From cf3927ebe152269b62947af31eea9e69f43bb4fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20Canouil?=
 <8896044+mcanouil@users.noreply.github.com>
Date: Sat, 27 Jun 2026 15:55:25 +0200
Subject: [PATCH] fix(filters): fix include-dark with {{< meta >}}-resolved
 image paths
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Quarto adds a spurious extension when an image src is resolved via
{{< meta >}}, turning foo.png into foo.png.png. The include-dark.lua
filter then produced foo.png-dark.png (dark) and foo.png.png (light),
neither of which exists on disk.

Detect the double-extension case by checking whether the stem returned
by split_extension itself carries the same extension (e.g. foo.png has
stem foo and ext .png, then split_extension(foo) has no extension, so
no double; but foo.png.png has stem foo.png and ext .png, then
split_extension(foo.png) also returns .png — same extension twice).
Strip the outer spurious extension before generating the dark/light pair.

Closes quarto-dev/quarto-cli#14583
---
 filters/include-dark.lua | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/filters/include-dark.lua b/filters/include-dark.lua
index 9158098981..4804d8b749 100644
--- a/filters/include-dark.lua
+++ b/filters/include-dark.lua
@@ -3,7 +3,7 @@ local function dark_path(src)
   return path[1] .. "-dark" .. path[2]
 end
 
-local function new_image(img, src, class) 
+local function new_image(img, src, class)
   local new_classes = pandoc.List.filter(img.classes, function(c)
     return c ~= "include-dark"
   end)
@@ -15,10 +15,14 @@ end
 
 function Image(img)
   if img.classes:includes("include-dark") then
-    local dark_img = new_image(img, dark_path(img.src), "dark-content")
-    local light_img = new_image(img, img.src, "light-content")
+    local stem, ext = pandoc.path.split_extension(img.src)
+    local _, inner_ext = pandoc.path.split_extension(stem)
+    -- Quarto adds a spurious extension when src is resolved via {{< meta >}};
+    -- strip it when the same extension appears twice (e.g. foo.png.png).
+    local src = (inner_ext == ext) and stem or img.src
+    local dark_img = new_image(img, dark_path(src), "dark-content")
+    local light_img = new_image(img, src, "light-content")
     return {dark_img, light_img}
   end
   return img
 end
-