The section indexes returned by the parse API when the section parameter is set, in both the sections array and the edit links, start at 1 instead of the section index, causing the edit links to open the wrong section.

For example, the API call https://en.wikipedia.org/w/api.php?action=parse&page=Toronto&prop=text%7Csections&section=9 starts the edit links at 1 and the indexes in the sections array at 1 when they should start at 9.

The issue has to do with the sectionindex stored in the Parser::mHeadings array.

Also to note is that if a section that starts with T- is passed, the sections in <noinclude> tags before it need to be accounted for because simply returning T- prefixed section indexes won't work since the API still returns sections that are in <noinclude> tags.