If you care about security at all, you disable any previews on the lock screen. The lock screen is by definition visible to anyone without any authorization. Showing anything on it immediately destroys any secrecy. It must be obvious to anyone capable of elementary logic inference.
If you don't know how to disable it, you use your favorite search engine / LLM / knowledgeable relative to find out, and disable it.
But if you just didn't pay attention, "never thought about it", you don't care about security, and no amount of technical means would help, sorry.
> If you care about security at all, you disable any previews on the lock screen. The lock screen is by definition visible to anyone without any authorization. Showing anything on it immediately destroys any secrecy. It must be obvious to anyone capable of elementary logic inference.
With at least one combination of settings, it shows the message content only when the lockscreen has been unlocked, but not yet swiped away.
This is insidious indeed. Still I would suggest that any secret message, as it leaves the app that handles secrecy, ceases to be secret. This BTW also applies to copy-paste operations, screen readers, etc.
Disabling notification preview in the operating system settings doesn't prevent the issue, they're still saved in the database.
The only way they're not saved is to disable name/content in signal itself.
Maybe you're not as capable of elementary logical inference as you thought?
Disabling may be not sufficient (which is pretty insidious), but I still posit that enabling message preview is guaranteed secrecy loss.
But indeed, the idea that disabled notifications are still stored, and not directed to /dev/null immediately, cannot be inferred from just observing the behavior of the phone UI.