Session-sticky User-Agent rotation with full, modern browser profiles.

Assigns one random browser profile per session (keyed however you like — e.g. {user_id, host}). Every request during that session reuses the same UA + Accept-Language; after 30 minutes of inactivity the profile expires. Rotating a consistent identity per session looks far more like a real client than a fresh random UA on every request.

Guise.headers("https://example.com/")
#=> [{"user-agent", "Mozilla/5.0 …"}, {"referer", "https://example.com/"}]

Guise.headers("https://example.com/", {user_id, "example.com"})
#=> sticky UA + accept-language + referer for that session key

How the pool stays fresh

A modern UA string is a stable template plus one volatile part — the browser's major version (Chrome froze everything below the major to .0.0.0 years ago). So instead of a list of frozen strings that all rot together, the pool is rendered from @specs (engine × OS × weight) using a small version table in priv/versions.json. Bumping those few versions modernizes the whole pool at once and can't produce an inconsistent string. Refresh the table with:

mix guise.refresh

which pulls the current stable majors from endoflife.date and rewrites the JSON. The runtime never touches the network — it only reads the committed file at boot.

Configuration

Override individual browser versions (handy for tests or pinning):

config :guise, Guise,
  versions: %{"chrome" => "140.0.0.0"}

Or replace the pool wholesale with your own profiles — each a map with a required :ua and optional :accept_language (default en-US) and :weight (default 1); a bare string is taken as the UA. When :profiles is set it wins over the built-in specs and :versions is ignored:

config :guise, Guise,
  profiles: [
    %{ua: "MyBot/1.0 (+https://example.com/bot)", weight: 3},
    "Mozilla/5.0 (…) Chrome/140.0.0.0 Safari/537.36"
  ]