fix(cliproxy): harden xAI provider contracts

ui/src/lib/model-catalogs.ts

@@ -407,25 +407,21 @@ export const MODEL_CATALOGS: Record<string, ProviderCatalog> = {
         id: 'grok-4.3',
         name: 'Grok 4.3',
         description: 'General-purpose Grok model with a one-million-token context window',
-        extendedContext: true,
       },
       {
         id: 'grok-4.20-0309-reasoning',
         name: 'Grok 4.20 0309 Reasoning',
         description: 'Reasoning model with a two-million-token context window',
-        extendedContext: true,
       },
       {
         id: 'grok-4.20-0309-non-reasoning',
         name: 'Grok 4.20 0309 Non Reasoning',
         description: 'Non-reasoning model with a two-million-token context window',
-        extendedContext: true,
       },
       {
         id: 'grok-4.20-multi-agent-0309',
         name: 'Grok 4.20 Multi Agent 0309',
         description: 'Multi-agent model with a two-million-token context window',
-        extendedContext: true,
       },
       {
         id: 'grok-3-mini',
@@ -1124,7 +1120,8 @@ export function buildUiCatalog(
   provider: string,
   liveCatalog: ProviderCatalog | undefined
 ): ProviderCatalog | undefined {
-  const staticCatalog = MODEL_CATALOGS[provider.toLowerCase()];
+  const normalizedProvider = provider.toLowerCase();
+  const staticCatalog = MODEL_CATALOGS[normalizedProvider];
   if (!liveCatalog || liveCatalog.models.length === 0) {
     return staticCatalog;
   }
@@ -1145,7 +1142,10 @@ export function buildUiCatalog(
       issueUrl: staticModel?.issueUrl,
       deprecated: staticModel?.deprecated,
       deprecationReason: staticModel?.deprecationReason,
-      extendedContext: model.extendedContext ?? staticModel?.extendedContext,
+      extendedContext:
+        normalizedProvider === 'xai'
+          ? undefined
+          : (model.extendedContext ?? staticModel?.extendedContext),
       presetMapping: staticModel?.presetMapping,
     };
   });
@@ -1344,5 +1344,6 @@ export function supportsExtendedContext(
   modelId: string,
   catalogOverride?: ProviderCatalog
 ): boolean {
+  if (provider.toLowerCase() === 'xai') return false;
   return findCatalogModel(provider, modelId, catalogOverride)?.extendedContext === true;
 }

ui/tests/unit/ui/lib/model-catalogs-xai.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { MODEL_CATALOGS } from '@/lib/model-catalogs';
+import { buildUiCatalog, MODEL_CATALOGS, supportsExtendedContext } from '@/lib/model-catalogs';
 
 describe('xAI model catalog defaults', () => {
   it('mirrors the CLIProxyAPI text catalog and default tier routing', () => {
@@ -27,4 +27,31 @@ describe('xAI model catalog defaults', () => {
       haiku: 'grok-composer-2.5-fast',
     });
   });
+
+  it('does not expose Claude [1m] suffix support for xAI model IDs', () => {
+    const catalog = MODEL_CATALOGS.xai;
+
+    for (const model of catalog.models) {
+      expect(model.extendedContext).not.toBe(true);
+      expect(supportsExtendedContext('xai', model.id)).toBe(false);
+    }
+  });
+
+  it('strips generic extended-context metadata from live xAI catalogs', () => {
+    const catalog = buildUiCatalog('xai', {
+      provider: 'xai',
+      displayName: 'xAI (Grok)',
+      defaultModel: 'grok-4.3',
+      models: [
+        {
+          id: 'grok-4.3',
+          name: 'Grok 4.3',
+          extendedContext: true,
+        },
+      ],
+    });
+
+    expect(catalog?.models[0]?.extendedContext).toBeUndefined();
+    expect(supportsExtendedContext('xai', 'grok-4.3', catalog)).toBe(false);
+  });
 });