mono updates

.env.example

@@ -1,9 +1,19 @@
-# Base domain all service hosts are derived from, e.g. accounts.<domain>.
+# Base domain all service hosts are derived from, e.g. accounts.<domain>. Used by
+# `just dev` too, so a locally-run worker hands out the same addresses it would deployed.
 RECFLARE_DOMAIN=rec.example.com
 
 # Optional per-app subdomain overrides, as a compact JSON object keyed by the
-# worker's directory name. Defaults to the directory name when unset.
+# worker's directory name. Defaults to the directory name when unset. Use "@" to
+# put a worker on the APEX of the domain rather than a subdomain.
 # RECFLARE_SUBDOMAINS='{"playersettings":"settings"}'
+#
+# The combined `mono` worker (an alternative to deploying the services separately:
+# it mounts most of them in one deployable and routes on the first path segment, so
+# every address is https://<domain>/rooms, https://<domain>/auth, …) belongs on the
+# apex, and won't hand out the right addresses anywhere else. It ships only when you
+# ask for it — `just deploy-mono`, never `just deploy` — since it's an alternative to
+# the split set, not part of it:
+# RECFLARE_SUBDOMAINS='{"mono":"@"}'
 
 # Id of the shared `recflare` D1 database (create it manually with
 # `wrangler d1 create recflare`). All D1-backed workers bind this one database.