fix(web): warn before creating missing session directories (#317)

web/src/hooks/useMachinePathsExists.ts

@@ -0,0 +1,58 @@
+import { useCallback, useEffect, useState } from 'react'
+import type { ApiClient } from '@/api/client'
+
+export function useMachinePathsExists(
+    api: ApiClient,
+    machineId: string | null,
+    paths: string[]
+): {
+    pathExistence: Record<string, boolean>
+    checkPathsExists: (pathsToCheck: string[]) => Promise<Record<string, boolean>>
+} {
+    const [pathExistence, setPathExistence] = useState<Record<string, boolean>>({})
+
+    useEffect(() => {
+        setPathExistence({})
+    }, [machineId])
+
+    useEffect(() => {
+        let cancelled = false
+
+        if (!machineId || paths.length === 0) {
+            setPathExistence({})
+            return () => {
+                cancelled = true
+            }
+        }
+
+        void api.checkMachinePathsExists(machineId, paths)
+            .then((result) => {
+                if (cancelled) return
+                setPathExistence(result.exists ?? {})
+            })
+            .catch(() => {
+                if (cancelled) return
+                setPathExistence({})
+            })
+
+        return () => {
+            cancelled = true
+        }
+    }, [api, machineId, paths])
+
+    const checkPathsExists = useCallback(async (pathsToCheck: string[]) => {
+        if (!machineId || pathsToCheck.length === 0) {
+            return {}
+        }
+
+        const result = await api.checkMachinePathsExists(machineId, pathsToCheck)
+        const exists = result.exists ?? {}
+        setPathExistence((current) => ({ ...current, ...exists }))
+        return exists
+    }, [api, machineId])
+
+    return {
+        pathExistence,
+        checkPathsExists,
+    }
+}