The short version:
In which OpenType feature should I put a pos rule that contextually positions a base glyph when combined with a certain diacritic mark?
The long version:
I would like to respace the Hebrew letter VAV when combined with the diacritical mark DAGESH in order to make room for the DAGESH.
This is very similar to the situation with l with middle dot (used in Catalan), which typically requires more space (x advance) than just l.
Note that while there's a unicode character Hebrew Letter Vav with Dagesh, it decomposes into VAV followed by DAGESH, so to the best of my understanding it's irrelevant (i.e., including a glyph for this character in a font won't help, as it will be ignored).
It sounds like the most straight-forward way to respace VAV when combined with DAGESH would be using contextual positioning (the VAV would be the target and the DAGESH would provide the context).
Is that right?
Where should I put this pos rule?