diff --git a/oilpriceapi/streaming/client.py b/oilpriceapi/streaming/client.py
index 6ebe55e..16f4f32 100644
--- a/oilpriceapi/streaming/client.py
+++ b/oilpriceapi/streaming/client.py
@@ -27,6 +27,7 @@
 import json
 import logging
 import random
+import sys
 from types import TracebackType
 from typing import TYPE_CHECKING, Any, AsyncIterator, Dict, List, Optional, Type
 
@@ -115,7 +116,22 @@ async def connect(self) -> None:
         # also accepts the Authorization header (connection.rb find_verified_user).
         sep = "&" if "?" in self._cable_url else "?"
         url = f"{self._cable_url}{sep}token={self._api_key}"
-        headers = {"Authorization": f"Token {self._api_key}"}
+        # Identify the SDK on the handshake exactly as the HTTP client does.
+        # The upgrade request is an ordinary HTTP request, so without these
+        # headers a streaming client is indistinguishable from a hand-rolled
+        # WebSocket and drops out of SDK attribution entirely. The Go SDK
+        # (stream.go) already sets the User-Agent here.
+        from ..version import SDK_NAME, SDK_VERSION
+
+        python_version = (
+            f"{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}"
+        )
+        headers = {
+            "Authorization": f"Token {self._api_key}",
+            "User-Agent": f"{SDK_NAME}/{SDK_VERSION} python/{python_version}",
+            "X-SDK-Name": SDK_NAME,
+            "X-SDK-Version": SDK_VERSION,
+        }
 
         self._ws = await websockets.connect(
             url,
diff --git a/tests/unit/test_sdk_attribution.py b/tests/unit/test_sdk_attribution.py
new file mode 100644
index 0000000..a87b1f7
--- /dev/null
+++ b/tests/unit/test_sdk_attribution.py
@@ -0,0 +1,111 @@
+"""Server-side attribution contract for the Python SDK.
+
+`MinimalAnalyticsService#detect_sdk_info` in oilpriceapi-api parses
+sdk_language/sdk_version out of the User-Agent with exactly the regex
+pinned below. A User-Agent that stops matching it still returns 200 --
+the request succeeds and the SDK silently disappears from adoption
+reporting. That is a failure no HTTP-level test would catch, so these
+tests assert the *parsed* language and version rather than a substring.
+
+Keep SERVER_SDK_REGEX in step with
+app/services/minimal_analytics_service.rb (detect_sdk_info).
+"""
+
+import re
+
+import pytest
+
+from oilpriceapi import OilPriceAPI
+from oilpriceapi.version import SDK_NAME, SDK_VERSION
+
+SERVER_SDK_REGEX = re.compile(
+    r"oilpriceapi-([a-z0-9-]+)/v?([\d]+\.[\d]+\.?[\d]*)", re.IGNORECASE
+)
+
+
+def _parse(user_agent):
+    return SERVER_SDK_REGEX.search(user_agent or "")
+
+
+def test_sdk_name_and_version_are_shaped_for_the_server_regex():
+    match = _parse(f"{SDK_NAME}/{SDK_VERSION}")
+    assert match is not None, f"{SDK_NAME}/{SDK_VERSION} does not parse server-side"
+    assert match.group(1) == "python"
+    assert match.group(2) == SDK_VERSION
+
+
+def test_sync_client_user_agent_parses_to_python_and_the_real_version():
+    client = OilPriceAPI(api_key="test_key")
+    match = _parse(client.headers.get("User-Agent"))
+
+    assert match is not None, "sync client User-Agent is not attributable server-side"
+    assert match.group(1) == "python"
+    assert match.group(2) == SDK_VERSION
+
+
+def test_async_client_user_agent_parses_to_python_and_the_real_version():
+    from oilpriceapi import AsyncOilPriceAPI
+
+    client = AsyncOilPriceAPI(api_key="test_key")
+    match = _parse(client.headers.get("User-Agent"))
+
+    assert match is not None, "async client User-Agent is not attributable server-side"
+    assert match.group(1) == "python"
+    assert match.group(2) == SDK_VERSION
+
+
+@pytest.mark.asyncio
+async def test_streaming_handshake_sends_an_attributable_user_agent(monkeypatch):
+    """The ActionCable upgrade is an ordinary HTTP request.
+
+    Without a User-Agent a streaming client is indistinguishable from a
+    hand-rolled WebSocket and drops out of SDK attribution entirely. The Go
+    SDK already sets one on its handshake (stream.go).
+    """
+    from oilpriceapi.streaming import client as streaming_client
+
+    captured = {}
+
+    class _FakeWS:
+        """Scripted ActionCable peer: welcome, then confirm_subscription."""
+
+        def __init__(self):
+            self._frames = iter(
+                ['{"type": "welcome"}', '{"type": "confirm_subscription"}']
+            )
+
+        async def recv(self):
+            return next(self._frames)
+
+        async def send(self, _data):
+            return None
+
+        async def close(self):
+            return None
+
+    async def _fake_connect(url, **kwargs):
+        captured["url"] = url
+        captured["headers"] = kwargs.get("additional_headers") or {}
+        return _FakeWS()
+
+    class _FakeWebsockets:
+        connect = staticmethod(_fake_connect)
+
+    monkeypatch.setattr(
+        streaming_client, "_import_websockets", lambda: _FakeWebsockets
+    )
+
+    stream = streaming_client.PriceStream(
+        cable_url="wss://api.oilpriceapi.com/cable", api_key="test_key"
+    )
+    await stream.connect()
+
+    headers = {k.lower(): v for k, v in captured["headers"].items()}
+    match = _parse(headers.get("user-agent"))
+
+    assert match is not None, (
+        "WebSocket handshake sent no attributable User-Agent; "
+        f"headers were {sorted(headers)}"
+    )
+    assert match.group(1) == "python"
+    assert match.group(2) == SDK_VERSION