A lot of it is integrated into the product at this point. If you have a particularly tricky bug, you can just tell Claude "I have this bug. I expected output 'foo' and got output 'bar'. What went wrong?" It will inspect the code and sometimes suggest a fix. If you run it and it still doesn't work, you can say "Nope, still not working", and Claude will add debug output to the whole program, tell you to run it again, and paste the debug output back into the console. Then it will use your example to write tests, and run against them.