html: improve inline math with whitespaces

src/markdown_lib/common.py

@@ -237,6 +237,7 @@ def markup_to_markdown(text: str, format_: str = "html") -> str:
         # some needed preprocessing
         soup = BeautifulSoup(text, "html.parser")
         markdown_lib.html_preprocessing.div_checklists(soup)
+        markdown_lib.html_preprocessing.handle_newlines_in_math(soup)
         markdown_lib.html_preprocessing.iframes_to_links(soup)
         markdown_lib.html_preprocessing.streamline_tables(soup)
         markdown_lib.html_preprocessing.synology_note_station_fix_img_src(soup)

src/markdown_lib/html_preprocessing.py

@@ -1,7 +1,12 @@
 """HTML preprocessing functions to prepare for Pandoc conversion."""
 
+import logging
+import string
+
 from bs4 import BeautifulSoup
 
+LOGGER = logging.getLogger("jimmy")
+
 
 def div_checklists(soup: BeautifulSoup):
     """Convert div checklists to plain HTML checklists."""
@@ -18,6 +23,20 @@ def div_checklists(soup: BeautifulSoup):
             child.name = "li"
 
 
+def handle_newlines_in_math(soup: BeautifulSoup):
+    """
+    - Escape unescaped newlines inside tex math blocks.
+    - Strip trailing (escaped) whitespace.
+    """
+    for annotation in soup.find_all("annotation"):
+        if (encoding := annotation.attrs.get("encoding")) != "application/x-tex":
+            LOGGER.debug(f'Unsupported annotation encoding "{encoding}"')
+            continue
+        annotation.string = annotation.string.rstrip("\\" + string.whitespace).replace(
+            "\n\n", "\n\\\\\n"
+        )
+
+
 def iframes_to_links(soup: BeautifulSoup):
     """Convert iframes to simple links."""
     for iframe in soup.find_all("iframe"):