I have a handful of old TP-Link wifi switch devices, but I haven't kept up on the play by play developments. I just know at some point newer ones stopped working with that access method (and I haven't bought any since).

Is KLAP that old local-network UDP protocol with "XOR encryption" ? Or is that something else?

Does using TPAP with your library still require connecting the devices to their "cloud" (warning: surveillance!) ? Or does your library effectively restore the local-only workflow of never allowing the devices Internet access, and controlling them locally ?

That XOR protocol is a different one, and older than anything in the article. It is the original TP-Link Smart Home protocol used by the Kasa line (HS100, HS110 and similar): JSON on port 9999, obfuscated with an XOR autokey cipher, with no authentication at all.

Tapo devices never spoke it. Their original protocol was an AES passthrough over HTTP, KLAP replaced that in 2023, and TPAP is the newest. As far as I know, newer Kasa hardware and firmware moved to KLAP as well, which would explain why your access method stopped working on the newer ones. My library only covers Tapo devices; for Kasa, python-kasa is the one to look at.

On the cloud: the devices do have to be set up through the phone app with a TP-Link cloud account. Once set up, though, most functions of most devices can be used locally through the library, with neither the devices nor the library having internet access. The main catch is credentials: if you change the account password, for example, the devices need to be online for a little while to pick up the new one.

Note that KLAP, afaik, is only for the TAPO range of devices. Those are mostly cameras, doorbells, sensors, robot vacuums, and the like.