Both managed authorized_keys files lacked a trailing newline. sshd reads the final key fine on its own, but any subsequent append (tooling, a follow-up key, or the validation harness) concatenated onto the last key line, fusing two keys into one unparseable blob and silently breaking public-key auth for both. Add the trailing newline so the files concatenate safely. 🤖 Generated with [Crush](https://github.com/charmassociates/crush) Assisted-by: GLM-5 via Crush <crush@charm.land>