The update banner only fires when the browser sees sw.js change, but the
cache name was a hand-bumped constant — so a deploy that touched only
app.js/index.html/style.css left sw.js byte-identical, no new worker
installed, and the banner never showed (and cached assets never refreshed).
Have the server render sw.js at serve time, substituting a __BUILD_HASH__
placeholder with a SHA-256 over the assets the worker caches (index.html,
style.css, app.js, manifest.json, icon.svg). Any asset change now yields a
new cache name and a byte-different sw.js, which is exactly the signal that
makes the browser install a new worker. The hash is memoised and only
recomputed when a file's size/modtime changes, so it needs no server
restart. Served unsubstituted (dev/static host), sw.js stays a valid constant.
Alexander Heldt
16799ad7c7