nginx: addSSL + explicit tailscale listen for atproto-likes (copy)

Sync of the canonical module in the project repo. forceSSL would have bounced
the gateway's plain-HTTP hop back to the gateway; and the oc vhost's explicit
listen on 100.84.190.30:80 was shadowing this vhost on the tailnet, serving the
opencode UI for Host: atproto.commoninternet.net.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SmEK2voMnBa23495aLk1Ce

nix/atproto-likes.nix

@@ -1,5 +1,4 @@
-# atproto-likes — the "most-liked accounts" web UI, run as a docker-compose stack
-# behind the host's nginx.
+# atproto-likes — the "most-liked accounts" web UI, run as a docker-compose stack behind nginx.
 #
 # ⚠️  COPY. Canonical source:
 #     /srv/project-orchestrator/projects/notplants-atproto/nix/atproto-likes.nix
@@ -16,12 +15,16 @@
 #     proxying to the container on 127.0.0.1:8731
 #   * ports 80/443 open (they were closed — only 22 was public)
 #
-# DNS: *.commoninternet.net is a wildcard pointing at 143.244.213.108, which is NOT
-# this host. Until an explicit A record
-#     atproto.commoninternet.net -> 168.119.126.100
-# overrides that wildcard, ACME's HTTP-01 challenge cannot succeed and the domain
-# keeps resolving elsewhere. nginx still starts in the meantime — NixOS installs a
-# self-signed placeholder cert — so nothing else on the host is affected.
+# DNS: atproto.commoninternet.net resolves to 143.244.213.108 — the operator's
+# gateway (tailnet peer `gateway-server-aug2-9pm`, 100.80.66.110), which fronts this
+# host rather than pointing at it directly. So what arrives here is the gateway's
+# back-end hop, and the gateway needs a route for this hostname to either
+#     http://100.84.190.30       (tailnet, preferred)
+#     http://168.119.126.100     (public)
+# preserving the Host header, passing Upgrade/Connection through (the loading page
+# is a websocket), and allowing a long read timeout (a cold scan runs minutes).
+# ACME here can only succeed if the gateway forwards /.well-known/acme-challenge/;
+# otherwise the gateway should own the certificate and `enableACME` can go false.
 { config, pkgs, lib, ... }:
 
 let
@@ -63,8 +66,32 @@ in
     enable = true;
     recommendedProxySettings = true;
     virtualHosts.${domain} = {
-      forceSSL = true;
+      # addSSL, NOT forceSSL. DNS for this domain points at the gateway
+      # (143.244.213.108), which fronts this host — so the request that actually
+      # arrives here is the gateway's back-end hop. If that hop is plain HTTP and
+      # we answered with a 301 to https://atproto.commoninternet.net/, it would
+      # resolve straight back to the gateway: a redirect loop. Serve both schemes
+      # and let the gateway decide where TLS terminates.
+      addSSL = true;
+      # Keeps retrying; it can only succeed if the gateway forwards
+      # /.well-known/acme-challenge/ here, since the A record is the gateway's.
+      # Until then nginx uses the self-signed placeholder NixOS installs, and the
+      # acme-atproto… unit sits in `failed`. Set this false if the gateway is to
+      # own the certificate permanently.
       enableACME = true;
+      # The `oc.commoninternet.net` vhost binds explicitly to the tailscale IP on
+      # port 80. nginx prefers the most specific listen address, so a request to
+      # 100.84.190.30:80 was only ever matched against THAT server block — this
+      # vhost, listening on 0.0.0.0, never got a look in, and a gateway hop over
+      # the tailnet was served the opencode UI instead. Listing the tailscale
+      # address explicitly here puts both vhosts on that socket, so server_name
+      # decides, which is what we want.
+      listen = [
+        { addr = "0.0.0.0";        port = 80;  ssl = false; }
+        { addr = "0.0.0.0";        port = 443; ssl = true;  }
+        { addr = "100.84.190.30";  port = 80;  ssl = false; }
+        { addr = "100.84.190.30";  port = 443; ssl = true;  }
+      ];
       locations."/" = {
         proxyPass = "http://127.0.0.1:${toString hostPort}";
         # The loading page streams scan progress over a websocket.