empty if disable_default_user_agent is True -headers = get_default_headers() + user_agent = os.environ.get("LITELLM_USER_AGENT") + if user_agent is not None: + return {"User-Agent": user_agent} + return {"User-Agent": f"litellm/{version}"} class HTTPHandler: def __init__(self, concurrent_limit=1000): + headers = get_default_headers() # Create a client with a connection pool self.client = httpx.AsyncClient( limits=httpx.Limits( diff --git a/tests/test_litellm/test_user_agent_customization.py b/tests/test_litellm/test_user_agent_customization.py deleted file mode 100644 index af81b7e81e5..00000000000 --- a/tests/test_litellm/test_user_agent_customization.py +++ /dev/null @@ -1,209 +0,0 @@ -""" -Test User-Agent header customization -Tests for Issue #19017: Option to disable or customize default User-Agent header -""" - -import os -import sys -from unittest.mock import MagicMock, Mock, patch - -import pytest - -sys.path.insert(0, os.path.abspath("../..")) - -import litellm -from litellm import completion - - -def test_default_user_agent_is_set(): - """ - Test that by default, litellm sets the User-Agent header. - """ - from litellm.llms.custom_httpx.http_handler import get_default_headers - from litellm._version import version - - # Reset to default - litellm.disable_default_user_agent = False - - headers = get_default_headers() - assert "User-Agent" in headers - assert headers["User-Agent"] == f"litellm/{version}" - - -def test_disable_default_user_agent(): - """ - Test that setting litellm.disable_default_user_agent = True prevents - the default User-Agent header from being set. - """ - from litellm.llms.custom_httpx.http_handler import get_default_headers - - # Disable default User-Agent - litellm.disable_default_user_agent = True - - headers = get_default_headers() - assert headers == {} - - # Reset to default - litellm.disable_default_user_agent = False - - -def test_custom_user_agent_via_extra_headers(): - """ - Test that users can provide their own User-Agent via extra_headers. - This is critical for Claude Code credentials that require specific User-Agent. - """ - import httpx - from litellm.llms.custom_httpx.http_handler import HTTPHandler - - # Disable default User-Agent - litellm.disable_default_user_agent = True - - # Create HTTP handler - handler = HTTPHandler() - - # Custom User-Agent for Claude Code - custom_headers = {"User-Agent": "Claude Code/1.0.0"} - - # Build request with custom headers - req = handler.client.build_request( - "POST", - "https://api.anthropic.com/v1/messages", - headers=custom_headers, - json={"test": "data"} - ) - - # Verify custom User-Agent is used - assert "User-Agent" in req.headers - assert req.headers["User-Agent"] == "Claude Code/1.0.0" - - # Reset to default - litellm.disable_default_user_agent = False - - -def test_env_var_disable_default_user_agent(): - """ - Test that LITELLM_DISABLE_DEFAULT_USER_AGENT environment variable works. - """ - from litellm.llms.custom_httpx.http_handler import get_default_headers - - # Test with env var - with patch.dict(os.environ, {"LITELLM_DISABLE_DEFAULT_USER_AGENT": "True"}): - # Manually set the flag (in real usage, this would be done at import time) - litellm.disable_default_user_agent = True - - headers = get_default_headers() - assert headers == {} - - # Reset to default - litellm.disable_default_user_agent = False - - -@pytest.mark.asyncio -async def test_async_http_handler_respects_disable_flag(): - """ - Test that AsyncHTTPHandler also respects the disable_default_user_agent flag. - """ - from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler, get_default_headers - - # Disable default User-Agent - litellm.disable_default_user_agent = True - - # Create async handler - handler = AsyncHTTPHandler() - - # Check that headers are empty - headers = get_default_headers() - assert headers == {} - - await handler.close() - - # Reset to default - litellm.disable_default_user_agent = False - - -def test_override_user_agent_without_disabling(): - """ - Test that users can override User-Agent by passing it in extra_headers, - even without disabling the default. - - Note: httpx will use the last header value when building the request. - """ - import httpx - from litellm.llms.custom_httpx.http_handler import HTTPHandler - - # Default User-Agent is enabled - litellm.disable_default_user_agent = False - - # Create HTTP handler (will have default User-Agent) - handler = HTTPHandler() - - # Custom User-Agent provided in request - custom_headers = {"User-Agent": "MyCustomAgent/2.0.0"} - - # Build request with custom headers - httpx merges headers - req = handler.client.build_request( - "POST", - "https://api.anthropic.com/v1/messages", - headers=custom_headers, - json={"test": "data"} - ) - - # The custom User-Agent should override the default - assert "User-Agent" in req.headers - # httpx uses the request-level header over the client-level header - assert req.headers["User-Agent"] == "MyCustomAgent/2.0.0" - - -def test_claude_code_use_case(): - """ - Test the specific use case from Issue #19017: - Claude Code credentials that require specific User-Agent. - """ - # Disable default User-Agent globally - litellm.disable_default_user_agent = True - - # This is what the user would do in their code - custom_headers = {"User-Agent": "Claude Code"} - - # Verify the headers can be passed through - from litellm.llms.custom_httpx.http_handler import get_default_headers - default_headers = get_default_headers() - - # Default headers should be empty - assert default_headers == {} - - # Custom headers would be used in the actual request - assert custom_headers["User-Agent"] == "Claude Code" - - # Reset - litellm.disable_default_user_agent = False - - -def test_backwards_compatibility(): - """ - Test that existing code continues to work without any changes. - By default, the User-Agent header should still be set. - """ - from litellm.llms.custom_httpx.http_handler import get_default_headers - from litellm._version import version - - # Ensure default behavior is maintained - litellm.disable_default_user_agent = False - - headers = get_default_headers() - assert "User-Agent" in headers - assert headers["User-Agent"] == f"litellm/{version}" - - # Create HTTP handler - from litellm.llms.custom_httpx.http_handler import HTTPHandler - handler = HTTPHandler() - - # Build a request - req = handler.client.build_request( - "GET", - "https://api.openai.com/v1/models" - ) - - # Default User-Agent should be present - assert "User-Agent" in req.headers - assert "litellm" in req.headers["User-Agent"] From b87076875be0a7a9a7449430a0efb9406f5bdcde Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 02:09:40 +0530 Subject: [PATCH 5/6] refactor: drop disable_default_user_agent setting --- litellm/__init__.py | 1 - 1 file changed, 1 deletion(-) diff --git a/litellm/__init__.py b/litellm/__init__.py index 5998032b8e8..e5c09702b9b 100644 --- a/litellm/__init__.py +++ b/litellm/__init__.py @@ -254,7 +254,6 @@ disable_streaming_logging: bool = False disable_token_counter: bool = False disable_add_transform_inline_image_block: bool = False disable_add_user_agent_to_request_tags: bool = False -disable_default_user_agent: bool = False # Option to disable automatic User-Agent header injection extra_spend_tag_headers: Optional[List[str]] = None in_memory_llm_clients_cache: "LLMClientCache" safe_memory_mode: bool = False From 980ec2afe80af21a880bb77cd3879b7538495332 Mon Sep 17 00:00:00 2001 From: jayy-77 <1427jay@gmail.com> Date: Wed, 28 Jan 2026 02:09:47 +0530 Subject: [PATCH 6/6] test: cover LITELLM_USER_AGENT override in custom_httpx handlers --- .../llms/custom_httpx/test_http_handler.py | 84 +++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/tests/test_litellm/llms/custom_httpx/test_http_handler.py b/tests/test_litellm/llms/custom_httpx/test_http_handler.py index 0b154474d48..65f08ef5021 100644 --- a/tests/test_litellm/llms/custom_httpx/test_http_handler.py +++ b/tests/test_litellm/llms/custom_httpx/test_http_handler.py @@ -471,3 +471,87 @@ def test_ssl_ecdh_curve(env_curve, litellm_curve, expected_curve, should_call, m assert isinstance(ssl_context, ssl.SSLContext) finally: litellm.ssl_ecdh_curve = original_value + + +def test_default_user_agent_is_litellm_version(monkeypatch): + from litellm._version import version + from litellm.llms.custom_httpx.http_handler import get_default_headers + + monkeypatch.delenv("LITELLM_USER_AGENT", raising=False) + + assert get_default_headers()["User-Agent"] == f"litellm/{version}" + + +def test_user_agent_can_be_overridden_via_env_var(monkeypatch): + from litellm.llms.custom_httpx.http_handler import get_default_headers + + monkeypatch.setenv("LITELLM_USER_AGENT", "Claude Code") + + assert get_default_headers()["User-Agent"] == "Claude Code" + + +def test_user_agent_env_var_can_be_empty_string(monkeypatch): + from litellm.llms.custom_httpx.http_handler import get_default_headers + + monkeypatch.setenv("LITELLM_USER_AGENT", "") + + assert get_default_headers()["User-Agent"] == "" + + +def test_user_agent_override_is_not_appended_to_default(monkeypatch): + from litellm.llms.custom_httpx.http_handler import HTTPHandler + + monkeypatch.delenv("LITELLM_USER_AGENT", raising=False) + + handler = HTTPHandler() + try: + req = handler.client.build_request( + "GET", + "https://example.com", + headers={"user-agent": "Claude Code"}, + ) + + assert req.headers.get_list("User-Agent") == ["Claude Code"] + finally: + handler.close() + + +def test_sync_http_handler_uses_env_user_agent(monkeypatch): + from litellm.llms.custom_httpx.http_handler import HTTPHandler + + monkeypatch.setenv("LITELLM_USER_AGENT", "Claude Code") + + handler = HTTPHandler() + try: + req = handler.client.build_request("GET", "https://example.com") + assert req.headers.get("User-Agent") == "Claude Code" + finally: + handler.close() + + +@pytest.mark.asyncio +async def test_async_http_handler_uses_env_user_agent(monkeypatch): + from litellm.llms.custom_httpx.http_handler import AsyncHTTPHandler + + monkeypatch.setenv("LITELLM_USER_AGENT", "Claude Code") + + handler = AsyncHTTPHandler() + try: + req = handler.client.build_request("GET", "https://example.com") + assert req.headers.get("User-Agent") == "Claude Code" + finally: + await handler.close() + + +@pytest.mark.asyncio +async def test_httpx_handler_uses_env_user_agent(monkeypatch): + from litellm.llms.custom_httpx.httpx_handler import HTTPHandler + + monkeypatch.setenv("LITELLM_USER_AGENT", "Claude Code") + + handler = HTTPHandler() + try: + req = handler.client.build_request("GET", "https://example.com") + assert req.headers.get("User-Agent") == "Claude Code" + finally: + await handler.close()