fix: strip spurious default-image-extension from shortcode and empty-URL image sources#14634
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…URL image sources Pandoc appends default-image-extension to any extensionless image source at parse time, with no URL guard (confirmed against Pandoc HEAD source). This breaks two cases: - A shortcode used as an image source is parsed without an extension, so Pandoc appends the default. When the shortcode later resolves to a path that already has its own extension, the result carries a doubled extension (e.g. logo.png.png, or logo.png.svg in Typst where the default differs) (#14583). - An extensionless URL ending in a slash gets the extension appended, breaking embed/iframe syntax (#6092). The shortcode case is fixed after the shortcode resolves, where the resolved path is finally known: the appended default extension is stripped only when the resolved path already carries an extension of its own, so the multi-format workflow (a shortcode resolving to an extensionless path) keeps its appended extension. The URL case is fixed in the normalize stage, only for the provably-spurious empty-filename form; a URL with a non-empty last segment is indistinguishable from a real file after parsing and is left untouched.
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This was referenced Jun 29, 2026
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Pandoc appends
default-image-extensionto any extensionless image source at parse time. No URL guard exists in Pandoc (confirmed against Pandoc HEAD source). This breaks two cases:) has no extension when parsed, so Pandoc appends the default. When the shortcode later resolves to a path that already has an extension, the result carries a doubled extension (e.g.logo.png.png, orlogo.png.svgin Typst where the default differs from HTML). Reported in Image missing https://quarto.org/docs/computations/python.html#positron #14583; fix(filters): fix include-dark with meta-resolved image paths quarto-web#2086 worked around it locally ininclude-dark.lua.) gets the extension appended, breaking embed/iframe syntax.Fix
The shortcode case is fixed after the shortcode resolves in
shortcodes.lua, where the resolved path is finally known: the appended default extension is stripped only when the resolved path already carries an extension of its own. This preserves the multi-format workflow — a shortcode resolving to an extensionless path (e.g.figures/plot) keeps the appended default so format-specific rendering still works.The URL case is fixed in the normalize stage (
fixupdatauri.lua), only for the provably-spurious empty-filename form (path ends in/.ext). A URL with a non-empty last segment — such ashttps://badgen.net/badge/nameparsed tohttps://badgen.net/badge/name.png— is byte-identical to a real file URL after parsing and is left untouched. The documented workaround (default-image-extension: "") remains for badge-style URLs; a proper fix requires a URI guard upstream in Pandoc.Fixes #14583, related to #6092