straylight: remove MCP (fleet teardown for V3)

Kyle 2026-09-22: tear down MCP across the fleet. Drops the mcp/mcpkg imports
(agent, mcp user, packages), the unikernel-host agent overrides and kvm group,
the mcp-br0 bridge + FORWARD drop, the low-port sysctl (only MCNS/mc-proxy
needed it; Mattermost binds 8065), MCP firewall ports (53, 8443, 9443, 9444,
9555; keeps 443 for tailscale serve and 8080 for open-webui) and the MCNS
nameservers/~mcp.metacircular.net domain. State under /srv/mcp is kept.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

hw/straylight/default.nix

@@ -204,8 +204,6 @@ in
     ./hardware-configuration.nix
     ../../configs/desktop.nix
     ../../configs/qemu.nix
-    ../../configs/mcpkg.nix
-    ../../configs/mcp.nix # MCP agent + mcp user (straylight is becoming the core host)
   ];
 
   config = {
@@ -307,49 +305,6 @@ in
       };
     };
 
-    # straylight is the unikernel host. The shared mcp.nix locks the agent
-    # down with PrivateDevices=true, which hides /dev/kvm and /dev/net/tun.
-    # Relax that here (only on straylight) so the agent can boot Nanos
-    # unikernel VMs under QEMU/KVM and (Phase 2) manage TAP devices.
-    systemd.services.mcp-agent.serviceConfig = {
-      PrivateDevices = lib.mkForce false;
-      DeviceAllow = [ "/dev/kvm rw" "/dev/net/tun rw" ];
-      SupplementaryGroups = [ "kvm" ];
-      AmbientCapabilities = [ "CAP_NET_ADMIN" ];
-      # The agent launches each unikernel as a daemonized QEMU process in its
-      # own cgroup. With the default KillMode=control-group, restarting the
-      # agent would SIGKILL every running VM. KillMode=process kills only the
-      # agent's main process on stop/restart, so VMs survive an agent upgrade.
-      # (If a VM does die, the agent's startup Recover restarts it.)
-      KillMode = lib.mkForce "process";
-    };
-    # Let the mcp user reach /dev/kvm directly as well.
-    users.users.mcp.extraGroups = [ "kvm" ];
-
-    # Isolated host-only bridge for unikernel VMs (Phase 2). Each unikernel
-    # gets a TAP on this bridge and a 10.99.0.0/24 static IP. The bridge has
-    # NO uplink and NO NAT, and the firewall drops any VM traffic leaving the
-    # bridge, so a VM can reach only the host gateway (10.99.0.1) -- mediation
-    # is enforced by network topology, not convention.
-    networking.bridges.mcp-br0.interfaces = [ ];
-    networking.interfaces.mcp-br0.ipv4.addresses = [
-      { address = "10.99.0.1"; prefixLength = 24; }
-    ];
-    # The host accepts traffic from VMs (so mc-proxy on the gateway can serve
-    # them); the FORWARD drop prevents VMs from routing anywhere off-bridge.
-    networking.firewall.trustedInterfaces = [ "mcp-br0" ];
-    networking.firewall.extraCommands = ''
-      iptables -D FORWARD -i mcp-br0 ! -o mcp-br0 -j DROP 2>/dev/null || true
-      iptables -A FORWARD -i mcp-br0 ! -o mcp-br0 -j DROP
-    '';
-    networking.firewall.extraStopCommands = ''
-      iptables -D FORWARD -i mcp-br0 ! -o mcp-br0 -j DROP 2>/dev/null || true
-    '';
-
-    # Allow rootless containers (podman) to bind low ports (53 for MCNS,
-    # 443/8443/9443 for mc-proxy) as straylight takes over the core role.
-    boot.kernel.sysctl."net.ipv4.ip_unprivileged_port_start" = 53;
-
     hardware.bluetooth.enable = true;        # enables BlueZ + bluetooth.service
 
     programs.steam.enable = true;
@@ -486,21 +441,11 @@ in
       };
     };
 
-    # Open ports: DNS (53), mc-proxy (443/8443/9443), agent (9444), master (9555), open-webui (8080).
+    # Open ports: tailscale serve for Mattermost (443), open-webui (8080). MCP's DNS,
-    networking.firewall.allowedTCPPorts = [ 53 443 8080 8443 9443 9444 9555 ];
+    # mc-proxy, agent and master ports went with MCP (torn down 2026-09-22 for V3).
-    networking.firewall.allowedUDPPorts = [ 53 ];
+    networking.firewall.allowedTCPPorts = [ 443 8080 ];
     # llama.cpp OpenAI-compatible API: tailnet only (localhost is always allowed).
     networking.firewall.interfaces.tailscale0.allowedTCPPorts = [ 11434 11435 ];
 
-    # DNS: MCNS for internal zones, public resolvers as fallback.
-    networking.nameservers = [
-      "192.168.88.181"
-      "100.95.252.120"
-      "1.1.1.1"
-      "8.8.8.8"
-    ];
-    services.resolved.settings.Resolve.Domains = [
-      "~mcp.metacircular.net"
-    ];
   };
 }