fix

app/pdf/document.py

@@ -13,6 +13,9 @@ logger = logging.getLogger(__name__)
 HEADING_TAGS = ("h1", "h2", "h3", "h4", "h5", "h6")
 ID_SAFE = re.compile(r"[^a-zA-Z0-9_-]+")
 
+# Matches a width declaration in percent, but never max-width or min-width.
+PERCENT_WIDTH = re.compile(r"(?<![\w-])width\s*:\s*\d+(?:\.\d+)?%", re.IGNORECASE)
+
 TOC_PLACEHOLDER = "\u2007\u2007\u2007"  # figure spaces, keeps the pass 1 layout stable
 
 
@@ -70,6 +73,55 @@ class SourceDocument:
         base.set("href", base_url)
         self.head.insert(0, base)
 
+    # -- images ---------------------------------------------------------
+    def relax_percentage_image_widths(self) -> int:
+        """Replace percentage widths of images inside table cells by auto.
+
+        WeasyPrint resolves such a percentage against a cell width that is not
+        known yet while the table is being laid out. The image comes out zero
+        wide and disappears from the PDF without any error, so it is not even
+        reported as a missing asset. Rendering the image at its intrinsic size
+        capped by max-width gives the result the document intended.
+
+        Only relevant for WeasyPrint, Chromium lays these images out correctly.
+        Returns the number of images that were changed.
+        """
+        changed = 0
+        for cell in self.body.iter("td", "th"):
+            for image in cell.iter("img"):
+                if self._relax_image_width(image):
+                    changed += 1
+
+        if changed:
+            logger.info(
+                "Percentage width of images inside table cells replaced by auto",
+                extra={"images": changed},
+            )
+        return changed
+
+    @staticmethod
+    def _relax_image_width(image) -> bool:
+        touched = False
+
+        if (image.get("width") or "").strip().endswith("%"):
+            del image.attrib["width"]
+            touched = True
+
+        style = image.get("style") or ""
+        if PERCENT_WIDTH.search(style):
+            style = PERCENT_WIDTH.sub("width: auto", style)
+            touched = True
+
+        if not touched:
+            return False
+
+        if "max-width" not in style.lower():
+            stripped = style.strip().rstrip(";")
+            style = f"{stripped}; max-width: 100%" if stripped else "max-width: 100%"
+
+        image.set("style", style)
+        return True
+
     # -- headings -------------------------------------------------------
     def collect_headings(self, max_depth: int) -> list[Heading]:
         """Assign ids to headings that lack one and return them in document order."""