Niblr invoices have carried a logo since the day templates shipped. No invoice ever showed one. Two silent failures, a library that logs and carries on, and the test that finally looked at the PDF.
Niblr's public repo is generated from the private one on every release: hosted code deleted, seams swapped, a leak scan, then CI that migrates and builds it. How it works, and what broke first.
We wrote a test that stops our pricing page advertising features we haven't built. It worked. Then a second, editable copy of that data drifted for five days on the page most people see.
Four bugs I shipped or nearly shipped in one week building Niblr — every one of them with a green test suite. What they had in common, and what I changed.