I would change

"Codex starts encrypting prompts, uses ciphertext for inference instead"

to just

"Codex starts encrypting prompts"

That is enough.

Maybe you could say sub agent prompts. The article can say the rest.

Not everything is encrypted though, session data (even from the sub-agent) remains unencrypted, only select things like the prompt the (main) agent sends the sub-agent is encrypted, rest of communication between the two seems still to be plain-text.

Regardless, I've updated the title from "Codex starts encrypting prompts, uses ciphertext for inference instead" to "Codex starts encrypting sub-agent prompts", hope this makes it clearer for everyone :)