diff --git a/src/cliproxy/account-manager.ts b/src/cliproxy/account-manager.ts
index a65947c9..fc42bc12 100644
--- a/src/cliproxy/account-manager.ts
+++ b/src/cliproxy/account-manager.ts
@@ -14,6 +14,9 @@ import { CLIProxyProvider } from './types';
 import { getCliproxyDir, getAuthDir } from './config-generator';
 import { PROVIDER_TYPE_VALUES } from './auth/auth-types';
 
+/** Account tier for quota management */
+export type AccountTier = 'free' | 'pro' | 'ultra' | 'unknown';
+
 /** Account information */
 export interface AccountInfo {
   /** Account identifier (email or custom name) */
@@ -32,6 +35,12 @@ export interface AccountInfo {
   createdAt: string;
   /** Last usage time */
   lastUsedAt?: string;
+  /** User-paused state (skip in quota rotation) */
+  paused?: boolean;
+  /** ISO timestamp when paused */
+  pausedAt?: string;
+  /** Account tier: free, pro, ultra */
+  tier?: AccountTier;
 }
 
 /** Provider accounts configuration */
@@ -330,6 +339,76 @@ export function setDefaultAccount(provider: CLIProxyProvider, accountId: string)
   return true;
 }
 
+/**
+ * Pause an account (skip in quota rotation)
+ */
+export function pauseAccount(provider: CLIProxyProvider, accountId: string): boolean {
+  const registry = loadAccountsRegistry();
+  const providerAccounts = registry.providers[provider];
+
+  if (!providerAccounts?.accounts[accountId]) {
+    return false;
+  }
+
+  providerAccounts.accounts[accountId].paused = true;
+  providerAccounts.accounts[accountId].pausedAt = new Date().toISOString();
+  saveAccountsRegistry(registry);
+  return true;
+}
+
+/**
+ * Resume a paused account
+ */
+export function resumeAccount(provider: CLIProxyProvider, accountId: string): boolean {
+  const registry = loadAccountsRegistry();
+  const providerAccounts = registry.providers[provider];
+
+  if (!providerAccounts?.accounts[accountId]) {
+    return false;
+  }
+
+  providerAccounts.accounts[accountId].paused = false;
+  providerAccounts.accounts[accountId].pausedAt = undefined;
+  saveAccountsRegistry(registry);
+  return true;
+}
+
+/**
+ * Check if an account is paused
+ */
+export function isAccountPaused(provider: CLIProxyProvider, accountId: string): boolean {
+  const accounts = getProviderAccounts(provider);
+  const account = accounts.find((a) => a.id === accountId);
+  return account?.paused ?? false;
+}
+
+/**
+ * Update account tier
+ */
+export function setAccountTier(
+  provider: CLIProxyProvider,
+  accountId: string,
+  tier: AccountTier
+): boolean {
+  const registry = loadAccountsRegistry();
+  const providerAccounts = registry.providers[provider];
+
+  if (!providerAccounts?.accounts[accountId]) {
+    return false;
+  }
+
+  providerAccounts.accounts[accountId].tier = tier;
+  saveAccountsRegistry(registry);
+  return true;
+}
+
+/**
+ * Get non-paused accounts for a provider
+ */
+export function getActiveAccounts(provider: CLIProxyProvider): AccountInfo[] {
+  return getProviderAccounts(provider).filter((a) => !a.paused);
+}
+
 /**
  * Remove an account
  */
diff --git a/src/cliproxy/quota-fetcher.ts b/src/cliproxy/quota-fetcher.ts
index d2daa236..6748601d 100644
--- a/src/cliproxy/quota-fetcher.ts
+++ b/src/cliproxy/quota-fetcher.ts
@@ -9,7 +9,12 @@ import * as fs from 'node:fs';
 import * as path from 'node:path';
 import { getAuthDir } from './config-generator';
 import { CLIProxyProvider } from './types';
-import { getProviderAccounts, type AccountInfo } from './account-manager';
+import {
+  getProviderAccounts,
+  setAccountTier,
+  type AccountInfo,
+  type AccountTier,
+} from './account-manager';
 
 /** Individual model quota info */
 export interface ModelQuota {
@@ -45,6 +50,8 @@ export interface QuotaResult {
   accountId?: string;
   /** GCP project ID for this account */
   projectId?: string;
+  /** Detected account tier based on model access */
+  tier?: AccountTier;
 }
 
 /** Google Cloud Code API endpoints */
@@ -104,6 +111,38 @@ interface TokenRefreshResponse {
   error_description?: string;
 }
 
+/**
+ * Detect account tier from quota API model list.
+ * Ultra accounts have access to experimental/preview models.
+ * Pro accounts have standard model access.
+ * Free/unknown accounts have limited model access.
+ */
+export function detectTier(quotaResult: QuotaResult): AccountTier {
+  if (!quotaResult.success || quotaResult.models.length === 0) {
+    return 'unknown';
+  }
+
+  const modelNames = quotaResult.models.map((m) => m.name.toLowerCase());
+
+  // Ultra indicators: experimental, preview, ultra in name
+  const ultraIndicators = ['ultra', 'experimental', 'preview', '2.5-pro', '3-ultra'];
+  const hasUltra = modelNames.some((name) =>
+    ultraIndicators.some((indicator) => name.includes(indicator))
+  );
+
+  if (hasUltra) return 'ultra';
+
+  // Pro indicators: gemini-2.0, gemini-3, pro models
+  const proIndicators = ['gemini-2', 'gemini-3', '-pro'];
+  const hasPro = modelNames.some((name) =>
+    proIndicators.some((indicator) => name.includes(indicator))
+  );
+
+  if (hasPro) return 'pro';
+
+  return 'free';
+}
+
 /** loadCodeAssist response */
 interface LoadCodeAssistResponse {
   cloudaicompanionProject?: string | { id?: string };
@@ -522,10 +561,26 @@ export async function fetchAccountQuota(
   if (!result.success && result.error?.includes('expired') && authData.refreshToken) {
     const refreshResult = await refreshAccessToken(authData.refreshToken);
     if (refreshResult.accessToken) {
-      return fetchAvailableModels(refreshResult.accessToken, projectId);
+      const retryResult = await fetchAvailableModels(refreshResult.accessToken, projectId);
+      // Detect and persist tier for retry result
+      if (retryResult.success) {
+        const tier = detectTier(retryResult);
+        retryResult.tier = tier;
+        retryResult.accountId = accountId;
+        setAccountTier(provider, accountId, tier);
+      }
+      return retryResult;
     }
   }
 
+  // Detect and persist tier for successful result
+  if (result.success) {
+    const tier = detectTier(result);
+    result.tier = tier;
+    result.accountId = accountId;
+    setAccountTier(provider, accountId, tier);
+  }
+
   return result;
 }
 
diff --git a/src/cliproxy/quota-manager.ts b/src/cliproxy/quota-manager.ts
new file mode 100644
index 00000000..69a60005
--- /dev/null
+++ b/src/cliproxy/quota-manager.ts
@@ -0,0 +1,379 @@
+/**
+ * Quota Manager for Hybrid Auto+Manual Account Selection
+ *
+ * Provides pre-flight quota checking with caching, tier-based failover,
+ * and cooldown tracking for exhausted accounts.
+ *
+ * Key features:
+ * - 30-second in-memory cache for quota results
+ * - Tier-priority failover (ultra > pro by default)
+ * - Cooldown tracking for exhausted accounts
+ * - Respects paused accounts from manual config
+ * - Graceful degradation on API failures
+ */
+
+import { CLIProxyProvider } from './types';
+import { QuotaResult, fetchAccountQuota } from './quota-fetcher';
+import {
+  getDefaultAccount,
+  getProviderAccounts,
+  isAccountPaused,
+  setDefaultAccount,
+  touchAccount,
+  type AccountInfo,
+} from './account-manager';
+import { loadOrCreateUnifiedConfig } from '../config/unified-config-loader';
+
+// ============================================================================
+// QUOTA CACHE (30-second TTL)
+// ============================================================================
+
+interface CacheEntry {
+  result: QuotaResult;
+  timestamp: number;
+}
+
+const CACHE_TTL_MS = 30_000; // 30 seconds
+const quotaCache = new Map<string, CacheEntry>();
+
+function getCacheKey(provider: CLIProxyProvider, accountId: string): string {
+  return `${provider}:${accountId}`;
+}
+
+/**
+ * Get cached quota result if still valid
+ */
+export function getCachedQuota(provider: CLIProxyProvider, accountId: string): QuotaResult | null {
+  const key = getCacheKey(provider, accountId);
+  const entry = quotaCache.get(key);
+
+  if (!entry) return null;
+
+  if (Date.now() - entry.timestamp > CACHE_TTL_MS) {
+    quotaCache.delete(key);
+    return null;
+  }
+
+  return entry.result;
+}
+
+/**
+ * Cache quota result
+ */
+export function setCachedQuota(
+  provider: CLIProxyProvider,
+  accountId: string,
+  result: QuotaResult
+): void {
+  const key = getCacheKey(provider, accountId);
+  quotaCache.set(key, { result, timestamp: Date.now() });
+}
+
+/**
+ * Clear all cached quota results
+ */
+export function clearQuotaCache(): void {
+  quotaCache.clear();
+}
+
+// ============================================================================
+// COOLDOWN TRACKING
+// ============================================================================
+
+interface CooldownEntry {
+  until: number; // timestamp when cooldown expires
+}
+
+const cooldownMap = new Map<string, CooldownEntry>();
+
+/**
+ * Check if account is on cooldown
+ */
+export function isOnCooldown(provider: CLIProxyProvider, accountId: string): boolean {
+  const key = getCacheKey(provider, accountId);
+  const entry = cooldownMap.get(key);
+
+  if (!entry) return false;
+
+  if (Date.now() > entry.until) {
+    cooldownMap.delete(key);
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Apply cooldown to an exhausted account
+ */
+export function applyCooldown(
+  provider: CLIProxyProvider,
+  accountId: string,
+  minutes: number
+): void {
+  const key = getCacheKey(provider, accountId);
+  cooldownMap.set(key, { until: Date.now() + minutes * 60 * 1000 });
+}
+
+/**
+ * Clear cooldown for an account
+ */
+export function clearCooldown(provider: CLIProxyProvider, accountId: string): void {
+  const key = getCacheKey(provider, accountId);
+  cooldownMap.delete(key);
+}
+
+// ============================================================================
+// PRE-FLIGHT CHECK
+// ============================================================================
+
+/**
+ * Result of pre-flight quota check
+ */
+export interface PreflightResult {
+  /** Whether to proceed with session */
+  proceed: boolean;
+  /** Account to use (may differ from original default) */
+  accountId: string;
+  /** If switched, the original account ID */
+  switchedFrom?: string;
+  /** Reason for switch or failure */
+  reason?: string;
+  /** Average quota percentage of selected account */
+  quotaPercent?: number;
+}
+
+/**
+ * Calculate average quota percentage from models
+ */
+function calculateAverageQuota(quota: QuotaResult): number {
+  if (!quota.success || quota.models.length === 0) {
+    return 100; // Assume OK if no data
+  }
+  const total = quota.models.reduce((sum, m) => sum + m.percentage, 0);
+  return total / quota.models.length;
+}
+
+/**
+ * Find healthy account with remaining quota
+ * Respects tier priority and skips paused/cooldown accounts
+ */
+export async function findHealthyAccount(
+  provider: CLIProxyProvider,
+  exclude: string[]
+): Promise<{ id: string; tier: string; lastQuota: number } | null> {
+  const config = loadOrCreateUnifiedConfig();
+  const tierPriority = config.quota_management?.auto?.tier_priority ?? ['ultra', 'pro'];
+  const threshold = config.quota_management?.auto?.exhaustion_threshold ?? 5;
+
+  const accounts = getProviderAccounts(provider);
+
+  // Filter available accounts
+  const available = accounts.filter(
+    (a) =>
+      !exclude.includes(a.id) && !isAccountPaused(provider, a.id) && !isOnCooldown(provider, a.id)
+  );
+
+  if (available.length === 0) return null;
+
+  // Fetch quota for each available account (with caching)
+  const withQuotas = await Promise.all(
+    available.map(async (account) => {
+      let quota = getCachedQuota(provider, account.id);
+      if (!quota) {
+        try {
+          quota = await fetchAccountQuota(provider, account.id);
+          setCachedQuota(provider, account.id, quota);
+        } catch {
+          quota = { success: false, models: [], lastUpdated: Date.now() };
+        }
+      }
+
+      const avgQuota = calculateAverageQuota(quota);
+
+      return {
+        id: account.id,
+        tier: account.tier || 'pro',
+        lastQuota: avgQuota,
+      };
+    })
+  );
+
+  // Filter by threshold
+  const healthy = withQuotas.filter((a) => a.lastQuota >= threshold);
+  if (healthy.length === 0) return null;
+
+  // Sort by tier priority then quota descending
+  healthy.sort((a, b) => {
+    const tierA = tierPriority.indexOf(a.tier);
+    const tierB = tierPriority.indexOf(b.tier);
+    const tierOrderA = tierA === -1 ? 999 : tierA;
+    const tierOrderB = tierB === -1 ? 999 : tierB;
+
+    if (tierOrderA !== tierOrderB) return tierOrderA - tierOrderB;
+    return b.lastQuota - a.lastQuota;
+  });
+
+  return healthy[0];
+}
+
+/**
+ * Find and switch to a healthy account
+ */
+async function findAndSwitch(
+  provider: CLIProxyProvider,
+  excludeAccountId: string,
+  reason: string
+): Promise<PreflightResult> {
+  const alternative = await findHealthyAccount(provider, [excludeAccountId]);
+
+  if (!alternative) {
+    // No alternatives: use original anyway (graceful degradation)
+    return {
+      proceed: true,
+      accountId: excludeAccountId,
+      reason: `${reason}, no alternatives available`,
+    };
+  }
+
+  // Switch default
+  setDefaultAccount(provider, alternative.id);
+  touchAccount(provider, alternative.id);
+
+  return {
+    proceed: true,
+    accountId: alternative.id,
+    switchedFrom: excludeAccountId,
+    reason,
+    quotaPercent: alternative.lastQuota,
+  };
+}
+
+/**
+ * Perform pre-flight quota check before session start
+ *
+ * Checks if default account has sufficient quota, auto-switches if needed.
+ * Respects paused accounts, tier priority, and cooldown settings.
+ *
+ * @param provider - CLIProxy provider (only 'agy' supports quota)
+ * @returns PreflightResult with account to use and any switch info
+ */
+export async function preflightCheck(provider: CLIProxyProvider): Promise<PreflightResult> {
+  // Only Antigravity supports quota checking
+  if (provider !== 'agy') {
+    const defaultAccount = getDefaultAccount(provider);
+    return { proceed: true, accountId: defaultAccount?.id || '' };
+  }
+
+  const config = loadOrCreateUnifiedConfig();
+  const quotaConfig = config.quota_management;
+
+  // Skip if preflight disabled or mode is manual
+  if (!quotaConfig?.auto?.preflight_check || quotaConfig?.mode === 'manual') {
+    const defaultAccount = getDefaultAccount(provider);
+    return { proceed: true, accountId: defaultAccount?.id || '' };
+  }
+
+  const defaultAccount = getDefaultAccount(provider);
+  if (!defaultAccount) {
+    return { proceed: false, accountId: '', reason: 'No accounts configured' };
+  }
+
+  // Check forced_default override (manual mode)
+  const forcedDefault = quotaConfig.manual?.forced_default;
+  if (forcedDefault) {
+    const forcedAccount = getProviderAccounts(provider).find((a) => a.id === forcedDefault);
+    if (forcedAccount) {
+      return { proceed: true, accountId: forcedAccount.id, reason: 'Forced default override' };
+    }
+  }
+
+  // Check if default is paused
+  if (isAccountPaused(provider, defaultAccount.id)) {
+    return await findAndSwitch(provider, defaultAccount.id, 'Default account is paused');
+  }
+
+  // Check cooldown
+  if (isOnCooldown(provider, defaultAccount.id)) {
+    return await findAndSwitch(provider, defaultAccount.id, 'Default account on cooldown');
+  }
+
+  // Check quota (with cache)
+  let quota = getCachedQuota(provider, defaultAccount.id);
+  if (!quota) {
+    try {
+      quota = await fetchAccountQuota(provider, defaultAccount.id);
+      setCachedQuota(provider, defaultAccount.id, quota);
+    } catch {
+      // API failure: proceed anyway (graceful degradation)
+      return {
+        proceed: true,
+        accountId: defaultAccount.id,
+        reason: 'Quota check failed, proceeding',
+      };
+    }
+  }
+
+  // Calculate average quota
+  const avgQuota = calculateAverageQuota(quota);
+  const threshold = quotaConfig.auto?.exhaustion_threshold ?? 5;
+
+  if (avgQuota < threshold) {
+    // Apply cooldown to exhausted account
+    applyCooldown(provider, defaultAccount.id, quotaConfig.auto?.cooldown_minutes ?? 5);
+    return await findAndSwitch(
+      provider,
+      defaultAccount.id,
+      `Quota exhausted (${avgQuota.toFixed(1)}%)`
+    );
+  }
+
+  return {
+    proceed: true,
+    accountId: defaultAccount.id,
+    quotaPercent: avgQuota,
+  };
+}
+
+/**
+ * Get quota status for all accounts of a provider
+ * Used by CLI status command
+ */
+export async function getQuotaStatus(provider: CLIProxyProvider): Promise<{
+  accounts: Array<{
+    account: AccountInfo;
+    quota: number;
+    paused: boolean;
+    onCooldown: boolean;
+    isDefault: boolean;
+  }>;
+}> {
+  const accounts = getProviderAccounts(provider);
+  const defaultAccount = getDefaultAccount(provider);
+
+  const results = await Promise.all(
+    accounts.map(async (account) => {
+      let quota = getCachedQuota(provider, account.id);
+      if (!quota && provider === 'agy') {
+        try {
+          quota = await fetchAccountQuota(provider, account.id);
+          setCachedQuota(provider, account.id, quota);
+        } catch {
+          quota = { success: false, models: [], lastUpdated: Date.now() };
+        }
+      }
+
+      const avgQuota = quota ? calculateAverageQuota(quota) : 100;
+
+      return {
+        account,
+        quota: avgQuota,
+        paused: isAccountPaused(provider, account.id),
+        onCooldown: isOnCooldown(provider, account.id),
+        isDefault: defaultAccount?.id === account.id,
+      };
+    })
+  );
+
+  return { accounts: results };
+}
diff --git a/src/config/unified-config-types.ts b/src/config/unified-config-types.ts
index 6a20a4d4..ac17e17d 100644
--- a/src/config/unified-config-types.ts
+++ b/src/config/unified-config-types.ts
@@ -16,8 +16,9 @@
  * Version 4 = Copilot API integration (GitHub Copilot proxy)
  * Version 5 = Remote proxy configuration (connect to remote CLIProxyAPI)
  * Version 6 = Customizable auth tokens (API key and management secret)
+ * Version 7 = Quota management for hybrid auto+manual account control
  */
-export const UNIFIED_CONFIG_VERSION = 6;
+export const UNIFIED_CONFIG_VERSION = 7;
 
 /**
  * Account configuration (formerly in profiles.json).
@@ -342,12 +343,93 @@ export interface WebSearchConfig {
   customMcp?: unknown[];
 }
 
+// ============================================================================
+// QUOTA MANAGEMENT CONFIGURATION (v7+)
+// ============================================================================
+
+/**
+ * Auto quota management configuration.
+ * Controls automatic failover behavior.
+ */
+export interface AutoQuotaConfig {
+  /** Enable pre-flight quota check before requests (default: true) */
+  preflight_check: boolean;
+  /** Quota percentage below which account is "exhausted" (default: 5) */
+  exhaustion_threshold: number;
+  /** Tier priority for failover, highest to lowest (default: ['ultra', 'pro']) */
+  tier_priority: string[];
+  /** Minutes to skip exhausted account before retry (default: 5) */
+  cooldown_minutes: number;
+}
+
+/**
+ * Manual quota management configuration.
+ * User-controlled overrides for account selection.
+ */
+export interface ManualQuotaConfig {
+  /** User-paused accounts (stored in accounts.json) */
+  paused_accounts: string[];
+  /** Force use of specific account (overrides auto-selection) */
+  forced_default: string | null;
+  /** Lock to specific tier only */
+  tier_lock: string | null;
+}
+
+/**
+ * Quota management mode.
+ * - auto: Fully automatic failover based on quota
+ * - manual: User controls everything, no auto-switching
+ * - hybrid: Auto-failover with user overrides (default)
+ */
+export type QuotaManagementMode = 'auto' | 'manual' | 'hybrid';
+
+/**
+ * Quota management configuration section.
+ * Controls hybrid auto+manual account selection for multi-account setups.
+ */
+export interface QuotaManagementConfig {
+  /** Management mode (default: hybrid) */
+  mode: QuotaManagementMode;
+  /** Auto mode settings */
+  auto: AutoQuotaConfig;
+  /** Manual mode settings */
+  manual: ManualQuotaConfig;
+}
+
+/**
+ * Default auto quota configuration.
+ */
+export const DEFAULT_AUTO_QUOTA_CONFIG: AutoQuotaConfig = {
+  preflight_check: true,
+  exhaustion_threshold: 5,
+  tier_priority: ['ultra', 'pro'],
+  cooldown_minutes: 5,
+};
+
+/**
+ * Default manual quota configuration.
+ */
+export const DEFAULT_MANUAL_QUOTA_CONFIG: ManualQuotaConfig = {
+  paused_accounts: [],
+  forced_default: null,
+  tier_lock: null,
+};
+
+/**
+ * Default quota management configuration.
+ */
+export const DEFAULT_QUOTA_MANAGEMENT_CONFIG: QuotaManagementConfig = {
+  mode: 'hybrid',
+  auto: { ...DEFAULT_AUTO_QUOTA_CONFIG },
+  manual: { ...DEFAULT_MANUAL_QUOTA_CONFIG },
+};
+
 /**
  * Main unified configuration structure.
  * Stored in ~/.ccs/config.yaml
  */
 export interface UnifiedConfig {
-  /** Config version (5 for remote proxy support) */
+  /** Config version (7 for quota management) */
   version: number;
   /** Default profile name to use when none specified */
   default?: string;
@@ -367,6 +449,8 @@ export interface UnifiedConfig {
   copilot?: CopilotConfig;
   /** CLIProxy server configuration for remote/local mode */
   cliproxy_server?: CliproxyServerConfig;
+  /** Quota management configuration (v7+) */
+  quota_management?: QuotaManagementConfig;
 }
 
 /**
@@ -455,6 +539,7 @@ export function createEmptyUnifiedConfig(): UnifiedConfig {
     },
     copilot: { ...DEFAULT_COPILOT_CONFIG },
     cliproxy_server: { ...DEFAULT_CLIPROXY_SERVER_CONFIG },
+    quota_management: { ...DEFAULT_QUOTA_MANAGEMENT_CONFIG },
   };
 }