Wallpaper from a link

Point set — or scoot’s [wallpaper] image — at a link: downloaded once, cached, then shown like any other image.

A wallpaper from a link

Point set (or scoot’s [wallpaper] image) at an http:// or https:// URL and the daemon downloads it once and caches it, then shows the file like any other image. Until the download lands — and when it fails — the compositor’s background shows and the error says why; nothing blocks and nothing retries in a loop.

scootbg set https://example.com/hills.jpg
scootbg set https://example.com/hills.jpg --sha256 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08

Key	Type	Default	Meaning
image (a URL)	string, http(s)://, at most 4096 bytes	—	Downloaded once, then shown. Needs curl on PATH; file:// and other schemes are refused (give the path itself).
--sha256 / sha256	64 hex digits, as sha256sum prints	none	Pins the download’s bytes: anything else fails instead of showing. With a path, refused. Applies live: changing it re-downloads.

How it works. The cache is $XDG_CACHE_HOME/scootbg/ (~/.cache/scootbg/ when XDG_CACHE_HOME is unset, empty or relative), one file per URL, named for the URL’s SHA-256. A file already there is shown as is (re-checked against sha256 when one is pinned); otherwise the worker thread — never the event loop — runs curl --fail --location (redirects followed, five at most; http and https only), capped at 32 MiB and sixty seconds, verifies the pin when given, checks the bytes start as PNG, JPEG or WebP, and renames the temporary file into place atomically. Two daemons racing on one entry both download; the rename settles it, and the cache never holds a partial file. An error page, a file past the cap, a hash mismatch, no network, or no curl is an error naming the URL, and nothing is cached — a fixed link is picked up by the next request. A failed download is tried again on a new set, any apply-config (even an unchanged reload — scoot sends one per reload), a reconfigured output, or a restart; nothing polls. Prefer https, and pin sha256 so a changed byte fails loudly instead of landing on screen.

The cache is yours to inspect and clear. To re-download a link (its image changed upstream and no sha256 pins the old bytes), remove its file from the cache directory and set the URL again; to drop every download, remove the directory (scootbg re-creates it). query’s shows names both the cached file (image) and the link (url).

When the link does not show, in order: scootbg set prints the reason (and the daemon’s stderr has it once). No curl on PATH says so; a host nothing resolves or answers names curl’s exit; a 404 or other HTTP error says exited 22; an error page (a login wall, say) says the bytes “do not start as a PNG, JPEG or WebP” and caches nothing; a file past 32 MiB says so (link something smaller); a sha256 mismatch prints both hashes (copy the actual one into the config, or drop the pin); a cache directory nobody can write names it. Offline at startup, the background shows until the next set, apply-config, reconfigure, or restart with the network back.

From Nix: fetch at build time

A look’s image — and a settings.wallpaper.image you write — takes { url, hash } as well as a path or a plain string URL: the profile fetches it once with pkgs.fetchurl (the hash verified by Nix, the file cached in the store), and scootbg sees an ordinary file. A plain string URL works too, and then scootbg itself downloads and caches it at runtime (above).

# Fetched at build time (verified, in the store, no network at runtime):
programs.scoot.settings.wallpaper = {
  image = {
    url = "https://example.com/hills.jpg";
    hash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
  };
  mode = "fill";
};

# Or fetched by scootbg at runtime (cached under ~/.cache/scootbg/):
programs.scoot.settings.wallpaper = {
  image = "https://example.com/hills.jpg";
  sha256 = "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08";
  mode = "fill";
};

A set without string url and hash fails evaluation. A per-output output.<name>.image takes the same { url, hash } set. Runtime downloads need curl on PATH: the flake’s scootbg package carries it (appended after your own PATH, so yours still wins).