--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mod_muc_auto_hats/mod_muc_auto_hats.lua	Wed Mar 25 18:47:51 2026 +0000
@@ -0,0 +1,35 @@
+local jid = require "prosody.util.jid";
+local sha256 = require "prosody.util.hashes".sha256;
+local st = require "prosody.util.stanza";
+
+local host_hats = module:get_option("muc_auto_hats_by_host");
+
+for hat_host, hat_config in pairs(host_hats) do
+	if not hat_config.uri then
+		hat_config.uri = ("xmpp:%s/hats/%s"):format(module.host, sha256(hat_host..","..module.host, true));
+	end
+	if not hat_config.title then
+		hat_config.title = hat_host;
+	end
+end
+
+module:hook("muc-build-occupant-presence", function (event)
+	local pres = event.stanza;
+
+	local bare_jid = event.occupant and event.occupant.bare_jid or event.bare_jid;
+	local occ_host = jid.host(bare_jid);
+
+	local host_hat = host_hats[occ_host];
+
+	if not host_hat then
+		return;
+	end
+
+	local hats_el = pres:get_child("hats", "urn:xmpp:hats:0");
+	if not hats_el then
+		hats_el = st.stanza("hats", "urn:xmpp:hats:0");
+		pres:add_direct_child(hats_el);
+	end
+
+	hats_el:text_tag("hat", nil, { uri = host_hat.uri, title = host_hat.title });
+end);