I'm running out of Claude session limits in a single planning + implementation session even when using sonnet for the implementation. This isn't even super complex work - it was refactoring a data model, modifying templates/apis/services, etc. It has also gotten notably more 'lazy' like it updated the data model and not the template until I specifically pointed that out.

My backup has been Opencode + Kimi K2. It's definitely not as strong as even Sonnet but it's pretty fast and is serviceable for basic web app work like the above.