0.50.x - Claude models strange behviour manipulating HTML

[smarterdigitalltd]

I’m finding, even with trusty Sonnet 3.5, there’s been a real degradation of manipulating basic HTML:

• missing closing tags
• indentation “misses”
• completely ignoring instructions to change a style
• appending sections to the bottom of the page rather than in their correct place
• unable to move a section from place A to place B. The below seems to happen:

As you can see, it tried to copy a section, apply it elsewhere and then delete the original - but it seemed to then delete the copied section meaning there was no real change to the page

(yes I know I can copy/paste this myself… but this is just indicative of noticeable weirdness)

[smarterdigitalltd]

In fact to come back on this: I’m having similar issues with Gemini 2.5 pro 05-06, gpt-4.1, o4-mini

I’m trying to swap the position of 2 HTML sections, but none of them can do it!