Most status lines show where your session is. Mine shows what each prompt just did to it: context added, cost added, and whether the cache held. Here's what I watch and the repo if you want a starting point.
On September 30th a Claude Code agent session ran cat .env. The file held every credential I use to work on CertWatch, my certificate monitoring product, and all 31 of them landed in the session transcript. That transcript was sent to the model provider’s API and written to a log file on my laptop.
Monitoring is built around known failure modes. This works well for predictable problems. The limitation is that monitoring is only as good as the assumptions baked into it.
Reliability is less about tools or processes and more about a mindset. It’s the discipline of designing for failure, observing reality, and constantly closing the gap between how we think things work and how they actually behave in production.