carbonio-auth service missing entirely — no package, no registration, no systemd unit — causing 502 on webmail login

Running Carbonio CE, carbonio-core 4.5.12-1jammy, Ubuntu 22.04.5.

Webmail/admin login fails with 502 Bad Gateway on GET /zx/login/v3/auth/config. Traced this to the carbonio-proxy upstream carbonio-auth, which routes to 127.78.0.1:20008 (an Envoy sidecar). The sidecar itself is up and listening, but nothing is registered behind it.

What I've confirmed:

• consul catalog services shows no carbonio-auth entry at all (not unhealthy — completely absent)
• No .hcl file for it exists in /etc/zextras/service-discover/ (only carbonio-proxy.hcl references the name, as a destination)
• No systemd unit carbonio-auth-sidecar.service exists anywhere on disk
• dpkg -S carbonio-auth-sidecar returns no matching package
• apt-cache search carbonio | grep auth and apt list -a carbonio-auth* show only carbonio-auth-ui (a frontend module), no backend service
• Not served directly by mailboxd either (curl localhost:8080/zx/login/v3/auth/config → 404)
• No trace of any process ever attempting to register this service name in mailbox.log
• pending-setups -a runs clean, nothing pending
• Full zmcontrol restart and individual service restarts don't resolve it
• Repointing the proxy upstream to carbonio-user-management (the service that appears to actually handle auth-related SOAP requests) also didn't resolve it — reverted that change

What's healthy: everything else — mail delivery, IMAP, SMTP, LDAP, MTA, proxy itself, mailbox backend. This is isolated to the webmail/admin login flow specifically.

Found one other user with the exact same symptom (community.zextras.com/forum/carbonio-general-thread/carbonio-auth-problem/, Feb 2024) with no public resolution shown.

Is carbonio-auth supposed to be provided by a specific package? Was it possibly deprecated/replaced by carbonio-user-management in a later version and this proxy template just wasn't updated to match? Any pointers appreciated.