fix(server): 付费会话「活跃即续期」——根治 macOS 常驻隧道一天多掉线

根因:付费连接凭证硬编码 24h TTL(paidCredentialTTL),而客户端只在 _connect()
(用户/看门狗前台重连)才重签,服务端从不因流量续期。macOS sysext(root)隧道独立于
GUI app 常驻,用户关窗后 Dart 看门狗根本不运行 → 凭证 24h 到期、下次 agent 重注册
用「未过期」快照整表覆盖并重渲染 sing-box → REALITY 会话被剔除、永久黑洞。该逻辑
四端共用同一份 Dart,故为全端共性(macOS 最易现形)。

修法(方案 A,服务端、与客户端生命周期无关,一改修四端):
- ReportUsage 收到某 dp_uuid 有流量,若属付费套餐(!AdGate)即把其凭证 expires_at
  顶到 now+PaidCredentialTTL。活跃会话永不过期;免费凭证 TTL 编码日额度、绝不续期
  (否则击穿日限)。每报按 user 缓存一次 entitlement 查询。
- 新增 NodeStore.RenewCredential(纯 UPDATE,WHERE expires_at>now 不复活已过期会话)。
- 24h 提为 nodes.PaidCredentialTTL 单一真相源,httpapi 引用它消除漂移。
- 纯 DB 续期,无需再 push agent(现有 REALITY 用户仍在,只要 DB 行不过期,下次
  重注册快照仍含它)。可移植 SQL(? 占位 + Go 端算时间,无 MySQL 专属构造)。

测试:handler 层付费续期/免费不续期(mock);store 层真 SQLite 续期/不复活已过期。
go test ./... 全绿、go vet 干净。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FEVUXAbFT6bF1Qw27RHWoD

server/internal/nodes/credential_renew_sqlite_test.go

@@ -0,0 +1,127 @@
+package nodes_test
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+	"time"
+
+	"github.com/wangjia/pangolin/server/internal/config"
+	"github.com/wangjia/pangolin/server/internal/nodes"
+	"github.com/wangjia/pangolin/server/internal/store"
+)
+
+// --------------------------------------------------------------------------
+// RenewCredential is the DB half of "renew-on-activity" (the fix for a paid
+// session silently dropping ~1 day in — the connect credential's 24h TTL with
+// nothing refreshing it while a persistent macOS sysext tunnel outlives the GUI
+// app). Pure-Go modernc sqlite → runs in the default no-docker path alongside
+// entitlement_override_sqlite_test.go. Exercises the actual UPDATE SQL (column
+// names, the expires_at > now guard) the handler mock can't cover.
+// --------------------------------------------------------------------------
+
+func openRenewTestDB(t *testing.T) *sql.DB {
+	t.Helper()
+	db, err := store.Open(&config.Config{Driver: "sqlite", DSN: ":memory:"})
+	if err != nil {
+		t.Fatalf("store.Open: %v", err)
+	}
+	t.Cleanup(func() { db.Close() })
+	if err := store.MigrateUp(db, "sqlite"); err != nil {
+		t.Fatalf("MigrateUp: %v", err)
+	}
+	return db
+}
+
+// seedRenewNode inserts a provider + node (provider_id is a FK) and returns the
+// node id, on which credentials can be hung.
+func seedRenewNode(t *testing.T, db *sql.DB) int64 {
+	t.Helper()
+	ctx := context.Background()
+	res, err := db.ExecContext(ctx,
+		`INSERT INTO providers (name, api_kind, regions, pool)
+		 VALUES ('renew-test', 'vultr', '["HK"]', 'consumable')`)
+	if err != nil {
+		t.Fatalf("seed provider: %v", err)
+	}
+	providerID, err := res.LastInsertId()
+	if err != nil {
+		t.Fatalf("provider id: %v", err)
+	}
+	res, err = db.ExecContext(ctx, `
+		INSERT INTO nodes
+		  (uuid, region, name_zh, name_en, tier, endpoint, reality_pbk, reality_sni, provider_id, status)
+		VALUES ('renew-node', 'HK', '香港', 'HK', 'pro', '1.2.3.4:443', 'pbk', 'sni.example.com', ?, 'up')
+	`, providerID)
+	if err != nil {
+		t.Fatalf("seed node: %v", err)
+	}
+	nodeID, err := res.LastInsertId()
+	if err != nil {
+		t.Fatalf("node id: %v", err)
+	}
+	return nodeID
+}
+
+func insertRenewCred(t *testing.T, db *sql.DB, nodeID int64, dpUUID string, expiresAt time.Time) {
+	t.Helper()
+	if _, err := db.ExecContext(context.Background(),
+		`INSERT INTO connect_credentials (node_id, dp_uuid, protocol, flow, expires_at)
+		 VALUES (?, ?, 3, 'xtls-rprx-vision', ?)`,
+		nodeID, dpUUID, expiresAt.UTC()); err != nil {
+		t.Fatalf("insert credential %s: %v", dpUUID, err)
+	}
+}
+
+func readRenewExpiry(t *testing.T, db *sql.DB, dpUUID string) time.Time {
+	t.Helper()
+	var exp time.Time
+	if err := db.QueryRowContext(context.Background(),
+		`SELECT expires_at FROM connect_credentials WHERE dp_uuid = ?`, dpUUID).Scan(&exp); err != nil {
+		t.Fatalf("read expiry %s: %v", dpUUID, err)
+	}
+	return exp.UTC()
+}
+
+// TestRenewCredential_BumpsActive: a still-active credential's expiry is pushed
+// forward to the requested time.
+func TestRenewCredential_BumpsActive(t *testing.T) {
+	db := openRenewTestDB(t)
+	st := nodes.NewSQLNodeStore(db)
+	nodeID := seedRenewNode(t, db)
+
+	now := time.Now().UTC()
+	insertRenewCred(t, db, nodeID, "dp-active", now.Add(1*time.Hour)) // still active
+
+	newExp := now.Add(nodes.PaidCredentialTTL)
+	if err := st.RenewCredential(context.Background(), "dp-active", newExp); err != nil {
+		t.Fatalf("RenewCredential: %v", err)
+	}
+
+	got := readRenewExpiry(t, db, "dp-active")
+	if got.Sub(newExp).Abs() > time.Second {
+		t.Errorf("expiry = %v, want ~%v (renewed)", got, newExp)
+	}
+}
+
+// TestRenewCredential_LeavesExpired: an already-expired credential is NOT
+// resurrected (the expires_at > now guard) — a disconnected session must go
+// through a fresh /connect, not get silently revived by a late usage report.
+func TestRenewCredential_LeavesExpired(t *testing.T) {
+	db := openRenewTestDB(t)
+	st := nodes.NewSQLNodeStore(db)
+	nodeID := seedRenewNode(t, db)
+
+	now := time.Now().UTC()
+	expiredAt := now.Add(-1 * time.Hour)
+	insertRenewCred(t, db, nodeID, "dp-expired", expiredAt) // already expired
+
+	if err := st.RenewCredential(context.Background(), "dp-expired", now.Add(nodes.PaidCredentialTTL)); err != nil {
+		t.Fatalf("RenewCredential: %v", err)
+	}
+
+	got := readRenewExpiry(t, db, "dp-expired")
+	if got.After(now) {
+		t.Errorf("expiry = %v, want unchanged (still expired, before %v)", got, now)
+	}
+}