I got a ton of value from this book. It actually pushed me to dive deeper into profiling and eventually start building Rust perf tooling of my own https://github.com/pawurb/hotpath-rs
I was thinking rails-pg-extras could output to Claude Code since it can see the actual codebase, and generate PRs.
For example, instead of just "add this index", it could see the models and relationships, figure out the right migration syntax, spot N+1 queries in controllers that are causing the slow lookups in the first place.
The workflow would be pretty clean too - let your MCP tool do what it's good at (finding the problems), then hand it off to Claude Code/Cursor/etc that understands the Rails apps to actually write the fixes.
The watch can't have a cellular plan of its own. It must be associated with the plan that's on the iPhone it's tethered to. If you use a dummy iPhone for this purpose, then the SIM for your primary number needs to be on that phone.