From 67b43cec22977d6c71539e0fcdd7b9eaf4c0fb75 Mon Sep 17 00:00:00 2001
From: Simon Hornby <liquidwicked64@gmail.com>
Date: Fri, 5 Sep 2025 15:10:15 +0200
Subject: [PATCH 1/4] chore: test that checks if the client spec version is
 sent

---
 tests/unit_tests/test_client.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tests/unit_tests/test_client.py b/tests/unit_tests/test_client.py
index e63edece..55b06b03 100644
--- a/tests/unit_tests/test_client.py
+++ b/tests/unit_tests/test_client.py
@@ -1,4 +1,5 @@
 import json
+import re
 import threading
 import time
 import uuid
@@ -1487,3 +1488,21 @@ def test_uc_bootstrap_initializes_offline_connector():
     assert unleash_client.is_enabled("testFlag")
 
     unleash_client.destroy()
+
+@responses.activate
+def test_spec_header_is_sent_when_fetching_features():
+    responses.add(
+        responses.GET, URL + FEATURES_URL, json=MOCK_FEATURE_RESPONSE, status=200
+    )
+
+    unleash_client = UnleashClient(
+        URL, APP_NAME, disable_metrics=True, disable_registration=True
+    )
+    unleash_client.initialize_client()
+    client_spec = responses.calls[0].request.headers[
+        "Unleash-Client-Spec"
+    ]
+
+    ## assert that the client spec looks like a semver string
+    semver_regex = r"^\d+\.\d+\.\d+(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$"
+    assert re.match(semver_regex, client_spec)

From daa0f9c5a18f614ce077fb28dfacfe19efe59fe3 Mon Sep 17 00:00:00 2001
From: Simon Hornby <liquidwicked64@gmail.com>
Date: Fri, 5 Sep 2025 15:10:44 +0200
Subject: [PATCH 2/4] fix: include client spec header on feature fetches

---
 UnleashClient/__init__.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/UnleashClient/__init__.py b/UnleashClient/__init__.py
index a7435335..2d91ff42 100644
--- a/UnleashClient/__init__.py
+++ b/UnleashClient/__init__.py
@@ -23,6 +23,7 @@
     StreamingConnector,
 )
 from UnleashClient.constants import (
+    APPLICATION_HEADERS,
     DISABLED_VARIATION,
     ETAG,
     METRIC_LAST_SENT_TIME,
@@ -290,6 +291,7 @@ def initialize_client(self, fetch_toggles: bool = True) -> None:
                 start_scheduler = False
                 base_headers = {
                     **self.unleash_custom_headers,
+                    **APPLICATION_HEADERS,
                     "unleash-connection-id": self.connection_id,
                     "unleash-appname": self.unleash_app_name,
                     "unleash-instanceid": self.unleash_instance_id,

From ca4bb2b35eff4efe37b6034eba0043ff33c56656 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 5 Sep 2025 13:12:29 +0000
Subject: [PATCH 3/4] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 tests/unit_tests/test_client.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tests/unit_tests/test_client.py b/tests/unit_tests/test_client.py
index 55b06b03..2d331f1b 100644
--- a/tests/unit_tests/test_client.py
+++ b/tests/unit_tests/test_client.py
@@ -1489,6 +1489,7 @@ def test_uc_bootstrap_initializes_offline_connector():
 
     unleash_client.destroy()
 
+
 @responses.activate
 def test_spec_header_is_sent_when_fetching_features():
     responses.add(
@@ -1499,9 +1500,7 @@ def test_spec_header_is_sent_when_fetching_features():
         URL, APP_NAME, disable_metrics=True, disable_registration=True
     )
     unleash_client.initialize_client()
-    client_spec = responses.calls[0].request.headers[
-        "Unleash-Client-Spec"
-    ]
+    client_spec = responses.calls[0].request.headers["Unleash-Client-Spec"]
 
     ## assert that the client spec looks like a semver string
     semver_regex = r"^\d+\.\d+\.\d+(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$"

From 97973c0b37bf49b571c0fbc9b89ceea18eb28430 Mon Sep 17 00:00:00 2001
From: Simon Hornby <liquidwicked64@gmail.com>
Date: Fri, 5 Sep 2025 15:13:01 +0200
Subject: [PATCH 4/4] chore: format

---
 tests/unit_tests/test_client.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tests/unit_tests/test_client.py b/tests/unit_tests/test_client.py
index 55b06b03..2d331f1b 100644
--- a/tests/unit_tests/test_client.py
+++ b/tests/unit_tests/test_client.py
@@ -1489,6 +1489,7 @@ def test_uc_bootstrap_initializes_offline_connector():
 
     unleash_client.destroy()
 
+
 @responses.activate
 def test_spec_header_is_sent_when_fetching_features():
     responses.add(
@@ -1499,9 +1500,7 @@ def test_spec_header_is_sent_when_fetching_features():
         URL, APP_NAME, disable_metrics=True, disable_registration=True
     )
     unleash_client.initialize_client()
-    client_spec = responses.calls[0].request.headers[
-        "Unleash-Client-Spec"
-    ]
+    client_spec = responses.calls[0].request.headers["Unleash-Client-Spec"]
 
     ## assert that the client spec looks like a semver string
     semver_regex = r"^\d+\.\d+\.\d+(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?(\+[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$"