Scheduled city snapshots

A city's .atlas can build itself on a schedule: crawl the city's ArcGIS hub, exit quietly when nothing changed, and publish a new versioned bundle when something did. The reusable workflow lives in this repository (.github/workflows/snapshot.yml); this repository's own scheduler runs it weekly over the public proof cities. A city IT team runs the same workflow in a repository of their own, so every employee works off the same enriched .atlas at whatever cadence the team chooses.

What a run does

1. Crawls the city into the fmg-archive committed on the state branch. Captures are content-addressed: an unchanged city registers nothing. Beside the city's own hub, every crawl queries the USGS national hydrography services on hydro.nationalmap.gov for the city's window — watersheds, subwatersheds, named streams, waterbodies — so a runner with an egress allowlist needs that host beside the hub's.
2. Composes the bundle. Its filename embeds the capture day and a content stamp over everything inside.
3. Gates: if that exact filename is already a release asset, the run ends — "unchanged". The gate catches data changes, tool changes, and policy revisions alike, because the stamp covers them all.
4. Otherwise commits the archive delta (durable, diffable history at any cadence — weekly, monthly, quarterly) and uploads the bundle to the rolling snapshot-<city> release. Every published version stays as an asset; <city>-latest.atlas always names the newest, so one URL serves the whole team.

Setting it up in your own repository

One-time, in a (typically private) repository:

git switch --orphan snapshots
# your city's curation, if it is not one of the public proof cities:
cp /path/to/cities_local.go .
git add -A && git commit -m "snapshot state"
git push -u origin snapshots
git switch main

Then a workflow:

name: City snapshot
on:
  schedule:
    - cron: "0 6 * * 1"   # weekly; monthly/quarterly are equally safe
  workflow_dispatch:
permissions:
  contents: write
jobs:
  snapshot:
    uses: FelineStateMachine/atlas/.github/workflows/snapshot.yml@main
    with:
      city: your-city-slug

The cities_local.go on the state branch is adopted into the build, so a private city's curation never has to be published. Employees fetch https://github.com/<org>/<repo>/releases/download/snapshot-<city>/<city>-latest.atlas and drop it into their Atlas bundles directory — or IT mirrors it onto a share the app watches.