diff --git a/web/src/App.tsx b/web/src/App.tsx
index 7ab0798c2..a92a0c397 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -11,6 +11,7 @@ import { useSyncingState } from '@/hooks/useSyncingState'
 import { usePushNotifications } from '@/hooks/usePushNotifications'
 import { useViewportHeight } from '@/hooks/useViewportHeight'
 import { useVisibilityReporter } from '@/hooks/useVisibilityReporter'
+import { useAutoSpawn } from '@/hooks/useAutoSpawn'
 import { queryKeys } from '@/lib/query-keys'
 import { AppContextProvider } from '@/lib/app-context'
 import { fetchLatestMessages } from '@/lib/message-window-store'
@@ -143,12 +144,13 @@ function AppInner() {
         if (!token || !api) return
         const { pathname, search, hash, state } = router.history.location
         const searchParams = new URLSearchParams(search)
-        if (!searchParams.has('server') && !searchParams.has('hub') && !searchParams.has('token')) {
+        const authKeys = ['server', 'hub', 'token', 'spawn', 'machine', 'dir', 'boot']
+        if (!authKeys.some(k => searchParams.has(k))) {
             return
         }
-        searchParams.delete('server')
-        searchParams.delete('hub')
-        searchParams.delete('token')
+        for (const key of authKeys) {
+            searchParams.delete(key)
+        }
         const nextSearch = searchParams.toString()
         const nextHref = `${pathname}${nextSearch ? `?${nextSearch}` : ''}${hash}`
         router.history.replace(nextHref, state)
@@ -246,6 +248,9 @@ function AppInner() {
         return { all: true }
     }, [selectedSessionId])
 
+    // Auto-spawn session from URL params (?spawn=true&machine=xxx&dir=/path)
+    useAutoSpawn(api)
+
     const { subscriptionId } = useSSE({
         enabled: Boolean(api && token),
         token: token ?? '',
diff --git a/web/src/hooks/useAutoSpawn.ts b/web/src/hooks/useAutoSpawn.ts
new file mode 100644
index 000000000..6c323d411
--- /dev/null
+++ b/web/src/hooks/useAutoSpawn.ts
@@ -0,0 +1,84 @@
+import { useEffect, useRef } from 'react'
+import { useNavigate } from '@tanstack/react-router'
+import type { ApiClient } from '@/api/client'
+
+const AUTO_SPAWN_ACTIVE_POLL_INTERVAL_MS = 500
+const AUTO_SPAWN_ACTIVE_POLL_ATTEMPTS = 30
+
+// Capture spawn params at module load time, before any effect can clean the URL
+const initialSearch = typeof window !== 'undefined' ? window.location.search : ''
+const initialQuery = new URLSearchParams(initialSearch)
+const SPAWN_PARAMS = {
+    spawn: initialQuery.get('spawn') === 'true',
+    machine: initialQuery.get('machine'),
+    dir: initialQuery.get('dir'),
+    boot: initialQuery.get('boot'),
+} as const
+
+function sleep(ms: number): Promise<void> {
+    return new Promise((resolve) => {
+        setTimeout(resolve, ms)
+    })
+}
+
+async function waitForSessionActive(api: ApiClient, sessionId: string): Promise<boolean> {
+    for (let attempt = 0; attempt < AUTO_SPAWN_ACTIVE_POLL_ATTEMPTS; attempt += 1) {
+        try {
+            const { session } = await api.getSession(sessionId)
+            if (session.active) {
+                return true
+            }
+        } catch {
+        }
+
+        await sleep(AUTO_SPAWN_ACTIVE_POLL_INTERVAL_MS)
+    }
+
+    return false
+}
+
+export function useAutoSpawn(api: ApiClient | null) {
+    const navigate = useNavigate()
+    const attemptedRef = useRef(false)
+
+    useEffect(() => {
+        if (!api || attemptedRef.current) return
+        if (!SPAWN_PARAMS.spawn || !SPAWN_PARAMS.machine || !SPAWN_PARAMS.dir) return
+        const machineId = SPAWN_PARAMS.machine
+        const directory = SPAWN_PARAMS.dir
+
+        attemptedRef.current = true
+
+        api.checkMachinePathsExists(machineId, [directory]).then(async (exists) => {
+            if (exists.exists[directory] === false) {
+                console.error('Auto-spawn blocked: missing directory requires explicit confirmation')
+                return
+            }
+
+            const result = await api.spawnSession(machineId, directory)
+            if (result.type === 'success') {
+                if (SPAWN_PARAMS.boot) {
+                    try {
+                        const active = await waitForSessionActive(api, result.sessionId)
+                        if (!active) {
+                            console.error('Auto-spawn boot message skipped: session did not become active in time')
+                        } else {
+                            await api.sendMessage(result.sessionId, SPAWN_PARAMS.boot)
+                        }
+                    } catch (err) {
+                        console.error('Auto-spawn boot message failed:', err)
+                    }
+                }
+                navigate({
+                    to: '/sessions/$sessionId',
+                    params: { sessionId: result.sessionId },
+                    replace: true,
+                })
+            } else {
+                console.error('Auto-spawn failed:', result.message)
+            }
+        }).catch((err) => {
+            console.error('Auto-spawn error:', err)
+        })
+    }, [api, navigate])
+}