Fix render relative img URLs

app/labs/lab_export.py

@@ -10,6 +10,7 @@
 
 import concurrent.futures
 import logging
+import re
 import requests
 import warnings
 import yaml
@@ -334,6 +335,20 @@ def _validate_html(self, body):
         except Exception as exc:
             raise LabBuildError(exc, source='HTML')
 
+    def render_relative_uris(self, template_str):
+        """Render relative URIs in HTML content."""
+        def replace_relative_uri(match):
+            attr = match.group(1)
+            relpath = match.group(2)
+            url = self._make_raw(self.parent_url + relpath)
+            return f'{attr}="{url}"'
+
+        return re.sub(
+            r'(src|href)="\./([^"]+)"',
+            replace_relative_uri,
+            template_str,
+        )
+
 
 def get_github_user(username):
     url = GITHUB_USERNAME_URL.format(username=username)

app/labs/views.py

@@ -73,6 +73,7 @@ def export_lab(request):
             f"\n{traceback.format_exc()}")
         return report_exception_response(request, exc)
 
+    template_str = context.render_relative_uris(template_str)
     response = LabCache.put(request, template_str)
 
     return response