Create standalone browser port of LTX Athena with authenticated native API transport

frontend/hooks/use-backend.ts

@@ -0,0 +1,94 @@
+import { useState, useEffect, useCallback } from 'react'
+import { resetBackendCredentials } from '../lib/backend'
+import { logger } from '../lib/logger'
+
+export type BackendProcessStatus = 'alive' | 'restarting' | 'dead'
+
+interface BackendHealthStatusPayload {
+  status: BackendProcessStatus
+  exitCode?: number | null
+}
+
+interface UseBackendReturn {
+  processStatus: BackendProcessStatus | null
+  connected: boolean
+  isLoading: boolean
+}
+
+function toBackendHealthStatus(value: unknown): BackendHealthStatusPayload | null {
+  if (!value || typeof value !== 'object') {
+    return null
+  }
+
+  const record = value as { status?: unknown; exitCode?: unknown }
+  if (record.status !== 'alive' && record.status !== 'restarting' && record.status !== 'dead') {
+    return null
+  }
+
+  return {
+    status: record.status,
+    exitCode: typeof record.exitCode === 'number' || record.exitCode === null ? record.exitCode : undefined,
+  }
+}
+
+export function useBackend(): UseBackendReturn {
+  const [processStatus, setProcessStatus] = useState<BackendProcessStatus | null>(null)
+  const [isLoading, setIsLoading] = useState(true)
+
+  const handleBackendStatus = useCallback((payload: BackendHealthStatusPayload) => {
+    setProcessStatus(payload.status)
+
+    if (payload.status === 'alive') {
+      // Main has verified HTTP reachability before publishing 'alive' and may
+      // have spawned a fresh backend with a new port/token — drop cached creds
+      // so the next backendFetch picks up the current values.
+      resetBackendCredentials()
+      setIsLoading(false)
+      return
+    }
+
+    if (payload.status === 'restarting') {
+      return
+    }
+
+    setIsLoading(false)
+  }, [])
+
+  useEffect(() => {
+    let cancelled = false
+
+    const applyStatus = (value: unknown) => {
+      const payload = toBackendHealthStatus(value)
+      if (!payload || cancelled) {
+        return
+      }
+      handleBackendStatus(payload)
+    }
+
+    const unsubscribe = window.electronAPI.onBackendHealthStatus((data: BackendHealthStatusPayload) => {
+      applyStatus(data)
+    })
+
+    const init = async () => {
+      try {
+        const snapshot = await window.electronAPI.getBackendHealthStatus()
+        applyStatus(snapshot)
+      } catch (err) {
+        logger.error(`Failed to load backend health status snapshot: ${err}`)
+      }
+    }
+
+    void init()
+
+    return () => {
+      cancelled = true
+      unsubscribe()
+    }
+  }, [handleBackendStatus])
+
+  return {
+    processStatus,
+    connected: processStatus === 'alive',
+    isLoading,
+  }
+}