diff --git a/server/internal/httpapi/nodes.go b/server/internal/httpapi/nodes.go
index 4e1c942..00e0c85 100644
--- a/server/internal/httpapi/nodes.go
+++ b/server/internal/httpapi/nodes.go
@@ -116,6 +116,7 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	// 1. Load user entitlement (dp_uuid + plan).
 	ent, err := a.store.EntitlementForUser(r.Context(), uid)
 	if err != nil {
+		slog.Error("connect: entitlement load failed", "user", uid, "err", err)
 		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
 		return
 	}
@@ -124,6 +125,21 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// 1.5 GB 综合配额卡控(todo #5 Phase 2)：按账户当日综合流量卡，超 plan.daily_mb 即拒。
+	// 对免费(与分钟门双卡)与付费(高上限防滥用)统一生效；daily_mb NULL = 不限。
+	if ent.DailyMB.Valid {
+		usedBytes, qerr := a.store.AccountDayBytes(r.Context(), uid, time.Now().UTC())
+		if qerr != nil {
+			slog.Error("connect: account day bytes failed", "user", uid, "err", qerr)
+			apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
+			return
+		}
+		if usedBytes >= ent.DailyMB.Int64*(1<<20) {
+			apierr.WriteJSON(w, http.StatusForbidden, apierr.ErrQuotaExhausted)
+			return
+		}
+	}
+
 	// 2. Determine TTL from plan.
 	var ttl time.Duration
 	if ent.AdGate {
@@ -142,9 +158,21 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	}
 	expiresAt := time.Now().UTC().Add(ttl)
 
+	// 2.5 Per-device dp_uuid (todo #5 Phase 2): each device gets its own data-plane
+	// credential so the node reports per-device traffic counters. Falls back to the
+	// account-level dp_uuid when the device isn't registered yet (legacy clients).
+	dpUUID := ent.DpUUID
+	if devDp, _, derr := a.store.EnsureDeviceDpUUID(r.Context(), uid, req.DeviceID); derr == nil && devDp != "" {
+		dpUUID = devDp
+	} else if derr != nil {
+		slog.Info("connect: per-device dp_uuid unavailable, using account credential",
+			"user", uid, "device", req.DeviceID, "err", derr.Error())
+	}
+
 	// 3. Resolve node.
 	node, err := a.store.NodeByUUID(r.Context(), nodeUUID)
 	if err != nil {
+		slog.Error("connect: node load failed", "node", nodeUUID, "err", err)
 		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
 		return
 	}
@@ -155,7 +183,7 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 
 	// 4. Build the agentv1.Credential.
 	cred := &agentv1.Credential{
-		DpUUID:        ent.DpUUID,
+		DpUUID:        dpUUID,
 		Protocol:      agentv1.ProtocolBoth,
 		Flow:          "xtls-rprx-vision",
 		ExpiresAtUnix: expiresAt.Unix(),
@@ -181,9 +209,10 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	// 7. Render and return the full sing-box CLIENT config JSON.
 	//    split_cn=1/true → 国内 IP/域名直连(#5);客户端按 smartRoute 偏好传。
 	splitCN := r.URL.Query().Get("split_cn") == "1" || r.URL.Query().Get("split_cn") == "true"
-	cfgJSON, renderErr := BuildClientConfig(node, ent.DpUUID, a.deriveKey,
+	cfgJSON, renderErr := BuildClientConfig(node, dpUUID, a.deriveKey,
 		ClientConfigOpts{SplitCN: splitCN, RulesBaseURL: a.rulesBaseURL})
 	if renderErr != nil {
+		slog.Error("connect: build client config failed", "node", nodeUUID, "err", renderErr)
 		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
 		return
 	}
diff --git a/server/internal/store/connect_schema_test.go b/server/internal/store/connect_schema_test.go
new file mode 100644
index 0000000..bc95066
--- /dev/null
+++ b/server/internal/store/connect_schema_test.go
@@ -0,0 +1,71 @@
+package store_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/wangjia/pangolin/server/internal/nodes"
+)
+
+// TestSQLite_ConnectPathSchema guards the "no such column: p.daily_mb" class of
+// regression that 500'd /v1/nodes/{id}/connect: the connect handler's store
+// queries must bind to the schema the migrations actually produce. Each
+// 000015-dependent query runs against a fully-migrated real SQLite DB — if any
+// references a column/table no migration creates, the call fails with a SQL
+// error and this test goes red. (The live outage was operational — binary
+// deployed ahead of the migration — but this also catches a query that names a
+// column no migration adds.)
+func TestSQLite_ConnectPathSchema(t *testing.T) {
+	ctx := context.Background()
+	db := openSQLite(t)
+	ns := nodes.NewSQLNodeStore(db)
+	seedUser(t, db, 1)
+
+	// EntitlementForUser: the exact query that broke (SELECT ... p.daily_mb ...).
+	// With a PRO subscription, DailyMB must come back from plans.daily_mb (102400,
+	// seeded by migration 000015).
+	var proID int64
+	if err := db.QueryRow(`SELECT id FROM plans WHERE code='pro'`).Scan(&proID); err != nil {
+		t.Fatalf("lookup pro plan: %v", err)
+	}
+	if _, err := db.Exec(
+		`INSERT INTO subscriptions (user_id, plan_id, expires_at, source)
+		 VALUES (1, ?, ?, 'trial')`,
+		proID, time.Now().UTC().Add(24*time.Hour)); err != nil {
+		t.Fatalf("seed subscription: %v", err)
+	}
+	ent, err := ns.EntitlementForUser(ctx, 1)
+	if err != nil {
+		t.Fatalf("EntitlementForUser: %v", err) // a missing daily_mb column lands here
+	}
+	if ent == nil {
+		t.Fatal("EntitlementForUser returned nil entitlement")
+	}
+	if ent.PlanCode != "pro" {
+		t.Errorf("PlanCode = %q, want pro", ent.PlanCode)
+	}
+	if !ent.DailyMB.Valid || ent.DailyMB.Int64 != 102400 {
+		t.Errorf("DailyMB = %+v, want valid 102400", ent.DailyMB)
+	}
+
+	// EnsureDeviceDpUUID: exercises devices.dp_uuid (000015 ADD COLUMN). Mints a
+	// per-device data-plane credential into the new column.
+	if _, err := db.Exec(
+		`INSERT INTO devices (id, uuid, user_id, name, platform)
+		 VALUES (1, 'dev-uuid', 1, 'dev', 'windows')`); err != nil {
+		t.Fatalf("seed device: %v", err)
+	}
+	dp, devID, err := ns.EnsureDeviceDpUUID(ctx, 1, "dev-uuid")
+	if err != nil {
+		t.Fatalf("EnsureDeviceDpUUID: %v", err) // missing devices.dp_uuid lands here
+	}
+	if dp == "" || devID != 1 {
+		t.Errorf("EnsureDeviceDpUUID = (%q, %d), want non-empty dp + devID 1", dp, devID)
+	}
+
+	// AccountDayBytes: GB-quota query run right after entitlement; must bind cleanly.
+	if _, err := ns.AccountDayBytes(ctx, 1, time.Now().UTC()); err != nil {
+		t.Fatalf("AccountDayBytes: %v", err)
+	}
+}