gh-140006: Preserve fish prompt status in venv activation

Author: ThanhNguyxn

Lib/test/test_venv.py

@@ -772,6 +772,16 @@ def test_activate_shell_script_has_no_dos_newlines(self):
                 error_message = f"CR LF found in line {i}"
                 self.assertNotEndsWith(line, b'\r\n', error_message)
 
+    @requireVenvCreate
+    def test_activate_fish_script_preserves_status(self):
+        venv_dir = pathlib.Path(self.env_dir)
+        rmtree(venv_dir)
+        script_path = venv_dir / self.bindir / 'activate.fish'
+        venv.create(venv_dir)
+        script = script_path.read_text(encoding='utf-8')
+        self.assertIn('return $old_status', script)
+        self.assertNotIn('echo "exit $old_status" | .', script)
+
     @requireVenvCreate
     def test_scm_ignore_files_git(self):
         """

Lib/venv/scripts/common/activate.fish

@@ -60,7 +60,7 @@ if test -z "$VIRTUAL_ENV_DISABLE_PROMPT"
         printf "%s(%s)%s " (set_color 4B8BBE) __VENV_PROMPT__ (set_color normal)
 
         # Restore the return status of the previous command.
-        echo "exit $old_status" | .
+        return $old_status
         # Output the original/"old" prompt.
         _old_fish_prompt
     end

Misc/NEWS.d/next/Library/2026-02-07-16-36-00.gh-issue-140006.H3z8kW.rst

@@ -0,0 +1,3 @@
+Fix ``venv``'s ``activate.fish`` prompt hook to preserve the previous command
+status without sourcing ``exit`` from stdin, avoiding prompt corruption in
+interactive fish sessions.