UPDATE: I stand corrected, it's not a stray, it's the closing fence of a code block that contains another code block. Still, same effect.
There's a stray code block fence (triple backtick) in continuous-improvement.mdc:
When you @-import that rule in your CLAUDE.md, it'll mess up everything below that fence. I noticed because the rules that I imported after that didn't do anything – because they were part of a code block, and Claude looked at it and basically just shrugged.