diff --git a/mac/README.md b/mac/README.md
index 8fd54a3..e7733e3 100644
--- a/mac/README.md
+++ b/mac/README.md
@@ -1,6 +1,19 @@
 # pricegod label daemon (macOS)
 
-One service on `localhost:7790` that drives **both** printers over raw USB:
+One service on `localhost:7791` that drives **both** printers over raw USB:
+
+> **Port 7791, and you normally talk to 7790.** The Node `rfid-daemon` owns 7790 — it drives the
+> Chafon gun and the Dymo scale, and it is what the PriceGod extension is configured against. It
+> proxies `/printer/*` to this service, so the extension keeps ONE front door: `/printer/status`,
+> `/printer/print-encode`, `/printer/recover` and so on land here. `GET /devices` on 7790 reports
+> all four devices at once.
+>
+> They stay separate processes deliberately. This side needs libusb (UHF READ answers with raw
+> bytes on the bulk-IN endpoint, so `lp -o raw` cannot drive it); the other needs node-serialport
+> and node-hid. And they cannot share a flat namespace — `/status`, `/read-tag`, `/write-tag` and
+> `/recover` exist on both and mean different things: the gun in your hand versus the antenna in
+> the printer. The prefix is what keeps that unambiguous.
+
 
 | device | role | how |
 |---|---|---|
diff --git a/mac/daemon.py b/mac/daemon.py
index 639befd..364258e 100644
--- a/mac/daemon.py
+++ b/mac/daemon.py
@@ -28,6 +28,7 @@ import json
 import sys
 import threading
 import time
+import os
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from urllib.parse import urlparse, parse_qs
 
@@ -356,7 +357,15 @@ class Handler(BaseHTTPRequestHandler):
 
 
 def main():
-    port = 7790
+    # 7791, not 7790. The Node rfid-daemon owns 7790: it is what the PriceGod extension talks to,
+    # it drives the Chafon gun and the Dymo scale, and it has the larger route surface. Both
+    # services binding one port is not the only clash either — /status, /read-tag, /write-tag and
+    # /recover exist on BOTH and mean different things (the gun versus this printer), so they can
+    # never be merged into one flat namespace safely.
+    #
+    # The Node daemon proxies /printer/* here instead, which keeps one front door on 7790 for the
+    # extension and leaves these route names unambiguous. Override with --port or UROVO_PORT.
+    port = int(os.environ.get('UROVO_PORT', 7791))
     if '--port' in sys.argv:
         port = int(sys.argv[sys.argv.index('--port') + 1])
     srv = ThreadingHTTPServer(('127.0.0.1', port), Handler)