feat: default task Browser iframe to Tailscale IP when available

Detect the host's Tailscale IPv4 on demand via `tailscale status --json`
and use it as the default URL for the per-task Browser tab iframe
(`http://<ip>:3000`), falling back to `http://localhost:3000` when
Tailscale isn't running. Surfaced through the existing config endpoint
as a read-only computed key (`tailscale_ip`), like `home_dir` — no new
persisted setting, no fnox plumbing, and no dependency on the user
having run `fulcrum expose`. The dev server is reachable from any
tailnet client out of the box, even when MagicDNS isn't configured.

chore: bump version to 5.8.0

Author: knowsuchagency

.claude-plugin/marketplace.json

@@ -8,7 +8,7 @@
       "name": "fulcrum",
       "source": "./plugins/fulcrum",
       "description": "Task orchestration for Claude Code",
-      "version": "5.7.1"
+      "version": "5.8.0"
     }
   ]
 }

cli/src/mcp/index.ts

@@ -12,7 +12,7 @@ export async function runMcpServer(urlOverride?: string, portOverride?: string)
 
   const server = new McpServer({
     name: 'fulcrum',
-    version: '5.7.1',
+    version: '5.8.0',
   })
 
   registerTools(server, client)

desktop/neutralino.config.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://raw.githubusercontent.com/neutralinojs/neutralinojs/main/schemas/neutralino.config.schema.json",
   "applicationId": "io.fulcrum.desktop",
-  "version": "5.7.1",
+  "version": "5.8.0",
   "defaultMode": "window",
   "port": 0,
   "documentRoot": "/resources/",
@@ -26,7 +26,7 @@
   ],
   "globalVariables": {
     "APP_NAME": "Fulcrum",
-    "APP_VERSION": "5.7.1"
+    "APP_VERSION": "5.8.0"
   },
   "modes": {
     "window": {

frontend/hooks/use-config.ts

@@ -36,8 +36,6 @@ export function usePort() {
 }
 
 // Tailscale hostname for this Fulcrum host. Populated by `fulcrum expose`.
-// When non-null and the UI is served from a non-localhost host, the task
-// browser preview rewrites `localhost:<port>` URLs to this hostname.
 export function useTailscaleHostname() {
   const query = useConfig(CONFIG_KEYS.TAILSCALE_HOSTNAME)
 
@@ -48,6 +46,19 @@ export function useTailscaleHostname() {
   }
 }
 
+// Tailscale IPv4 address for this Fulcrum host. Populated by `fulcrum expose`.
+// Preferred over the hostname for browser preview defaults since IPs always
+// resolve from any tailnet client.
+export function useTailscaleIp() {
+  const query = useConfig(CONFIG_KEYS.TAILSCALE_IP)
+
+  return {
+    ...query,
+    data: (query.data?.value as string | null) ?? null,
+    isDefault: query.data?.isDefault ?? true,
+  }
+}
+
 // Public domain serving this Fulcrum instance through Cloudflare Tunnel.
 export function usePublicDomain() {
   const query = useConfig(CONFIG_KEYS.PUBLIC_DOMAIN)

frontend/hooks/use-task-view-state.ts

@@ -1,6 +1,7 @@
 import { useQueryClient, useMutation } from '@tanstack/react-query'
 import { useCallback, useEffect, useMemo, useRef } from 'react'
 import { useTask } from './use-tasks'
+import { useTailscaleIp } from './use-config'
 import type { Task, ViewState, DiffOptions, FilesViewState } from '@/types'
 
 interface PendingUpdates {
@@ -10,11 +11,11 @@ interface PendingUpdates {
   filesViewState?: Partial<FilesViewState>
 }
 
-const getDefaultBrowserUrl = () => 'http://localhost:3000'
+const LOCALHOST_BROWSER_URL = 'http://localhost:3000'
 
 const DEFAULT_VIEW_STATE: ViewState = {
   activeTab: 'diff',
-  browserUrl: getDefaultBrowserUrl(),
+  browserUrl: LOCALHOST_BROWSER_URL,
   diffOptions: {
     wrap: true,
     ignoreWhitespace: true,
@@ -35,15 +36,22 @@ export function useTaskViewState(taskId: string) {
   const latestViewStateRef = useRef<ViewState>(DEFAULT_VIEW_STATE)
 
   const { data: task } = useTask(taskId)
+  const { data: tailscaleIp } = useTailscaleIp()
+
+  const defaultBrowserUrl = tailscaleIp
+    ? `http://${tailscaleIp}:3000`
+    : LOCALHOST_BROWSER_URL
 
   // Parse viewState from task, merge with defaults
   const viewState: ViewState = useMemo(() => {
     const stored = task?.viewState
-    if (!stored) return DEFAULT_VIEW_STATE
+    if (!stored) {
+      return { ...DEFAULT_VIEW_STATE, browserUrl: defaultBrowserUrl }
+    }
 
     return {
       activeTab: stored.activeTab ?? DEFAULT_VIEW_STATE.activeTab,
-      browserUrl: stored.browserUrl ?? DEFAULT_VIEW_STATE.browserUrl,
+      browserUrl: stored.browserUrl ?? defaultBrowserUrl,
       diffOptions: {
         ...DEFAULT_VIEW_STATE.diffOptions,
         ...stored.diffOptions,
@@ -53,7 +61,7 @@ export function useTaskViewState(taskId: string) {
         ...stored.filesViewState,
       },
     }
-  }, [task?.viewState])
+  }, [task?.viewState, defaultBrowserUrl])
 
   useEffect(() => {
     latestViewStateRef.current = viewState

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@knowsuchagency/fulcrum",
   "private": true,
-  "version": "5.7.1",
+  "version": "5.8.0",
   "description": "Harness Attention. Orchestrate Agents. Ship.",
   "license": "PolyForm-Perimeter-1.0.0",
   "type": "module",

plugins/fulcrum/.claude-plugin/marketplace.json

@@ -8,7 +8,7 @@
       "name": "fulcrum",
       "source": "./",
       "description": "Task orchestration for Claude Code",
-      "version": "5.7.1",
+      "version": "5.8.0",
       "skills": [
         "./skills/fulcrum"
       ],

plugins/fulcrum/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "fulcrum",
   "description": "Fulcrum task orchestration for Claude Code",
-  "version": "5.7.1",
+  "version": "5.8.0",
   "author": {
     "name": "Fulcrum"
   },

server/routes/config.ts

@@ -20,6 +20,7 @@ import {
 } from '../lib/settings'
 import { spawn } from 'child_process'
 import { testNotificationChannel, sendNotification, type NotificationPayload } from '../services/notification-service'
+import { detectTailscaleIp } from './server-expose'
 
 export { CONFIG_KEYS } from '../../shared/config-keys'
 import { CONFIG_KEYS } from '../../shared/config-keys'
@@ -259,6 +260,9 @@ app.get('/:key', (c) => {
   if (key === 'home_dir') {
     return c.json({ key, value: os.homedir(), isDefault: true })
   }
+  if (key === 'tailscale_ip') {
+    return c.json({ key, value: detectTailscaleIp(), isDefault: true })
+  }
 
   // Resolve key to nested path
   const path = resolveConfigKey(key)

server/routes/mcp.ts

@@ -20,7 +20,7 @@ mcpRoutes.all('/', async (c) => {
   // Create MCP server
   const server = new McpServer({
     name: 'fulcrum',
-    version: '5.7.1',
+    version: '5.8.0',
   })
 
   // Client connects back to this server