I agree with what I think you meant: it is not a bug in Claude. However "javascript on the backend" is exactly what Claude Code is! It's a node.js implementation of automation components that feed and pull from the Claude model.
I have a VERY hard time believing that they only use JSON serialization between the model and the TUI. If they're seriealizing JSON between agents, tools, or other components, then this problem is going to continue to persist for a very long time.
This symptom was affecting display of numbers in the TUI, but the real bug/design flaw is using jq or JSON as a transport mechanism between components or between tools. JSON's number range is famously poor and it even architecture-dependent. So if you use jq or JSON to connect components or tools, you will have this same problem silently occurring elsewhere without visibility in the UI.
This is a bigger deal than it seems like! A confidence-inducing fix would include a blog post describing a top-to-bottom audit of jq/JSON used as a transport layer between tools and components. Not just a patch to the most visible problem.
It made it to the front page at about #11. Then apparently the editors renamed it to the (less interesting/more convoluted) title of the page it linked to. I didn't cause or approve that change. Why does HN rewrite my post? Is it because it was negative to Claude Code?
I have a VERY hard time believing that they only use JSON serialization between the model and the TUI. If they're seriealizing JSON between agents, tools, or other components, then this problem is going to continue to persist for a very long time.