Nothing here talks to a server at runtime, so a cached shell is the whole
editor. The worker reads the build's hashed asset names out of the entry
document, which precaches without a build step; the document itself stays
network-first, or it would keep naming the assets of the build it was
cached with. Matching ignores Vary: a precached asset is fetched without
the page's Origin, and a server answering "Vary: Origin" never matches it.
Verified in a headless Chromium with the network cut.
Steffen Becker
b19409aacb