From 5c801b0aec55c72868873a1b0b60dd4c6614a7db Mon Sep 17 00:00:00 2001
From: Christophe Dervieux <christophe.dervieux@gmail.com>
Date: Fri, 29 May 2026 16:24:01 +0200
Subject: [PATCH] fix(pdf): recognize luaotfload missing-font error for
 fallback fonts

When a font listed in monofontfallback (or any *fontfallback) is absent,
luaotfload reports it via 'luaotfload | ... reason: Font "X;-fallback"
not found' and fontspec never raises its own catchable error, so Quarto's
missing-package detector saw nothing and the PDF render failed with no
auto-install attempt. The primary monofont case worked only because
fontspec also fires there.

Add a packageMatcher for the luaotfload format and strip the ;-fallback
suffix luaotfload appends internally before building the tlmgr search term,
so 'DejaVu Sans Mono' resolves to the dejavu CTAN package.

Closes #14558
---
 news/changelog-1.10.md                    |  1 +
 src/command/render/latexmk/parse-error.ts | 15 +++++++++++++++
 tests/unit/latexmk/parse-error.test.ts    |  3 +++
 3 files changed, 19 insertions(+)

diff --git a/news/changelog-1.10.md b/news/changelog-1.10.md
index e59c72deb4f..cde9ab05d03 100644
--- a/news/changelog-1.10.md
+++ b/news/changelog-1.10.md
@@ -25,6 +25,7 @@ All changes included in 1.10:
 ### `pdf`
 
 - ([#13588](https://github.com/quarto-dev/quarto-cli/issues/13588)): Fix Lua error when rendering PDF with `reference-location: margin` and a footnote alongside a figure with `fig-cap`. (author: @mcanouil)
+- ([#14553](https://github.com/quarto-dev/quarto-cli/issues/14553), [#14558](https://github.com/quarto-dev/quarto-cli/issues/14558)): Fix PDF render failing instead of auto-installing a missing font referenced by `monofontfallback` (and other `mainfont`/`sansfont`/`monofont` fallbacks).
 
 ### `typst`
 
diff --git a/src/command/render/latexmk/parse-error.ts b/src/command/render/latexmk/parse-error.ts
index 09cb24949a3..e0ad5cf3539 100644
--- a/src/command/render/latexmk/parse-error.ts
+++ b/src/command/render/latexmk/parse-error.ts
@@ -265,6 +265,14 @@ const formatFontFilter = (match: string, _text: string) => {
   return /[.]/.test(base) ? base : fontSearchTerm(base);
 };
 
+// luaotfload appends ';-fallback' internally to each fallback-chain entry
+// (registered via monofontfallback / luaotfload.add_fallback) to prevent
+// recursive fallback resolution. Strip it before building the search term.
+// https://github.com/quarto-dev/quarto-cli/issues/14558
+const luaotfloadFontFilter = (match: string, text: string) => {
+  return formatFontFilter(match.replace(/;-fallback$/, ""), text);
+};
+
 const estoPdfFilter = (_match: string, _text: string) => {
   return "epstopdf";
 };
@@ -291,6 +299,13 @@ const packageMatchers = [
     regex: /.*\(fontspec\)\s+The font "([^"]+)" cannot be.*/g,
     filter: formatFontFilter,
   },
+  {
+    // luaotfload fallback-chain font (monofontfallback) missing. fontspec does
+    // not fire its own error in this path, so this is the only signal.
+    // https://github.com/quarto-dev/quarto-cli/issues/14558
+    regex: /.*luaotfload.*reason: Font "([^"]+)" not found.*/g,
+    filter: luaotfloadFontFilter,
+  },
   {
     regex: /.*Package widetext error: Install the ([^ ]+) package.*/g,
     filter: (match: string, _text: string) => {
diff --git a/tests/unit/latexmk/parse-error.test.ts b/tests/unit/latexmk/parse-error.test.ts
index 4771a6d7b40..49d3edd7522 100644
--- a/tests/unit/latexmk/parse-error.test.ts
+++ b/tests/unit/latexmk/parse-error.test.ts
@@ -35,6 +35,9 @@ unitTest("Detect missing files with `findMissingFontsAndPackages`", async () =>
   assertFound('! Font \\JY3/mc/m/n/10=file:HaranoAjiMincho-Regular.otf:-kern;jfm=ujis at 9.24713pt not loadable: metric data not found or bad.', "HaranoAjiMincho-Regular.otf");
   assertFound('! The font "Noto Emoji" cannot be found.', fontSearchTerm("Noto Emoji"));
   assertFound('! Package fontspec Error: The font "DejaVu Sans" cannot be found.', fontSearchTerm("DejaVu Sans"));
+  // luaotfload fallback-chain font (monofontfallback) - https://github.com/quarto-dev/quarto-cli/issues/14558
+  // luaotfload appends ;-fallback internally; it must be stripped before building the search term
+  assertFound('luaotfload | db : Reload initiated (formats: otf,ttf,ttc); reason: Font "DejaVu Sans Mono;-fallback" not found.', fontSearchTerm("DejaVu Sans Mono"));
   assertFound("! LaTeX Error: File `framed.sty' not found.", "framed.sty");
   assertFound("! LaTeX Error: File 'framed.sty' not found.", "framed.sty");
   assertFound("/usr/local/bin/mktexpk: line 123: mf: command not found", "mf");