fix(providers): honor authIndex for OpenAI discovery and connectivity test

- useModelDiscovery: openaiCompatibility branch now forwards
  resolvedAuthIndex into modelsApi.fetchModelsViaApiCall, mirroring the
  gemini/codex/claude branches. Configs that rely on a backend-resolved
  auth index without a local plaintext key can now list models.
- useConnectivityTest: runOpenAIKey accepts an authIndex fallback when
  entry.apiKey is empty, sets Authorization: Bearer $TOKEN$ in that
  case, and forwards authIndex on the /api-call request so the gateway
  can substitute the upstream token.
- useModelDiscovery: reset stale results when baseUrl / apiKey /
  apiKeyEntries / headers / authIndex change, so reopening the discovery
  panel after editing fields re-fetches instead of showing the previous
  endpoint's models.

src/features/providers/sheets/forms/useConnectivityTest.ts

@@ -199,7 +199,8 @@ export function useConnectivityTest(
       }
       const entry = apiKeyEntries?.[idx];
       const entryKey = (entry?.apiKey ?? '').trim();
-      if (!entryKey) {
+      const resolvedAuthIndex = (authIndex ?? '').trim() || undefined;
+      if (!entryKey && !resolvedAuthIndex) {
         updateOpenaiStatus(idx, {
           state: 'error',
           message: messages.apiKeyRequired,
@@ -221,7 +222,11 @@ export function useConnectivityTest(
         ...parseHeadersText(entry?.headersText ?? ''),
       };
       if (!hasHeader(headerObj, 'authorization')) {
-        headerObj.Authorization = `Bearer ${entryKey}`;
+        if (entryKey) {
+          headerObj.Authorization = `Bearer ${entryKey}`;
+        } else if (resolvedAuthIndex) {
+          headerObj.Authorization = 'Bearer $TOKEN$';
+        }
       }
 
       updateOpenaiStatus(idx, { state: 'loading', message: '' });
@@ -229,6 +234,7 @@ export function useConnectivityTest(
       try {
         const result = await apiCallApi.request(
           {
+            authIndex: resolvedAuthIndex,
             method: 'POST',
             url: endpoint,
             header: headerObj,
@@ -267,6 +273,7 @@ export function useConnectivityTest(
     },
     [
       apiKeyEntries,
+      authIndex,
       baseUrl,
       brand,
       formHeaders,

src/features/providers/sheets/forms/useModelDiscovery.ts

@@ -1,4 +1,4 @@
-import { useCallback, useState } from 'react';
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { modelsApi } from '@/services/api';
 import { buildHeaderObject } from '@/utils/headers';
 import type { ModelInfo } from '@/utils/models';
@@ -119,7 +119,8 @@ export function useModelDiscovery(
           next = await modelsApi.fetchModelsViaApiCall(
             baseUrl,
             entryKey,
-            headers
+            headers,
+            resolvedAuthIndex
           );
         } catch (firstErr) {
           // Some OpenAI-compatible endpoints expose /models without auth, or
@@ -159,5 +160,22 @@ export function useModelDiscovery(
     setHasFetched(false);
   }, []);
 
+  const inputSignature = useMemo(() => {
+    const headerSig = formHeaders
+      .map((h) => `${h.key}:${h.value}`)
+      .join('|');
+    const entriesSig = (apiKeyEntries ?? [])
+      .map((e) => `${e.apiKey ?? ''}::${e.headersText ?? ''}`)
+      .join('|');
+    return `${baseUrl}||${apiKey ?? ''}||${fallbackApiKey ?? ''}||${authIndex ?? ''}||${headerSig}||${entriesSig}`;
+  }, [apiKey, apiKeyEntries, authIndex, baseUrl, fallbackApiKey, formHeaders]);
+
+  const lastSignatureRef = useRef(inputSignature);
+  useEffect(() => {
+    if (lastSignatureRef.current === inputSignature) return;
+    lastSignatureRef.current = inputSignature;
+    reset();
+  }, [inputSignature, reset]);
+
   return { available, loading, error, models, hasFetched, fetch, reset };
 }