feat(server): add --mdns-domain flag to customize mDNS hostname

Allow users to specify a custom domain name for mDNS service discovery
instead of the hardcoded 'opencode.local'. This enables running multiple
OpenCode instances on the same network with distinct mDNS names.

The option can be set via CLI flag (--mdns-domain) or config file
(server.mdnsDomain).

Closes #11794

packages/opencode/src/cli/cmd/web.ts

@@ -63,7 +63,7 @@ export const WebCommand = cmd({
         UI.println(
           UI.Style.TEXT_INFO_BOLD + "  mDNS:              ",
           UI.Style.TEXT_NORMAL,
-          `opencode.local:${server.port}`,
+          `${opts.mdnsDomain}:${server.port}`,
         )
       }
 

packages/opencode/src/cli/network.ts

@@ -17,6 +17,11 @@ const options = {
     describe: "enable mDNS service discovery (defaults hostname to 0.0.0.0)",
     default: false,
   },
+  "mdns-domain": {
+    type: "string" as const,
+    describe: "custom domain name for mDNS service (default: opencode.local)",
+    default: "opencode.local",
+  },
   cors: {
     type: "string" as const,
     array: true,
@@ -36,9 +41,11 @@ export async function resolveNetworkOptions(args: NetworkOptions) {
   const portExplicitlySet = process.argv.includes("--port")
   const hostnameExplicitlySet = process.argv.includes("--hostname")
   const mdnsExplicitlySet = process.argv.includes("--mdns")
+  const mdnsDomainExplicitlySet = process.argv.includes("--mdns-domain")
   const corsExplicitlySet = process.argv.includes("--cors")
 
   const mdns = mdnsExplicitlySet ? args.mdns : (config?.server?.mdns ?? args.mdns)
+  const mdnsDomain = mdnsDomainExplicitlySet ? args["mdns-domain"] : (config?.server?.mdnsDomain ?? args["mdns-domain"])
   const port = portExplicitlySet ? args.port : (config?.server?.port ?? args.port)
   const hostname = hostnameExplicitlySet
     ? args.hostname
@@ -49,5 +56,5 @@ export async function resolveNetworkOptions(args: NetworkOptions) {
   const argsCors = Array.isArray(args.cors) ? args.cors : args.cors ? [args.cors] : []
   const cors = [...configCors, ...argsCors]
 
-  return { hostname, port, mdns, cors }
+  return { hostname, port, mdns, mdnsDomain, cors }
 }

packages/opencode/src/config/config.ts

@@ -860,6 +860,7 @@ export namespace Config {
       port: z.number().int().positive().optional().describe("Port to listen on"),
       hostname: z.string().optional().describe("Hostname to listen on"),
       mdns: z.boolean().optional().describe("Enable mDNS service discovery"),
+      mdnsDomain: z.string().optional().describe("Custom domain name for mDNS service (default: opencode.local)"),
       cors: z.array(z.string()).optional().describe("Additional domains to allow for CORS"),
     })
     .strict()

packages/opencode/src/server/mdns.ts

@@ -7,17 +7,18 @@ export namespace MDNS {
   let bonjour: Bonjour | undefined
   let currentPort: number | undefined
 
-  export function publish(port: number) {
+  export function publish(port: number, domain?: string) {
     if (currentPort === port) return
     if (bonjour) unpublish()
 
     try {
+      const host = domain ?? "opencode.local"
       const name = `opencode-${port}`
       bonjour = new Bonjour()
       const service = bonjour.publish({
         name,
         type: "http",
-        host: "opencode.local",
+        host,
         port,
         txt: { path: "/" },
       })

packages/opencode/src/server/server.ts

@@ -563,7 +563,13 @@ export namespace Server {
     return result
   }
 
-  export function listen(opts: { port: number; hostname: string; mdns?: boolean; cors?: string[] }) {
+  export function listen(opts: {
+    port: number
+    hostname: string
+    mdns?: boolean
+    mdnsDomain?: string
+    cors?: string[]
+  }) {
     _corsWhitelist = opts.cors ?? []
 
     const args = {
@@ -591,7 +597,7 @@ export namespace Server {
       opts.hostname !== "localhost" &&
       opts.hostname !== "::1"
     if (shouldPublishMDNS) {
-      MDNS.publish(server.port!)
+      MDNS.publish(server.port!, opts.mdnsDomain)
     } else if (opts.mdns) {
       log.warn("mDNS enabled but hostname is loopback; skipping mDNS publish")
     }