fix(cliproxy): harden quota guards and review follow-ups

ui/src/components/account/flow-viz/account-card.tsx

@@ -315,7 +315,7 @@ export function AccountCard({
                   </div>
                 </TooltipTrigger>
                 <TooltipContent side="top" className="max-w-xs">
-                  {quota && <QuotaTooltipContent quota={quota} resetTime={resetTime} />}
+                  <QuotaTooltipContent quota={quota} resetTime={resetTime} />
                 </TooltipContent>
               </Tooltip>
             </TooltipProvider>

ui/src/components/cliproxy/provider-editor/account-item.tsx

@@ -424,7 +424,7 @@ export function AccountItem({
                     )}
                   </TooltipTrigger>
                   <TooltipContent side="bottom" className="max-w-xs">
-                    {quota && <QuotaTooltipContent quota={quota} resetTime={nextReset} />}
+                    <QuotaTooltipContent quota={quota} resetTime={nextReset} />
                   </TooltipContent>
                 </Tooltip>
               </TooltipProvider>

ui/src/components/shared/quota-tooltip-content.tsx

@@ -22,7 +22,7 @@ import {
 } from '@/lib/utils';
 
 interface QuotaTooltipContentProps {
-  quota: UnifiedQuotaResult;
+  quota: UnifiedQuotaResult | null | undefined;
   resetTime: string | null;
 }
 
@@ -62,7 +62,13 @@ function getClaudeWindowDisplayLabel(rateLimitType: string, fallback: string): s
  * Uses type guards for proper TypeScript narrowing
  */
 export function QuotaTooltipContent({ quota, resetTime }: QuotaTooltipContentProps) {
-  if (!quota?.success) return null;
+  if (!quota) {
+    return <p className="text-xs text-muted-foreground">Loading quota...</p>;
+  }
+
+  if (!quota.success) {
+    return <p className="text-xs text-destructive">{quota.error || 'Failed to load quota'}</p>;
+  }
 
   // Antigravity (agy) provider tooltip
   if (isAgyQuotaResult(quota)) {

ui/src/lib/utils.ts

@@ -618,45 +618,97 @@ export type UnifiedQuotaResult =
   | GeminiCliQuotaResult
   | GhcpQuotaResult;
 
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null;
+}
+
+function isFiniteNumber(value: unknown): value is number {
+  return typeof value === 'number' && Number.isFinite(value);
+}
+
 /** Type guard: Check if quota result is from Antigravity (agy) provider */
 export function isAgyQuotaResult(quota: UnifiedQuotaResult): quota is QuotaResult {
-  return 'models' in quota && Array.isArray((quota as QuotaResult).models);
+  if (!isRecord(quota)) return false;
+  const models = (quota as Partial<QuotaResult>).models;
+  return typeof quota.success === 'boolean' && Array.isArray(models);
 }
 
 /** Type guard: Check if quota result is from Codex provider */
 export function isCodexQuotaResult(quota: UnifiedQuotaResult): quota is CodexQuotaResult {
-  return (
-    'windows' in quota && 'planType' in quota && Array.isArray((quota as CodexQuotaResult).windows)
+  if (!isRecord(quota)) return false;
+
+  const candidate = quota as Partial<CodexQuotaResult>;
+  if (typeof candidate.success !== 'boolean') return false;
+  if (!Array.isArray(candidate.windows)) return false;
+  if (!('planType' in candidate)) return false;
+
+  return candidate.windows.every(
+    (window) =>
+      isRecord(window) &&
+      typeof window.label === 'string' &&
+      isFiniteNumber(window.usedPercent) &&
+      isFiniteNumber(window.remainingPercent)
   );
 }
 
 /** Type guard: Check if quota result is from Claude provider */
 export function isClaudeQuotaResult(quota: UnifiedQuotaResult): quota is ClaudeQuotaResult {
-  return (
-    'windows' in quota &&
-    !('planType' in quota) &&
-    Array.isArray((quota as ClaudeQuotaResult).windows)
+  if (!isRecord(quota)) return false;
+
+  const candidate = quota as Partial<ClaudeQuotaResult>;
+  if (typeof candidate.success !== 'boolean') return false;
+  if (!Array.isArray(candidate.windows)) return false;
+  if ('planType' in candidate) return false;
+
+  return candidate.windows.every(
+    (window) =>
+      isRecord(window) &&
+      typeof window.rateLimitType === 'string' &&
+      isFiniteNumber(window.remainingPercent) &&
+      typeof window.status === 'string'
   );
 }
 
 /** Type guard: Check if quota result is from Gemini CLI provider */
 export function isGeminiQuotaResult(quota: UnifiedQuotaResult): quota is GeminiCliQuotaResult {
-  return 'buckets' in quota && Array.isArray((quota as GeminiCliQuotaResult).buckets);
+  if (!isRecord(quota)) return false;
+
+  const candidate = quota as Partial<GeminiCliQuotaResult>;
+  if (typeof candidate.success !== 'boolean') return false;
+  if (!Array.isArray(candidate.buckets)) return false;
+
+  return candidate.buckets.every(
+    (bucket) =>
+      isRecord(bucket) &&
+      typeof bucket.id === 'string' &&
+      isFiniteNumber(bucket.remainingFraction) &&
+      isFiniteNumber(bucket.remainingPercent) &&
+      Array.isArray(bucket.modelIds)
+  );
 }
 
 /** Type guard: Check if quota result is from GitHub Copilot (ghcp) provider */
 export function isGhcpQuotaResult(quota: UnifiedQuotaResult): quota is GhcpQuotaResult {
-  const candidate = quota as GhcpQuotaResult;
-  const snapshots = candidate.snapshots as Record<string, unknown> | null | undefined;
+  if (!isRecord(quota)) return false;
 
-  return (
-    'snapshots' in quota &&
-    typeof snapshots === 'object' &&
-    snapshots !== null &&
-    'premiumInteractions' in snapshots &&
-    'chat' in snapshots &&
-    'completions' in snapshots
-  );
+  const candidate = quota as Partial<GhcpQuotaResult>;
+  const snapshots = candidate.snapshots as Record<string, unknown> | null | undefined;
+  if (typeof candidate.success !== 'boolean') return false;
+  if (!isRecord(snapshots)) return false;
+
+  const snapshotKeys: Array<keyof GhcpQuotaResult['snapshots']> = [
+    'premiumInteractions',
+    'chat',
+    'completions',
+  ];
+  return snapshotKeys.every((key) => {
+    const snapshot = snapshots[key] as Record<string, unknown> | undefined;
+    return (
+      isRecord(snapshot) &&
+      isFiniteNumber(snapshot.percentRemaining) &&
+      isFiniteNumber(snapshot.percentUsed)
+    );
+  });
 }
 
 // ==================== Unified Quota Helpers ====================

ui/tests/unit/ui/lib/quota-utils.test.ts

@@ -15,6 +15,7 @@ import {
   getProviderMinQuota,
   getProviderResetTime,
   isAgyQuotaResult,
+  isClaudeQuotaResult,
   isCodexQuotaResult,
   isGeminiQuotaResult,
   isGhcpQuotaResult,
@@ -22,6 +23,7 @@ import {
 import type {
   CodexQuotaWindow,
   CodexQuotaResult,
+  ClaudeQuotaResult,
   GeminiCliBucket,
   GeminiCliQuotaResult,
   GhcpQuotaResult,
@@ -1002,6 +1004,56 @@ describe('isCodexQuotaResult', () => {
   });
 });
 
+describe('isClaudeQuotaResult', () => {
+  it('returns true for valid Claude quota result', () => {
+    const quota: ClaudeQuotaResult = {
+      success: true,
+      windows: [
+        {
+          rateLimitType: 'five_hour',
+          label: 'Session limit',
+          status: 'allowed',
+          utilization: 0.5,
+          usedPercent: 50,
+          remainingPercent: 50,
+          resetAt: '2026-01-30T12:00:00Z',
+        },
+      ],
+      coreUsage: {
+        fiveHour: {
+          rateLimitType: 'five_hour',
+          label: 'Session limit',
+          remainingPercent: 50,
+          resetAt: '2026-01-30T12:00:00Z',
+          status: 'allowed',
+        },
+        weekly: null,
+      },
+      lastUpdated: Date.now(),
+    };
+    expect(isClaudeQuotaResult(quota)).toBe(true);
+  });
+
+  it('returns false for Codex quota result', () => {
+    const quota: CodexQuotaResult = {
+      success: true,
+      windows: [],
+      planType: 'free',
+      lastUpdated: Date.now(),
+    };
+    expect(isClaudeQuotaResult(quota as unknown as ClaudeQuotaResult)).toBe(false);
+  });
+
+  it('returns false when Claude windows are malformed', () => {
+    const malformed = {
+      success: true,
+      windows: [{ rateLimitType: 'five_hour', label: 'Session limit' }],
+      lastUpdated: Date.now(),
+    };
+    expect(isClaudeQuotaResult(malformed as unknown as ClaudeQuotaResult)).toBe(false);
+  });
+});
+
 describe('isGeminiQuotaResult', () => {
   it('returns true for valid Gemini quota result', () => {
     const quota: GeminiCliQuotaResult = {