feat(server): 免费版账户级分钟卡控 + 累加式看广告加时(#21 后端)

免费版此前形同虚设:ConnectNode 每次连接发固定 daily_minutes×1min TTL、
从不扣减已用,重连即崭新 10 分钟,日额度从未强制。改为账户级(全设备共享)
真卡控 + 累加式看广告加时:

- migration 000020: usage_daily 加 ad_bonus_minutes(sqlite+mysql)。
  当日额度 = plans.daily_minutes + ad_bonus_minutes;剩余 = 额度 − minutes_used。
- usage.store.AddAdBonusMinutes: 事务内累加封顶(替代布尔 MarkAdUnlocked),
  返回新总额+本次实际加时;GetDay/GetUsageRange 补读 ad_bonus_minutes。
- usage.service.UnlockAd: verify+nonce 后 +adBonusPerAd(10) 封顶 adDailyBonusCeiling(120),
  返回 granted+remaining;TodaySummary 加 MinutesCap/AdBonusMinutes。
- usage.ads DevVerifier: 放行式占位校验(nonce 防重放仍生效),接真 AdMob 前
  让看广告加时流程可端到端跑通;main.go 按 ADS_DEV_MODE/默认装配。
- ads/unlock: 204 → 200 返回 {granted_minutes, minutes_remaining}。
- ConnectNode 免费门: 读 AccountDayMinutes(used,bonus) → remaining≤0 拒 QUOTA_EXHAUSTED,
  否则 TTL=remaining(凭证到点硬切断兜底)。nodes.store 加 AccountDayMinutes。
- /me: 补 ad_bonus_minutes,quota_today_min 分母改 daily+bonus,加 quota_cap_min。
- quota.CheckFreeConnect 同步累加语义(免费基础 10 分钟不再需先看广告)。
- openapi + 契约/迁移版本/集成测试同步;新增 SQLite AddAdBonusMinutes 单测。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/internal/httpapi/account.go

@@ -31,7 +31,8 @@ type meResponse struct {
 	// Web user-center fields.
 	DevicesUsed   int       `json:"devices_used"`
 	DevicesMax    int       `json:"devices_max"`
-	QuotaTodayMin *int      `json:"quota_today_min"` // null = unlimited (pro/team)
+	QuotaTodayMin *int      `json:"quota_today_min"` // 剩余分钟; null = unlimited (pro/team)
+	QuotaCapMin   *int      `json:"quota_cap_min"`   // 当日额度 = daily + 看广告 bonus; null = unlimited
 	DataTodayGB   float64   `json:"data_today_gb"`
 	WeeklyGB      []float64 `json:"weekly_gb"` // last 7 days, oldest→newest
 	TOTPEnabled   bool      `json:"totp_enabled"`
@@ -99,11 +100,12 @@ func (a *AccountAPI) GetMe(w http.ResponseWriter, r *http.Request) {
 	// 日期在 Go 端算好传 ?,不用 MySQL 专属 UTC_DATE()(否则 SQLite 报错→恒 0)。
 	var todayBytes uint64
 	var todayMinutes int
+	var todayAdBonus int
 	today := time.Now().UTC().Format("2006-01-02")
 	_ = a.db.QueryRowContext(ctx, `
-		SELECT COALESCE(bytes_up, 0) + COALESCE(bytes_down, 0), COALESCE(minutes_used, 0)
+		SELECT COALESCE(bytes_up, 0) + COALESCE(bytes_down, 0), COALESCE(minutes_used, 0), COALESCE(ad_bonus_minutes, 0)
 		FROM usage_daily WHERE user_id = ? AND date = ?
-	`, uid, today).Scan(&todayBytes, &todayMinutes)
+	`, uid, today).Scan(&todayBytes, &todayMinutes, &todayAdBonus)
 
 	resp := meResponse{
 		UUID:        uuid,
@@ -121,11 +123,14 @@ func (a *AccountAPI) GetMe(w http.ResponseWriter, r *http.Request) {
 		resp.ExpiresAt = &s
 	}
 	// quota_today_min: null when the plan is unlimited, else remaining minutes.
+	// 额度 = plan.daily_minutes + 当日看广告累加的 ad_bonus_minutes(账户共享)。
 	if dailyMinutes.Valid {
-		rem := int(dailyMinutes.Int64) - todayMinutes
+		cap := int(dailyMinutes.Int64) + todayAdBonus
+		rem := cap - todayMinutes
 		if rem < 0 {
 			rem = 0
 		}
+		resp.QuotaCapMin = &cap
 		resp.QuotaTodayMin = &rem
 	}
 

server/internal/httpapi/contract_test.go

@@ -56,6 +56,6 @@ func TestContractMeResponse(t *testing.T) {
 	assertFrozenKeys(t, "/v1/me", jsonTagSet(meResponse{}),
 		"uuid", "email", "dp_uuid", "plan", "expires_at",
 		"devices_used", "devices_max",
-		"quota_today_min", "data_today_gb", "weekly_gb", "totp_enabled",
+		"quota_today_min", "quota_cap_min", "data_today_gb", "weekly_gb", "totp_enabled",
 	)
 }

server/internal/httpapi/nodes.go

@@ -206,16 +206,33 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	// 2. Determine TTL from plan.
 	var ttl time.Duration
 	if ent.AdGate {
-		// Free plan: flat 10-minute session for MVP (full ad-gate in a later pass).
+		// Free plan: enforce the account-wide daily minute quota (shared across
+		// ALL devices). allowance = plan.daily_minutes + 当日看广告累加的 bonus;
+		// remaining = allowance − minutes_used. Credential TTL = remaining so the
+		// data-plane hard-cuts when time runs out (backstop even if the client
+		// countdown is bypassed). remaining ≤ 0 → 拒 QUOTA_EXHAUSTED, client 弹广告/升级.
 		dm := int64(10)
 		if ent.DailyMinutes.Valid {
 			dm = ent.DailyMinutes.Int64
 		}
-		if dm <= 0 {
-			apierr.WriteJSON(w, http.StatusForbidden, apierr.ErrQuotaExhausted)
+		used, bonus, qerr := a.store.AccountDayMinutes(r.Context(), uid, time.Now().UTC())
+		if qerr != nil {
+			slog.Error("connect: account day minutes failed", "user", uid, "err", qerr)
+			apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
 			return
 		}
-		ttl = time.Duration(dm) * freeMinuteTTL
+		remaining := dm + int64(bonus) - int64(used)
+		if remaining <= 0 {
+			w.Header().Set("Content-Type", "application/json; charset=utf-8")
+			w.WriteHeader(http.StatusForbidden)
+			_ = json.NewEncoder(w).Encode(map[string]any{
+				"code":       "QUOTA_EXHAUSTED",
+				"message_zh": "今日免费时长已用完，看广告加时或升级会员",
+				"message_en": "Daily free minutes used up. Watch an ad to add time or upgrade.",
+			})
+			return
+		}
+		ttl = time.Duration(remaining) * freeMinuteTTL
 	} else {
 		ttl = paidCredentialTTL
 	}