From 84cb686e3d12d4ad46aa52ca4f3dcdac403bfd22 Mon Sep 17 00:00:00 2001
From: David Brownman <xavdid@stripe.com>
Date: Tue, 2 Jun 2026 17:10:06 -0700
Subject: [PATCH] Add source field to user-agent header

---
 stripe/_api_requestor.py    | 19 +++++++++++++++++++
 tests/test_api_requestor.py | 31 +++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/stripe/_api_requestor.py b/stripe/_api_requestor.py
index 10bdebdcc..514c8ba82 100644
--- a/stripe/_api_requestor.py
+++ b/stripe/_api_requestor.py
@@ -1,7 +1,10 @@
 from io import BytesIO, IOBase
+import functools
+import hashlib
 import json
 import os
 import platform
+import socket
 from typing import (
     Any,
     AsyncIterable,
@@ -72,6 +75,19 @@
 _default_proxy: Optional[str] = None
 
 
+@functools.lru_cache(maxsize=None)
+def _get_uname_hash() -> Optional[str]:
+    try:
+        parts: List[str] = list(platform.uname())
+        try:
+            parts.append(socket.gethostname())
+        except Exception:
+            pass
+        return hashlib.md5(" ".join(parts).encode()).hexdigest()
+    except Exception:
+        return None
+
+
 def _maybe_emit_stripe_notice(rheaders: Mapping[str, str]) -> None:
     notice = rheaders.get("Stripe-Notice")
     if notice:
@@ -525,6 +541,9 @@ def request_headers(
             "lang": "python",
             "httplib": self._get_http_client().name,
         }
+        uname_hash = _get_uname_hash()
+        if uname_hash is not None:
+            ua["source"] = uname_hash
         attr_funcs: List[Tuple[str, Callable[[], str]]] = [
             ("lang_version", platform.python_version),
         ]
diff --git a/tests/test_api_requestor.py b/tests/test_api_requestor.py
index ff3530359..326be0bb9 100644
--- a/tests/test_api_requestor.py
+++ b/tests/test_api_requestor.py
@@ -1,5 +1,6 @@
 import datetime
 import json
+import re
 import tempfile
 import uuid
 from collections import OrderedDict
@@ -788,6 +789,36 @@ def fail():
             last_call.get_raw_header("X-Stripe-Client-User-Agent")
         )
 
+    def test_source_field_is_md5_hex(self, requestor, http_client_mock):
+        http_client_mock.stub_request(
+            "get", path=self.v1_path, rbody="{}", rcode=200
+        )
+        requestor.request("get", self.v1_path, {}, base_address="api")
+
+        last_call = http_client_mock.get_last_call()
+        client_ua = json.loads(
+            last_call.get_raw_header("X-Stripe-Client-User-Agent")
+        )
+        assert "source" in client_ua
+        assert re.fullmatch(r"[0-9a-f]{32}", client_ua["source"])
+
+    def test_source_field_absent_when_uname_fails(
+        self, requestor, mocker, http_client_mock
+    ):
+        http_client_mock.stub_request(
+            "get", path=self.v1_path, rbody="{}", rcode=200
+        )
+        mocker.patch(
+            "stripe._api_requestor._get_uname_hash", return_value=None
+        )
+        requestor.request("get", self.v1_path, {}, base_address="api")
+
+        last_call = http_client_mock.get_last_call()
+        client_ua = json.loads(
+            last_call.get_raw_header("X-Stripe-Client-User-Agent")
+        )
+        assert "source" not in client_ua
+
     def test_uses_given_idempotency_key(self, requestor, http_client_mock):
         method = "post"
         http_client_mock.stub_request(