Lanefan
Victoria Rules
Correct, there seems to be no clear answer on the confined-space question.If, by this, you are implying that the spell gives a definitive rules answer to what happens when polymorph interacts with tight spaces, you are 100% wrong.
But I don't think that's what was being said. I read it as simply trying to point out that your idea of the "flash of light" transform doesn't mesh with the RAW as - to be a bit pedantic - use of the word "meld" does imply a fluidic transformation from one form to another, much like Professor McGonagall when she turns into a cat.
What would be nice is a note on how long this transformation takes to occur, and also on what if anything unusual happens should you take damage while transforming.
Lanefan