diff --git a/backend/internal/domain/channel_monitor_quota.go b/backend/internal/domain/channel_monitor_quota.go
index 656163dddf..fed21dedb7 100644
--- a/backend/internal/domain/channel_monitor_quota.go
+++ b/backend/internal/domain/channel_monitor_quota.go
@@ -20,11 +20,17 @@ import "time"
 //   - "7d-sonnet"  Claude 7 天 Sonnet 独立额度
 //   - "7d-fable"   Claude 7 天 Fable 独立额度
 //   - "weekly"     周窗口（Kimi/Zhipu coding plan）
+//   - "daily"      日窗口（Gemini 日配额 / Grok 日请求）
 //   - "30d"        30 天窗口（Grok 月度）
-//   - "total"      无窗口语义的总量额度（Gemini/Antigravity 等）
+//   - "total"      无窗口语义的总量额度（Antigravity per-model 等）
+//
+// 同一 Window 可能出现多条（Gemini 多档日配额、Antigravity per-model、
+// Grok requests/tokens），用 Label 区分：Label 是机器 token（requests/tokens/
+// shared/pro/flash 或模型名），前端已知 token 走 i18n，未知原样展示。
 type MonitorQuotaTier struct {
 	Window      string  `json:"window"`
-	UsedPercent float64 `json:"used_percent"` // 0-100；仅有绝对值时按 used/limit 计算
+	Label       string  `json:"label,omitempty"`
+	UsedPercent float64 `json:"used_percent"` // 0-100+；仅有绝对值时按 used/limit 计算
 	Used        float64 `json:"used,omitempty"`
 	Limit       float64 `json:"limit,omitempty"`
 	ResetAt     string  `json:"reset_at,omitempty"` // RFC3339；未知时留空
@@ -44,8 +50,11 @@ type MonitorQuotaSnapshot struct {
 	Balances  []MonitorBalance   `json:"balances,omitempty"`          // 多币种余额（如 DeepSeek CNY+USD）
 	Currency  string             `json:"currency,omitempty"`          // 主余额币种
 	PlanLevel string             `json:"plan_level,omitempty"`        // 套餐等级（如智谱 level）
-	Error     string             `json:"error,omitempty"`             // Success=false 时的错误摘要
-	FetchedAt time.Time          `json:"fetched_at"`
+	// CredentialInvalid 上游 401/403 鉴权失败（区别于网络/解析错误），
+	// 检测状态据此推导 failed 而非 error。
+	CredentialInvalid bool      `json:"credential_invalid,omitempty"`
+	Error             string    `json:"error,omitempty"` // Success=false 时的错误摘要
+	FetchedAt         time.Time `json:"fetched_at"`
 }
 
 // MonitorBalance 单币种余额条目。
diff --git a/backend/internal/repository/channel_monitor_repo.go b/backend/internal/repository/channel_monitor_repo.go
index aa8b12ff8b..c4586bc38c 100644
--- a/backend/internal/repository/channel_monitor_repo.go
+++ b/backend/internal/repository/channel_monitor_repo.go
@@ -3,6 +3,7 @@ package repository
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
 	"fmt"
 	"strings"
 	"time"
@@ -10,6 +11,7 @@ import (
 	dbent "github.com/Wei-Shaw/sub2api/ent"
 	"github.com/Wei-Shaw/sub2api/ent/channelmonitor"
 	"github.com/Wei-Shaw/sub2api/ent/channelmonitorhistory"
+	"github.com/Wei-Shaw/sub2api/internal/domain"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 	"github.com/lib/pq"
 
@@ -51,10 +53,14 @@ func (r *channelMonitorRepository) Create(ctx context.Context, m *service.Channe
 		SetJitterSeconds(m.JitterSeconds).
 		SetCreatedBy(m.CreatedBy).
 		SetExtraHeaders(channelMonitorHeadersForPersistence(m)).
-		SetBodyOverrideMode(defaultBodyModeRepo(m.BodyOverrideMode))
+		SetBodyOverrideMode(defaultBodyModeRepo(m.BodyOverrideMode)).
+		SetCheckMode(defaultCheckModeRepo(m.CheckMode))
 	if m.TemplateID != nil {
 		builder = builder.SetTemplateID(*m.TemplateID)
 	}
+	if m.AccountID != nil {
+		builder = builder.SetAccountID(*m.AccountID)
+	}
 	if m.BodyOverride != nil {
 		builder = builder.SetBodyOverride(m.BodyOverride)
 	}
@@ -118,12 +124,18 @@ func (r *channelMonitorRepository) Update(ctx context.Context, m *service.Channe
 		SetIntervalSeconds(m.IntervalSeconds).
 		SetJitterSeconds(m.JitterSeconds).
 		SetExtraHeaders(channelMonitorHeadersForPersistence(m)).
-		SetBodyOverrideMode(defaultBodyModeRepo(m.BodyOverrideMode))
+		SetBodyOverrideMode(defaultBodyModeRepo(m.BodyOverrideMode)).
+		SetCheckMode(defaultCheckModeRepo(m.CheckMode))
 	if m.TemplateID != nil {
 		updater = updater.SetTemplateID(*m.TemplateID)
 	} else {
 		updater = updater.ClearTemplateID()
 	}
+	if m.AccountID != nil {
+		updater = updater.SetAccountID(*m.AccountID)
+	} else {
+		updater = updater.ClearAccountID()
+	}
 	if m.BodyOverride != nil {
 		updater = updater.SetBodyOverride(m.BodyOverride)
 	} else {
@@ -237,6 +249,9 @@ func (r *channelMonitorRepository) InsertHistoryBatch(ctx context.Context, rows
 		if row.PingLatencyMs != nil {
 			c = c.SetPingLatencyMs(*row.PingLatencyMs)
 		}
+		if row.Quota != nil {
+			c = c.SetQuota(row.Quota)
+		}
 		bulk = append(bulk, c)
 	}
 	if _, err := client.ChannelMonitorHistory.CreateBulk(bulk...).Save(ctx); err != nil {
@@ -276,6 +291,7 @@ func (r *channelMonitorRepository) ListHistory(ctx context.Context, monitorID in
 			PingLatencyMs: row.PingLatencyMs,
 			Message:       row.Message,
 			CheckedAt:     row.CheckedAt,
+			Quota:         row.Quota,
 		}
 		out = append(out, entry)
 	}
@@ -324,6 +340,20 @@ func assignNullInt(dst **int, n sql.NullInt64) {
 	*dst = &v
 }
 
+// scanMonitorQuota 把裸 SQL 读出的 JSONB quota 列解包为配额快照。
+// NULL（探活模式旧行）返回 nil；解析失败也返回 nil 并由调用方日志感知，
+// 不阻断列表渲染（与聚合层"失败仅日志"的原则一致）。
+func scanMonitorQuota(data []byte) *domain.MonitorQuotaSnapshot {
+	if len(data) == 0 {
+		return nil
+	}
+	snapshot := &domain.MonitorQuotaSnapshot{}
+	if err := json.Unmarshal(data, snapshot); err != nil {
+		return nil
+	}
+	return snapshot
+}
+
 // ComputeAvailability 计算指定窗口内每个模型的可用率与平均延迟。
 // "可用" = status IN (operational, degraded)。
 //
@@ -396,7 +426,7 @@ func (r *channelMonitorRepository) ListLatestForMonitorIDs(ctx context.Context,
 	}
 	const q = `
 		SELECT DISTINCT ON (monitor_id, model)
-		    monitor_id, model, status, latency_ms, ping_latency_ms, checked_at
+		    monitor_id, model, status, latency_ms, ping_latency_ms, checked_at, quota
 		FROM channel_monitor_histories
 		WHERE monitor_id = ANY($1)
 		ORDER BY monitor_id, model, checked_at DESC
@@ -411,11 +441,13 @@ func (r *channelMonitorRepository) ListLatestForMonitorIDs(ctx context.Context,
 		var monitorID int64
 		l := &service.ChannelMonitorLatest{}
 		var latency, ping sql.NullInt64
-		if err := rows.Scan(&monitorID, &l.Model, &l.Status, &latency, &ping, &l.CheckedAt); err != nil {
+		var quota []byte
+		if err := rows.Scan(&monitorID, &l.Model, &l.Status, &latency, &ping, &l.CheckedAt, &quota); err != nil {
 			return nil, fmt.Errorf("scan latest batch row: %w", err)
 		}
 		assignNullInt(&l.LatencyMs, latency)
 		assignNullInt(&l.PingLatencyMs, ping)
+		l.Quota = scanMonitorQuota(quota)
 		out[monitorID] = append(out[monitorID], l)
 	}
 	if err := rows.Err(); err != nil {
@@ -757,12 +789,17 @@ func entToServiceMonitor(row *dbent.ChannelMonitor) *service.ChannelMonitor {
 		ExtraHeaders:         headers,
 		BodyOverrideMode:     row.BodyOverrideMode,
 		BodyOverride:         row.BodyOverride,
+		CheckMode:            defaultCheckModeRepo(row.CheckMode),
 		DuplicateOperationID: duplicateOperationID,
 	}
 	if row.TemplateID != nil {
 		id := *row.TemplateID
 		out.TemplateID = &id
 	}
+	if row.AccountID != nil {
+		id := *row.AccountID
+		out.AccountID = &id
+	}
 	return out
 }
 
@@ -807,6 +844,14 @@ func defaultAPIModeRepo(apiMode string) string {
 	return apiMode
 }
 
+// defaultCheckModeRepo 空串归一为 probe（存量行有列默认值，这里兜底防御）。
+func defaultCheckModeRepo(checkMode string) string {
+	if checkMode == "" {
+		return "probe"
+	}
+	return checkMode
+}
+
 func emptySliceIfNil(in []string) []string {
 	if in == nil {
 		return []string{}
diff --git a/backend/internal/service/channel_monitor_aggregator.go b/backend/internal/service/channel_monitor_aggregator.go
index 09020f5fa4..b6f632bf4b 100644
--- a/backend/internal/service/channel_monitor_aggregator.go
+++ b/backend/internal/service/channel_monitor_aggregator.go
@@ -204,6 +204,8 @@ func buildStatusSummary(
 		if l, ok := latestByModel[primary]; ok {
 			summary.PrimaryStatus = l.Status
 			summary.PrimaryLatencyMs = l.LatencyMs
+			// 配额快照只挂主模型行（quota 模式唯一行 / quota_probe 的主行）。
+			summary.LatestQuota = l.Quota
 		}
 		if a, ok := availByModel[primary]; ok {
 			summary.Availability7d = a.AvailabilityPct
@@ -242,6 +244,7 @@ func buildUserViewFromSummary(
 	}
 	if primaryLatest != nil {
 		view.PrimaryPingLatencyMs = primaryLatest.PingLatencyMs
+		view.LatestQuota = primaryLatest.Quota
 	}
 	return view
 }
diff --git a/backend/internal/service/channel_monitor_checker.go b/backend/internal/service/channel_monitor_checker.go
index 910a6e80d9..bc8aa70645 100644
--- a/backend/internal/service/channel_monitor_checker.go
+++ b/backend/internal/service/channel_monitor_checker.go
@@ -170,6 +170,11 @@ type providerAdapter struct {
 var providerAdapters = map[string]providerAdapter{
 	MonitorProviderOpenAI: providerOpenAIChatAdapter,
 	MonitorProviderGrok:   providerGrokChatAdapter,
+	// 国产 3 家（配额模式引入）：均为 OpenAI 兼容 Chat Completions，
+	// 仅智谱路径前缀不同（/api/paas/v4/chat/completions）。
+	MonitorProviderKimi:     providerKimiChatAdapter,
+	MonitorProviderZhipu:    providerZhipuChatAdapter,
+	MonitorProviderDeepseek: providerDeepseekChatAdapter,
 	MonitorProviderAnthropic: {
 		buildPath: func(string) string { return providerAnthropicPath },
 		buildBody: func(model, prompt string) ([]byte, error) {
@@ -212,6 +217,15 @@ var providerOpenAIChatAdapter = newOpenAICompatibleChatAdapter(providerOpenAIPat
 //nolint:gochecknoglobals // 适配器表是只读静态数据，初始化后不变更。
 var providerGrokChatAdapter = newOpenAICompatibleChatAdapter(providerGrokPath)
 
+//nolint:gochecknoglobals // 适配器表是只读静态数据，初始化后不变更。
+var providerKimiChatAdapter = newOpenAICompatibleChatAdapter(providerOpenAIPath)
+
+//nolint:gochecknoglobals // 适配器表是只读静态数据，初始化后不变更。
+var providerZhipuChatAdapter = newOpenAICompatibleChatAdapter(providerZhipuPath)
+
+//nolint:gochecknoglobals // 适配器表是只读静态数据，初始化后不变更。
+var providerDeepseekChatAdapter = newOpenAICompatibleChatAdapter(providerOpenAIPath)
+
 func newOpenAICompatibleChatAdapter(path string) providerAdapter {
 	return providerAdapter{
 		buildPath: func(string) string { return path },
@@ -257,8 +271,8 @@ func providerAdapterFor(provider, apiMode string) (providerAdapter, string, bool
 	return adapter, MonitorAPIModeChatCompletions, ok
 }
 
-// isSupportedProvider 校验 provider 字符串是否在 adapter 表中。
-// 供 validate.go 的 validateProvider 复用，避免两份 switch 漂移。
+// isSupportedProvider 校验 provider 字符串是否在探活 adapter 表中。
+// 注意：完整的 provider 合法性（含仅配额模式的 antigravity）走 validate.go 的 monitorProviders。
 func isSupportedProvider(p string) bool {
 	_, ok := providerAdapters[p]
 	return ok
@@ -447,6 +461,10 @@ var bodyMergeKeyDenyList = map[string]map[string]bool{
 	MonitorProviderGrok:      {"model": true, "messages": true, "stream": true},
 	MonitorProviderAnthropic: {"model": true, "messages": true},
 	MonitorProviderGemini:    {"contents": true},
+	// 国产 3 家与 OpenAI Chat Completions 同构。
+	MonitorProviderKimi:     {"model": true, "messages": true, "stream": true},
+	MonitorProviderZhipu:    {"model": true, "messages": true, "stream": true},
+	MonitorProviderDeepseek: {"model": true, "messages": true, "stream": true},
 }
 
 func checkAPIMode(opts *CheckOptions) string {
@@ -463,8 +481,20 @@ func bodyMergeDenyKey(provider, apiMode string) string {
 	return provider
 }
 
+// isOpenAICompatibleChatProvider 该 provider 的探活请求是否为 OpenAI Chat
+// Completions 同构（replace 模式的 body 校验按 messages 必填处理）。
+func isOpenAICompatibleChatProvider(provider string) bool {
+	switch provider {
+	case MonitorProviderOpenAI, MonitorProviderGrok,
+		MonitorProviderKimi, MonitorProviderZhipu, MonitorProviderDeepseek:
+		return true
+	default:
+		return false
+	}
+}
+
 func validateReplaceRequestBody(provider, apiMode string, body map[string]any) error {
-	if provider != MonitorProviderOpenAI && provider != MonitorProviderGrok {
+	if !isOpenAICompatibleChatProvider(provider) {
 		return nil
 	}
 	switch defaultAPIMode(apiMode) {
diff --git a/backend/internal/service/channel_monitor_const.go b/backend/internal/service/channel_monitor_const.go
index 6a41add298..4ed6a026ea 100644
--- a/backend/internal/service/channel_monitor_const.go
+++ b/backend/internal/service/channel_monitor_const.go
@@ -45,10 +45,12 @@ const (
 	monitorChallengeMin = 1
 	monitorChallengeMax = 50
 
-	// providerOpenAIPath OpenAI Chat Completions 路径。
+	// providerOpenAIPath OpenAI Chat Completions 路径（Kimi / DeepSeek 同为 OpenAI 兼容）。
 	providerOpenAIPath = "/v1/chat/completions"
 	// providerGrokPath Grok OpenAI-compatible Chat Completions 路径。
 	providerGrokPath = "/v1/chat/completions"
+	// providerZhipuPath 智谱 OpenAI 兼容 Chat Completions 路径（前缀与官方不同）。
+	providerZhipuPath = "/api/paas/v4/chat/completions"
 	// providerOpenAIResponsesPath OpenAI Responses API 路径。
 	providerOpenAIResponsesPath = "/v1/responses"
 	// providerAnthropicPath Anthropic Messages 路径。
@@ -56,11 +58,36 @@ const (
 	// providerGeminiPathTemplate Gemini generateContent 路径模板（含 model 占位）。
 	providerGeminiPathTemplate = "/v1beta/models/%s:generateContent"
 
-	// MonitorProviderOpenAI / Anthropic / Gemini / Grok provider 字符串常量（也是 ent enum 的实际值）。
-	MonitorProviderOpenAI    = "openai"
-	MonitorProviderAnthropic = "anthropic"
-	MonitorProviderGemini    = "gemini"
-	MonitorProviderGrok      = "grok"
+	// MonitorProviderOpenAI 等 provider 字符串常量（也是 ent enum 的实际值）。
+	// 后 4 个 provider（antigravity/kimi/zhipu/deepseek）为配额模式引入：
+	// antigravity 无探活 adapter（仅配额），其余 3 个复用 OpenAI 兼容探活。
+	MonitorProviderOpenAI     = "openai"
+	MonitorProviderAnthropic  = "anthropic"
+	MonitorProviderGemini     = "gemini"
+	MonitorProviderGrok       = "grok"
+	MonitorProviderAntigravity = "antigravity"
+	MonitorProviderKimi       = "kimi"
+	MonitorProviderZhipu      = "zhipu"
+	MonitorProviderDeepseek   = "deepseek"
+
+	// MonitorCheckMode 检测模式（channel_monitors.check_mode）。
+	//   probe       - LLM 探活（默认，原有行为）
+	//   quota       - 仅查关联账号用量/余额，零 LLM 成本
+	//   quota_probe - 探活 + 配额并存（配额快照挂到主模型历史行）
+	MonitorCheckModeProbe     = "probe"
+	MonitorCheckModeQuota     = "quota"
+	MonitorCheckModeQuotaProbe = "quota_probe"
+
+	// MonitorDefaultQuotaModel 是 quota 模式监控未显式指定模型时占位的虚拟模型名
+	// （primary_model 列 NotEmpty，用 "quota" 让历史行/时间线机制无需特判）。
+	MonitorDefaultQuotaModel = "quota"
+
+	// monitorQuotaFetchCacheTTL 配额快照缓存时长。多个监控可能关联同一账号，
+	// 而 interval 最小 15s 且国产配额服务无缓存，TTL 防止打爆上游配额端点。
+	monitorQuotaFetchCacheTTL = 5 * time.Minute
+	// monitorQuotaDegradedUsedPercent 任一用量窗口使用率超过该阈值时，
+	// 配额检查状态记为 degraded（对齐账号页展示阈值）。
+	monitorQuotaDegradedUsedPercent = 90.0
 
 	// MonitorDefaultGrokModel 是新增 Grok 监控未显式指定模型时使用的轻量测活模型。
 	MonitorDefaultGrokModel = "grok-4.5"
@@ -118,7 +145,16 @@ var (
 		"CHANNEL_MONITOR_NOT_FOUND", "channel monitor not found",
 	)
 	ErrChannelMonitorInvalidProvider = infraerrors.BadRequest(
-		"CHANNEL_MONITOR_INVALID_PROVIDER", "provider must be one of openai/anthropic/gemini/grok",
+		"CHANNEL_MONITOR_INVALID_PROVIDER", "provider must be one of openai/anthropic/gemini/grok/antigravity/kimi/zhipu/deepseek",
+	)
+	ErrChannelMonitorInvalidCheckMode = infraerrors.BadRequest(
+		"CHANNEL_MONITOR_INVALID_CHECK_MODE", "check_mode must be one of probe/quota/quota_probe; antigravity only supports quota",
+	)
+	ErrChannelMonitorAccountRequired = infraerrors.BadRequest(
+		"CHANNEL_MONITOR_ACCOUNT_REQUIRED", "account_id is required for quota-based check_mode",
+	)
+	ErrChannelMonitorProviderIncompatible = infraerrors.BadRequest(
+		"CHANNEL_MONITOR_PROVIDER_INCOMPATIBLE", "monitor provider must match the linked account platform",
 	)
 	ErrChannelMonitorInvalidAPIMode = infraerrors.BadRequest(
 		"CHANNEL_MONITOR_INVALID_API_MODE", "api_mode must be chat_completions or responses; responses is only supported for openai",
diff --git a/backend/internal/service/channel_monitor_quota_fetcher.go b/backend/internal/service/channel_monitor_quota_fetcher.go
new file mode 100644
index 0000000000..83d8e0f455
--- /dev/null
+++ b/backend/internal/service/channel_monitor_quota_fetcher.go
@@ -0,0 +1,429 @@
+package service
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/domain"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/xai"
+)
+
+// 渠道监控「配额模式」的配额抓取器。
+//
+// 不直接对接上游，而是把账号侧现成的用量服务归一成 domain.MonitorQuotaSnapshot：
+//   - 海外 5 家（anthropic/openai/gemini/antigravity/grok）→ AccountUsageService.GetUsage
+//   - 国产 coding plan（kimi/zhipu/deepseek）→ CNProviderQuotaService.QueryUsage
+//   - 国产 payg（kimi/deepseek）→ CNProviderBalanceService.QueryBalance
+//     （zhipu payg 无公开余额端点，QueryBalance 会返回该错误，原样透出）
+//
+// Fetch 永不返回 error：所有失败都降级为 Success=false 的快照照常入库，
+// 由 deriveQuotaCheckResult 推导为 failed/error 状态。
+//
+// 多个监控可能关联同一账号，而 interval 最小 15s 且国产配额服务自身无缓存，
+// 所以成功快照统一带 monitorQuotaFetchCacheTTL 缓存，防止打爆上游配额端点。
+
+// monitorUsageSource 海外平台账号用量查询（AccountUsageService 天然满足）。
+type monitorUsageSource interface {
+	GetUsage(ctx context.Context, accountID int64, force ...bool) (*UsageInfo, error)
+}
+
+// monitorCNQuotaSource 国产 coding plan 滚动窗口额度探测（CNProviderQuotaService 天然满足）。
+type monitorCNQuotaSource interface {
+	QueryUsage(ctx context.Context, accountID int64) (*CNProviderQuotaProbeResult, error)
+}
+
+// monitorCNBalanceSource 国产 payg 余额探测（CNProviderBalanceService 天然满足）。
+type monitorCNBalanceSource interface {
+	QueryBalance(ctx context.Context, accountID int64) (*CNProviderBalanceResult, error)
+}
+
+// monitorAccountSource 账号加载（AccountRepository 天然满足）。
+type monitorAccountSource interface {
+	GetByID(ctx context.Context, id int64) (*Account, error)
+}
+
+// ChannelMonitorQuotaFetcher 配额抓取器（带成功快照 TTL 缓存）。
+type ChannelMonitorQuotaFetcher struct {
+	usage     monitorUsageSource
+	cnQuota   monitorCNQuotaSource
+	cnBalance monitorCNBalanceSource
+	accounts  monitorAccountSource
+
+	mu    sync.Mutex
+	cache map[int64]monitorQuotaCacheEntry
+}
+
+type monitorQuotaCacheEntry struct {
+	snapshot *domain.MonitorQuotaSnapshot
+	expiry   time.Time
+}
+
+// NewChannelMonitorQuotaFetcher 构造配额抓取器。
+func NewChannelMonitorQuotaFetcher(
+	usage monitorUsageSource,
+	cnQuota monitorCNQuotaSource,
+	cnBalance monitorCNBalanceSource,
+	accounts monitorAccountSource,
+) *ChannelMonitorQuotaFetcher {
+	return &ChannelMonitorQuotaFetcher{
+		usage:     usage,
+		cnQuota:   cnQuota,
+		cnBalance: cnBalance,
+		accounts:  accounts,
+		cache:     make(map[int64]monitorQuotaCacheEntry),
+	}
+}
+
+// LoadAccount 加载账号（不走缓存）。供 Create/Update 时校验
+// provider 与 account.platform 一致；账号不存在时返回错误。
+func (f *ChannelMonitorQuotaFetcher) LoadAccount(ctx context.Context, id int64) (*Account, error) {
+	if f == nil || f.accounts == nil {
+		return nil, fmt.Errorf("quota fetcher is not configured")
+	}
+	return f.accounts.GetByID(ctx, id)
+}
+
+// Fetch 抓取账号的最新配额快照。永不返回 error：失败降级为
+// Success=false 快照（Error 带摘要），保证检测历史的时间线连续。
+func (f *ChannelMonitorQuotaFetcher) Fetch(ctx context.Context, accountID int64) *domain.MonitorQuotaSnapshot {
+	now := time.Now()
+
+	if cached, ok := f.cachedSnapshot(accountID, now); ok {
+		return cached
+	}
+
+	snapshot := f.fetchUncached(ctx, accountID, now)
+	if snapshot.Success {
+		f.storeSnapshot(accountID, snapshot, now.Add(monitorQuotaFetchCacheTTL))
+	}
+	return snapshot
+}
+
+func (f *ChannelMonitorQuotaFetcher) cachedSnapshot(accountID int64, now time.Time) (*domain.MonitorQuotaSnapshot, bool) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	entry, ok := f.cache[accountID]
+	if !ok || now.After(entry.expiry) {
+		return nil, false
+	}
+	return entry.snapshot, true
+}
+
+func (f *ChannelMonitorQuotaFetcher) storeSnapshot(accountID int64, snapshot *domain.MonitorQuotaSnapshot, expiry time.Time) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.cache[accountID] = monitorQuotaCacheEntry{snapshot: snapshot, expiry: expiry}
+}
+
+func (f *ChannelMonitorQuotaFetcher) fetchUncached(ctx context.Context, accountID int64, now time.Time) *domain.MonitorQuotaSnapshot {
+	if f == nil {
+		return quotaErrorSnapshot("usage", "quota fetcher is not configured", now)
+	}
+
+	account, err := f.LoadAccount(ctx, accountID)
+	if err != nil || account == nil {
+		// FK ON DELETE SET NULL 后 account_id 可能为空/失效；显式报「账号未关联」，
+		// 推导为 degraded（配置问题，不是渠道故障）。
+		slog.Warn("channel_monitor: load linked account failed",
+			"account_id", accountID, "error", err)
+		return quotaErrorSnapshot("usage", "linked account not found", now)
+	}
+
+	switch account.Platform {
+	case domain.PlatformKimi, domain.PlatformZhipu, domain.PlatformDeepseek:
+		if account.IsCodingPlan() {
+			return f.fetchCNQuota(ctx, accountID, now)
+		}
+		return f.fetchCNBalance(ctx, accountID, now)
+	default:
+		return f.fetchUsage(ctx, accountID, now)
+	}
+}
+
+// fetchUsage 海外平台：AccountUsageService.GetUsage → 快照。
+func (f *ChannelMonitorQuotaFetcher) fetchUsage(ctx context.Context, accountID int64, now time.Time) *domain.MonitorQuotaSnapshot {
+	if f.usage == nil {
+		return quotaErrorSnapshot("usage", "usage service is not configured", now)
+	}
+	usage, err := f.usage.GetUsage(ctx, accountID)
+	if err != nil {
+		msg := truncateMessage(sanitizeErrorMessage(err.Error()))
+		return &domain.MonitorQuotaSnapshot{
+			Source:            "usage",
+			Success:           false,
+			CredentialInvalid: isCredentialErrorMessage(msg),
+			Error:             msg,
+			FetchedAt:         now,
+		}
+	}
+	snapshot := &domain.MonitorQuotaSnapshot{
+		Source:          "usage",
+		Success:         true,
+		PlanLevel:       usage.SubscriptionTier,
+		Tiers:           usageQuotaTiers(usage),
+		FetchedAt:       now,
+	}
+	if snapshot.PlanLevel == "" {
+		snapshot.PlanLevel = usage.SubscriptionTierRaw
+	}
+	return snapshot
+}
+
+// usageQuotaTiers 把 UsageInfo 的各平台窗口归一为 tier 列表（无数据的窗口跳过）。
+func usageQuotaTiers(usage *UsageInfo) []domain.MonitorQuotaTier {
+	if usage == nil {
+		return nil
+	}
+	tiers := make([]domain.MonitorQuotaTier, 0, 8)
+	appendProgressTier(&tiers, "5h", "", usage.FiveHour)
+	appendProgressTier(&tiers, "7d", "", usage.SevenDay)
+	appendProgressTier(&tiers, "7d-sonnet", "", usage.SevenDaySonnet)
+	appendProgressTier(&tiers, "7d-fable", "", usage.SevenDayFable)
+	appendProgressTier(&tiers, "30d", "", usage.ThirtyDay)
+	// Gemini 多档日配额：同 Window 不同 Label。
+	appendProgressTier(&tiers, "daily", "shared", usage.GeminiSharedDaily)
+	appendProgressTier(&tiers, "daily", "pro", usage.GeminiProDaily)
+	appendProgressTier(&tiers, "daily", "flash", usage.GeminiFlashDaily)
+	// Grok requests/tokens 两个日窗口 + 月度计费窗口。
+	appendQuotaWindowTier(&tiers, "daily", "requests", usage.GrokRequestQuota)
+	appendQuotaWindowTier(&tiers, "daily", "tokens", usage.GrokTokenQuota)
+	// Antigravity per-model 总量额度，Label = 模型名（按名排序保证输出稳定）。
+	for _, model := range sortedQuotaModelNames(usage.AntigravityQuota) {
+		q := usage.AntigravityQuota[model]
+		if q == nil {
+			continue
+		}
+		tiers = append(tiers, domain.MonitorQuotaTier{
+			Window:      "total",
+			Label:       model,
+			UsedPercent: float64(q.Utilization),
+			ResetAt:     q.ResetTime,
+		})
+	}
+	if len(tiers) == 0 {
+		return nil
+	}
+	return tiers
+}
+
+func appendProgressTier(tiers *[]domain.MonitorQuotaTier, window, label string, p *UsageProgress) {
+	if p == nil {
+		return
+	}
+	tier := domain.MonitorQuotaTier{
+		Window:      window,
+		Label:       label,
+		UsedPercent: p.Utilization,
+	}
+	if p.ResetsAt != nil {
+		tier.ResetAt = p.ResetsAt.UTC().Format(time.RFC3339)
+	}
+	if p.LimitRequests > 0 {
+		tier.Used = float64(p.UsedRequests)
+		tier.Limit = float64(p.LimitRequests)
+	}
+	*tiers = append(*tiers, tier)
+}
+
+func appendQuotaWindowTier(tiers *[]domain.MonitorQuotaTier, window, label string, q *xai.QuotaWindow) {
+	if q == nil || q.Limit == nil || *q.Limit <= 0 {
+		return
+	}
+	used := *q.Limit
+	if q.Remaining != nil {
+		used = *q.Limit - *q.Remaining
+		if used < 0 {
+			used = 0
+		}
+	}
+	tier := domain.MonitorQuotaTier{
+		Window:      window,
+		Label:       label,
+		Used:        float64(used),
+		Limit:       float64(*q.Limit),
+		UsedPercent: float64(used) / float64(*q.Limit) * 100,
+	}
+	if q.ResetAt != "" {
+		tier.ResetAt = q.ResetAt
+	} else if q.ResetUnix != nil && *q.ResetUnix > 0 {
+		tier.ResetAt = time.Unix(*q.ResetUnix, 0).UTC().Format(time.RFC3339)
+	}
+	*tiers = append(*tiers, tier)
+}
+
+func sortedQuotaModelNames(quotas map[string]*AntigravityModelQuota) []string {
+	names := make([]string, 0, len(quotas))
+	for name := range quotas {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	return names
+}
+
+// fetchCNQuota 国产 coding plan：CNProviderQuotaService.QueryUsage → 快照。
+func (f *ChannelMonitorQuotaFetcher) fetchCNQuota(ctx context.Context, accountID int64, now time.Time) *domain.MonitorQuotaSnapshot {
+	if f.cnQuota == nil {
+		return quotaErrorSnapshot("cn_quota", "cn quota service is not configured", now)
+	}
+	result, err := f.cnQuota.QueryUsage(ctx, accountID)
+	if err != nil {
+		msg := truncateMessage(sanitizeErrorMessage(err.Error()))
+		return &domain.MonitorQuotaSnapshot{
+			Source:            "cn_quota",
+			Success:           false,
+			CredentialInvalid: isCredentialErrorMessage(msg),
+			Error:             msg,
+			FetchedAt:         now,
+		}
+	}
+	snapshot := &domain.MonitorQuotaSnapshot{
+		Source:    "cn_quota",
+		Success:   result.Success,
+		PlanLevel: result.PlanLevel,
+		Error:     result.Error,
+		FetchedAt: now,
+	}
+	if !result.Success && !result.CredentialValid {
+		snapshot.CredentialInvalid = true
+	}
+	if len(result.Tiers) > 0 {
+		snapshot.Tiers = make([]domain.MonitorQuotaTier, 0, len(result.Tiers))
+		for _, t := range result.Tiers {
+			snapshot.Tiers = append(snapshot.Tiers, domain.MonitorQuotaTier{
+				Window:      t.Window,
+				UsedPercent: t.UsedPercent,
+				ResetAt:     t.ResetAt,
+			})
+		}
+	}
+	if !snapshot.Success {
+		snapshot.Error = firstNonEmpty(snapshot.Error, "cn quota probe failed")
+	}
+	return snapshot
+}
+
+// fetchCNBalance 国产 payg：CNProviderBalanceService.QueryBalance → 快照。
+func (f *ChannelMonitorQuotaFetcher) fetchCNBalance(ctx context.Context, accountID int64, now time.Time) *domain.MonitorQuotaSnapshot {
+	if f.cnBalance == nil {
+		return quotaErrorSnapshot("cn_balance", "cn balance service is not configured", now)
+	}
+	result, err := f.cnBalance.QueryBalance(ctx, accountID)
+	if err != nil {
+		msg := truncateMessage(sanitizeErrorMessage(err.Error()))
+		return &domain.MonitorQuotaSnapshot{
+			Source:            "cn_balance",
+			Success:           false,
+			CredentialInvalid: isCredentialErrorMessage(msg),
+			Error:             msg,
+			FetchedAt:         now,
+		}
+	}
+	snapshot := &domain.MonitorQuotaSnapshot{
+		Source:    "cn_balance",
+		Success:   result.Success,
+		Currency:  result.Currency,
+		Error:     result.Error,
+		FetchedAt: now,
+	}
+	if result.Success {
+		balance := result.Balance
+		snapshot.Balance = &balance
+	} else if result.StatusCode == 401 || result.StatusCode == 403 {
+		snapshot.CredentialInvalid = true
+	}
+	if len(result.Balances) > 0 {
+		snapshot.Balances = make([]domain.MonitorBalance, 0, len(result.Balances))
+		for _, b := range result.Balances {
+			snapshot.Balances = append(snapshot.Balances, domain.MonitorBalance{
+				Currency: b.Currency,
+				Balance:  b.Balance,
+			})
+		}
+	}
+	if !snapshot.Success {
+		snapshot.Error = firstNonEmpty(snapshot.Error, "cn balance probe failed")
+	}
+	return snapshot
+}
+
+// quotaErrorSnapshot 构造统一错误快照。
+func quotaErrorSnapshot(source, message string, now time.Time) *domain.MonitorQuotaSnapshot {
+	return &domain.MonitorQuotaSnapshot{
+		Source:    source,
+		Success:   false,
+		Error:     truncateMessage(sanitizeErrorMessage(message)),
+		FetchedAt: now,
+	}
+}
+
+// isCredentialErrorMessage 上游 401/403 鉴权失败的启发式识别
+// （海外 GetUsage 的错误没有结构化状态码，只能看文本）。
+func isCredentialErrorMessage(msg string) bool {
+	msg = strings.ToLower(msg)
+	return strings.Contains(msg, "401") ||
+		strings.Contains(msg, "403") ||
+		strings.Contains(msg, "unauthorized") ||
+		strings.Contains(msg, "forbidden") ||
+		strings.Contains(msg, "invalid_api_key") ||
+		strings.Contains(msg, "authentication")
+}
+
+// deriveQuotaCheckResult 把配额快照推导为检测状态（复用既有 status 枚举，
+// 时间线/可用率机制自动生效）：
+//   - 查询成功且无告警        → operational
+//   - 任一窗口使用率 >= 阈值或余额耗尽 → degraded
+//   - 账号未关联（配置问题）    → degraded
+//   - 凭据失效（401/403）     → failed
+//   - 网络/解析等其他错误      → error
+func deriveQuotaCheckResult(snapshot *domain.MonitorQuotaSnapshot, model string, checkedAt time.Time) *CheckResult {
+	res := &CheckResult{Model: model, CheckedAt: checkedAt}
+	if snapshot == nil {
+		res.Status = MonitorStatusError
+		res.Message = "quota snapshot missing"
+		return res
+	}
+
+	switch {
+	case !snapshot.Success && snapshot.CredentialInvalid:
+		res.Status = MonitorStatusFailed
+		res.Message = snapshot.Error
+	case !snapshot.Success && strings.Contains(snapshot.Error, "linked account not found"):
+		res.Status = MonitorStatusDegraded
+		res.Message = snapshot.Error
+	case !snapshot.Success:
+		res.Status = MonitorStatusError
+		res.Message = snapshot.Error
+	default:
+		if hint := quotaDegradedHint(snapshot); hint != "" {
+			res.Status = MonitorStatusDegraded
+			res.Message = hint
+		} else {
+			res.Status = MonitorStatusOperational
+		}
+	}
+	return res
+}
+
+// quotaDegradedHint 生成 degraded 的 message（指出触发告警的窗口/余额）；
+// 空串表示无告警。
+func quotaDegradedHint(snapshot *domain.MonitorQuotaSnapshot) string {
+	for _, tier := range snapshot.Tiers {
+		if tier.UsedPercent >= monitorQuotaDegradedUsedPercent {
+			name := tier.Window
+			if tier.Label != "" {
+				name = tier.Label + "/" + tier.Window
+			}
+			return fmt.Sprintf("quota high: %s at %s%%", name, strconv.FormatFloat(tier.UsedPercent, 'f', 1, 64))
+		}
+	}
+	if snapshot.Balance != nil && *snapshot.Balance <= 0 {
+		return fmt.Sprintf("balance depleted (%s)", firstNonEmpty(snapshot.Currency, "?"))
+	}
+	return ""
+}
diff --git a/backend/internal/service/channel_monitor_service.go b/backend/internal/service/channel_monitor_service.go
index 248b72133d..9b0bb07639 100644
--- a/backend/internal/service/channel_monitor_service.go
+++ b/backend/internal/service/channel_monitor_service.go
@@ -11,6 +11,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/Wei-Shaw/sub2api/internal/domain"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -77,6 +78,10 @@ type ChannelMonitorService struct {
 	// scheduler 由 wire 通过 SetScheduler 注入；CRUD 后调用对应钩子即时同步任务。
 	// 测试或未注入场景下保持 nil，所有钩子调用变为 no-op。
 	scheduler MonitorScheduler
+	// quotaFetcher 由 wire 通过 SetQuotaFetcher 注入（accountUsage/CN 服务在本服务
+	// 之后构造，构造参数注入会破坏既有依赖顺序）。nil 时 fail-closed：
+	// 配额模式的检测产出「未配置」错误快照，Create/Update 关联账号直接报错。
+	quotaFetcher *ChannelMonitorQuotaFetcher
 }
 
 const maxChannelMonitorNameRunes = 100
@@ -150,6 +155,10 @@ func (s *ChannelMonitorService) Create(ctx context.Context, p ChannelMonitorCrea
 	if err := validateExtraHeaders(p.ExtraHeaders); err != nil {
 		return nil, err
 	}
+	if err := s.validateLinkedAccount(ctx, p.Provider, p.AccountID); err != nil {
+		return nil, err
+	}
+	checkMode := defaultCheckMode(p.CheckMode)
 	encrypted, err := s.encryptor.Encrypt(p.APIKey)
 	if err != nil {
 		return nil, fmt.Errorf("encrypt api key: %w", err)
@@ -160,7 +169,7 @@ func (s *ChannelMonitorService) Create(ctx context.Context, p ChannelMonitorCrea
 		APIMode:          defaultAPIMode(p.APIMode),
 		Endpoint:         normalizeEndpoint(p.Endpoint),
 		APIKey:           encrypted, // 注意：传入 repository 时该字段为密文
-		PrimaryModel:     normalizeMonitorPrimaryModel(p.Provider, p.PrimaryModel),
+		PrimaryModel:     normalizeMonitorPrimaryModel(p.Provider, checkMode, p.PrimaryModel),
 		ExtraModels:      normalizeModels(p.ExtraModels),
 		GroupName:        strings.TrimSpace(p.GroupName),
 		Enabled:          p.Enabled,
@@ -171,6 +180,8 @@ func (s *ChannelMonitorService) Create(ctx context.Context, p ChannelMonitorCrea
 		ExtraHeaders:     emptyHeadersIfNil(p.ExtraHeaders),
 		BodyOverrideMode: defaultBodyMode(p.BodyOverrideMode),
 		BodyOverride:     p.BodyOverride,
+		CheckMode:        checkMode,
+		AccountID:        cloneInt64Pointer(p.AccountID),
 	}
 	if err := s.repo.Create(ctx, m); err != nil {
 		return nil, fmt.Errorf("create channel monitor: %w", err)
@@ -236,6 +247,8 @@ func (s *ChannelMonitorService) Duplicate(
 		ExtraHeaders:         cloneChannelMonitorHeaders(source.ExtraHeaders),
 		BodyOverrideMode:     source.BodyOverrideMode,
 		BodyOverride:         bodyOverride,
+		CheckMode:            defaultCheckMode(source.CheckMode),
+		AccountID:            cloneInt64Pointer(source.AccountID),
 		DuplicateOperationID: operationID,
 	}
 	if err := s.repo.Create(ctx, duplicate); err != nil {
@@ -290,11 +303,22 @@ func (s *ChannelMonitorService) decryptAPIKeyForDuplicate(source *ChannelMonitor
 		return "", ErrChannelMonitorAPIKeyDecryptFailed
 	}
 	plain, err := s.encryptor.Decrypt(source.APIKey)
-	if err != nil || strings.TrimSpace(plain) == "" {
+	if err != nil {
 		slog.Warn("channel_monitor: decrypt api key for duplicate failed",
 			"monitor_id", source.ID, "error", err)
 		return "", ErrChannelMonitorAPIKeyDecryptFailed
 	}
+	// quota 模式明文为空串是合法状态（api_key_encrypted 存的是加密空串）：
+	// 重加密空串即可。若在此报错，克隆出的配额监控会被 runner 当作
+	// 解密失败而 Unschedule，静默停摆。
+	if strings.TrimSpace(plain) == "" {
+		if monitorCheckModeUsesQuota(defaultCheckMode(source.CheckMode)) {
+			return "", nil
+		}
+		slog.Warn("channel_monitor: decrypted api key for duplicate is empty",
+			"monitor_id", source.ID)
+		return "", ErrChannelMonitorAPIKeyDecryptFailed
+	}
 	return plain, nil
 }
 
@@ -343,10 +367,16 @@ func cloneChannelMonitorJSONMap(source map[string]any) (map[string]any, error) {
 }
 
 // validateCreateParams 把 Create 入参的所有校验聚拢为一个函数，避免 Create 主体超过 30 行。
+// 按 check_mode 分支：probe 沿用 endpoint+api_key 必填；quota 只需关联账号；
+// quota_probe 两者皆需。
 func validateCreateParams(p ChannelMonitorCreateParams) error {
 	if err := validateProvider(p.Provider); err != nil {
 		return err
 	}
+	checkMode := defaultCheckMode(p.CheckMode)
+	if err := validateCheckMode(p.Provider, checkMode); err != nil {
+		return err
+	}
 	if err := validateAPIMode(p.Provider, p.APIMode); err != nil {
 		return err
 	}
@@ -356,18 +386,45 @@ func validateCreateParams(p ChannelMonitorCreateParams) error {
 	if err := validateJitter(p.JitterSeconds, p.IntervalSeconds); err != nil {
 		return err
 	}
-	if err := validateEndpoint(p.Endpoint); err != nil {
-		return err
+	usesQuota := monitorCheckModeUsesQuota(checkMode)
+	// probe 分支（含 quota_probe 的探活部分）仍需 endpoint + api_key；
+	// quota 模式 endpoint/api_key 留空，避免要求用户填无意义的占位值。
+	if checkMode != MonitorCheckModeQuota {
+		if err := validateEndpoint(p.Endpoint); err != nil {
+			return err
+		}
+		if strings.TrimSpace(p.APIKey) == "" {
+			return ErrChannelMonitorMissingAPIKey
+		}
 	}
-	if strings.TrimSpace(p.APIKey) == "" {
-		return ErrChannelMonitorMissingAPIKey
+	if usesQuota && (p.AccountID == nil || *p.AccountID <= 0) {
+		return ErrChannelMonitorAccountRequired
 	}
-	if normalizeMonitorPrimaryModel(p.Provider, p.PrimaryModel) == "" {
+	if normalizeMonitorPrimaryModel(p.Provider, checkMode, p.PrimaryModel) == "" {
 		return ErrChannelMonitorMissingPrimaryModel
 	}
 	return nil
 }
 
+// validateLinkedAccount 校验关联账号存在且平台与监控 provider 一致。
+// fetcher 未注入时 fail-closed（拒绝创建配额监控，而不是创建后静默坏）。
+func (s *ChannelMonitorService) validateLinkedAccount(ctx context.Context, provider string, accountID *int64) error {
+	if accountID == nil || *accountID <= 0 {
+		return nil
+	}
+	if s.quotaFetcher == nil {
+		return ErrChannelMonitorAccountRequired
+	}
+	account, err := s.quotaFetcher.LoadAccount(ctx, *accountID)
+	if err != nil || account == nil {
+		return ErrChannelMonitorAccountRequired
+	}
+	if account.Platform != provider {
+		return ErrChannelMonitorProviderIncompatible
+	}
+	return nil
+}
+
 // Update 更新监控。APIKey 字段：nil 或空字符串 = 不修改；非空 = 加密后覆盖。
 func (s *ChannelMonitorService) Update(ctx context.Context, id int64, p ChannelMonitorUpdateParams) (*ChannelMonitor, error) {
 	existing, err := s.repo.GetByID(ctx, id)
@@ -382,6 +439,14 @@ func (s *ChannelMonitorService) Update(ctx context.Context, id int64, p ChannelM
 	if err != nil {
 		return nil, err
 	}
+	if err := s.validateProbeAPIKey(existing, newPlainAPIKey); err != nil {
+		return nil, err
+	}
+	if p.Provider != nil || p.CheckMode != nil || p.AccountID != nil {
+		if err := s.revalidateLinkedAccount(ctx, existing); err != nil {
+			return nil, err
+		}
+	}
 
 	if err := s.repo.Update(ctx, existing); err != nil {
 		return nil, fmt.Errorf("update channel monitor: %w", err)
@@ -401,6 +466,76 @@ func (s *ChannelMonitorService) Update(ctx context.Context, id int64, p ChannelM
 	return existing, nil
 }
 
+// validateMonitorModeFields 校验 check_mode 与其它字段的组合约束
+// （在 provider/check_mode/account_id/endpoint 全部应用后调用）：
+//   - quota / quota_probe 必须关联账号
+//   - probe / quota_probe 必须持有 endpoint（探活目标）
+func validateMonitorModeFields(m *ChannelMonitor) error {
+	checkMode := defaultCheckMode(m.CheckMode)
+	if monitorCheckModeUsesQuota(checkMode) && m.AccountID == nil {
+		return ErrChannelMonitorAccountRequired
+	}
+	if checkMode != MonitorCheckModeQuota && strings.TrimSpace(m.Endpoint) == "" {
+		return ErrChannelMonitorInvalidEndpoint
+	}
+	return nil
+}
+
+// validateProbeAPIKey 探活模式（probe / quota_probe）必须持有可用明文 key：
+// 存量密文解密为空串（quota 监控切回探活但未重填 key）时拒绝。
+// 密文损坏的情况交给既有 APIKeyDecryptFailed 链路（Get/RunCheck 会显式报错）。
+func (s *ChannelMonitorService) validateProbeAPIKey(m *ChannelMonitor, newPlainKey string) error {
+	if defaultCheckMode(m.CheckMode) == MonitorCheckModeQuota {
+		return nil
+	}
+	if strings.TrimSpace(newPlainKey) != "" {
+		return nil
+	}
+	if strings.TrimSpace(m.APIKey) == "" {
+		return ErrChannelMonitorMissingAPIKey
+	}
+	plain, err := s.encryptor.Decrypt(m.APIKey)
+	if err != nil {
+		return nil
+	}
+	if strings.TrimSpace(plain) == "" {
+		return ErrChannelMonitorMissingAPIKey
+	}
+	return nil
+}
+
+// revalidateLinkedAccount 在 provider/check_mode/account_id 任一变化后复核关联账号：
+//   - 账号已被删除或平台失配：probe 模式自动解绑（静默修复），
+//     quota 模式显式报错（配额监控必须有可用数据源）
+func (s *ChannelMonitorService) revalidateLinkedAccount(ctx context.Context, m *ChannelMonitor) error {
+	usesQuota := monitorCheckModeUsesQuota(defaultCheckMode(m.CheckMode))
+	if m.AccountID == nil {
+		if usesQuota {
+			return ErrChannelMonitorAccountRequired
+		}
+		return nil
+	}
+	if s.quotaFetcher == nil {
+		return ErrChannelMonitorAccountRequired
+	}
+	account, err := s.quotaFetcher.LoadAccount(ctx, *m.AccountID)
+	if err != nil || account == nil {
+		if usesQuota {
+			return ErrChannelMonitorAccountRequired
+		}
+		m.AccountID = nil
+		return nil
+	}
+	if account.Platform != m.Provider {
+		if usesQuota {
+			return ErrChannelMonitorProviderIncompatible
+		}
+		m.AccountID = nil
+		return nil
+	}
+	return nil
+}
+
 // applyAPIKeyUpdate 处理 Update 中的 APIKey 字段：
 //   - 入参 raw 为 nil 或空白：不修改 existing.APIKey（仍为密文），返回 updated=false
 //   - 非空：加密后写入 existing.APIKey；同时把明文返回给调用方，
@@ -454,6 +589,9 @@ func (s *ChannelMonitorService) ListHistory(ctx context.Context, id int64, model
 // 写历史记录并更新 last_checked_at。返回每个模型的检测结果。
 // 仅当 channel_monitor_enabled=true 且 channel_monitor_mode=v1 时真正探测；
 // mode=v2 时返回 ErrChannelMonitorActiveProbesRetired，不产生上游流量。
+//
+// 按 check_mode 分派：probe（默认，现状探活）/ quota（仅查关联账号配额，
+// 零 LLM 成本）/ quota_probe（探活 + 配额快照挂主模型行）。
 func (s *ChannelMonitorService) RunCheck(ctx context.Context, id int64) ([]*CheckResult, error) {
 	rt := s.probeRuntime(ctx)
 	if !rt.Enabled {
@@ -466,14 +604,59 @@ func (s *ChannelMonitorService) RunCheck(ctx context.Context, id int64) ([]*Chec
 	if err != nil {
 		return nil, err
 	}
-	if m.APIKeyDecryptFailed {
+	checkMode := defaultCheckMode(m.CheckMode)
+	if checkMode != MonitorCheckModeQuota && m.APIKeyDecryptFailed {
 		return nil, ErrChannelMonitorAPIKeyDecryptFailed
 	}
-	results := s.runChecksConcurrent(ctx, m)
+
+	var results []*CheckResult
+	switch checkMode {
+	case MonitorCheckModeQuota:
+		results = s.runQuotaOnlyCheck(ctx, m)
+	case MonitorCheckModeQuotaProbe:
+		results = s.runChecksConcurrent(ctx, m)
+		attachQuotaSnapshot(results, s.fetchQuotaSnapshot(ctx, m))
+	default:
+		results = s.runChecksConcurrent(ctx, m)
+	}
 	s.persistCheckResults(ctx, m, results)
 	return results, nil
 }
 
+// runQuotaOnlyCheck quota 模式：一次配额抓取 → 单条 CheckResult
+// （Model=PrimaryModel，默认 "quota"；无 ping/latency，状态由快照推导）。
+func (s *ChannelMonitorService) runQuotaOnlyCheck(ctx context.Context, m *ChannelMonitor) []*CheckResult {
+	snapshot := s.fetchQuotaSnapshot(ctx, m)
+	res := deriveQuotaCheckResult(snapshot, m.PrimaryModel, time.Now())
+	res.Quota = snapshot
+	return []*CheckResult{res}
+}
+
+// fetchQuotaSnapshot 抓取关联账号配额。未关联账号 / fetcher 未注入时返回
+// 显式错误快照（不返回 error，保证检测周期与历史时间线连续）。
+func (s *ChannelMonitorService) fetchQuotaSnapshot(ctx context.Context, m *ChannelMonitor) *domain.MonitorQuotaSnapshot {
+	if m.AccountID == nil {
+		return quotaErrorSnapshot("usage", "linked account not found", time.Now())
+	}
+	if s.quotaFetcher == nil {
+		return quotaErrorSnapshot("usage", "quota fetcher is not configured", time.Now())
+	}
+	return s.quotaFetcher.Fetch(ctx, *m.AccountID)
+}
+
+// attachQuotaSnapshot quota_probe：把配额快照挂到主模型行（results[0]）。
+// 配额失败不改变探活状态，仅在探活 message 为空时附注失败原因。
+func attachQuotaSnapshot(results []*CheckResult, snapshot *domain.MonitorQuotaSnapshot) {
+	if len(results) == 0 || snapshot == nil {
+		return
+	}
+	primary := results[0]
+	primary.Quota = snapshot
+	if !snapshot.Success && strings.TrimSpace(primary.Message) == "" {
+		primary.Message = truncateMessage("quota fetch failed: " + snapshot.Error)
+	}
+}
+
 // persistCheckResults 写入本次检测的历史记录并更新 last_checked_at。
 // 任一写库失败都只记日志，不影响调用方拿到 results（与 MVP 期望一致：宁可漏记历史也要先返回结果）。
 func (s *ChannelMonitorService) persistCheckResults(ctx context.Context, m *ChannelMonitor, results []*CheckResult) {
@@ -487,6 +670,7 @@ func (s *ChannelMonitorService) persistCheckResults(ctx context.Context, m *Chan
 			PingLatencyMs: r.PingLatencyMs,
 			Message:       r.Message,
 			CheckedAt:     r.CheckedAt,
+			Quota:         r.Quota,
 		})
 	}
 	if err := s.repo.InsertHistoryBatch(ctx, rows); err != nil {
@@ -541,6 +725,14 @@ func (s *ChannelMonitorService) SetScheduler(sched MonitorScheduler) {
 	s.scheduler = sched
 }
 
+// SetQuotaFetcher 由 wire 注入配额抓取器（账号侧用量服务聚合）。
+func (s *ChannelMonitorService) SetQuotaFetcher(fetcher *ChannelMonitorQuotaFetcher) {
+	if s == nil {
+		return
+	}
+	s.quotaFetcher = fetcher
+}
+
 // ListEnabledMonitors 返回所有 enabled=true 的监控（解密后），供 runner 启动时建立任务表。
 func (s *ChannelMonitorService) ListEnabledMonitors(ctx context.Context) ([]*ChannelMonitor, error) {
 	all, err := s.repo.ListEnabled(ctx)
@@ -693,14 +885,36 @@ func applyMonitorUpdate(existing *ChannelMonitor, p ChannelMonitorUpdateParams)
 		providerChanged = existing.Provider != *p.Provider
 		existing.Provider = *p.Provider
 	}
-	if p.Endpoint != nil {
-		if err := validateEndpoint(*p.Endpoint); err != nil {
+	if p.CheckMode != nil {
+		mode := defaultCheckMode(*p.CheckMode)
+		if err := validateCheckMode(existing.Provider, mode); err != nil {
 			return err
 		}
+		existing.CheckMode = mode
+	}
+	if p.AccountID != nil {
+		if *p.AccountID > 0 {
+			id := *p.AccountID
+			existing.AccountID = &id
+		} else {
+			existing.AccountID = nil // 0 = 清空关联
+		}
+	}
+	if p.Endpoint != nil {
+		// quota 模式允许清空 endpoint（校验由 validateMonitorModeFields 兜底）。
+		if strings.TrimSpace(*p.Endpoint) != "" {
+			if err := validateEndpoint(*p.Endpoint); err != nil {
+				return err
+			}
+		}
 		existing.Endpoint = normalizeEndpoint(*p.Endpoint)
 	}
+	// 模式与字段的组合校验（provider/check_mode/account_id/endpoint 全部应用后）。
+	if err := validateMonitorModeFields(existing); err != nil {
+		return err
+	}
 	if p.PrimaryModel != nil {
-		primaryModel := normalizeMonitorPrimaryModel(existing.Provider, *p.PrimaryModel)
+		primaryModel := normalizeMonitorPrimaryModel(existing.Provider, defaultCheckMode(existing.CheckMode), *p.PrimaryModel)
 		if primaryModel == "" {
 			return ErrChannelMonitorMissingPrimaryModel
 		}
diff --git a/backend/internal/service/channel_monitor_types.go b/backend/internal/service/channel_monitor_types.go
index 20ab1da935..298e037ee1 100644
--- a/backend/internal/service/channel_monitor_types.go
+++ b/backend/internal/service/channel_monitor_types.go
@@ -1,6 +1,10 @@
 package service
 
-import "time"
+import (
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/domain"
+)
 
 // MonitorBodyOverrideMode 自定义请求体处理模式。
 //
@@ -45,6 +49,11 @@ type ChannelMonitor struct {
 	CreatedAt       time.Time
 	UpdatedAt       time.Time
 
+	// 配额模式（check_mode = quota / quota_probe）：
+	// 关联已有账号复用账号侧用量服务，Endpoint/APIKey 可为空（quota 模式）。
+	CheckMode string  // probe（默认）/ quota / quota_probe；空串按 probe 处理
+	AccountID *int64  // 关联账号 ID；账号删除后被 DB 置空（监控保留并报「账号未关联」）
+
 	// 请求自定义快照（来自模板拷贝 or 用户手填，运行时直接读取）
 	TemplateID       *int64            // 仅用于 UI 分组 + 一键应用，运行时不用
 	ExtraHeaders     map[string]string // 与 adapter 默认 headers 合并，用户优先
@@ -89,6 +98,10 @@ type ChannelMonitorCreateParams struct {
 	ExtraHeaders     map[string]string
 	BodyOverrideMode string
 	BodyOverride     map[string]any
+
+	// 配额模式：CheckMode 空串默认 probe；quota/quota_probe 必须关联账号。
+	CheckMode string
+	AccountID *int64
 }
 
 // ChannelMonitorUpdateParams 更新参数（指针字段表示"未提供则不更新"）。
@@ -112,6 +125,11 @@ type ChannelMonitorUpdateParams struct {
 	ExtraHeaders     *map[string]string
 	BodyOverrideMode *string
 	BodyOverride     *map[string]any
+
+	// 配额模式：CheckMode nil = 不更新；AccountID nil = 不更新，
+	// 指向 0 = 清空关联（退回 probe 模式时由 CheckMode 分支兜底）。
+	CheckMode *string
+	AccountID *int64
 }
 
 // CheckResult 单个模型一次检测的结果。
@@ -122,6 +140,8 @@ type CheckResult struct {
 	PingLatencyMs *int
 	Message       string
 	CheckedAt     time.Time
+	// Quota 配额模式附带快照（quota 模式唯一数据；quota_probe 挂在主模型行）。
+	Quota *domain.MonitorQuotaSnapshot
 }
 
 // UserMonitorView 用户只读视图：监控概览（含主模型最近状态 + 7d 可用率 + 附加模型最近状态）。
@@ -137,6 +157,9 @@ type UserMonitorView struct {
 	Availability7d       float64 // 0-100
 	ExtraModels          []ExtraModelStatus
 	Timeline             []UserMonitorTimelinePoint // 主模型最近 N 个历史点（按 checked_at DESC，最新在前）
+	// LatestQuota 主模型最近一次配额快照；channel_monitor_show_quota=false
+	// 时由 handler 服务端剥离。
+	LatestQuota *domain.MonitorQuotaSnapshot
 }
 
 // UserMonitorTimelinePoint 用户视图 timeline 单点数据（去除 message 以减小响应体）。
@@ -183,6 +206,7 @@ type ChannelMonitorHistoryRow struct {
 	PingLatencyMs *int
 	Message       string
 	CheckedAt     time.Time
+	Quota         *domain.MonitorQuotaSnapshot
 }
 
 // ChannelMonitorHistoryEntry 历史记录查询返回行（含 ent 主键 ID）。
@@ -194,6 +218,7 @@ type ChannelMonitorHistoryEntry struct {
 	PingLatencyMs *int
 	Message       string
 	CheckedAt     time.Time
+	Quota         *domain.MonitorQuotaSnapshot
 }
 
 // ChannelMonitorLatest 最近一次检测的简明信息（用于 UserMonitorView 聚合）。
@@ -203,6 +228,7 @@ type ChannelMonitorLatest struct {
 	LatencyMs     *int
 	PingLatencyMs *int
 	CheckedAt     time.Time
+	Quota         *domain.MonitorQuotaSnapshot
 }
 
 // ChannelMonitorAvailability 单个模型在某窗口内的可用率与平均延迟（用于 UserMonitorDetail 聚合）。
@@ -223,4 +249,5 @@ type MonitorStatusSummary struct {
 	PrimaryLatencyMs *int
 	Availability7d   float64 // 0-100，无历史时为 0
 	ExtraModels      []ExtraModelStatus
+	LatestQuota      *domain.MonitorQuotaSnapshot // 主模型最近配额快照（配额模式）
 }
diff --git a/backend/internal/service/channel_monitor_validate.go b/backend/internal/service/channel_monitor_validate.go
index 7740dc83b7..faf7247fbc 100644
--- a/backend/internal/service/channel_monitor_validate.go
+++ b/backend/internal/service/channel_monitor_validate.go
@@ -9,15 +9,81 @@ import (
 // 渠道监控参数校验与归一化辅助函数。
 // 校验失败一律返回 channel_monitor_const.go 中预定义的 Err* 错误，错误信息不含具体 IP/hostname，避免泄露内网拓扑。
 
+// monitorProviders 渠道监控支持的全部 provider（与迁移 226 的 CHECK 约束一致）。
+// 不再以 adapter 表为唯一来源：antigravity 没有探活 adapter，但支持配额模式。
+//
+//nolint:gochecknoglobals // 静态查表，初始化后不变。
+var monitorProviders = map[string]struct{}{
+	MonitorProviderOpenAI:      {},
+	MonitorProviderAnthropic:   {},
+	MonitorProviderGemini:      {},
+	MonitorProviderGrok:        {},
+	MonitorProviderAntigravity: {},
+	MonitorProviderKimi:        {},
+	MonitorProviderZhipu:       {},
+	MonitorProviderDeepseek:    {},
+}
+
+// probeCapableProviders 支持探活（probe / quota_probe）的 provider。
+// antigravity 上游无 Chat/Responses 可打（仅 IDE 代理形态），只允许配额模式。
+//
+//nolint:gochecknoglobals // 静态查表，初始化后不变。
+var probeCapableProviders = map[string]struct{}{
+	MonitorProviderOpenAI:    {},
+	MonitorProviderAnthropic: {},
+	MonitorProviderGemini:    {},
+	MonitorProviderGrok:      {},
+	MonitorProviderKimi:      {},
+	MonitorProviderZhipu:     {},
+	MonitorProviderDeepseek:  {},
+}
+
 // validateProvider 校验 provider 字符串。
-// 唯一来源于 providerAdapters：新增 provider 只需要在 channel_monitor_checker.go 注册 adapter。
 func validateProvider(p string) error {
-	if !isSupportedProvider(p) {
+	if _, ok := monitorProviders[p]; !ok {
 		return ErrChannelMonitorInvalidProvider
 	}
 	return nil
 }
 
+// providerSupportsProbe 该 provider 是否注册了探活 adapter（antigravity 为 false）。
+func providerSupportsProbe(p string) bool {
+	_, ok := probeCapableProviders[p]
+	return ok
+}
+
+// defaultCheckMode 空串归一为 probe，保证存量数据与旧客户端兼容。
+func defaultCheckMode(checkMode string) string {
+	if strings.TrimSpace(checkMode) == "" {
+		return MonitorCheckModeProbe
+	}
+	return strings.TrimSpace(checkMode)
+}
+
+// monitorCheckModeUsesQuota 该模式是否需要关联账号查配额。
+func monitorCheckModeUsesQuota(checkMode string) bool {
+	return checkMode == MonitorCheckModeQuota || checkMode == MonitorCheckModeQuotaProbe
+}
+
+// validateCheckMode 校验 check_mode 与 provider 的组合矩阵：
+//
+//	provider                | probe | quota | quota_probe
+//	------------------------+-------+-------+------------
+//	openai/anthropic/...    |  Y    |  Y    |  Y
+//	antigravity（无 adapter）|  N    |  Y    |  N
+func validateCheckMode(provider, checkMode string) error {
+	checkMode = defaultCheckMode(checkMode)
+	switch checkMode {
+	case MonitorCheckModeProbe, MonitorCheckModeQuota, MonitorCheckModeQuotaProbe:
+	default:
+		return ErrChannelMonitorInvalidCheckMode
+	}
+	if checkMode != MonitorCheckModeQuota && !providerSupportsProbe(provider) {
+		return ErrChannelMonitorInvalidCheckMode
+	}
+	return nil
+}
+
 // validateAPIMode 校验 provider 与 api_mode 的组合。
 // responses 只对 OpenAI 有意义；其它 provider 使用 chat_completions 作为默认占位。
 func validateAPIMode(provider, apiMode string) error {
@@ -124,13 +190,18 @@ func normalizeModels(in []string) []string {
 	return out
 }
 
-// normalizeMonitorPrimaryModel applies the Grok health-check default while
-// preserving the existing required-model behavior for every other provider.
-func normalizeMonitorPrimaryModel(provider, model string) string {
+// normalizeMonitorPrimaryModel applies provider/check_mode defaults while
+// preserving the existing required-model behavior:
+//   - Grok 探活默认轻量测活模型
+//   - quota 模式占位 "quota"（primary_model 列 NotEmpty；历史行/时间线机制无需特判）
+func normalizeMonitorPrimaryModel(provider, checkMode, model string) string {
 	model = strings.TrimSpace(model)
 	if model == "" && provider == MonitorProviderGrok {
 		return MonitorDefaultGrokModel
 	}
+	if model == "" && monitorCheckModeUsesQuota(defaultCheckMode(checkMode)) {
+		return MonitorDefaultQuotaModel
+	}
 	return model
 }