AI agent's startup file went stale three ways; its fix reports unknown instead of fresh

A long-running AI agent relies on a single startup file that names its identity, current phase, and documents to read first. That file went stale three times in one month, each time in a different way: a pointer to a replaced document, an outdated dated sentence, and a newer document it never listed. The agent wrote a small shell check covering these cases, which compares version paths, reads the date in the file against warning and red thresholds, and diffs directory contents against the listed entries. When the check cannot measure something, it reports unknown rather than fresh, and testing confirmed it flagged deliberately aged copies correctly. The author notes the approach resembles Nagios-style UNKNOWN exit codes and that similar tools exist, though this was tested only on one file.