Audit Chain Teaching Example

python3 examples/audit/audit_chain.py
python3 -m unittest discover -s examples/audit -v

The verifier requires a caller-supplied trusted checkpoint, containing both count and chain head. Tests demonstrate mutation, truncation, insertion, reordering and rewriting under a different checkpoint. No private signing key, public verification service, storage retention or multi-writer protocol is implemented here. A checkpoint supplied by the same attacker as the log is not independent evidence. Use only synthetic metadata in this exercise.