I see that all these problems are interesting details. But I find them just that, details. Many of them can be ignored in an initial implementation, in a way that would allow to fill them in later, if need be. Somehow the lack of handling of all these subtleties does not preclude the file:/ scheme from being implemented.

If there is a will, there is a way. I think the will is lacking here. The developers themselves do no care. I can see why the Chrome team is opposed to that: it's the Google's interest to eliminate all things offline. I didn't expect Mozilla folks to be so unreceptive though. Having the unix domain socket support would be a distinct advantage.