CS does not check disk files when it's running

For now, CS only compare meta date with disk files when it's started. If a file is missing afterwards, the CS remains unknown. This could result in data lost.

No source file, test, or entry point is named. Start by locating the CS startup comparison described in the issue and determine how a file missing after startup is represented while CS is running. Done means the missing-file condition is detected after startup instead of leaving CS unknown, with the data-loss case covered by a test.

Written by the indexing model from the issue text.