fix(settings): проверять доступность текущего источника без гонок

lib/data-source.tsx

@@ -1,6 +1,6 @@
 "use client"
 
-import { createContext, useContext, useEffect, useState, useCallback } from "react"
+import { createContext, useContext, useEffect, useState, useCallback, useMemo, useRef } from "react"
 import {
   configuredBackendUrl,
   defaultDataSourceMode,
@@ -9,7 +9,7 @@ import {
   LOCAL_DEFAULT_BACKEND_URL,
   resolveStoredBackendUrl,
 } from "@/lib/backend-url"
-import { resolveApiUrl } from "@/shared/api/http-client"
+import { getBackendHealth } from "@/shared/api/backend-health"
 
 // ── types ─────────────────────────────────────────────────────────────────────
 
@@ -31,6 +31,7 @@ interface DataSourceContextValue {
   prefsHydrated: boolean
   /** undefined = не проверялось, true = OK, false = недоступен */
   backendStatus: boolean | undefined
+  backendChecking: boolean
   checkBackend:  () => Promise<void>
 }
 
@@ -68,16 +69,30 @@ export function DataSourceProvider({ children }: { children: React.ReactNode })
   const [mode, setModeState] = useState<DataSourceMode>(defaultDataSourceMode)
   const [backendUrl, setBackendUrlState] = useState(initialBackendUrl)
   const [prefsHydrated, setPrefsHydrated] = useState(false)
-  const [backendStatus, setBackendStatus] = useState<boolean | undefined>(undefined)
+  const healthToken = useMemo(() => Symbol(backendUrl), [backendUrl])
+  const [health, setHealth] = useState<{ token: symbol; value: boolean | undefined; checking: boolean }>(() => ({ token: healthToken, value: undefined, checking: false }))
+  const backendStatus = health.token === healthToken ? health.value : undefined
+  const backendChecking = health.token === healthToken && health.checking
+  const healthSession = useRef<{token:symbol;active:boolean;revision:number;controller?:AbortController}>({token:healthToken,active:true,revision:0})
+  useEffect(() => {
+    const scope = {token:healthToken,active:true,revision:0,controller:undefined as AbortController | undefined}
+    healthSession.current = scope
+    return () => { scope.active = false; scope.controller?.abort() }
+  }, [healthToken])
   const backendUrlLocked = isBackendUrlLocked()
   const mockModeAvailable = isMockDataSourceAvailable()
 
   useEffect(() => {
-    const storedMode = readStoredMode()
-    const url = resolveStoredBackendUrl(localStorage.getItem(LS_BACKEND))
-    setModeState(storedMode)
-    setBackendUrlState(url)
-    setPrefsHydrated(true)
+    let active = true
+    queueMicrotask(() => {
+      if (!active) return
+      const storedMode = readStoredMode()
+      const url = resolveStoredBackendUrl(localStorage.getItem(LS_BACKEND))
+      setModeState(storedMode)
+      setBackendUrlState(url)
+      setPrefsHydrated(true)
+    })
+    return () => { active = false }
   }, [])
 
   const setMode = useCallback((m: DataSourceMode) => {
@@ -94,14 +109,20 @@ export function DataSourceProvider({ children }: { children: React.ReactNode })
   }, [backendUrlLocked])
 
   const checkBackend = useCallback(async () => {
-    const healthUrl = resolveApiUrl(backendUrl, "/health")
+    const scope = healthSession.current
+    if (!scope.active || scope.token !== healthToken) return
+    const revision = ++scope.revision
+    scope.controller?.abort()
+    const controller = new AbortController(); scope.controller = controller
+    const current = () => scope.active && scope.revision === revision && !controller.signal.aborted
+    setHealth({token:healthToken,value:undefined,checking:true})
     try {
-      const res = await fetch(healthUrl, { signal: AbortSignal.timeout(3000) })
-      setBackendStatus(res.ok)
+      await getBackendHealth(backendUrl, controller.signal)
+      if (current()) setHealth({token:healthToken,value:true,checking:false})
     } catch {
-      setBackendStatus(false)
+      if (current()) setHealth({token:healthToken,value:false,checking:false})
     }
-  }, [backendUrl])
+  }, [backendUrl, healthToken])
 
   useEffect(() => {
     if (!prefsHydrated || mode !== "live") return
@@ -110,7 +131,7 @@ export function DataSourceProvider({ children }: { children: React.ReactNode })
 
   return (
     <DataSourceContext.Provider
-      value={{ mode, setMode, backendUrl, setBackendUrl, backendUrlLocked, mockModeAvailable, prefsHydrated, backendStatus, checkBackend }}
+      value={{ mode, setMode, backendUrl, setBackendUrl, backendUrlLocked, mockModeAvailable, prefsHydrated, backendStatus, backendChecking, checkBackend }}
     >
       {children}
     </DataSourceContext.Provider>