fogbound-packs

Fogbound region packs

Neighbourhood and district data for the Fogbound app, served as static JSON over GitHub Pages.

Why these are not in the app

Nothing ships inside the app. Berlin and Hamburg used to, on the argument that it should work on first launch with no network; that lost to a better one, that a region is dead weight for everyone who does not live in it. Dropping both took the JS bundle from 6.40 MB to 4.14. A new user opens Progress, is told there is no map for where they are, and is offered the region that covers them — the screen everyone outside Berlin already saw, now the screen everyone sees.

Baden-Württemberg settles it on its own: 23.9 MB, which cannot be trimmed because boundaries are 16 of those megabytes and they are the data. A pack only one state’s residents need is exactly what should not ship to everybody.

Why they are not in the site repo

fogbound-site is four small files and a privacy policy, and its history should stay that way. Packs are bulk: each rebuild adds another copy that git keeps forever. Here that is expected, and this repo can be discarded and recreated without touching the site.

The manifest stays on the site — fogbound-site/regions/index.json — because it is the one URL a shipped app version has baked in and can never move. It carries absolute pack URLs, so everything here can move host at any time.

Why Pages rather than Releases

Pages serves content-encoding: gzip and release assets do not. This data compresses about 4.5×: Baden-Württemberg is 23.9 MB on disk and 5.32 MB over the wire. That is the difference between a download people accept and one they cancel.

Pages picks its own compression level, and it is not the gzipSync level 9 the manifest measures with — it lands about 3% larger. Inside the rounding a “5 MB” label does, and worth knowing rather than assuming: the manifest is written before the packs are pushed, so it cannot measure the thing it describes.

Building a pack

In the app repo:

node scripts/build-boundaries.mjs baden-wuerttemberg --count   # levels, before anything expensive
PROBE=Stuttgart node scripts/build-boundaries.mjs baden-wuerttemberg --dry
node scripts/build-boundaries.mjs baden-wuerttemberg           # writes dist/packs/
node scripts/build-manifest.mjs --out ../fogbound-site/regions/index.json

The manifest is generated, never hand-edited: it carries a wire figure measured by compressing each pack, and typing that by hand is how a download button comes to overstate its cost fivefold.

Downloadable packs are written to a gitignored dist/packs/ rather than assets/boundaries/, so a 24 MB file can never be committed to the app or required into its bundle by accident.