From 7f614b1239476ebc8f926bd8171b23d4640b23c3 Mon Sep 17 00:00:00 2001
From: Savannah Ostrowski <savannah@python.org>
Date: Tue, 4 Aug 2026 19:25:17 -0700
Subject: [PATCH 1/4] Preserve argparse prog for programmatic module-as-main
 execution

---
 Lib/argparse.py           |  3 +++
 Lib/test/test_argparse.py | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 0840c4c45cffaa..be5a594f0f360c 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1964,6 +1964,9 @@ def _prog_name(prog=None):
     if modspec is None:
         # simple script
         return _os.path.basename(arg0)
+    if modspec.name != '__main__' and arg0 != modspec.origin:
+        # imported module executed as main without altering sys.argv[0]
+        return _os.path.basename(arg0)
     py = _os.path.basename(_sys.executable)
     if modspec.name != '__main__':
         # imported module or package
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 287fcb7a084a49..ae02cd11804e50 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -7346,6 +7346,19 @@ def test_module(self, compiled=False):
     def test_module_compiled(self):
         self.test_module(compiled=True)
 
+    def test_module_as_main_without_altering_argv(self):
+        basename = 'module' + os_helper.FS_NONASCII
+        modulename = f'{self.dirname}.{basename}'
+        self.make_script(self.dirname, basename)
+        runner_source = textwrap.dedent(f'''\
+            import runpy
+            runpy._run_module_as_main({modulename!r}, alter_argv=False)
+        ''')
+        runner = script_helper.make_script(
+            self.dirname, 'runner', runner_source)
+        self.check_usage(os.path.basename(runner), runner,
+                         PYTHONPATH=os.curdir)
+
     def test_package(self, compiled=False):
         basename = 'subpackage' + os_helper.FS_NONASCII
         packagename = f'{self.dirname}.{basename}'

From 1e72ca776f60b393335767bf66a60bb6ee335483 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Wed, 5 Aug 2026 02:36:24 +0000
Subject: [PATCH 2/4] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst     | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst

diff --git a/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst b/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst
new file mode 100644
index 00000000000000..dc67858e54a497
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst
@@ -0,0 +1,3 @@
+Fix :class:`argparse.ArgumentParser` to preserve the program name from
+``sys.argv[0]`` when a named module is executed as the main program without
+replacing ``sys.argv[0]``.

From 8d1379d2241e8951dcdab8929366485b92d9c565 Mon Sep 17 00:00:00 2001
From: Savannah Ostrowski <savannah@python.org>
Date: Tue, 4 Aug 2026 19:37:20 -0700
Subject: [PATCH 3/4] Improve comment

---
 Lib/argparse.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/argparse.py b/Lib/argparse.py
index be5a594f0f360c..25994d7a389efa 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1965,7 +1965,7 @@ def _prog_name(prog=None):
         # simple script
         return _os.path.basename(arg0)
     if modspec.name != '__main__' and arg0 != modspec.origin:
-        # imported module executed as main without altering sys.argv[0]
+        # named module executed as main without altering sys.argv[0]
         return _os.path.basename(arg0)
     py = _os.path.basename(_sys.executable)
     if modspec.name != '__main__':

From b576d71cd383b87880d004f91328c575fa690f64 Mon Sep 17 00:00:00 2001
From: Savannah Ostrowski <savannah@python.org>
Date: Tue, 4 Aug 2026 21:10:30 -0700
Subject: [PATCH 4/4] Normalize NEWS entry line endings

---
 .../Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst    | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst b/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst
index dc67858e54a497..219c6a94b91cb6 100644
--- a/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst
+++ b/Misc/NEWS.d/next/Library/2026-08-05-02-36-18.gh-issue-155009.YiJAiP.rst
@@ -1,3 +1,3 @@
-Fix :class:`argparse.ArgumentParser` to preserve the program name from
-``sys.argv[0]`` when a named module is executed as the main program without
+Fix :class:`argparse.ArgumentParser` to preserve the program name from
+``sys.argv[0]`` when a named module is executed as the main program without
 replacing ``sys.argv[0]``.