Journalling flash storage algorithm

Have you seen: http://www.espruino.com/FlashEEPROM

While it doesn't have filenames, it will store numbered items in a journalled way, but actually within pages (rather than one page for each item) so it's a bit more efficient.

Yours is probably better for big blocks of data that don't change often though. I hacked something very simple up for the google sheets tutorial for the Pico but it would be way better to have something in a module.

By the look of it you've spotted E.memoryArea too - that could be really interesting if your code could make the data easily available - however actually implementing pipe like you've done is still the best bet for HTTP - as even if you had a massive string you wouldn't be able to just write it with Socket.write.