From d3f01172943a20af4b0dc4cfe3dbede82c9dea8d Mon Sep 17 00:00:00 2001
From: Christophe Dervieux <christophe.dervieux@gmail.com>
Date: Thu, 22 Oct 2026 14:01:27 +0200
Subject: [PATCH 1/2] Keep KOMA classes working with pdf-standard under
 KOMA-Script 3.49.3

KOMA-Script 3.49.3 turned the 3.49.2 warning about \DocumentMetadata into
a fatal error for every KOMA class (scrartcl, scrreprt, scrbook) that has
no tagging support file. Quarto emits \DocumentMetadata whenever
pdf-standard is set and defaults to scrartcl, so every pdf-standard PDF
render fails once TeX Live ships the new KOMA-Script.

KOMA documents \komascript_documentmetadata_test: as the hook packages
and wrapper classes define before loading the class to replace this
check. Defining it as a no-op right after \DocumentMetadata restores the
3.49.2 behaviour, i.e. what 1.9 and 1.10 produced, with no change in
class or layout. The cs_if_exist guard keeps an existing definition.
Non-KOMA classes never read the macro.

Known tradeoff: this bypasses a deliberate KOMA check, and KOMA classes
still do not tag sectioning commands (#14422); that is addressed
separately. KOMA calls the hook provisional, so a later release may need
a different approach.

Fixes #15143

(cherry picked from commit 03c9314b0e66fac24b776da579ac0a786cbadfd5)
---
 src/resources/formats/pdf/pandoc/template.tex | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/resources/formats/pdf/pandoc/template.tex b/src/resources/formats/pdf/pandoc/template.tex
index 5ce3e586c35..00ba246571a 100644
--- a/src/resources/formats/pdf/pandoc/template.tex
+++ b/src/resources/formats/pdf/pandoc/template.tex
@@ -1,4 +1,12 @@
 $document-metadata.latex()$
+$if(pdfstandard)$
+$-- KOMA-Script 3.49.3 aborts on \DocumentMetadata unless \komascript_documentmetadata_test: exists;
+$-- a no-op keeps the 3.49.2 behaviour (#15143). The guard keeps a definition made earlier.
+\ExplSyntaxOn
+\cs_if_exist:NF \komascript_documentmetadata_test:
+  { \cs_new:Npn \komascript_documentmetadata_test: { } }
+\ExplSyntaxOff
+$endif$
 % Options for packages loaded elsewhere
 $passoptions.latex()$
 %

From f274e0a375d35f03c2e788e3cf9c4218b17f8b7a Mon Sep 17 00:00:00 2001
From: Christophe Dervieux <christophe.dervieux@gmail.com>
Date: Thu, 22 Oct 2026 14:59:19 +0200
Subject: [PATCH 2/2] Add changelog entry for #15143 backport

---
 news/changelog-1.10.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/news/changelog-1.10.md b/news/changelog-1.10.md
index c2fcee0b8b8..9a0536b6955 100644
--- a/news/changelog-1.10.md
+++ b/news/changelog-1.10.md
@@ -2,6 +2,8 @@
 
 ## In this release
 
+- ([#15143](https://github.com/quarto-dev/quarto-cli/issues/15143)): Fix PDF rendering with `pdf-standard` failing with `\DocumentMetadata not supported!` after updating to KOMA-Script 3.49.3, which provides the default document classes.
+
 ## In previous releases
 
 - ([#14920](https://github.com/quarto-dev/quarto-cli/issues/14920)): Correct the Windows ARM diagnostic for x64 R crashes with stable native ARM64 R installation guidance, including reinstalling packages and configuring `QUARTO_R`.