Dashboard UI: subdomain checkbox, drop proxy path/host

Follow the backend to the subdomain-only model:
- Service editor + create form: replace the Proxy path / Proxy host text fields
  with a single "Expose" checkbox (writes proxy: { caddy: {} } or removes proxy).
- ServiceSummary/DeploymentSummary type: proxy_path/proxy_host → subdomain.
- ServiceCard / ServiceDetail: show the subdomain, linking to
  <subdomain>.<domain> via a new subdomainUrl() helper (domain derived from the
  dashboard's own host; null on a bare host / off mode).

app/src/components/ServiceCard.tsx

@@ -2,7 +2,7 @@ import { ExternalLink, Play, RefreshCw, Server, Square, Terminal } from "lucide-
 import { Link } from "react-router-dom"
 import type { ServiceSummary, HealthStatus } from "@/types"
 import { useServiceAction } from "@/services/api/hooks"
-import { runnerLabel } from "@/lib/labels"
+import { runnerLabel, subdomainUrl } from "@/lib/labels"
 import { HealthBadge } from "./HealthBadge"
 import { StackBadge } from "./StackBadge"
 
@@ -58,13 +58,13 @@ export function ServiceCard({ service, health }: ServiceCardProps) {
               {runnerLabel(service.runner)}
             </span>
           )}
-          {service.proxy_path && (
+          {service.subdomain && (
             <a
-              href={service.proxy_path + "/"}
+              href={subdomainUrl(service.subdomain) ?? undefined}
               className="flex items-center gap-1 text-[var(--primary)] hover:underline"
             >
               <ExternalLink size={12} />
-              {service.proxy_path}
+              {service.subdomain}
             </a>
           )}
           {service.port && (

app/src/components/detail/CreateDeploymentForm.tsx

@@ -39,8 +39,7 @@ export function CreateDeploymentForm({
   const [runTarget, setRunTarget] = useState(prefill?.runTarget ?? prefill?.name ?? "")
   const [port, setPort] = useState("")
   const [health, setHealth] = useState("/health")
-  const [path, setPath] = useState("")
-  const [host, setHost] = useState("")
+  const [expose, setExpose] = useState(true)
   const [schedule, setSchedule] = useState("0 2 * * *")
   const [busy, setBusy] = useState<string | null>(null)
   const [error, setError] = useState("")
@@ -75,14 +74,7 @@ export function CreateDeploymentForm({
         },
       }
     }
-    if (path || host) {
-      base.proxy = {
-        caddy: {
-          ...(path ? { path_prefix: path.startsWith("/") ? path : `/${path}` } : {}),
-          ...(host ? { host } : {}),
-        },
-      }
-    }
+    if (port && expose) base.proxy = { caddy: {} }
     return base
   }
 
@@ -160,8 +152,14 @@ export function CreateDeploymentForm({
         <>
           <TextField label="Port" value={port} onChange={setPort} width="w-32" mono placeholder="9001" />
           <TextField label="Health path" value={health} onChange={setHealth} width="w-48" mono />
-          <TextField label="Proxy path" value={path} onChange={setPath} width="w-48" mono placeholder={`/${name || "name"}`} />
-          <TextField label="Proxy host" value={host} onChange={setHost} mono placeholder="my-service.lan (optional)" />
+          <Field label="Expose" hint="Route through the gateway at <name>.<gateway.domain>. Off: reachable only at host:port.">
+            <label className="flex items-center gap-2 text-sm cursor-pointer">
+              <input type="checkbox" checked={expose} onChange={(e) => setExpose(e.target.checked)} />
+              <span className="font-mono text-[var(--muted)]">
+                {expose ? `${name || "name"}.<gateway.domain>` : "off (host:port only)"}
+              </span>
+            </label>
+          </Field>
         </>
       ) : (
         <TextField label="Schedule" value={schedule} onChange={setSchedule} width="w-48" mono placeholder="0 2 * * *" />

app/src/components/detail/ServiceFields.tsx

@@ -18,7 +18,7 @@ export function ServiceFields({ service, onSave, onDelete }: Props) {
   const run = obj(m.run)
   const internal = obj(obj(obj(m.expose).http).internal)
   const httpExpose = obj(obj(m.expose).http)
-  const caddy = obj(obj(m.proxy).caddy)
+  const caddyRaw = obj(m.proxy).caddy
 
   const [saving, setSaving] = useState(false)
   const [saved, setSaved] = useState(false)
@@ -29,8 +29,8 @@ export function ServiceFields({ service, onSave, onDelete }: Props) {
   )
   const [port, setPort] = useState(internal.port != null ? String(internal.port) : "")
   const [health, setHealth] = useState((httpExpose.health_path as string) ?? "")
-  const [proxyPath, setProxyPath] = useState((caddy.path_prefix as string) ?? "")
-  const [proxyHost, setProxyHost] = useState((caddy.host as string) ?? "")
+  // Exposed at <service-name>.<gateway.domain> when proxy.caddy is present + enabled.
+  const [expose, setExpose] = useState(caddyRaw !== undefined && obj(caddyRaw).enable !== false)
 
   const { element: envEditor, merged } = useEnvSecrets(obj(obj(m.defaults).env) as Record<string, string>)
 
@@ -62,16 +62,8 @@ export function ServiceFields({ service, onSave, onDelete }: Props) {
         delete config.expose
       }
 
-      if (proxyPath || proxyHost) {
-        config.proxy = {
-          caddy: {
-            ...(proxyPath ? { path_prefix: proxyPath } : {}),
-            ...(proxyHost ? { host: proxyHost } : {}),
-          },
-        }
-      } else {
-        delete config.proxy
-      }
+      if (expose) config.proxy = { caddy: {} }
+      else delete config.proxy
 
       const env = merged()
       if (Object.keys(env).length > 0) config.defaults = { ...obj(config.defaults), env }
@@ -117,23 +109,21 @@ export function ServiceFields({ service, onSave, onDelete }: Props) {
         placeholder="/health"
         hint="HTTP path castle polls to report up/down."
       />
-      <TextField
-        label="Proxy path"
-        value={proxyPath}
-        onChange={setProxyPath}
-        width="w-48"
-        mono
-        placeholder="/my-service"
-        hint="Gateway prefix — reachable at gateway:9000<path>/ (reverse-proxied to the port)."
-      />
-      <TextField
-        label="Proxy host"
-        value={proxyHost}
-        onChange={setProxyHost}
-        mono
-        placeholder="my-service.lan"
-        hint="Optional: route a whole hostname to this service instead of a path (lets a root-based app serve unchanged)."
-      />
+      <Field
+        label="Expose"
+        hint="Route this service through the gateway at <service-name>.<gateway.domain>. Unchecked: reachable only at its own host:port."
+      >
+        <label className="flex items-center gap-2 text-sm cursor-pointer">
+          <input
+            type="checkbox"
+            checked={expose}
+            onChange={(e) => setExpose(e.target.checked)}
+          />
+          <span className="font-mono text-[var(--muted)]">
+            {expose ? `${service.id}.<gateway.domain>` : "off (host:port only)"}
+          </span>
+        </label>
+      </Field>
       {envEditor}
       <FormFooter
         saving={saving}