From d95a11d20b88c423e5d5f1f7e394c2c95e885fd6 Mon Sep 17 00:00:00 2001
From: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Date: Mon, 30 Dec 2024 21:02:25 +0200
Subject: [PATCH 1/4] Add 404 page

---
 .github/workflows/render.yml | 4 +++-
 peps/conf.py                 | 5 +++++
 requirements.txt             | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/render.yml b/.github/workflows/render.yml
index eb9c107b809..ffceabc3be9 100644
--- a/.github/workflows/render.yml
+++ b/.github/workflows/render.yml
@@ -42,7 +42,9 @@ jobs:
           python -m pip install --upgrade pip
 
       - name: Render PEPs
-        run: make dirhtml JOBS=$(nproc)
+        run: |
+          make dirhtml JOBS=$(nproc)
+          mv build/404/index.html build/404.html
 
         # remove the .doctrees folder when building for deployment as it takes two thirds of disk space
       - name: Clean up files
diff --git a/peps/conf.py b/peps/conf.py
index f566a42ee53..8205e011ba3 100644
--- a/peps/conf.py
+++ b/peps/conf.py
@@ -19,6 +19,7 @@
 
 # Add any Sphinx extension module names here, as strings.
 extensions = [
+    "notfound.extension",
     "pep_sphinx_extensions",
     "sphinx.ext.extlinks",
     "sphinx.ext.intersphinx",
@@ -85,6 +86,10 @@
     "pypi": ("https://pypi.org/project/%s/", "%s"),
 }
 
+# sphinx-notfound-page
+# https://sphinx-notfound-page.readthedocs.io/en/latest/faq.html#does-this-extension-work-with-github-pages
+notfound_urls_prefix = None
+
 # -- Options for HTML output -------------------------------------------------
 
 _PSE_PATH = _ROOT / "pep_sphinx_extensions"
diff --git a/requirements.txt b/requirements.txt
index ffb858ea649..67f89f4eadf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,6 +4,7 @@ Pygments >= 2.9.0
 # See https://github.com/sphinx-doc/sphinx/pull/11100
 Sphinx >= 5.1.1, != 6.1.0, != 6.1.1, < 8.1.0
 docutils >= 0.19.0
+sphinx-notfound-page
 
 # For tests
 pytest

From 9dd4932cd9fbf57b40903a2c8d5b01bebd90009d Mon Sep 17 00:00:00 2001
From: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Date: Tue, 31 Dec 2024 11:38:44 +0200
Subject: [PATCH 2/4] Move 404 page in Makefile

---
 .github/workflows/render.yml | 4 +---
 Makefile                     | 1 +
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/render.yml b/.github/workflows/render.yml
index ffceabc3be9..eb9c107b809 100644
--- a/.github/workflows/render.yml
+++ b/.github/workflows/render.yml
@@ -42,9 +42,7 @@ jobs:
           python -m pip install --upgrade pip
 
       - name: Render PEPs
-        run: |
-          make dirhtml JOBS=$(nproc)
-          mv build/404/index.html build/404.html
+        run: make dirhtml JOBS=$(nproc)
 
         # remove the .doctrees folder when building for deployment as it takes two thirds of disk space
       - name: Clean up files
diff --git a/Makefile b/Makefile
index 373a8a1ee11..25bb1b3d748 100644
--- a/Makefile
+++ b/Makefile
@@ -40,6 +40,7 @@ htmllive: _ensure-sphinx-autobuild html
 .PHONY: dirhtml
 dirhtml: BUILDER = dirhtml
 dirhtml: html
+dirhtml: mv $(BUILDDIR)/404/index.html $(BUILDDIR)/404.html
 
 ## linkcheck      to check validity of links within PEP sources
 .PHONY: linkcheck

From ce96a787fd22c16cb58943f125c51d6d07ba795c Mon Sep 17 00:00:00 2001
From: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Date: Tue, 31 Dec 2024 11:46:01 +0200
Subject: [PATCH 3/4] Move 404 page in Makefile

---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 25bb1b3d748..52cc4e27957 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,7 @@ htmllive: _ensure-sphinx-autobuild html
 .PHONY: dirhtml
 dirhtml: BUILDER = dirhtml
 dirhtml: html
-dirhtml: mv $(BUILDDIR)/404/index.html $(BUILDDIR)/404.html
+	mv $(BUILDDIR)/404/index.html $(BUILDDIR)/404.html
 
 ## linkcheck      to check validity of links within PEP sources
 .PHONY: linkcheck

From e26fdd0d689cc382895b9a818304b02ad7635cd5 Mon Sep 17 00:00:00 2001
From: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Date: Tue, 31 Dec 2024 11:48:02 +0200
Subject: [PATCH 4/4] Require version with notfound_urls_prefix

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
---
 requirements.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/requirements.txt b/requirements.txt
index 67f89f4eadf..ffcbe1a8aa6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@ Pygments >= 2.9.0
 # See https://github.com/sphinx-doc/sphinx/pull/11100
 Sphinx >= 5.1.1, != 6.1.0, != 6.1.1, < 8.1.0
 docutils >= 0.19.0
-sphinx-notfound-page
+sphinx-notfound-page >= 1.0.2
 
 # For tests
 pytest