How can I retrieve a page from the cache (if it's there) and avoid going to the network

[thosrtanner]

MDN suggests (if I'm reading it properly which is always a bit questionable), you can set "Cache-Control" to "only-if-cached" in the request, and it'll return a 503 if the page isn't in cached. However, I've tried doing this and I'm getting a 404 for pages that don't exist, which makes me think the page is being fetched anyway. certainly the time taken to do the fetch doesn't seem hugely different.

As for why, I'm trying to make sure the If-Modified-Since and If-None-Match headers get set appropriately on a request even after a browser restart, and that would seem to be more or less the best way (well, a lot easier than maintaining them separately)

[Mæstro]

Although this is not a direct answer, I can suggest a complement which you can use beside one, which I hope somebody else can provide. The extension Scrapbook X can save local copies of a webpage which are more easily accessed and managed.

[back2themoon]

The Greedy Cache extension might help? Cannot say.

[thosrtanner]

wow. setting a bit without a name in an attribute that isn't documented. - it might help, yes! that's scary though. I'll try it.