fix(tailshare): move configAtBuildRef to IpnProvider level

configAtBuildRef was local to TailscaleConfig, so navigating away from
/tailscale and back would remount the component and reset the ref, making
the restart-required banner disappear even if the config had changed.

Moving configAtBuild into IpnPrepareContext keeps it alive for the
lifetime of the provider.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/tailshare/src/contexts/IpnContext.tsx

@@ -70,6 +70,7 @@ function parseConfig(raw: string): TailshareConfig {
 
 export const IpnPrepareContext = createContext<{
   config: TailshareConfig
+  configAtBuild: TailshareConfig | null
   setConfig: (patch: Partial<TailshareConfig>) => void
   willBuild: boolean
   build: () => void
@@ -162,9 +163,13 @@ export function IpnProvider({ children }: { children: ReactNode }) {
 
   if (typeof window !== "undefined") Object.assign(window, { ipn })
 
+  const configAtBuildRef = useRef<TailshareConfig | null>(null)
+  if (willBuild && !configAtBuildRef.current) configAtBuildRef.current = config
+  const configAtBuild = configAtBuildRef.current
+
   const prepare = useMemo<NonNullable<ContextType<typeof IpnPrepareContext>>>(
-    () => ({ config, setConfig, willBuild, build, workerAvailable, connectionMode }),
-    [config, setConfig, willBuild, build, workerAvailable, connectionMode],
+    () => ({ config, configAtBuild, setConfig, willBuild, build, workerAvailable, connectionMode }),
+    [config, configAtBuild, setConfig, willBuild, build, workerAvailable, connectionMode],
   )
 
   return (

packages/tailshare/src/pages/tailscale.tsx

@@ -30,7 +30,7 @@ import {
   getWaitingFiles,
 } from "@webnet/tsconnect-redux"
 import { IpnContext, IpnPrepareContext, useIpnSelector } from "../contexts/IpnContext"
-import { use, useRef } from "react"
+import { use } from "react"
 import styles from "./tailscale.scss"
 import { CopyIcon, DownloadIcon, TrashIcon } from "@phosphor-icons/react"
 import { useDisclosure } from "@mantine/hooks"
@@ -91,13 +91,7 @@ function TailscaleConfig() {
   const dispatch = useTailshareDispatch()
   const ipn = use(IpnContext)
   const prepare = use(IpnPrepareContext)!
-  const { config, setConfig, workerAvailable, connectionMode } = prepare
-
-  const configAtBuildRef = useRef<typeof config | null>(null)
-  if (prepare.willBuild && !configAtBuildRef.current) {
-    configAtBuildRef.current = config
-  }
-  const built = configAtBuildRef.current
+  const { config, configAtBuild: built, setConfig, workerAvailable, connectionMode } = prepare
   const requireRestart =
     built &&
     (config.hostname !== built.hostname ||