fix: neutralise inline code in title scaffolds for Typst output

CHANGELOG.md

@@ -5,10 +5,15 @@
 ### Bug Fixes
 
 - fix: unwrap Quarto's `DecoratedCodeBlock` Div to prevent double filename wrapping in Typst output.
+- fix: evaluate theorem/example title strings as Typst markup so inline code renders correctly instead of being stringified.
 - fix: normalise code blocks with no or unknown language class to `default` for consistent styling across all formats.
 - fix: default to `#` comment symbol for unknown code block languages (`default`, `txt`, etc.) in annotation detection.
 - fix: support code annotations with `syntax-highlighting: idiomatic` (native Typst highlighting) via a `show raw.line` rule.
 
+### New Features
+
+- feat: support per-hotfix `quarto-version` thresholds for independent auto-disable.
+
 ### Refactoring
 
 - refactor: extract language normalisation into dedicated `_modules/language.lua` module.

_extensions/code-window/_extension.yml

@@ -6,3 +6,5 @@ contributes:
   filters:
     - at: pre-quarto
       path: main.lua
+    - at: post-quarto
+      path: _modules/hotfix/typst-title-fix.lua

_extensions/code-window/_modules/hotfix/skylighting-typst-fix.lua

@@ -218,18 +218,64 @@ function Pandoc(doc)
   return doc
 end
 
---- Wrap inline Code elements with a background box in Typst output.
-function Code(el)
+--- Check if a Div is a Quarto title scaffold (inline-only content).
+--- @param div pandoc.Div
+--- @return boolean
+local function is_title_scaffold(div)
+  if div.attributes['__quarto_custom_scaffold'] ~= 'true' then
+    return false
+  end
+  for _, child in ipairs(div.content) do
+    if child.t ~= 'Plain' and child.t ~= 'Para' then
+      return false
+    end
+  end
+  return true
+end
+
+--- Walk the document tree and convert inline Code to RawInline with
+--- background styling. Code in title scaffolds is converted to plain
+--- Typst backtick code to avoid Skylighting tokens with inner quotes
+--- that would break the string parameter Quarto generates.
+--- The typst-title-fix post-quarto filter then evaluates the string
+--- as markup so the backtick code renders with proper inline styling.
+local function process_inline_code(doc)
   if not quarto.doc.is_format('typst') then
-    return el
+    return doc
   end
-  return process_typst_inline(el)
+
+  local code_filter = { Code = function(el) return process_typst_inline(el) end }
+  local title_filter = {
+    Code = function(el)
+      return pandoc.RawInline('typst', '`' .. el.text .. '`')
+    end,
+  }
+
+  local function walk_blocks(blocks)
+    local new_blocks = {}
+    for _, blk in ipairs(blocks) do
+      if blk.t == 'Div' then
+        if is_title_scaffold(blk) then
+          table.insert(new_blocks, blk:walk(title_filter))
+        else
+          blk.content = walk_blocks(blk.content)
+          table.insert(new_blocks, blk)
+        end
+      else
+        table.insert(new_blocks, blk:walk(code_filter))
+      end
+    end
+    return pandoc.Blocks(new_blocks)
+  end
+
+  doc.blocks = walk_blocks(doc.blocks)
+  return doc
 end
 
 return {
   set_wrapper = set_wrapper,
   filters = {
     { Pandoc = Pandoc },
-    { Code = Code },
+    { Pandoc = process_inline_code },
   },
 }

_extensions/code-window/_modules/hotfix/typst-title-fix.lua

@@ -0,0 +1,106 @@
+--- @module typst-title-fix
+--- @license MIT
+--- @copyright 2026 Mickaël Canouil
+--- @author Mickaël Canouil
+--- @brief Hot-fix for Quarto rendering theorem titles as string parameters.
+--- Quarto renders custom type titles as title: "..." (string mode) which
+--- stringifies any Typst markup. This post-quarto filter scans the source
+--- for cross-reference div IDs, then injects Typst wrapper functions that
+--- evaluate string titles as Typst markup via eval(mode: "markup").
+
+--- Mapping from Quarto cross-reference prefix to Typst function name.
+local PREFIX_TO_FUNC = {
+  thm = 'theorem',
+  lem = 'lemma',
+  cor = 'corollary',
+  prp = 'proposition',
+  cnj = 'conjecture',
+  def = 'definition',
+  exm = 'example',
+  exr = 'exercise',
+  sol = 'solution',
+}
+
+--- Typst wrapper template. %s is replaced with the function name.
+local WRAPPER_TEMPLATE = [==[
+#let _cw-orig-%s = %s
+#let %s(title: none, ..args) = {
+  let t = if title != none and type(title) == str {
+    eval(title, mode: "markup")
+  } else {
+    title
+  }
+  _cw-orig-%s(title: t, ..args)
+}]==]
+
+--- Build Typst code that wraps each theorem function to eval string titles.
+--- @param func_names table List of function names to wrap
+--- @return string Typst code
+local function build_wrappers(func_names)
+  local parts = { '// code-window: hot-fix for Quarto rendering theorem titles as strings.' }
+  for _, name in ipairs(func_names) do
+    table.insert(parts, string.format(WRAPPER_TEMPLATE, name, name, name, name))
+  end
+  return table.concat(parts, '\n')
+end
+
+--- Scan source files for cross-reference div IDs and return the
+--- corresponding Typst function names.
+--- @return table List of function names
+local function detect_theorem_types()
+  local func_names = {}
+  local seen = {}
+  for _, input_file in ipairs(PANDOC_STATE.input_files) do
+    local f = io.open(input_file, 'r')
+    if f then
+      local source = f:read('*a')
+      f:close()
+      for prefix in source:gmatch('::: *{#(%w+)%-') do
+        if PREFIX_TO_FUNC[prefix] and not seen[prefix] then
+          table.insert(func_names, PREFIX_TO_FUNC[prefix])
+          seen[prefix] = true
+        end
+      end
+    end
+  end
+  return func_names
+end
+
+return {
+  {
+    Pandoc = function(doc)
+      if not quarto.doc.is_format('typst') then
+        return doc
+      end
+
+      -- Check if the hotfix is enabled via metadata set by the pre-quarto filter.
+      local hotfix_meta = doc.meta['_code-window-hotfix']
+      if hotfix_meta then
+        local enabled = hotfix_meta['typst-title']
+        if enabled and pandoc.utils.stringify(enabled) == 'false' then
+          return doc
+        end
+      end
+
+      -- Guard: skip if already injected.
+      for _, blk in ipairs(doc.blocks) do
+        if blk.t == 'RawBlock' and blk.format == 'typst'
+            and blk.text:find('code-window: hot-fix for Quarto rendering theorem titles', 1, true) then
+          return doc
+        end
+      end
+
+      local func_names = detect_theorem_types()
+      if #func_names == 0 then
+        return doc
+      end
+
+      -- Insert at the start of doc.blocks. RawBlocks placed here appear
+      -- after the Typst template preamble (where make-frame defines the
+      -- theorem functions), so the wrappers can reference them.
+      table.insert(doc.blocks, 1, pandoc.RawBlock('typst', build_wrappers(func_names)))
+
+      return doc
+    end,
+  },
+}

_extensions/code-window/code-window.lua

@@ -43,6 +43,7 @@ local DEFAULTS = {
 local HOTFIX_DEFAULTS = {
   ['code-annotations'] = true,
   ['skylighting'] = true,
+  ['typst-title'] = true,
 }
 
 local CURRENT_FORMAT = nil
@@ -454,27 +455,50 @@ function Meta(meta)
       '"skylighting-fix" is deprecated. Use "hotfix: { skylighting: true/false }" instead.')
   end
 
-  -- Parse hotfix options with version-based auto-disable.
+  -- Parse hotfix options with per-hotfix version-based auto-disable.
+  -- Each hotfix value can be:
+  --   boolean/string: true/false to enable/disable
+  --   map: { enabled: true/false, quarto-version: "x.y.z" }
+  -- A global quarto-version key is also supported as a fallback.
   local hotfix = {}
-  local hotfix_version_override = false
+  local global_version_disabled = false
   if hotfix_meta then
     local version_str = hotfix_meta['quarto-version']
     if version_str then
       version_str = pandoc.utils.stringify(version_str)
       if version_str ~= '' then
         local ok, threshold = pcall(pandoc.types.Version, version_str)
         if ok and quarto.version >= threshold then
-          hotfix_version_override = true
+          global_version_disabled = true
         end
       end
     end
   end
 
   for key, default in pairs(HOTFIX_DEFAULTS) do
-    if hotfix_version_override then
+    local entry = hotfix_meta and hotfix_meta[key]
+    if entry ~= nil and pandoc.utils.type(entry) == 'table' then
+      -- Map form: { enabled: bool, quarto-version: "x.y.z" }
+      local enabled = true
+      if entry['enabled'] ~= nil then
+        enabled = pandoc.utils.stringify(entry['enabled']) == 'true'
+      end
+      local ver = entry['quarto-version']
+      if ver then
+        ver = pandoc.utils.stringify(ver)
+        if ver ~= '' then
+          local ok, threshold = pcall(pandoc.types.Version, ver)
+          if ok and quarto.version >= threshold then
+            enabled = false
+          end
+        end
+      end
+      hotfix[key] = enabled
+    elseif entry ~= nil then
+      -- Simple boolean/string form
+      hotfix[key] = pandoc.utils.stringify(entry) == 'true'
+    elseif global_version_disabled then
       hotfix[key] = false
-    elseif hotfix_meta and hotfix_meta[key] ~= nil then
-      hotfix[key] = pandoc.utils.stringify(hotfix_meta[key]) == 'true'
     else
       hotfix[key] = default
     end
@@ -487,9 +511,19 @@ function Meta(meta)
     typst_wrapper = opts['wrapper'],
     hotfix_code_annotations = hotfix['code-annotations'],
     hotfix_skylighting = hotfix['skylighting'],
+    hotfix_typst_title = hotfix['typst-title'],
     code_annotations = annotations_enabled,
   }
 
+  -- Store hotfix state in metadata so the post-quarto typst-title-fix filter
+  -- can read it (it runs as a separate filter and has no access to CONFIG).
+  if not meta['_code-window-hotfix'] then
+    meta['_code-window-hotfix'] = {}
+  end
+  meta['_code-window-hotfix']['typst-title'] = pandoc.MetaString(
+    hotfix['typst-title'] and 'true' or 'false'
+  )
+
   -- Cache syntax highlighting background colour for Typst contrast-aware annotations.
   if CURRENT_FORMAT == 'typst' then
     local hm = PANDOC_WRITER_OPTIONS and PANDOC_WRITER_OPTIONS.highlight_method