standalone without our server: basemap and DEM load from the CORS-enabled upstreams, same-origin proxy only when a probe proves it exists; drop dead kumi.systems mirror

README.md

@@ -68,8 +68,12 @@ The bundled nginx config (`default.conf`) is more than a file server:
 - `Cache-Control: no-store` for HTML and JS, so a changed `CONFIG` takes effect
   on reload.
 
-A plain static server without these proxies (e.g. `python3 -m http.server
-58881`) runs the UI, but terrain, basemap and road data will not load.
+The proxies are a convenience, not a requirement: every data source is also
+reachable directly from the browser (ESRI, the AWS elevation bucket and the
+Overpass mirrors all answer cross-origin requests), and the page probes for
+`/terrarium/` and `/esri/...` at start-up and switches to the proxy only when
+this same-origin proxy actually exists. Running the files from any static
+server therefore works as well - just without the nginx-side Overpass cache.
 
 ## Single-file build
 
@@ -86,10 +90,14 @@ python3 build.py --check            # build to a temp file and verify, write not
 `--check` fails if anything is left that would need a sibling file (an external
 `<script src>` or a CSS `<link>`).
 
-Runtime *data* is still fetched at load (tiles, Overpass, weather): serve the
-file from the Docker image for the full experience. Opened via `file://` or a
-proxy-less server it renders sky, clouds and UI with an "OFFLINE"-labelled
-ground grid instead of basemap tiles.
+Runtime *data* is fetched at load, but from public sources only: ESRI basemap
+tiles, the AWS elevation tiles and the Overpass mirrors are all CORS-enabled,
+and Open-Meteo needs no key. So the built file runs on its own - from any
+static server, and even opened directly via `file://`. Serving it from the
+Docker image additionally gives the nginx proxies and the 30-day Overpass
+cache, which is the gentlest option for the upstreams. If a source is
+unreachable, the scene degrades instead of failing: an "OFFLINE"-labelled
+ground grid in place of basemap tiles.
 
 ## Configuration