From ccff7c52f265c3ada2eb322de5462a8fa2d990ad Mon Sep 17 00:00:00 2001
From: johnslavik <bartosz@ilikepython.com>
Date: Thu, 18 Dec 2025 18:43:37 +0100
Subject: [PATCH 1/2] Fallback to basic REPL for non-TTY stdout

---
 Lib/_pyrepl/main.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Lib/_pyrepl/main.py b/Lib/_pyrepl/main.py
index 447eb1e551e774..cbffa6860aee25 100644
--- a/Lib/_pyrepl/main.py
+++ b/Lib/_pyrepl/main.py
@@ -11,6 +11,8 @@
         raise RuntimeError("Windows 10 TH2 or later required")
     if not os.isatty(sys.stdin.fileno()):
         raise OSError(errno.ENOTTY, "tty required", "stdin")
+    if not os.isatty(sys.stdout.fileno()):
+        raise OSError(errno.ENOTTY, "tty required", "stdout")
     from .simple_interact import check
     if err := check():
         raise RuntimeError(err)

From 8455a3dcf3e8fc0ef8d838ee4a03f790175b8d8c Mon Sep 17 00:00:00 2001
From: johnslavik <bartosz@ilikepython.com>
Date: Thu, 18 Dec 2025 20:28:06 +0100
Subject: [PATCH 2/2] Add news entry

---
 .../Library/2025-12-18-20-27-53.gh-issue-142948.dhySDC.rst     | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2025-12-18-20-27-53.gh-issue-142948.dhySDC.rst

diff --git a/Misc/NEWS.d/next/Library/2025-12-18-20-27-53.gh-issue-142948.dhySDC.rst b/Misc/NEWS.d/next/Library/2025-12-18-20-27-53.gh-issue-142948.dhySDC.rst
new file mode 100644
index 00000000000000..f35fe57f7e3b9a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-12-18-20-27-53.gh-issue-142948.dhySDC.rst
@@ -0,0 +1,3 @@
+The new REPL now falls back to basic REPL if stdout is non-interactive.
+Previously it could flood the output if such stdout was a broken pipe.
+Contributed by Bartosz Sławecki.