diff --git a/src/bun/index.js b/src/bun/index.js
index 6bbdf99..d0b4ad3 100644
--- a/src/bun/index.js
+++ b/src/bun/index.js
@@ -1,30 +1,34 @@
-import { createAppRpc } from '../desktop/rpc.js'
 import {
   closeSingleInstanceServer,
-  ensureSingleInstanceLock
+  ensureSingleInstanceLock,
+  setSingleInstanceHandlers
 } from '../desktop/single-instance.js'
-import {
+
+const gotSingleInstanceLock = await ensureSingleInstanceLock()
+
+if (!gotSingleInstanceLock) {
+  process.exit(0)
+}
+
+const { createAppRpc } = await import('../desktop/rpc.js')
+const {
   registerGlobalShortcuts,
   unregisterGlobalShortcuts
-} from '../desktop/spotlight.js'
-import {
+} = await import('../desktop/spotlight.js')
+const {
   createMainWindow,
   handleDeepLink,
   handleDeepLinkFromArgv,
   setupDevAuthServer,
   setupNavigationGestures,
   showMainWindow
-} from '../desktop/window.js'
+} = await import('../desktop/window.js')
 
-const gotSingleInstanceLock = await ensureSingleInstanceLock({
+setSingleInstanceHandlers({
   onDeepLink: handleDeepLink,
   onFocus: showMainWindow
 })
 
-if (!gotSingleInstanceLock) {
-  process.exit(0)
-}
-
 const rpc = createAppRpc()
 const mainWindow = await createMainWindow(rpc)
 
diff --git a/src/desktop/single-instance.js b/src/desktop/single-instance.js
index 13ad9f5..2e6c92d 100644
--- a/src/desktop/single-instance.js
+++ b/src/desktop/single-instance.js
@@ -1,7 +1,8 @@
 const PROTOCOL_PREFIX = 'farmcontrol://'
 const SINGLE_INSTANCE_HOST = '127.0.0.1'
+const SINGLE_INSTANCE_PATH = '/farmcontrol-instance'
 
-// Stable port derived from the app identifier so multiple apps don't collide.
+// Keep below Electrobun's RPC server range (50000+).
 function getSingleInstancePort() {
   const identifier = 'com.tombutcher.farmcontrol'
   let hash = 0
@@ -10,84 +11,131 @@ function getSingleInstancePort() {
     hash = (hash * 31 + char.charCodeAt(0)) | 0
   }
 
-  return 49152 + (Math.abs(hash) % 16383)
+  return 30000 + (Math.abs(hash) % 10000)
 }
 
-function findProtocolUrl(args) {
-  return args.find(
-    (arg) => typeof arg === 'string' && arg.startsWith(PROTOCOL_PREFIX)
-  )
+export function findProtocolUrl(args) {
+  const sources = args.filter((arg) => typeof arg === 'string')
+
+  for (const arg of sources) {
+    const trimmed = arg.trim().replace(/^['"]+|['"]+$/g, '')
+    const match = trimmed.match(/farmcontrol:\/\/\S+/i)
+    if (match) {
+      try {
+        return decodeURI(match[0])
+      } catch {
+        return match[0]
+      }
+    }
+  }
+
+  const combined = sources.join(' ')
+  const combinedMatch = combined.match(/farmcontrol:\/\/\S+/i)
+  if (combinedMatch) {
+    try {
+      return decodeURI(combinedMatch[0])
+    } catch {
+      return combinedMatch[0]
+    }
+  }
+
+  return undefined
 }
 
 function buildSecondInstanceMessage() {
   const url = findProtocolUrl(process.argv)
-  return url ? { type: 'deeplink', url } : { type: 'focus' }
+  return url
+    ? { type: 'deeplink', url, argv: process.argv }
+    : { type: 'focus', argv: process.argv }
 }
 
-function parseIncomingMessage(data) {
-  const text = data.toString().trim()
-  if (!text) return null
-
-  try {
-    return JSON.parse(text)
-  } catch {
+function resolveIncomingMessage(message) {
+  if (!message || typeof message !== 'object') {
     return null
   }
-}
 
-async function forwardToPrimaryInstance(message) {
-  await new Promise((resolve, reject) => {
-    Bun.connect({
-      hostname: SINGLE_INSTANCE_HOST,
-      port: getSingleInstancePort(),
-      socket: {
-        open(socket) {
-          socket.write(`${JSON.stringify(message)}\n`)
-          socket.end()
-          resolve()
-        },
-        data() {},
-        error(_socket, error) {
-          reject(error)
-        },
-        close() {
-          resolve()
-        }
-      }
-    }).catch(reject)
-  })
+  if (message.type === 'deeplink') {
+    const url = message.url || findProtocolUrl(message.argv || [])
+    return url ? { type: 'deeplink', url } : { type: 'focus' }
+  }
+
+  if (message.type === 'focus') {
+    return { type: 'focus' }
+  }
+
+  return null
 }
 
 let server = null
+let handlers = {
+  onDeepLink: null,
+  onFocus: null
+}
+const pendingMessages = []
 
-function startPrimaryInstanceServer({ onDeepLink, onFocus }) {
-  server = Bun.listen({
+function dispatchMessage(message) {
+  const resolved = resolveIncomingMessage(message)
+  if (!resolved) return
+
+  if (!handlers.onDeepLink && !handlers.onFocus) {
+    pendingMessages.push(resolved)
+    return
+  }
+
+  if (resolved.type === 'deeplink' && resolved.url) {
+    handlers.onDeepLink?.(resolved.url)
+  } else if (resolved.type === 'focus') {
+    handlers.onFocus?.()
+  }
+}
+
+function getSingleInstanceUrl() {
+  return `http://${SINGLE_INSTANCE_HOST}:${getSingleInstancePort()}${SINGLE_INSTANCE_PATH}`
+}
+
+async function forwardToPrimaryInstance(message) {
+  const response = await fetch(getSingleInstanceUrl(), {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(message)
+  })
+
+  if (!response.ok) {
+    throw new Error(`Forward failed with status ${response.status}`)
+  }
+}
+
+function startPrimaryInstanceServer() {
+  server = Bun.serve({
     hostname: SINGLE_INSTANCE_HOST,
     port: getSingleInstancePort(),
-    socket: {
-      data(socket, data) {
-        const message = parseIncomingMessage(data)
-        socket.end()
+    fetch: async (req) => {
+      const { pathname } = new URL(req.url)
 
-        if (!message) return
-
-        if (message.type === 'deeplink' && message.url) {
-          onDeepLink?.(message.url)
-        } else if (message.type === 'focus') {
-          onFocus?.()
-        }
+      if (req.method !== 'POST' || pathname !== SINGLE_INSTANCE_PATH) {
+        return new Response('Not found', { status: 404 })
       }
+
+      let message
+      try {
+        message = await req.json()
+      } catch {
+        return new Response('Bad request', { status: 400 })
+      }
+
+      dispatchMessage(message)
+      return new Response('ok')
     }
   })
 }
 
-export async function ensureSingleInstanceLock({ onDeepLink, onFocus }) {
+export async function ensureSingleInstanceLock() {
   if (process.platform === 'darwin') {
     return true
   }
 
   try {
-    startPrimaryInstanceServer({ onDeepLink, onFocus })
+    startPrimaryInstanceServer()
     return true
   } catch (error) {
     if (error?.code !== 'EADDRINUSE') {
@@ -105,6 +153,14 @@ export async function ensureSingleInstanceLock({ onDeepLink, onFocus }) {
   }
 }
 
+export function setSingleInstanceHandlers({ onDeepLink, onFocus }) {
+  handlers = { onDeepLink, onFocus }
+
+  while (pendingMessages.length > 0) {
+    dispatchMessage(pendingMessages.shift())
+  }
+}
+
 export function closeSingleInstanceServer() {
   server?.stop?.()
   server = null
diff --git a/src/desktop/window.js b/src/desktop/window.js
index 8d00a9b..8ce50d0 100644
--- a/src/desktop/window.js
+++ b/src/desktop/window.js
@@ -10,7 +10,7 @@ const isMacOS = process.platform === 'darwin'
 
 const DEV_SERVER_PORT = 5780
 const DEV_SERVER_URL = `http://localhost:${DEV_SERVER_PORT}`
-const PROTOCOL_PREFIX = 'farmcontrol://'
+import { findProtocolUrl } from './single-instance.js'
 
 let mainWindow = null
 let webviewDomReady = false
@@ -73,15 +73,13 @@ function sendNavigateToRenderer(redirectPath) {
 }
 
 export function handleDeepLink(url) {
-  if (!url?.startsWith(`${PROTOCOL_PREFIX}app`)) return
-  const redirectPath = url.replace(`${PROTOCOL_PREFIX}app`, '') || '/'
-  sendNavigateToRenderer(redirectPath)
-}
+  if (!url || typeof url !== 'string') return
 
-function findProtocolUrl(args) {
-  return args.find(
-    (arg) => typeof arg === 'string' && arg.startsWith(PROTOCOL_PREFIX)
-  )
+  const match = url.match(/^farmcontrol:\/\/app(.*)$/i)
+  if (!match) return
+
+  const redirectPath = match[1] || '/'
+  sendNavigateToRenderer(redirectPath.startsWith('/') ? redirectPath : `/${redirectPath}`)
 }
 
 export function handleDeepLinkFromArgv() {