A couple of points to your post:
That’s simply not true. All processing in LR and ACR take place with ProPhoto RGB primaries and thus color gamut.
Please provide evidence to support your statement !
I'm not sure what you meant by that, but in the link you posted (
http://www.colourspace.xyz/the-truth-about-lightroom-colour-management/)it says what Andrew (digidog) said about what it called "editing colour space":
"Lightroom’s editing space accomplishes this by using the RGB primaries and white point of ProPhoto RGB." The editing space is the one in which it does all its processing (i.e. editing of the image).
My understanding is that the Develop Module actually works in Miranda RGB (Gamut 1.0) and the Library module in Adobe RGB. Yes -
Nope. Start here (it’s old but nothing has changed):
http://digitaldog.net/files/18Color Management in Lightroom.pdf
I do luv it when protesters give me the evidence that I quoted the right info -- " Think of the underlying internal color space as having the RGB primaries and white point of ProPhoto RGB, but instead of 1.8 gamma encoding, this newspace uses a 1.0 gamma encoding." and this space is called
Melissa (I misspoke by calling it Miranda -- I must have been watching Serenity)
Meliessa space is ProPhoto RGB but with sRGB's Tone Response Curve (TRC), which approximates to a gamma of 2.2 not 1.0.
LR uses Melissa RGB for histograms and pixel values, as a sRGB gamma (close to 2.2 gamma) is closer to human perceptual TRC than is linear TRC. That means a mid-grey is half way up the scale, and not right down the left hand end.
It uses Adobe RGB for previews, as it stores previews in 8 bit encoding, and to store an image in a wide space such as ProPhoto using 8 bits risks visible staircases on tone wedges.
I'm pretty sure it uses sRGB in web module (not Adobe RGB as in the link) and in print module it uses the preview (Adobe RGB) for display, but sends to the printer whatever colour space you specify in the printer profile.