And watchdog is missing in the libraries.
What do you understand by the word "libraries"?
wdt_enable (WDTO_1S); // reset after one second, if no "pat the dog" received
wdt_reset (); // give me another second to do stuff (pat the dog)
An include file. A line to enable it. A line to pat the dog. Seems to me to be supported.
And if they release a different processor, they adjust those functions to support the new processor. It seems done to me.
I would disagree that is is anywhere close to "done".
Calling this part of "Arduino" is more than a bit of a stretch.
Yes the sketch itself is not directly touching the hardware but this header and these functions
are clearly not part of Arduino. They are AVR specific.
In his original post, Embed was talking about a "watchdog function in the Arduino Library that would allow processor-independent implementation of such function"
The only way to do that is to have an Arduino function wrapper to do this. Which means
it would need to be part of the core code or part of an Arduino library.
Today that simply does not exist.
While it is possible to easily make watchdog work on certain AVR based boards
by using the AVR specific header file and its proprietary function calls,
that fails to meet the OP's original request of having
a portable function that is processor independent.
To make it work, you have to step outside of Arduino and use
architecture specific proprietary functions.
Because of that, I'd say it isn't "done".
In terms of support by the bootloader. I'd call it's lack of support a bug, or
at least an issue related to an unintended oversight, particularly given
it is usually a line or two of code to fix it with no other s/w impact.