No memory, no cron/heartbeat, context mgmt is just "new chat", but enough to get you started.
Note: no sandboxing etc, I run this as unprivileged linux user. So it can blow up its homedir, but not mine. Ideally, I'd run it on a separate machine. (My hottest take here is "give it root on a $3 VPS, reset if it blows up" ;)
https://github.com/a-n-d-a-i/ULTRON
You may also enjoy CLIProxyAPI, which does the same thing (claude -p / codex exec) but shoves a OpenAI compatible API around it. Note: this probably violates every AI company's ToS (since it turns the precious subsidized subscription tokens into a generic API). OpenAI seems to tolerate such violations, for now, because they care about good. Anthropic and Google do not.
(Though Anthropic may auto-detect and bill it as extra usage; see elsewhere in this thread. Situation is very confusing right now.)
I don't have an especially heavyweight implementation, because I only use mine to review things I've written in my Apple Notes (journaling of various kinds, mostly) and give insights.