commit ca14496cfcc05f9e04b7400a71e3d478898f326c
Author: mizorewww <mizorewww@users.noreply.github.com>
Date:   Fri Oct 2 15:30:51 2026 +0800

    Add guarded X gift CLI and paused redemption site with admin code management

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f77b940
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,17 @@
+.venv/
+.private/
+__pycache__/
+*.har
+.env
+.env.*
+!.env.example
+*.db
+*.db-shm
+*.db-wal
+*.log
+*.tar.gz
+/sqlite/
+/bin/
+
+.playwright-cli/
+.cloudflare/
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..73bbf4e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,84 @@
+# XGift
+
+Go CLI + Premium 兑换站。网站：`https://xp.example.com`，后台：`/admin`。
+
+**当前付款关闭。** 已验证 X 赠送资格查询、固定套餐报价和 Stripe 结账链接生成；此前一次付款确认返回 HTTP 400，原订单处于 `unknown`，不得自动重试。网站目前可生成、管理兑换码，并核实账号是否允许赠送；符合条件时提示充值尚未开放，兑换码不消耗。不能将当前部署当作已经可成功自动充值的服务。
+
+## 构建
+
+需要 Go 1.27.1、CGO 与 C 编译器：
+
+```sh
+go build -o bin/xgift ./cmd/xgift
+go build -o bin/xgift-web ./cmd/xgift-web
+go vet ./...
+```
+
+按要求未保留测试文件，不运行测试。静态页面嵌入 Go 二进制，无 Node 运行依赖、外部字体或浏览器自动化依赖。
+
+## CLI
+
+```sh
+./bin/xgift status
+./bin/xgift import-chrome --profile Default
+./bin/xgift check
+./bin/xgift proxy --port 18791
+./bin/xgift username                  # 默认 6 个月，只生成/读取结账链接
+./bin/xgift username --months 3       # 3 个月，只生成/读取结账链接
+```
+
+`--pay` 是真实付款入口，当前不要运行。网站的暂停配置只管网站，不会禁用手动执行 CLI 的 `--pay`。
+
+- 仅允许 3 个月恰好 300 BDT、6 个月恰好 600 BDT。校验 X 报价和 Stripe 最终总额、币种、商品、数量、一次性模式及商户身份，任何不符都停止。
+- 内嵌 sing-box AnyTLS，只监听本机端口，不修改系统代理。代理配置从加密库读取。
+- 固定 X API / Stripe 入口，无网页识别或 ChatGPT Chrome 扩展。
+- 私有 API 可能变化；目前 Stripe 确认请求仍未跑通，不能保证链接或支付长期可用。
+- 按 X 固定用户 ID 保存订单。`creating`、`submitting`、`unknown`、`requires_action` 等不明/待处理状态阻止再次提交。不会为了重试重建订单或改变幂等键。
+- 同一收件人已有记录时，不能用另一枚兑换码或另一套餐重复付款。当前没有自动追加时长、自动退款或人工“强制成功”入口。
+
+## 兑换站
+
+用户填写兑换码和用户名，系统先以只读请求核实 X 是否允许赠送。X 不允许时明确提示，兑换码不使用；服务暂停或查询失败也不消耗兑换码。付款开放后的实现会原子锁定兑换码和收件人，使用同一订单校验流程；只有 Stripe 确认成功后才显示完成。付款结果不明时锁定为待核实，不自动重试，进程重启同样不重试。
+
+后台使用 HTTPS Basic Auth，用户名 `admin`，随机密码从权限为 `0600` 的文件读取。支持：
+
+- 每批 1–500 枚兑换码，绑定 3 或 6 个月，可自定义批次名称。
+- 兑换码明文只在生成响应中出现一次，可下载 TXT；数据库仅保存 SHA-256 摘要和末 8 位。
+- 分页浏览全部兑换码，查看账号和状态，停用未使用的码。
+- 同源 POST 校验、请求限流、禁止缓存与页面嵌入；用户接口不返回卡信息、Cookie 或 Stripe 付款链接。
+
+浏览器关闭/刷新不会保存兑换码明文。若生成响应丢失，请先核实批次，必要时停用失去明文的码；没有自动重复生成。
+
+## 本地数据
+
+`sqlite/vault.db` 的敏感记录采用 AES-256-GCM 加密，密钥通过 scrypt 派生；SQLite 结构和记录名称不是密文，不是 SQLCipher 全库加密。Cookie、卡、代理与订单记录分别加密。仅读取 Chrome 的 X `auth_token` / `ct0`。
+
+`sqlite/password-path` 保存密码文件位置，默认密码文件在 `/tmp/xgift-password-*`。请将原密码安全保存，`/tmp` 清理后不能恢复。也可通过 `XGIFT_PASSWORD_FILE` 或 CLI `--password-file` 指定持久路径。目录权限 `0700`，秘密文件 `0600`。
+
+`.private/`、`sqlite/`、数据库、日志、构建产物和环境秘密均不提交 Git。服务器密钥与本地密钥独立。本地 `.private/export/admin-password` 保存本次生成的后台密码，勿提交或分享。
+
+## 服务器部署
+
+目标服务器 `example-server`。使用专用无登录用户 `xgift`、systemd 服务和 Caddy HTTPS：
+
+| 路径 | 用途 |
+|---|---|
+| `/opt/xgift/bin/xgift-web` | 站点程序 |
+| `/opt/xgift/bin/xgift` | CLI，维护用 |
+| `/var/lib/xgift/vault.db` | 加密凭据及订单 |
+| `/var/lib/xgift/site.db` | 兑换码哈希、用户名、状态；访问权限保护，不是加密库 |
+| `/etc/xgift/vault-password` | 服务器独立密钥 |
+| `/etc/xgift/admin-password` | 后台密码 |
+| `/etc/xgift/site.env` | 服务配置，`XGIFT_PAYMENTS_ENABLED=false` |
+| `/etc/caddy/conf.d/xp.example.com.caddy` | 本站反向代理 |
+
+配置模板在 `deploy/`。程序仅允许绑定回环 IP；Caddy 必须覆盖 `X-Real-IP`，不能透传客户端提供的值。DNS 使用直连 A 记录，Caddy 自动签发 HTTPS 证书。现有站点配置不改动。
+
+```sh
+ssh example-server 'sudo systemctl status xgift --no-pager'
+ssh example-server 'sudo journalctl -u xgift --since "1 hour ago" --no-pager'
+```
+
+更新时先在服务器构建两个二进制，停止 `xgift`，备份数据及密钥，再替换程序并启动。不要覆盖线上 `site.db` 或用旧的本地 vault 覆盖线上订单。备份必须包含 `site.db`（停服或用 SQLite backup API，不能忽略 WAL）、`vault.db` 及独立密钥；所有备份同样限制权限。
+
+**开启付款前**：解决 Stripe HTTP 400、人工核实已有 `unknown` 订单，完成独立安全复查并取得新的实际付款指令。不要仅为试错打开环境开关。银行验证、风控和 X 赠送限制仍可能阻止自动完成。
diff --git a/cmd/xgift-web/main.go b/cmd/xgift-web/main.go
new file mode 100644
index 0000000..26cb7ab
--- /dev/null
+++ b/cmd/xgift-web/main.go
@@ -0,0 +1,18 @@
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"xgift/internal/site"
+)
+
+func main() {
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer cancel()
+	if err := site.Run(ctx); err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/cmd/xgift/main.go b/cmd/xgift/main.go
new file mode 100644
index 0000000..c50e6d9
--- /dev/null
+++ b/cmd/xgift/main.go
@@ -0,0 +1,268 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"xgift/internal/checkout"
+	"xgift/internal/chrome"
+	"xgift/internal/proxy"
+	"xgift/internal/vault"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, "xgift:", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	// Permit the requested `xgift username --pay` spelling as well as global flags.
+	args := os.Args[1:]
+	command := ""
+	rest := []string{}
+	for i := 0; i < len(args); i++ {
+		a := args[i]
+		if strings.HasPrefix(a, "-") {
+			rest = append(rest, a)
+			if a == "--db" || a == "--password-file" || a == "--profile" || a == "--port" || a == "--name" || a == "--months" {
+				i++
+				if i >= len(args) {
+					return errors.New("missing flag value")
+				}
+				rest = append(rest, args[i])
+			}
+		} else if command == "" {
+			command = a
+		} else {
+			return errors.New("unexpected argument")
+		}
+	}
+	f := flag.NewFlagSet("xgift", flag.ContinueOnError)
+	defaultDB := "sqlite/vault.db"
+	if exe, e := os.Executable(); e == nil {
+		if resolved, e := filepath.EvalSymlinks(exe); e == nil {
+			candidate := filepath.Join(filepath.Dir(resolved), "..", "sqlite", "vault.db")
+			if _, e = os.Stat(candidate); e == nil {
+				defaultDB = candidate
+			}
+		}
+	}
+	db := f.String("db", defaultDB, "encrypted SQLite record store")
+	key := f.String("password-file", os.Getenv("XGIFT_PASSWORD_FILE"), "owner-only password file")
+	profile := f.String("profile", "Default", "Chrome directory name")
+	port := f.Int("port", 0, "local proxy port; default automatic (proxy command: 18791)")
+	months := f.Int("months", 6, "Premium gift duration: 3 (300 BDT) or 6 (600 BDT)")
+	pay := f.Bool("pay", false, "pay only at the exact allowed BDT total")
+	name := f.String("name", "", "secret name for put")
+	f.Usage = func() {
+		fmt.Fprintln(f.Output(), "Usage: xgift <init|status|billing|import-chrome|put|proxy|check|username> [flags]\ninit reads a JSON object from stdin; put reads one JSON value from stdin.")
+		f.PrintDefaults()
+	}
+	if err := f.Parse(rest); err != nil {
+		if errors.Is(err, flag.ErrHelp) {
+			return nil
+		}
+		return err
+	}
+	if command == "" {
+		f.Usage()
+		return nil
+	}
+	if *port != 0 && (*port < 1024 || *port > 65535) {
+		return errors.New("port must be 1024..65535")
+	}
+	if command == "init" {
+		input, err := io.ReadAll(io.LimitReader(os.Stdin, 1024*1024))
+		if err != nil {
+			return err
+		}
+		defer clear(input)
+		var records map[string]json.RawMessage
+		if err = json.Unmarshal(input, &records); err != nil {
+			return errors.New("stdin must contain a JSON object of secrets")
+		}
+		if len(records) == 0 {
+			return errors.New("no secrets supplied")
+		}
+		if _, err = os.Stat(*db); !os.IsNotExist(err) {
+			return errors.New("vault already exists or path is inaccessible")
+		}
+		if *key == "" {
+			*key, err = vault.NewPassword()
+			if err != nil {
+				return err
+			}
+		}
+		v, err := vault.Open(*db, *key, true)
+		if err != nil {
+			return err
+		}
+		defer v.Close()
+		for n, b := range records {
+			if n == "vault-check" {
+				return errors.New("reserved secret name")
+			}
+			if err = v.Put(n, b); err != nil {
+				return err
+			}
+		}
+		// Save only the password's path, never the password, next to the vault.
+		if err = os.WriteFile(filepath.Join(filepath.Dir(*db), "password-path"), []byte(*key+"\n"), 0600); err != nil {
+			return err
+		}
+		fmt.Printf("Encrypted vault created: %s\nPassword file: %s\n", *db, *key)
+		return nil
+	}
+	if *key == "" {
+		p, err := os.ReadFile(filepath.Join(filepath.Dir(*db), "password-path"))
+		if err != nil {
+			return errors.New("set --password-file or XGIFT_PASSWORD_FILE")
+		}
+		*key = strings.TrimSpace(string(p))
+	}
+	v, err := vault.Open(*db, *key, false)
+	if err != nil {
+		return err
+	}
+	defer v.Close()
+	switch command {
+	case "billing":
+		raw, e := v.Get("card")
+		if e != nil {
+			return e
+		}
+		defer clear(raw)
+		var c map[string]any
+		if e = json.Unmarshal(raw, &c); e != nil {
+			return e
+		}
+		var fields map[string]string
+		if e = json.NewDecoder(io.LimitReader(os.Stdin, 65536)).Decode(&fields); e != nil {
+			return errors.New("billing expects a JSON object on stdin")
+		}
+		for n, value := range fields {
+			switch n {
+			case "billing_name", "email", "billing_country", "billing_postal_code", "billing_address_line1", "billing_city", "billing_state":
+				c[n] = value
+			default:
+				return errors.New("unsupported billing field")
+			}
+		}
+		raw, e = json.Marshal(c)
+		if e != nil {
+			return e
+		}
+		defer clear(raw)
+		if e = v.Put("card", raw); e != nil {
+			return e
+		}
+		fmt.Println("Billing information saved in encrypted SQLite")
+		return nil
+	case "status":
+		for _, n := range []string{"cookies", "card", "proxy"} {
+			b, e := v.Get(n)
+			if e != nil {
+				return e
+			}
+			if !json.Valid(b) {
+				return fmt.Errorf("invalid %s JSON", n)
+			}
+			clear(b)
+			fmt.Printf("%s: encrypted record verified\n", n)
+		}
+		return nil
+	case "import-chrome":
+		b, e := chrome.Extract(*profile)
+		if e != nil {
+			return e
+		}
+		defer clear(b)
+		if e = v.Put("cookies", b); e != nil {
+			return e
+		}
+		fmt.Println("X cookies refreshed in encrypted SQLite vault")
+		return nil
+	case "put":
+		if *name != "proxy" && *name != "card" && *name != "cookies" {
+			return errors.New("--name must be proxy, card or cookies")
+		}
+		b, e := io.ReadAll(io.LimitReader(os.Stdin, 1024*1024))
+		if e != nil {
+			return e
+		}
+		defer clear(b)
+		if !json.Valid(b) {
+			return errors.New("stdin must be valid JSON")
+		}
+		return v.Put(*name, b)
+	}
+	if command != "proxy" && command != "check" && !regexp.MustCompile(`^@?[A-Za-z0-9_]{1,15}$`).MatchString(command) {
+		return errors.New("invalid command or X username")
+	}
+	if command != "proxy" && command != "check" {
+		lock, e := os.OpenFile(filepath.Join(filepath.Dir(*db), "checkout.lock"), os.O_CREATE|os.O_RDWR, 0600)
+		if e != nil {
+			return e
+		}
+		defer lock.Close()
+		if e = syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); e != nil {
+			return errors.New("another checkout command is running")
+		}
+		defer syscall.Flock(int(lock.Fd()), syscall.LOCK_UN)
+	}
+	if *port == 0 {
+		if command == "proxy" {
+			*port = 18791
+		} else {
+			l, e := net.Listen("tcp", "127.0.0.1:0")
+			if e != nil {
+				return e
+			}
+			_, p, _ := net.SplitHostPort(l.Addr().String())
+			*port, _ = strconv.Atoi(p)
+			l.Close()
+		}
+	}
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer cancel()
+	config, err := v.Get("proxy")
+	if err != nil {
+		return err
+	}
+	defer clear(config)
+	instance, err := proxy.Start(ctx, config, *port)
+	if err != nil {
+		return err
+	}
+	defer instance.Close()
+	fmt.Fprintf(os.Stderr, "Embedded sing-box AnyTLS listening on 127.0.0.1:%d\n", *port)
+	if command == "proxy" {
+		<-ctx.Done()
+		return nil
+	}
+	if command == "check" {
+		return proxy.Check(ctx, *port)
+	}
+	result, e := checkout.Run(ctx, v, command, *pay, *port, *months)
+	if result != nil {
+		if e == nil || result.Status == "requires_action" || result.Status == "unknown" || result.Status == "submitting" {
+			fmt.Println(result.URL)
+		}
+		fmt.Fprintln(os.Stderr, "Checkout status:", result.Status)
+	}
+	return e
+}
diff --git a/deploy/Caddyfile b/deploy/Caddyfile
new file mode 100644
index 0000000..c0fe6f6
--- /dev/null
+++ b/deploy/Caddyfile
@@ -0,0 +1,7 @@
+xp.example.com {
+    encode zstd gzip
+    header Strict-Transport-Security "max-age=31536000"
+    reverse_proxy 127.0.0.1:8787 {
+        header_up X-Real-IP {remote_host}
+    }
+}
diff --git a/deploy/site.env.example b/deploy/site.env.example
new file mode 100644
index 0000000..ced37b1
--- /dev/null
+++ b/deploy/site.env.example
@@ -0,0 +1,6 @@
+XGIFT_ORIGIN=https://xp.example.com
+XGIFT_LISTEN=127.0.0.1:8787
+XGIFT_DATA_DIR=/var/lib/xgift
+XGIFT_PASSWORD_FILE=/etc/xgift/vault-password
+XGIFT_ADMIN_PASSWORD_FILE=/etc/xgift/admin-password
+XGIFT_PAYMENTS_ENABLED=false
diff --git a/deploy/xgift.service b/deploy/xgift.service
new file mode 100644
index 0000000..c148383
--- /dev/null
+++ b/deploy/xgift.service
@@ -0,0 +1,31 @@
+[Unit]
+Description=XGift redemption site
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=simple
+User=xgift
+Group=xgift
+WorkingDirectory=/opt/xgift
+EnvironmentFile=/etc/xgift/site.env
+ExecStart=/opt/xgift/bin/xgift-web
+Restart=on-failure
+RestartSec=5
+TimeoutStopSec=65
+UMask=0077
+NoNewPrivileges=true
+PrivateTmp=true
+PrivateDevices=true
+ProtectSystem=strict
+ProtectHome=true
+ProtectKernelTunables=true
+ProtectKernelModules=true
+ProtectControlGroups=true
+RestrictSUIDSGID=true
+ReadWritePaths=/var/lib/xgift
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX AF_NETLINK
+LimitCORE=0
+
+[Install]
+WantedBy=multi-user.target
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..f645d1c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,67 @@
+module xgift
+
+go 1.27.1
+
+require (
+	github.com/mattn/go-sqlite3 v1.14.52
+	github.com/sagernet/sing v0.9.6-0.20260922013354-87c33f17688f
+	github.com/sagernet/sing-box v1.14.2
+	golang.org/x/crypto v0.57.0
+)
+
+require (
+	github.com/andybalholm/brotli v1.1.0 // indirect
+	github.com/anytls/sing-anytls v0.0.11 // indirect
+	github.com/caddyserver/certmagic v0.25.3-0.20260421143802-60d9d8b415d6 // indirect
+	github.com/caddyserver/zerossl v0.1.5 // indirect
+	github.com/database64128/netx-go v0.1.1 // indirect
+	github.com/database64128/tfo-go/v2 v2.3.2 // indirect
+	github.com/florianl/go-nfqueue/v2 v2.1.0 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
+	github.com/go-chi/chi/v5 v5.2.5 // indirect
+	github.com/go-ole/go-ole v1.3.0 // indirect
+	github.com/godbus/dbus/v5 v5.2.2 // indirect
+	github.com/gofrs/uuid/v5 v5.5.1 // indirect
+	github.com/google/btree v1.1.3 // indirect
+	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/hashicorp/yamux v0.1.2 // indirect
+	github.com/jsimonetti/rtnetlink v1.4.1 // indirect
+	github.com/klauspost/compress v1.19.1 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
+	github.com/libdns/acmedns v0.5.0 // indirect
+	github.com/libdns/alidns v1.0.6 // indirect
+	github.com/libdns/cloudflare v0.2.2 // indirect
+	github.com/libdns/libdns v1.1.1 // indirect
+	github.com/logrusorgru/aurora v2.0.3+incompatible // indirect
+	github.com/mdlayher/netlink v1.11.2 // indirect
+	github.com/mdlayher/socket v0.6.0 // indirect
+	github.com/metacubex/utls v1.8.7 // indirect
+	github.com/mholt/acmez/v3 v3.1.6 // indirect
+	github.com/miekg/dns v1.1.72 // indirect
+	github.com/quic-go/qpack v0.6.0 // indirect
+	github.com/sagernet/bbolt v0.0.0-20260915102804-500ee1e84832 // indirect
+	github.com/sagernet/fswatch v0.1.2 // indirect
+	github.com/sagernet/gvisor v0.0.0-20260727.0-sing-box-mod.1 // indirect
+	github.com/sagernet/netlink v0.0.0-20260814022025-64455d367bbf // indirect
+	github.com/sagernet/nftables v0.3.0-mod.4 // indirect
+	github.com/sagernet/quic-go v0.61.0-sing-box-mod.7 // indirect
+	github.com/sagernet/sing-mux v0.3.8 // indirect
+	github.com/sagernet/sing-tun v0.9.6-0.20260924001923-ddaa4ca25e3b // indirect
+	github.com/sagernet/sing-usbip v0.0.0-20260817040617-28bd42667eca // indirect
+	github.com/sagernet/sing-vmess v0.2.8 // indirect
+	github.com/sagernet/smux v1.5.50-sing-box-mod.1 // indirect
+	github.com/vishvananda/netns v0.0.5 // indirect
+	github.com/zeebo/blake3 v0.2.4 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.1 // indirect
+	go.uber.org/zap/exp v0.3.0 // indirect
+	go4.org/netipx v0.0.0-20231129151722-fdeea329fbba // indirect
+	golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f // indirect
+	golang.org/x/mod v0.41.0 // indirect
+	golang.org/x/net v0.58.0 // indirect
+	golang.org/x/sync v0.23.0 // indirect
+	golang.org/x/sys v0.48.0 // indirect
+	golang.org/x/text v0.42.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
+	golang.org/x/tools v0.49.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..a8bfed4
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,141 @@
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+golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f h1:W3F4c+6OLc6H2lb//N1q4WpJkhzJCK5J6kUi1NTVXfM=
+golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f/go.mod h1:J1xhfL/vlindoeF/aINzNzt2Bket5bjo9sdOYzOsU80=
+golang.org/x/mod v0.41.0 h1:qJmnOUb4YB+FsEuM3HcWucdZASCPGhsX6uljO6pog0c=
+golang.org/x/mod v0.41.0/go.mod h1:Ek9pY8RKWXwsWvd3rQiHYtMqkjSUV+s1Rj7j4H5Ur6o=
+golang.org/x/net v0.58.0 h1:ynWG7rqYi4ccpTEuPZ2QGWHktVEM9DMCj9yzDE0Q7To=
+golang.org/x/net v0.58.0/go.mod h1:YwCddHnFlT7eLQqVprV19OnhLGtc5xOKgE0RyqgfWAU=
+golang.org/x/sync v0.23.0 h1:KameEIfc1IkluZyXWLn39Wd4tURc6GbCiISGiZm2bQk=
+golang.org/x/sync v0.23.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
+golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
+golang.org/x/term v0.46.0 h1:3+OXuTbaKDgwk8jTi3aSLHRlmWqHEUDUtxnbFigO4YE=
+golang.org/x/term v0.46.0/go.mod h1:+K02xbkittuwc0Am4abfA3Fc+XRGXkvBXNO88NCXPoc=
+golang.org/x/text v0.42.0 h1:JbOZXgfeCPU9gacVtYliJqOhD+zhrEqK4LfdpmlUZqI=
+golang.org/x/text v0.42.0/go.mod h1:ojzP1Z+2QtioaF8DTtO8K5q7JWVVYwZKenzujK0Zd0E=
+golang.org/x/time v0.15.0 h1:bbrp8t3bGUeFOx08pvsMYRTCVSMk89u4tKbNOZbp88U=
+golang.org/x/time v0.15.0/go.mod h1:Y4YMaQmXwGQZoFaVFk4YpCt4FLQMYKZe9oeV/f4MSno=
+golang.org/x/tools v0.49.0 h1:3NI7VXzL9+1WZD52Dx2ttoPwD5DWrFGpl9mFZDlmisI=
+golang.org/x/tools v0.49.0/go.mod h1:SJNXV9DBKT0UbdttsQjbfJlAE/q+y36++zo3uL3N0Oo=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/checkout/checkout.go b/internal/checkout/checkout.go
new file mode 100644
index 0000000..b98d3ae
--- /dev/null
+++ b/internal/checkout/checkout.go
@@ -0,0 +1,195 @@
+package checkout
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+	"regexp"
+	"strings"
+	"time"
+	"xgift/internal/vault"
+)
+
+type Record struct {
+	Username    string `json:"username"`
+	RecipientID string `json:"recipient_id"`
+	Months      int    `json:"months"`
+	Amount      int    `json:"amount_minor"`
+	Currency    string `json:"currency"`
+	ProductID   string `json:"product_id"`
+	SessionID   string `json:"session_id"`
+	URL         string `json:"url"`
+	Status      string `json:"status"`
+	Created     int64  `json:"created"`
+}
+
+var sessionPattern = regexp.MustCompile(`^cs_live_[A-Za-z0-9]+$`)
+
+func sessionURL(link, id string) bool {
+	u, e := url.Parse(link)
+	return e == nil && sessionPattern.MatchString(id) && u.Scheme == "https" && u.Host == "checkout.stripe.com" && u.User == nil && u.RawQuery == "" && (u.Path == "/g/pay/"+id || u.Path == "/c/pay/"+id)
+}
+func save(v *vault.Vault, r *Record) error {
+	b, e := json.Marshal(r)
+	if e != nil {
+		return e
+	}
+	return v.Put("checkout:"+r.RecipientID, b)
+}
+func Run(ctx context.Context, v *vault.Vault, user string, pay bool, port, months int) (*Record, error) {
+	return run(ctx, v, user, "", pay, port, months)
+}
+
+// RunForRecipient pins a redemption to the identity checked before reserving its code.
+func RunForRecipient(ctx context.Context, v *vault.Vault, user, expectedRecipient string, pay bool, port, months int) (*Record, error) {
+	if expectedRecipient == "" {
+		return nil, errors.New("expected recipient is required")
+	}
+	return run(ctx, v, user, expectedRecipient, pay, port, months)
+}
+
+func run(ctx context.Context, v *vault.Vault, user, expectedRecipient string, pay bool, port, months int) (*Record, error) {
+	user = strings.ToLower(strings.TrimPrefix(user, "@"))
+	if !regexp.MustCompile(`^[a-z0-9_]{1,15}$`).MatchString(user) {
+		return nil, errors.New("invalid username")
+	}
+	plan, e := planFor(months)
+	if e != nil {
+		return nil, e
+	}
+	x, e := newXClient(v, port)
+	if e != nil {
+		return nil, e
+	}
+	defer x.close()
+	recipient, e := x.recipient(ctx, user)
+	if e != nil {
+		return nil, e
+	}
+	if expectedRecipient != "" && recipient != expectedRecipient {
+		return nil, errors.New("recipient identity changed; refusing to create or pay an order")
+	}
+	// Fail closed on legacy records rather than silently bypassing an earlier attempt.
+	if _, e = v.Get("checkout:" + user); e == nil {
+		return nil, errors.New("legacy checkout requires migration before creating another order")
+	} else if !errors.Is(e, sql.ErrNoRows) {
+		return nil, e
+	}
+	var r Record
+	raw, e := v.Get("checkout:" + recipient)
+	if e == nil {
+		if json.Unmarshal(raw, &r) != nil || r.RecipientID != recipient || r.Months != plan.Months || r.Amount != plan.Minor || r.Currency != "BDT" || r.ProductID != plan.ProductID || !sessionURL(r.URL, r.SessionID) {
+			return nil, errors.New("existing checkout differs from this recipient or plan; refusing another order")
+		}
+	} else if !errors.Is(e, sql.ErrNoRows) {
+		return nil, e
+	}
+	if r.Status == "succeeded" {
+		return &r, nil
+	}
+	if r.Status != "" && r.Status != "created" && r.Status != "creating" {
+		return &r, fmt.Errorf("existing checkout status is %s; no payment will be resubmitted", r.Status)
+	}
+	if r.Status == "creating" {
+		return &r, errors.New("previous checkout creation outcome is unknown; inspect it before creating another")
+	}
+	if e = x.quote(ctx, user, plan); e != nil {
+		return nil, e
+	}
+	if r.SessionID == "" {
+		r = Record{Username: user, RecipientID: recipient, Months: plan.Months, Amount: plan.Minor, Currency: "BDT", ProductID: plan.ProductID, Status: "creating", Created: time.Now().Unix()}
+		// Persist before creating the external session. A crash must not silently create a second session.
+		if e = save(v, &r); e != nil {
+			return nil, e
+		}
+		r.SessionID, r.URL, e = x.create(ctx, user, recipient, plan)
+		if e != nil {
+			return &r, e
+		}
+		r.Status = "created"
+		if e = save(v, &r); e != nil {
+			return &r, e
+		}
+	}
+	s, e := newStripe(v, port)
+	if e != nil {
+		return &r, e
+	}
+	defer s.close()
+	page, e := s.page(ctx, &r, true)
+	if e != nil {
+		return &r, e
+	}
+	if e = page.guard(&r, plan, false); e != nil {
+		return &r, e
+	}
+	if page.PaymentStatus == "paid" && page.Status == "complete" {
+		r.Status = "succeeded"
+		return &r, save(v, &r)
+	}
+	if e = page.guard(&r, plan, true); e != nil {
+		return &r, e
+	}
+	if !pay {
+		return &r, nil
+	}
+	c, e := readCard(v)
+	if e != nil {
+		return &r, e
+	}
+	method, e := s.tokenize(ctx, &r, c)
+	if e != nil {
+		return &r, e
+	}
+	// Refresh after card creation; confirmation also pins the expected amount server-side.
+	page, e = s.page(ctx, &r, true)
+	if e != nil {
+		return &r, e
+	}
+	if e = page.guard(&r, plan, true); e != nil {
+		return &r, e
+	}
+	r.Status = "submitting"
+	if e = save(v, &r); e != nil {
+		return &r, e
+	}
+	_, confirmErr := s.confirm(ctx, &r, page, method, plan)
+	// Never issue confirm twice, even if the response is lost or a validation error occurs.
+	for i := 0; i < 6; i++ {
+		if i > 0 {
+			select {
+			case <-ctx.Done():
+				break
+			case <-time.After(2 * time.Second):
+			}
+		}
+		current, readErr := s.page(ctx, &r, true)
+		if readErr == nil && current.guard(&r, plan, false) == nil {
+			if current.Status == "complete" && current.PaymentStatus == "paid" {
+				r.Status = "succeeded"
+				return &r, save(v, &r)
+			}
+			if current.Intent != nil && current.Intent.Status == "requires_action" {
+				r.Status = "requires_action"
+				if e = save(v, &r); e != nil {
+					return &r, e
+				}
+				return &r, errors.New("bank authentication is required; use this existing checkout")
+			}
+		}
+		if confirmErr != nil {
+			break
+		}
+	}
+	r.Status = "unknown"
+	if e = save(v, &r); e != nil {
+		return &r, e
+	}
+	if confirmErr != nil {
+		return &r, confirmErr
+	}
+	return &r, errors.New("Stripe has not confirmed payment; automatic retry is blocked")
+}
diff --git a/internal/checkout/stripe.go b/internal/checkout/stripe.go
new file mode 100644
index 0000000..62420d6
--- /dev/null
+++ b/internal/checkout/stripe.go
@@ -0,0 +1,252 @@
+package checkout
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+	"xgift/internal/vault"
+)
+
+const xMerchant = "acct_EXAMPLE"
+
+type stripeClient struct {
+	http *http.Client
+	key  string
+}
+type stripeError struct {
+	Code, Type string
+	HTTP       int
+}
+
+func (e *stripeError) Error() string {
+	return fmt.Sprintf("Stripe rejected the request (HTTP %d, type=%s, code=%s)", e.HTTP, e.Type, e.Code)
+}
+func newStripe(v *vault.Vault, port int) (*stripeClient, error) {
+	key, e := v.Get("stripe-key")
+	if e != nil {
+		return nil, e
+	}
+	if !regexp.MustCompile(`^pk_live_[A-Za-z0-9]+$`).Match(key) {
+		return nil, errors.New("invalid Stripe merchant publishable key")
+	}
+	p, _ := url.Parse(fmt.Sprintf("http://127.0.0.1:%d", port))
+	return &stripeClient{http: &http.Client{Transport: &http.Transport{Proxy: http.ProxyURL(p), TLSHandshakeTimeout: 15 * time.Second}, Timeout: 35 * time.Second, CheckRedirect: func(*http.Request, []*http.Request) error { return errors.New("unexpected Stripe API redirect") }}, key: string(key)}, nil
+}
+func (s *stripeClient) close() { s.http.CloseIdleConnections() }
+func (s *stripeClient) call(ctx context.Context, method, path string, form url.Values, idempotency string, out any) error {
+	form.Set("key", s.key)
+	target := "https://api.stripe.com/v1/" + path
+	var input io.Reader
+	if method == "GET" {
+		target += "?" + form.Encode()
+	} else {
+		input = strings.NewReader(form.Encode())
+	}
+	req, e := http.NewRequestWithContext(ctx, method, target, input)
+	if e != nil {
+		return e
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	if idempotency != "" {
+		req.Header.Set("Idempotency-Key", idempotency)
+	}
+	res, e := s.http.Do(req)
+	if e != nil {
+		return errors.New("Stripe transport failed; request outcome may be unknown")
+	}
+	defer res.Body.Close()
+	raw, e := io.ReadAll(io.LimitReader(res.Body, 2<<20))
+	if e != nil {
+		return errors.New("Stripe response could not be read")
+	}
+	defer clear(raw)
+	var envelope struct {
+		Error *struct{ Type, Code string } `json:"error"`
+	}
+	if json.Unmarshal(raw, &envelope) != nil {
+		return errors.New("Stripe returned non-JSON data")
+	}
+	if envelope.Error != nil {
+		return &stripeError{Code: envelope.Error.Code, Type: envelope.Error.Type, HTTP: res.StatusCode}
+	}
+	if res.StatusCode != 200 {
+		return &stripeError{HTTP: res.StatusCode}
+	}
+	return json.Unmarshal(raw, out)
+}
+
+type paymentPage struct {
+	SessionID     string `json:"session_id"`
+	Currency      string `json:"currency"`
+	Mode          string `json:"mode"`
+	Live          bool   `json:"livemode"`
+	Status        string `json:"status"`
+	PaymentStatus string `json:"payment_status"`
+	Checksum      string `json:"init_checksum"`
+	SuccessURL    string `json:"success_url"`
+	CancelURL     string `json:"cancel_url"`
+	Account       struct {
+		ID string `json:"account_id"`
+	} `json:"account_settings"`
+	SetupFuture  json.RawMessage                    `json:"setup_future_usage"`
+	Subscription json.RawMessage                    `json:"subscription_data"`
+	SetupIntent  json.RawMessage                    `json:"setup_intent"`
+	Total        struct{ Due, Subtotal, Total int } `json:"total_summary"`
+	Group        struct {
+		Currency             string `json:"currency"`
+		Due, Subtotal, Total int
+		Items                []struct {
+			Name                      string `json:"name"`
+			Quantity, Subtotal, Total int
+			Price                     struct {
+				Currency, Type string
+				UnitAmount     int             `json:"unit_amount"`
+				Recurring      json.RawMessage `json:"recurring"`
+				Product        struct {
+					ID, Name string
+					Live     bool `json:"livemode"`
+				} `json:"product"`
+			} `json:"price"`
+		} `json:"line_items"`
+	} `json:"line_item_group"`
+	Intent *struct {
+		ID, Status, Currency string
+		Amount               int
+		AmountReceived       int `json:"amount_received"`
+	} `json:"payment_intent"`
+}
+
+func nullJSON(v json.RawMessage) bool { return len(v) == 0 || string(v) == "null" }
+func (p *paymentPage) guard(r *Record, plan Plan, before bool) error {
+	if p.SessionID != r.SessionID || p.Account.ID != xMerchant || !p.Live || p.Mode != "payment" || p.Currency != "bdt" || p.Group.Currency != "bdt" || p.SuccessURL != "https://x.com/"+r.Username+"/gift-premium/success" || p.CancelURL != "https://x.com/"+r.Username+"/gift-premium" {
+		return errors.New("Stripe merchant, session, recipient return URLs, currency or payment mode mismatch")
+	}
+	if !nullJSON(p.SetupFuture) || !nullJSON(p.Subscription) || !nullJSON(p.SetupIntent) {
+		return errors.New("recurring payments or saved-card setup are not allowed")
+	}
+	if p.Total.Total != plan.Minor || p.Total.Subtotal != plan.Minor || p.Group.Total != plan.Minor || p.Group.Subtotal != plan.Minor || len(p.Group.Items) != 1 {
+		return errors.New("Stripe final total or line item count does not match the exact allowed price")
+	}
+	item := p.Group.Items[0]
+	if item.Name != plan.Name() || item.Quantity != 1 || item.Subtotal != plan.Minor || item.Total != plan.Minor || item.Price.Currency != "bdt" || item.Price.Type != "one_time" || item.Price.UnitAmount != plan.Minor || !nullJSON(item.Price.Recurring) || item.Price.Product.ID != plan.ProductID || item.Price.Product.Name != plan.Name() || !item.Price.Product.Live {
+		return errors.New("Stripe product, duration, quantity or unit amount mismatch")
+	}
+	if p.Intent != nil {
+		if p.Intent.Currency != "bdt" || p.Intent.Amount != plan.Minor {
+			return errors.New("Stripe payment intent amount or currency mismatch")
+		}
+		if before {
+			return errors.New("an existing payment intent requires inspection before another submission")
+		}
+		if p.PaymentStatus == "paid" && (p.Intent.Status != "succeeded" || p.Intent.AmountReceived != plan.Minor) {
+			return errors.New("Stripe payment intent does not confirm the exact received amount")
+		}
+	}
+	if before && (p.Status != "open" || p.PaymentStatus != "unpaid" || p.Total.Due != plan.Minor || p.Group.Due != plan.Minor || p.Checksum == "") {
+		return errors.New("Stripe checkout is not open and unpaid at the exact authorized amount")
+	}
+	return nil
+}
+func (s *stripeClient) page(ctx context.Context, r *Record, init bool) (*paymentPage, error) {
+	method, path := "GET", "payment_pages/"+r.SessionID
+	form := url.Values{}
+	if init {
+		method = "POST"
+		path += "/init"
+		form.Set("browser_locale", "en")
+		form.Set("redirect_type", "url")
+	}
+	var page paymentPage
+	e := s.call(ctx, method, path, form, "", &page)
+	return &page, e
+}
+
+type card struct {
+	Number  string `json:"number"`
+	Month   string `json:"exp_month"`
+	Year    string `json:"exp_year"`
+	CVC     string `json:"cvc"`
+	Name    string `json:"billing_name"`
+	Email   string `json:"email"`
+	Country string `json:"billing_country"`
+	Postal  string `json:"billing_postal_code"`
+}
+
+func readCard(v *vault.Vault) (card, error) {
+	raw, e := v.Get("card")
+	if e != nil {
+		return card{}, e
+	}
+	defer clear(raw)
+	var c card
+	if json.Unmarshal(raw, &c) != nil {
+		return c, errors.New("invalid card record")
+	}
+	if !regexp.MustCompile(`^[0-9]{12,19}$`).MatchString(c.Number) || !regexp.MustCompile(`^(0[1-9]|1[0-2])$`).MatchString(c.Month) || !regexp.MustCompile(`^[0-9]{4}$`).MatchString(c.Year) || !regexp.MustCompile(`^[0-9]{3,4}$`).MatchString(c.CVC) || strings.TrimSpace(c.Name) == "" || !strings.Contains(c.Email, "@") {
+		return c, errors.New("card, cardholder name or email is incomplete")
+	}
+	sum := 0
+	for i, n := range c.Number {
+		d := int(n - '0')
+		if (len(c.Number)-i)%2 == 0 {
+			d *= 2
+			if d > 9 {
+				d -= 9
+			}
+		}
+		sum += d
+	}
+	if sum%10 != 0 {
+		return c, errors.New("card number checksum is invalid")
+	}
+	year, _ := strconv.Atoi(c.Year)
+	month, _ := strconv.Atoi(c.Month)
+	if !time.Now().Before(time.Date(year, time.Month(month)+1, 1, 0, 0, 0, 0, time.UTC)) {
+		return c, errors.New("card has expired")
+	}
+	if c.Country != "" && !regexp.MustCompile(`^[A-Z]{2}$`).MatchString(c.Country) {
+		return c, errors.New("invalid supplied billing country")
+	}
+	return c, nil
+}
+func (s *stripeClient) tokenize(ctx context.Context, r *Record, c card) (string, error) {
+	form := url.Values{"type": {"card"}, "card[number]": {c.Number}, "card[exp_month]": {c.Month}, "card[exp_year]": {c.Year}, "card[cvc]": {c.CVC}, "billing_details[name]": {c.Name}, "billing_details[email]": {c.Email}}
+	if c.Country != "" {
+		form.Set("billing_details[address][country]", c.Country)
+	}
+	if c.Postal != "" {
+		form.Set("billing_details[address][postal_code]", c.Postal)
+	}
+	var pm struct {
+		ID, Type string
+		Live     bool `json:"livemode"`
+	}
+	e := s.call(ctx, "POST", "payment_methods", form, idempotency(r, "method"), &pm)
+	if e != nil {
+		return "", e
+	}
+	if !pm.Live || pm.Type != "card" || !regexp.MustCompile(`^pm_[A-Za-z0-9]+$`).MatchString(pm.ID) {
+		return "", errors.New("invalid Stripe card token")
+	}
+	return pm.ID, nil
+}
+func idempotency(r *Record, operation string) string {
+	sum := sha256.Sum256([]byte("xgift-v1:" + operation + ":" + r.SessionID + ":" + r.RecipientID + ":" + strconv.Itoa(r.Months)))
+	return "xgift-" + hex.EncodeToString(sum[:])
+}
+func (s *stripeClient) confirm(ctx context.Context, r *Record, p *paymentPage, method string, plan Plan) (*paymentPage, error) {
+	form := url.Values{"payment_method": {method}, "expected_amount": {strconv.Itoa(plan.Minor)}, "expected_payment_method_type": {"card"}, "init_checksum": {p.Checksum}, "return_url": {"https://x.com/" + r.Username + "/gift-premium/success"}, "save_payment_method": {"false"}}
+	var result paymentPage
+	e := s.call(ctx, "POST", "payment_pages/"+r.SessionID+"/confirm", form, idempotency(r, "confirm"), &result)
+	return &result, e
+}
diff --git a/internal/checkout/xapi.go b/internal/checkout/xapi.go
new file mode 100644
index 0000000..b59798c
--- /dev/null
+++ b/internal/checkout/xapi.go
@@ -0,0 +1,216 @@
+package checkout
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+	"xgift/internal/vault"
+)
+
+type Plan struct {
+	Months, Minor int
+	ProductID     string
+}
+
+var ErrNotEligible = errors.New("recipient cannot receive Premium gifts")
+var ErrUserNotFound = errors.New("recipient was not found")
+
+// Eligibility is read-only: it neither creates a checkout nor submits a payment.
+func Eligibility(ctx context.Context, v *vault.Vault, user string, port int) (string, error) {
+	c, err := newXClient(v, port)
+	if err != nil {
+		return "", err
+	}
+	defer c.close()
+	return c.recipient(ctx, user)
+}
+
+func planFor(months int) (Plan, error) {
+	switch months {
+	case 3:
+		return Plan{3, 30000, "prod_EXAMPLE3MO"}, nil
+	case 6:
+		return Plan{6, 60000, "prod_EXAMPLE6MO"}, nil
+	}
+	return Plan{}, errors.New("only 3 months / 300 BDT or 6 months / 600 BDT are allowed")
+}
+func (p Plan) Name() string { return fmt.Sprintf("Premium Gift - %d months", p.Months) }
+
+type xClient struct {
+	http    *http.Client
+	headers http.Header
+}
+
+func newXClient(v *vault.Vault, port int) (*xClient, error) {
+	raw, e := v.Get("api-auth")
+	if e != nil {
+		return nil, errors.New("X API authentication metadata is missing or unreadable")
+	}
+	defer clear(raw)
+	var auth struct{ Authorization, UserAgent string }
+	if json.Unmarshal(raw, &auth) != nil || !strings.HasPrefix(auth.Authorization, "Bearer ") {
+		return nil, errors.New("invalid X API authentication metadata")
+	}
+	raw, e = v.Get("cookies")
+	if e != nil {
+		return nil, e
+	}
+	defer clear(raw)
+	var state struct {
+		Cookies []struct{ Name, Value, Domain string }
+	}
+	if e = json.Unmarshal(raw, &state); e != nil {
+		return nil, e
+	}
+	h := http.Header{"Authorization": {auth.Authorization}, "User-Agent": {auth.UserAgent}, "Content-Type": {"application/json"}, "Origin": {"https://x.com"}, "X-Twitter-Auth-Type": {"OAuth2Session"}, "X-Twitter-Active-User": {"yes"}, "X-Twitter-Client-Language": {"en"}}
+	found := map[string]bool{}
+	for _, c := range state.Cookies {
+		if c.Domain != ".x.com" && c.Domain != "x.com" {
+			return nil, errors.New("unexpected cookie domain")
+		}
+		if c.Name != "auth_token" && c.Name != "ct0" {
+			return nil, errors.New("unexpected cookie name")
+		}
+		if found[c.Name] || c.Value == "" || strings.ContainsAny(c.Value, "\r\n;") {
+			return nil, errors.New("invalid X cookie")
+		}
+		found[c.Name] = true
+		h.Add("Cookie", c.Name+"="+c.Value)
+		if c.Name == "ct0" {
+			h.Set("X-Csrf-Token", c.Value)
+		}
+	}
+	if !found["ct0"] || !found["auth_token"] {
+		return nil, errors.New("required X cookies missing")
+	}
+	p, _ := url.Parse(fmt.Sprintf("http://127.0.0.1:%d", port))
+	client := &http.Client{Transport: &http.Transport{Proxy: http.ProxyURL(p), TLSHandshakeTimeout: 15 * time.Second}, Timeout: 30 * time.Second, CheckRedirect: func(*http.Request, []*http.Request) error { return errors.New("unexpected X API redirect") }}
+	return &xClient{client, h}, nil
+}
+func (c *xClient) close() { c.http.CloseIdleConnections() }
+func (c *xClient) call(ctx context.Context, user, name, id string, variables any, mutation bool, out any) error {
+	target := "https://x.com/i/api/graphql/" + id + "/" + name
+	method := "GET"
+	var body []byte
+	if mutation {
+		method = "POST"
+		body, _ = json.Marshal(map[string]any{"variables": variables, "queryId": id})
+	} else {
+		b, _ := json.Marshal(variables)
+		q := url.Values{"variables": {string(b)}}
+		if name == "useSubscriptionProductDetailsByRestIdQuery" {
+			q.Set("features", `{"subscriptions_marketing_page_fetch_promotions":true}`)
+		}
+		target += "?" + q.Encode()
+	}
+	req, e := http.NewRequestWithContext(ctx, method, target, bytes.NewReader(body))
+	if e != nil {
+		return e
+	}
+	req.Header = c.headers.Clone()
+	req.Header.Set("Referer", "https://x.com/"+user+"/gift-premium")
+	res, e := c.http.Do(req)
+	if e != nil {
+		return fmt.Errorf("X %s request failed", name)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != 200 {
+		return fmt.Errorf("X %s returned HTTP %d; no payment attempted", name, res.StatusCode)
+	}
+	raw, e := io.ReadAll(io.LimitReader(res.Body, 2<<20))
+	if e != nil {
+		return e
+	}
+	var envelope struct {
+		Errors []json.RawMessage `json:"errors"`
+	}
+	if e = json.Unmarshal(raw, &envelope); e != nil {
+		return errors.New("X returned non-JSON data")
+	}
+	if len(envelope.Errors) > 0 {
+		return fmt.Errorf("X %s rejected the operation", name)
+	}
+	return json.Unmarshal(raw, out)
+}
+func (c *xClient) recipient(ctx context.Context, user string) (string, error) {
+	var r struct {
+		Data struct {
+			User struct {
+				Result struct {
+					ID       string `json:"rest_id"`
+					Eligible bool   `json:"premium_gifting_eligible"`
+					Core     struct {
+						Screen string `json:"screen_name"`
+					} `json:"core"`
+				} `json:"result"`
+			} `json:"user"`
+		} `json:"data"`
+	}
+	if e := c.call(ctx, user, "PremiumGiftingQuery", "kn8hCE6bHstQV2MtfYDTKg", map[string]string{"screenName": user}, false, &r); e != nil {
+		return "", e
+	}
+	u := r.Data.User.Result
+	if u.ID == "" {
+		return "", ErrUserNotFound
+	}
+	if !strings.EqualFold(u.Core.Screen, user) {
+		return "", errors.New("recipient identity or gift eligibility could not be verified")
+	}
+	if !u.Eligible {
+		return "", ErrNotEligible
+	}
+	return u.ID, nil
+}
+func (c *xClient) quote(ctx context.Context, user string, p Plan) error {
+	var r struct {
+		Data struct {
+			Product struct {
+				ID     string `json:"rest_id"`
+				Prices []struct {
+					Amount   int64  `json:"amount_local_micro"`
+					Currency string `json:"currency_code"`
+					Type     string `json:"price_type"`
+				} `json:"prices"`
+			} `json:"web_subscription_product_details_by_rest_id"`
+		} `json:"data"`
+	}
+	if e := c.call(ctx, user, "useSubscriptionProductDetailsByRestIdQuery", "Se1Bp6zcNnuXYXRecV2qLA", map[string]string{"stripeId": p.ProductID}, false, &r); e != nil {
+		return e
+	}
+	product := r.Data.Product
+	if product.ID != p.ProductID || len(product.Prices) != 1 {
+		return errors.New("unexpected X product or price list")
+	}
+	price := product.Prices[0]
+	if price.Type != "OneTime" || !strings.EqualFold(price.Currency, "bdt") || price.Amount != int64(p.Minor)*10000 {
+		return errors.New("X price is not exactly the allowed one-time BDT amount")
+	}
+	return nil
+}
+func (c *xClient) create(ctx context.Context, user, recipient string, p Plan) (string, string, error) {
+	var r struct {
+		Data struct {
+			Gift struct {
+				ID     string `json:"session_id"`
+				URL    string `json:"session_url"`
+				Status string `json:"session_status"`
+			} `json:"onetimepurchase_gift"`
+		} `json:"data"`
+	}
+	variables := map[string]string{"cancel_url": "https://x.com/" + user + "/gift-premium", "success_url": "https://x.com/" + user + "/gift-premium/success", "external_product_id": p.ProductID, "gift_recipient": recipient}
+	if e := c.call(ctx, user, "useOneTimePurchaseGiftMutation", "GqTVJ4S1526tLkxj69xIZw", variables, true, &r); e != nil {
+		return "", "", e
+	}
+	s := r.Data.Gift
+	if s.Status != "Unpaid" || !sessionURL(s.URL, s.ID) {
+		return "", "", errors.New("X did not return an unpaid matching Stripe checkout")
+	}
+	return s.ID, s.URL, nil
+}
diff --git a/internal/chrome/chrome.go b/internal/chrome/chrome.go
new file mode 100644
index 0000000..42fb8ed
--- /dev/null
+++ b/internal/chrome/chrome.go
@@ -0,0 +1,122 @@
+package chrome
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/sha1"
+	"crypto/sha256"
+	"database/sql"
+	"encoding/json"
+	"errors"
+	"fmt"
+	_ "github.com/mattn/go-sqlite3"
+	"golang.org/x/crypto/pbkdf2"
+	"net/url"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"time"
+)
+
+// Extract only the two X authentication cookies. No other site's credentials are read.
+func Extract(profile string) ([]byte, error) {
+	if profile != "Default" && !regexp.MustCompile(`^Profile [0-9]+$`).MatchString(profile) {
+		return nil, errors.New("invalid Chrome profile directory")
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil, err
+	}
+	path := filepath.Join(home, "Library/Application Support/Google/Chrome", profile, "Cookies")
+	if _, err = os.Stat(path); err != nil {
+		path = filepath.Join(filepath.Dir(path), "Network", "Cookies")
+	}
+	u := url.URL{Scheme: "file", Path: path, RawQuery: "mode=ro"}
+	db, err := sql.Open("sqlite3", u.String())
+	if err != nil {
+		return nil, err
+	}
+	defer db.Close()
+	var versionText string
+	if err = db.QueryRow("SELECT value FROM meta WHERE key='version'").Scan(&versionText); err != nil {
+		return nil, err
+	}
+	version, err := strconv.Atoi(versionText)
+	if err != nil {
+		return nil, err
+	}
+	secret, err := exec.Command("security", "find-generic-password", "-w", "-s", "Chrome Safe Storage").Output()
+	if err != nil {
+		return nil, errors.New("Chrome Safe Storage unavailable")
+	}
+	defer clear(secret)
+	key := pbkdf2.Key(bytes.TrimSuffix(secret, []byte("\n")), []byte("saltysalt"), 1003, 16, sha1.New)
+	defer clear(key)
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	rows, err := db.Query("SELECT host_key,name,value,encrypted_value,path,is_secure,is_httponly,expires_utc,samesite FROM cookies WHERE host_key IN ('.x.com','x.com') AND name IN ('auth_token','ct0')")
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	cookies := []map[string]any{}
+	found := map[string]bool{}
+	for rows.Next() {
+		var host, name, value, path string
+		var encrypted []byte
+		var secure, httpOnly, sameSite int
+		var expires int64
+		if err = rows.Scan(&host, &name, &value, &encrypted, &path, &secure, &httpOnly, &expires, &sameSite); err != nil {
+			return nil, err
+		}
+		if len(encrypted) > 0 {
+			if !bytes.HasPrefix(encrypted, []byte("v10")) || (len(encrypted)-3)%aes.BlockSize != 0 || len(encrypted) < 19 {
+				return nil, errors.New("unsupported cookie encryption")
+			}
+			raw := make([]byte, len(encrypted)-3)
+			cipher.NewCBCDecrypter(block, bytes.Repeat([]byte(" "), 16)).CryptBlocks(raw, encrypted[3:])
+			pad := int(raw[len(raw)-1])
+			if pad < 1 || pad > 16 || !bytes.Equal(raw[len(raw)-pad:], bytes.Repeat([]byte{byte(pad)}, pad)) {
+				return nil, errors.New("cookie decryption failed")
+			}
+			raw = raw[:len(raw)-pad]
+			if version >= 24 {
+				digest := sha256.Sum256([]byte(host))
+				if len(raw) < 32 || !bytes.Equal(raw[:32], digest[:]) {
+					return nil, errors.New("cookie integrity check failed")
+				}
+				raw = raw[32:]
+			}
+			value = string(raw)
+			clear(raw)
+		}
+		expiry := float64(-1)
+		if expires > 0 {
+			expiry = float64(expires)/1e6 - 11644473600
+			if expiry < float64(time.Now().Unix()) {
+				return nil, fmt.Errorf("X cookie %s expired", name)
+			}
+		}
+		same := "Lax"
+		if sameSite == 0 {
+			same = "None"
+		}
+		if sameSite == 2 {
+			same = "Strict"
+		}
+		cookies = append(cookies, map[string]any{"name": name, "value": value, "domain": host, "path": path, "secure": secure != 0, "httpOnly": httpOnly != 0, "expires": expiry, "sameSite": same})
+		found[name] = true
+	}
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+	if !found["auth_token"] || !found["ct0"] {
+		return nil, errors.New("required X cookies not found")
+	}
+	return json.Marshal(map[string]any{"cookies": cookies, "origins": []any{}})
+}
diff --git a/internal/proxy/proxy.go b/internal/proxy/proxy.go
new file mode 100644
index 0000000..fdd5b9a
--- /dev/null
+++ b/internal/proxy/proxy.go
@@ -0,0 +1,72 @@
+package proxy
+
+import (
+	"context"
+	stdjson "encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	box "github.com/sagernet/sing-box"
+	"github.com/sagernet/sing-box/adapter/certificate"
+	"github.com/sagernet/sing-box/adapter/endpoint"
+	"github.com/sagernet/sing-box/adapter/inbound"
+	"github.com/sagernet/sing-box/adapter/outbound"
+	boxservice "github.com/sagernet/sing-box/adapter/service"
+	"github.com/sagernet/sing-box/dns"
+	"github.com/sagernet/sing-box/dns/transport/local"
+	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing-box/protocol/anytls"
+	"github.com/sagernet/sing-box/protocol/mixed"
+	"github.com/sagernet/sing/common/json"
+)
+
+func Start(ctx context.Context, config []byte, port int) (*box.Box, error) {
+	in := inbound.NewRegistry()
+	mixed.RegisterInbound(in)
+	out := outbound.NewRegistry()
+	anytls.RegisterOutbound(out)
+	d := dns.NewTransportRegistry()
+	local.RegisterTransport(d)
+	ctx = box.Context(ctx, in, out, endpoint.NewRegistry(), d, boxservice.NewRegistry(), certificate.NewRegistry())
+	var raw map[string]any
+	if err := stdjson.Unmarshal(config, &raw); err != nil {
+		return nil, fmt.Errorf("invalid proxy configuration")
+	}
+	raw["log"] = map[string]any{"disabled": true}
+	raw["inbounds"] = []any{map[string]any{"type": "mixed", "listen": "127.0.0.1", "listen_port": port}}
+	data, err := stdjson.Marshal(raw)
+	if err != nil {
+		return nil, err
+	}
+	opts, err := json.UnmarshalExtendedContext[option.Options](ctx, data)
+	if err != nil {
+		return nil, fmt.Errorf("invalid embedded sing-box options")
+	}
+	instance, err := box.New(box.Options{Context: ctx, Options: opts})
+	if err != nil {
+		return nil, fmt.Errorf("initialize embedded sing-box: %w", err)
+	}
+	if err = instance.Start(); err != nil {
+		instance.Close()
+		return nil, fmt.Errorf("start embedded sing-box: %w", err)
+	}
+	return instance, nil
+}
+
+func Check(ctx context.Context, port int) error {
+	p, _ := url.Parse(fmt.Sprintf("http://127.0.0.1:%d", port))
+	tr := &http.Transport{Proxy: http.ProxyURL(p), TLSHandshakeTimeout: 15 * time.Second}
+	defer tr.CloseIdleConnections()
+	client := &http.Client{Transport: tr, Timeout: 25 * time.Second}
+	req, _ := http.NewRequestWithContext(ctx, "HEAD", "https://x.com", nil)
+	res, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("local proxy is running, but HTTPS to X failed: %w", err)
+	}
+	defer res.Body.Close()
+	fmt.Fprintf(os.Stderr, "X HTTPS reachable, HTTP status %d\n", res.StatusCode)
+	return nil
+}
diff --git a/internal/site/assets/admin.html b/internal/site/assets/admin.html
new file mode 100644
index 0000000..241ebca
--- /dev/null
+++ b/internal/site/assets/admin.html
@@ -0,0 +1,120 @@
+<!doctype html>
+<html lang="zh-CN">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width,initial-scale=1" />
+    <title>XGift · 管理后台</title>
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="stylesheet" href="/style.css" />
+    <script src="/admin.js" defer></script>
+  </head>
+  <body>
+    <header class="nav">
+      <a class="brand" href="/">X<span class="brand-dot">✦</span>GIFT</a
+      ><span class="eyebrow">ADMIN CONSOLE</span>
+    </header>
+    <main class="admin">
+      <div class="admin-heading">
+        <div>
+          <span class="step">CONTROL ROOM</span>
+          <h1>兑换码管理</h1>
+        </div>
+        <span id="service-status" class="pill">正在读取状态</span>
+      </div>
+      <div class="admin-grid">
+        <section class="card">
+          <h2>批量生成</h2>
+          <p class="muted">兑换码明文只在生成时显示，请立即下载保存。</p>
+          <form id="generate-form">
+            <label for="months">套餐</label
+            ><select id="months">
+              <option value="6">6 个月 Premium · 600 BDT</option>
+              <option value="3">3 个月 Premium · 300 BDT</option></select
+            ><label for="count">数量</label
+            ><input
+              id="count"
+              type="number"
+              min="1"
+              max="500"
+              value="10"
+              required
+            /><label for="batch">批次名称 <span>选填</span></label
+            ><input
+              id="batch"
+              maxlength="40"
+              placeholder="例如：十月赠礼"
+            /><button id="generate-button" type="submit">
+              生成兑换码 <span>＋</span>
+            </button>
+          </form>
+          <div id="admin-result" class="result" role="status" hidden></div>
+          <div id="generated" hidden>
+            <label for="new-codes">本次生成的兑换码</label
+            ><textarea id="new-codes" rows="9" readonly></textarea
+            ><button id="download" class="secondary" type="button">
+              下载兑换码 TXT</button
+            ><button id="clear-codes" class="secondary" type="button">
+              已保存，清除本页明文
+            </button>
+          </div>
+        </section>
+        <section class="card admin-info">
+          <span class="tiny-star">✦</span>
+          <h2>每一次兑换，<br />都有明确的状态。</h2>
+          <dl>
+            <dt>可使用</dt>
+            <dd>用户可以提交，停用后不可再兑换。</dd>
+            <dt>处理中</dt>
+            <dd>兑换码已锁定，请等待结果。</dd>
+            <dt>已完成</dt>
+            <dd>仅在支付服务确认成功后显示。</dd>
+            <dt>待核实</dt>
+            <dd>结果不确定或需要额外验证，必须人工核对，不会自动再次付款。</dd>
+          </dl>
+          <p class="muted">
+            付款限额：3 个月恰好 300 BDT；6 个月恰好 600
+            BDT。金额或币种不符时停止。
+          </p>
+        </section>
+      </div>
+      <section class="card table-card">
+        <div class="table-heading">
+          <h2>兑换码列表</h2>
+          <button id="refresh" class="secondary compact" type="button">
+            刷新
+          </button>
+        </div>
+        <p class="muted">
+          每页 100 条，展示末 8 位识别码。没有自动重试或强制标记成功入口。
+        </p>
+        <div class="table-scroll">
+          <table>
+            <thead>
+              <tr>
+                <th>识别码 / 批次</th>
+                <th>套餐</th>
+                <th>状态</th>
+                <th>用户名</th>
+                <th>创建时间</th>
+                <th>操作</th>
+              </tr>
+            </thead>
+            <tbody id="codes-body"></tbody>
+          </table>
+        </div>
+        <div class="pagination">
+          <button id="prev" class="secondary compact" type="button">
+            上一页</button
+          ><span id="page-label"></span
+          ><button id="next" class="secondary compact" type="button">
+            下一页
+          </button>
+        </div>
+      </section>
+    </main>
+    <footer>
+      <span>XGift · 管理后台</span
+      ><span>请勿分享管理员密码或未使用的兑换码</span>
+    </footer>
+  </body>
+</html>
diff --git a/internal/site/assets/admin.js b/internal/site/assets/admin.js
new file mode 100644
index 0000000..c0238cd
--- /dev/null
+++ b/internal/site/assets/admin.js
@@ -0,0 +1,177 @@
+"use strict";
+const statusNames = {
+  active: "可使用",
+  processing: "处理中",
+  succeeded: "已完成",
+  review: "待核实",
+  revoked: "已停用",
+};
+const result = document.querySelector("#admin-result"),
+  form = document.querySelector("#generate-form");
+let downloadText = "",
+  batchName = "codes",
+  page = 0;
+function show(text, error = false) {
+  result.hidden = false;
+  result.textContent = text;
+  result.classList.toggle("error", error);
+}
+async function api(path, body) {
+  const response = await fetch(
+    path,
+    body
+      ? {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify(body),
+        }
+      : {},
+  );
+  let data;
+  try {
+    data = await response.json();
+  } catch {
+    throw new Error("服务暂时不可用。");
+  }
+  if (!response.ok) throw new Error(data.message || "请求失败");
+  return data;
+}
+async function refresh() {
+  try {
+    const data = await api("/api/admin/codes?page=" + page);
+    document.querySelector("#prev").disabled = page === 0;
+    document.querySelector("#next").disabled = !data.has_more;
+    document.querySelector("#page-label").textContent =
+      "第 " + (page + 1) + " 页";
+    document.querySelector("#service-status").textContent =
+      data.payments_enabled ? "充值已开放" : "充值暂停 · 不会付款";
+    const body = document.querySelector("#codes-body");
+    body.replaceChildren();
+    for (const c of data.codes) {
+      const tr = document.createElement("tr");
+      const id = document.createElement("td");
+      id.textContent = "…" + c.hint;
+      const batch = document.createElement("small");
+      batch.textContent = c.batch;
+      id.append(batch);
+      tr.append(id);
+      const months = document.createElement("td");
+      months.textContent = c.months + " 个月";
+      tr.append(months);
+      const state = document.createElement("td");
+      const badge = document.createElement("span");
+      badge.className = "badge " + c.status;
+      badge.textContent = statusNames[c.status] || c.status;
+      badge.title = c.message;
+      state.append(badge);
+      tr.append(state);
+      const user = document.createElement("td");
+      user.textContent = c.username ? "@" + c.username : "—";
+      tr.append(user);
+      const date = document.createElement("td");
+      date.textContent = new Date(c.created * 1000).toLocaleString();
+      tr.append(date);
+      const action = document.createElement("td");
+      if (c.status === "active") {
+        const b = document.createElement("button");
+        b.type = "button";
+        b.className = "secondary compact";
+        b.textContent = "停用";
+        b.addEventListener("click", async () => {
+          if (!confirm("停用尾号 " + c.hint + " 的兑换码？此操作不可撤销。"))
+            return;
+          b.disabled = true;
+          try {
+            await api("/api/admin/revoke", { id: c.id });
+            await refresh();
+          } catch (e) {
+            show(e.message, true);
+            b.disabled = false;
+          }
+        });
+        action.append(b);
+      } else {
+        action.textContent = "—";
+      }
+      tr.append(action);
+      body.append(tr);
+    }
+    if (!data.codes.length) {
+      const tr = document.createElement("tr"),
+        td = document.createElement("td");
+      td.colSpan = 6;
+      td.textContent = "还没有兑换码，在上方生成第一批。";
+      tr.append(td);
+      body.append(tr);
+    }
+  } catch (e) {
+    show(e.message, true);
+  }
+}
+form.addEventListener("submit", async (e) => {
+  e.preventDefault();
+  if (
+    downloadText &&
+    !confirm("上一批兑换码已下载保存？生成下一批会替换当前显示。")
+  )
+    return;
+  const button = document.querySelector("#generate-button");
+  button.disabled = true;
+  try {
+    const data = await api("/api/admin/codes", {
+      months: Number(document.querySelector("#months").value),
+      count: Number(document.querySelector("#count").value),
+      batch: document.querySelector("#batch").value,
+    });
+    downloadText = data.codes.join("\n") + "\n";
+    batchName = "xgift-" + data.months + "mo-" + Date.now();
+    document.querySelector("#new-codes").value = downloadText;
+    document.querySelector("#generated").hidden = false;
+    show(
+      "已生成 " +
+        data.codes.length +
+        " 枚兑换码，请立即下载。本页刷新后无法恢复明文。",
+    );
+    page = 0;
+    await refresh();
+  } catch (e) {
+    show(e.message + " 若连接中断，请先核实批次列表，不要立即重复生成。", true);
+  } finally {
+    button.disabled = false;
+  }
+});
+document.querySelector("#download").addEventListener("click", () => {
+  const url = URL.createObjectURL(
+    new Blob([downloadText], { type: "text/plain;charset=utf-8" }),
+  );
+  const a = document.createElement("a");
+  a.href = url;
+  a.download = batchName + ".txt";
+  a.click();
+  setTimeout(() => URL.revokeObjectURL(url), 1000);
+});
+document.querySelector("#clear-codes").addEventListener("click", () => {
+  if (!confirm("确认已保存兑换码？清除后无法恢复明文。")) return;
+  downloadText = "";
+  document.querySelector("#new-codes").value = "";
+  document.querySelector("#generated").hidden = true;
+});
+document.querySelector("#refresh").addEventListener("click", refresh);
+refresh();
+window.addEventListener("beforeunload", (e) => {
+  if (downloadText) {
+    e.preventDefault();
+    e.returnValue = "";
+  }
+});
+
+document.querySelector("#prev").addEventListener("click", () => {
+  if (page > 0) {
+    page--;
+    refresh();
+  }
+});
+document.querySelector("#next").addEventListener("click", () => {
+  page++;
+  refresh();
+});
diff --git a/internal/site/assets/app.js b/internal/site/assets/app.js
new file mode 100644
index 0000000..02a856b
--- /dev/null
+++ b/internal/site/assets/app.js
@@ -0,0 +1,106 @@
+"use strict";
+const form = document.querySelector("#redeem-form"),
+  result = document.querySelector("#result");
+const buttons = [
+  document.querySelector("#redeem-button"),
+  document.querySelector("#status-button"),
+];
+let timer = null,
+  attempt = 0,
+  current = null;
+function show(text, error = false) {
+  result.hidden = false;
+  result.textContent = text;
+  result.classList.toggle("error", error);
+}
+function busy(value) {
+  buttons.forEach((b) => (b.disabled = value));
+}
+function input() {
+  return {
+    code: document.querySelector("#code").value.trim(),
+    username: document.querySelector("#username").value.trim(),
+  };
+}
+async function request(path, payload) {
+  const response = await fetch(path, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify(payload),
+  });
+  let data;
+  try {
+    data = await response.json();
+  } catch {
+    throw new Error("服务暂时不可用，请稍后查询兑换进度。");
+  }
+  return { response, data };
+}
+async function query() {
+  try {
+    const { response, data } = await request("/api/status", current);
+    show(
+      data.message ||
+        { active: "兑换码尚未使用。", revoked: "兑换码已停用。" }[
+          data.status
+        ] ||
+        "请联系管理员核实。",
+      !response.ok || data.status === "review",
+    );
+    if (data.status === "processing" && attempt++ < 36) {
+      timer = setTimeout(query, 5000);
+    } else {
+      busy(false);
+    }
+  } catch (e) {
+    show(e.message, true);
+    busy(false);
+  }
+}
+form.addEventListener("submit", async (e) => {
+  e.preventDefault();
+  clearTimeout(timer);
+  busy(true);
+  show("正在核实 X 账号和赠送资格…");
+  current = input();
+  attempt = 0;
+  try {
+    const { response, data } = await request("/api/redeem", current);
+    show(data.message, !response.ok || data.status === "review");
+    if (data.status === "processing") {
+      timer = setTimeout(query, 5000);
+    } else {
+      busy(false);
+    }
+  } catch {
+    show(
+      "连接中断，结果尚不确定。请点击「查询兑换进度」，不要更换兑换码重复提交。",
+      true,
+    );
+    busy(false);
+  }
+});
+buttons[1].addEventListener("click", () => {
+  if (!form.reportValidity()) return;
+  clearTimeout(timer);
+  current = input();
+  attempt = 0;
+  busy(true);
+  query();
+});
+
+fetch("/healthz")
+  .then((r) => {
+    if (!r.ok) throw new Error();
+    return r.json();
+  })
+  .then((data) => {
+    if (!data.payments_enabled) {
+      const notice = document.querySelector("#service-notice");
+      notice.textContent =
+        "充值暂未开放。可以先核实账号赠送资格，兑换码不会被使用。";
+      notice.hidden = false;
+      buttons[0].firstChild.textContent = "核实赠送资格 ";
+    }
+  })
+  .catch(() => {});
diff --git a/internal/site/assets/favicon.svg b/internal/site/assets/favicon.svg
new file mode 100644
index 0000000..f7b99da
--- /dev/null
+++ b/internal/site/assets/favicon.svg
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64"><rect width="64" height="64" rx="15" fill="#20231f"/><path d="M32 10Q35 27 54 32Q36 36 32 54Q28 36 10 32Q28 28 32 10Z" fill="#bfd67c"/></svg>
diff --git a/internal/site/assets/index.html b/internal/site/assets/index.html
new file mode 100644
index 0000000..c2d4b9d
--- /dev/null
+++ b/internal/site/assets/index.html
@@ -0,0 +1,100 @@
+<!doctype html>
+<html lang="zh-CN">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width,initial-scale=1" />
+    <meta name="color-scheme" content="light" />
+    <title>XGift · Premium 兑换</title>
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="stylesheet" href="/style.css" />
+    <script src="/app.js" defer></script>
+  </head>
+  <body>
+    <header class="nav">
+      <a class="brand" href="/">X<span class="brand-dot">✦</span>GIFT</a
+      ><span class="eyebrow">A LITTLE MORE PREMIUM</span>
+    </header>
+    <main class="landing">
+      <section class="intro">
+        <div class="pill"><span class="dot"></span> PREMIUM GIFT</div>
+        <h1>让你的 X，<br />多一点<span class="accent">可能。</span></h1>
+        <p class="lede">
+          一枚兑换码，一份 Premium。<br />输入你的用户名，接收属于你的赠礼。
+        </p>
+        <div class="benefits">
+          <div>
+            <span class="benefit-icon">✓</span
+            ><span>只需用户名<small>无需提供 X 密码</small></span>
+          </div>
+          <div>
+            <span class="benefit-icon">↗</span
+            ><span>进度随时可查<small>保留兑换码即可查询</small></span>
+          </div>
+        </div>
+        <div class="art" aria-hidden="true">
+          <span class="art-star">✦</span><span class="art-word">PREMIUM</span
+          ><span class="art-tag">A GIFT FOR YOU ↗</span>
+        </div>
+      </section>
+      <section class="card redeem-card">
+        <div class="card-top">
+          <span class="step">01 / REDEEM</span><span class="tiny-star">✦</span>
+        </div>
+        <h2>兑换你的 Premium</h2>
+        <p class="muted">套餐时长以兑换码为准。</p>
+        <div id="service-notice" class="result" role="status" hidden></div>
+        <form id="redeem-form">
+          <label for="code">兑换码</label
+          ><textarea
+            id="code"
+            name="code"
+            rows="2"
+            placeholder="粘贴 XG- 开头的完整兑换码"
+            maxlength="80"
+            required
+            spellcheck="false"
+            autocomplete="off"
+          ></textarea
+          ><label for="username">X 用户名 <span>不是显示名称</span></label>
+          <div class="username-input">
+            <span>@</span
+            ><input
+              id="username"
+              name="username"
+              placeholder="your_username"
+              maxlength="16"
+              pattern="@?[A-Za-z0-9_]{1,15}"
+              autocomplete="off"
+              spellcheck="false"
+              required
+            />
+          </div>
+          <p class="field-help">请核对用户名，赠送成功后无法更换账号。</p>
+          <button id="redeem-button" type="submit">
+            兑换 Premium <span>↗</span></button
+          ><button id="status-button" class="secondary" type="button">
+            查询兑换进度
+          </button>
+        </form>
+        <div
+          id="result"
+          class="result"
+          role="status"
+          aria-live="polite"
+          hidden
+        ></div>
+        <div class="card-note">
+          <span>ⓘ</span>
+          <p>
+            我们会先检查账号能否接收赠送。若 X
+            暂不允许赠送，会在这里告诉你，兑换码不会因此被使用。
+          </p>
+        </div>
+      </section>
+    </main>
+    <footer>
+      <span>XGift · 把 Premium 赠予你</span
+      ><span>独立兑换服务，与 X 无隶属关系</span>
+    </footer>
+  </body>
+</html>
diff --git a/internal/site/assets/style.css b/internal/site/assets/style.css
new file mode 100644
index 0000000..9fb6f16
--- /dev/null
+++ b/internal/site/assets/style.css
@@ -0,0 +1,517 @@
+:root {
+  --ink: #20231f;
+  --muted: #777c70;
+  --bg: #f5f5ee;
+  --line: #dedfd4;
+  --accent: #bfd67c;
+  --deep: #536b29;
+  --paper: #fffefa;
+}
+* {
+  box-sizing: border-box;
+}
+body {
+  margin: 0;
+  background: var(--bg);
+  color: var(--ink);
+  font-family:
+    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
+    "Microsoft YaHei", sans-serif;
+  -webkit-font-smoothing: antialiased;
+}
+.nav {
+  height: 108px;
+  margin: 0 auto;
+  max-width: 1240px;
+  padding: 0 44px;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  border-bottom: 1px solid var(--line);
+}
+a {
+  color: inherit;
+  text-decoration: none;
+}
+.brand {
+  font-size: 25px;
+  font-weight: 900;
+  letter-spacing: -1.4px;
+  display: flex;
+  align-items: center;
+  gap: 3px;
+}
+.brand-dot {
+  font-size: 22px;
+  color: var(--deep);
+  margin: 0 3px;
+}
+.eyebrow,
+.step {
+  font-size: 11px;
+  letter-spacing: 1.7px;
+  font-weight: 600;
+  color: var(--muted);
+}
+.landing {
+  max-width: 1152px;
+  margin: 68px auto 76px;
+  display: grid;
+  grid-template-columns: 1.05fr 1fr;
+  gap: 76px;
+  align-items: start;
+  padding: 0 24px;
+}
+.pill {
+  display: inline-flex;
+  align-items: center;
+  gap: 8px;
+  border: 1px solid var(--line);
+  border-radius: 30px;
+  padding: 9px 14px;
+  font-size: 10px;
+  font-weight: 600;
+  letter-spacing: 1.2px;
+}
+.dot {
+  height: 6px;
+  width: 6px;
+  background: #658031;
+  border-radius: 50%;
+}
+h1 {
+  font-size: clamp(38px, 4.6vw, 60px);
+  line-height: 1.2;
+  letter-spacing: -2px;
+  font-weight: 650;
+  margin: 24px 0;
+}
+.accent {
+  color: var(--deep);
+}
+.lede {
+  font-size: 16px;
+  line-height: 1.9;
+  color: #777b70;
+  margin: 0 0 28px;
+}
+.benefits {
+  display: flex;
+  gap: 32px;
+  font-size: 12px;
+}
+.benefits > div {
+  display: flex;
+  gap: 10px;
+  align-items: center;
+}
+.benefit-icon {
+  border: 1px solid var(--line);
+  width: 30px;
+  height: 30px;
+  border-radius: 50%;
+  display: grid;
+  place-items: center;
+}
+.benefits small {
+  display: block;
+  font-size: 10px;
+  color: var(--muted);
+  margin-top: 5px;
+}
+.art {
+  position: relative;
+  overflow: hidden;
+  background: #e3e9d2;
+  height: 171px;
+  border-radius: 14px;
+  margin-top: 36px;
+  border: 1px solid #d8dfc7;
+  transform: rotate(-2deg);
+}
+.art-star {
+  position: absolute;
+  font-size: 220px;
+  line-height: 1;
+  right: 8px;
+  top: -25px;
+  color: #c1ce9c;
+  transform: rotate(12deg);
+}
+.art-word {
+  position: absolute;
+  font-size: 36px;
+  letter-spacing: -1.5px;
+  font-weight: 700;
+  left: 26px;
+  top: 46px;
+}
+.art-tag {
+  position: absolute;
+  bottom: 25px;
+  left: 28px;
+  font-size: 9px;
+  letter-spacing: 2px;
+}
+.card {
+  background: var(--paper);
+  border: 1px solid var(--line);
+  border-radius: 20px;
+  padding: 34px;
+  box-shadow: 0 12px 32px #313b1910;
+}
+.card-top {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 19px;
+}
+.tiny-star {
+  font-size: 30px;
+  color: var(--deep);
+  line-height: 1;
+}
+h2 {
+  font-size: 24px;
+  font-weight: 600;
+  letter-spacing: -0.7px;
+  margin: 0 0 8px;
+}
+.muted {
+  font-size: 12px;
+  line-height: 1.7;
+  color: var(--muted);
+  margin: 0 0 22px;
+}
+label {
+  display: block;
+  font-size: 12px;
+  font-weight: 600;
+  margin: 23px 0 10px;
+}
+label span {
+  font-size: 10px;
+  color: var(--muted);
+  font-weight: 400;
+  margin-left: 5px;
+}
+input,
+textarea,
+select {
+  width: 100%;
+  font: inherit;
+  font-size: 13px;
+  border: 1px solid var(--line);
+  border-radius: 9px;
+  background: #fbfbf6;
+  color: var(--ink);
+  padding: 13px 14px;
+  outline: none;
+  transition:
+    border-color 0.2s,
+    box-shadow 0.2s;
+}
+textarea {
+  resize: vertical;
+  min-height: 72px;
+  line-height: 1.6;
+}
+input:focus,
+textarea:focus,
+select:focus {
+  border-color: #8fa960;
+  box-shadow: 0 0 0 3px #bfd67c30;
+}
+input::placeholder,
+textarea::placeholder {
+  color: #aaada1;
+}
+.username-input {
+  display: flex;
+  align-items: center;
+  position: relative;
+}
+.username-input > span {
+  position: absolute;
+  left: 14px;
+  color: var(--muted);
+  font-size: 15px;
+}
+.username-input input {
+  padding-left: 36px;
+}
+.field-help {
+  font-size: 10px;
+  color: var(--muted);
+  margin: 10px 0 24px;
+}
+button {
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  width: 100%;
+  border: 0;
+  border-radius: 9px;
+  background: var(--ink);
+  color: white;
+  padding: 15px 18px;
+  font: inherit;
+  font-size: 13px;
+  font-weight: 500;
+  transition: background 0.2s;
+}
+button:hover {
+  background: #414933;
+}
+button:disabled {
+  opacity: 0.55;
+  cursor: wait;
+}
+button span {
+  font-size: 18px;
+}
+.secondary {
+  background: transparent;
+  border: 1px solid var(--line);
+  color: var(--ink);
+  justify-content: center;
+  padding: 11px 14px;
+  margin-top: 10px;
+  font-size: 11px;
+}
+.secondary:hover {
+  background: #e9eddf;
+}
+.card-note {
+  border-top: 1px solid var(--line);
+  margin-top: 22px;
+  padding-top: 18px;
+  display: flex;
+  align-items: flex-start;
+  gap: 9px;
+  color: var(--muted);
+}
+.card-note > span {
+  font-size: 15px;
+}
+.card-note p {
+  margin: 0;
+  font-size: 10px;
+  line-height: 1.8;
+}
+.result {
+  padding: 14px;
+  border: 1px solid #d3dfb8;
+  border-radius: 9px;
+  background: #f1f5e6;
+  color: #485933;
+  margin-top: 18px;
+  font-size: 12px;
+  line-height: 1.8;
+  overflow-wrap: anywhere;
+}
+.result.error {
+  background: #fff4e9;
+  border-color: #ebd9c4;
+  color: #7c5936;
+}
+footer {
+  max-width: 1152px;
+  margin: 0 auto;
+  display: flex;
+  justify-content: space-between;
+  border-top: 1px solid var(--line);
+  padding: 25px 24px 35px;
+  font-size: 10px;
+  color: var(--muted);
+}
+[hidden] {
+  display: none !important;
+}
+.admin {
+  max-width: 1152px;
+  margin: 40px auto 60px;
+  padding: 0 24px;
+}
+.admin-heading {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 24px;
+}
+.admin-heading h1 {
+  font-size: 36px;
+  margin: 12px 0;
+}
+.admin-grid {
+  display: grid;
+  grid-template-columns: 1.1fr 1fr;
+  gap: 24px;
+}
+.admin-grid button[type="submit"] {
+  margin-top: 24px;
+}
+.admin-info {
+  background: #e8eddc;
+  box-shadow: none;
+}
+.admin-info h2 {
+  margin: 25px 0;
+  font-size: 30px;
+  line-height: 1.5;
+}
+dl {
+  font-size: 12px;
+}
+dt {
+  font-weight: 600;
+  margin: 16px 0 6px;
+}
+dd {
+  margin: 0;
+  color: #727b62;
+  line-height: 1.7;
+}
+.admin-info .muted {
+  border-top: 1px solid #cdd6bc;
+  margin-top: 24px;
+  padding-top: 18px;
+}
+.table-card {
+  margin-top: 25px;
+}
+.table-heading {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 15px;
+}
+.compact {
+  width: auto;
+  margin: 0;
+  padding: 8px 16px;
+}
+.table-scroll {
+  overflow: auto;
+}
+table {
+  width: 100%;
+  border-collapse: collapse;
+  text-align: left;
+  white-space: nowrap;
+  font-size: 11px;
+}
+th {
+  font-weight: 500;
+  color: var(--muted);
+  border-bottom: 1px solid var(--line);
+  padding: 10px 12px;
+}
+td {
+  padding: 15px 12px;
+  border-bottom: 1px solid #edeee5;
+}
+td small {
+  display: block;
+  color: var(--muted);
+  font-size: 10px;
+  margin-top: 5px;
+}
+.badge {
+  display: inline-block;
+  border-radius: 5px;
+  background: #edf1e4;
+  padding: 5px 8px;
+}
+.badge.review {
+  background: #f7e4c7;
+}
+.badge.revoked {
+  background: #e9e9e9;
+  color: #888;
+}
+.badge.succeeded {
+  background: #dceacc;
+  color: #416425;
+}
+#new-codes {
+  font-family: ui-monospace, monospace;
+  font-size: 10px;
+}
+.error-label {
+  color: #946125;
+}
+@media (max-width: 800px) {
+  .nav {
+    height: 80px;
+    padding: 0 24px;
+  }
+  .eyebrow {
+    font-size: 8px;
+    letter-spacing: 1px;
+  }
+  .landing {
+    grid-template-columns: 1fr;
+    gap: 30px;
+    margin: 35px auto 40px;
+    max-width: 530px;
+  }
+  .intro h1 {
+    font-size: 45px;
+  }
+  .intro .lede {
+    font-size: 14px;
+  }
+  .art {
+    display: none;
+  }
+  .card {
+    padding: 25px;
+    border-radius: 15px;
+  }
+  .benefits {
+    gap: 25px;
+    margin-top: 25px;
+  }
+  .admin-grid {
+    grid-template-columns: 1fr;
+  }
+  .admin-heading {
+    align-items: flex-start;
+    gap: 10px;
+  }
+  .admin-heading h1 {
+    font-size: 28px;
+  }
+  .admin-heading .pill {
+    font-size: 9px;
+  }
+  footer {
+    gap: 15px;
+    font-size: 9px;
+  }
+  .admin {
+    margin-top: 30px;
+  }
+  .table-card {
+    padding: 20px;
+  }
+  .admin-info h2 {
+    font-size: 25px;
+  }
+}
+@media (prefers-reduced-motion: reduce) {
+  * {
+    transition: none !important;
+  }
+}
+
+.pagination {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-top: 20px;
+  font-size: 11px;
+  color: var(--muted);
+}
diff --git a/internal/site/site.go b/internal/site/site.go
new file mode 100644
index 0000000..b701917
--- /dev/null
+++ b/internal/site/site.go
@@ -0,0 +1,559 @@
+package site
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"database/sql"
+	"embed"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"xgift/internal/checkout"
+	"xgift/internal/proxy"
+	"xgift/internal/vault"
+)
+
+//go:embed assets/*
+var assets embed.FS
+var usernamePattern = regexp.MustCompile(`^[a-z0-9_]{1,15}$`)
+var codePattern = regexp.MustCompile(`^XG-[A-F0-9]{48}$`)
+
+type server struct {
+	db        *sql.DB
+	vault     *vault.Vault
+	origin    string
+	adminHash [32]byte
+	payments  bool
+	port      int
+	lockPath  string
+	work      chan struct{}
+	jobs      sync.WaitGroup
+	ctx       context.Context
+	limitsMu  sync.Mutex
+	limits    map[string]limit
+}
+type limit struct {
+	start time.Time
+	count int
+}
+type codeRow struct {
+	ID       string `json:"id"`
+	Hint     string `json:"hint"`
+	Batch    string `json:"batch"`
+	Months   int    `json:"months"`
+	Status   string `json:"status"`
+	Username string `json:"username"`
+	Message  string `json:"message"`
+	Created  int64  `json:"created"`
+	Updated  int64  `json:"updated"`
+}
+
+func Run(ctx context.Context) error {
+	origin := os.Getenv("XGIFT_ORIGIN")
+	u, err := url.Parse(origin)
+	if err != nil || u.Scheme != "https" || u.Host == "" || u.Path != "" || u.RawQuery != "" || u.Fragment != "" || u.User != nil {
+		return errors.New("XGIFT_ORIGIN must be an HTTPS origin")
+	}
+	dir := os.Getenv("XGIFT_DATA_DIR")
+	if dir == "" {
+		return errors.New("XGIFT_DATA_DIR is required")
+	}
+	if err = os.MkdirAll(dir, 0700); err != nil {
+		return err
+	}
+	if err = os.Chmod(dir, 0700); err != nil {
+		return err
+	}
+	instance, err := os.OpenFile(filepath.Join(dir, "site.lock"), os.O_CREATE|os.O_RDWR, 0600)
+	if err != nil {
+		return err
+	}
+	defer instance.Close()
+	if err = syscall.Flock(int(instance.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
+		return errors.New("another site instance is using this data directory")
+	}
+	admin, err := privateFile(os.Getenv("XGIFT_ADMIN_PASSWORD_FILE"))
+	if err != nil {
+		return err
+	}
+	admin = []byte(strings.TrimSpace(string(admin)))
+	if len(admin) < 32 {
+		return errors.New("admin password must contain at least 32 characters")
+	}
+	s := &server{origin: origin, adminHash: sha256.Sum256(admin), payments: os.Getenv("XGIFT_PAYMENTS_ENABLED") == "true", lockPath: filepath.Join(dir, "checkout.lock"), work: make(chan struct{}, 1), ctx: ctx, limits: map[string]limit{}}
+	clear(admin)
+	v, err := vault.Open(filepath.Join(dir, "vault.db"), os.Getenv("XGIFT_PASSWORD_FILE"), false)
+	if err != nil {
+		return err
+	}
+	s.vault = v
+	defer v.Close()
+	dbpath := filepath.Join(dir, "site.db")
+	f, err := os.OpenFile(dbpath, os.O_CREATE|os.O_RDWR, 0600)
+	if err != nil {
+		return err
+	}
+	f.Close()
+	if err = os.Chmod(dbpath, 0600); err != nil {
+		return err
+	}
+	db, err := sql.Open("sqlite3", dbpath+"?_busy_timeout=5000&_journal_mode=WAL&_synchronous=FULL&_foreign_keys=on")
+	if err != nil {
+		return err
+	}
+	s.db = db
+	defer db.Close()
+	db.SetMaxOpenConns(1)
+	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS codes (
+ id TEXT PRIMARY KEY, hash TEXT NOT NULL UNIQUE, hint TEXT NOT NULL, batch TEXT NOT NULL,
+ months INTEGER NOT NULL CHECK(months IN (3,6)),
+ status TEXT NOT NULL CHECK(status IN ('active','processing','succeeded','review','revoked')),
+ username TEXT NOT NULL DEFAULT '', recipient_id TEXT UNIQUE,
+ message TEXT NOT NULL DEFAULT '', created INTEGER NOT NULL, updated INTEGER NOT NULL
+ ); CREATE INDEX IF NOT EXISTS codes_created ON codes(created);`)
+	if err != nil {
+		return err
+	}
+	// A crash is never interpreted as permission to submit the same payment again.
+	if _, err = db.Exec("UPDATE codes SET status='review',message=?,updated=? WHERE status='processing'", "订单需要人工核实，请联系管理员；请勿重复兑换。", time.Now().Unix()); err != nil {
+		return err
+	}
+	raw, err := v.Get("proxy")
+	if err != nil {
+		return err
+	}
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return err
+	}
+	s.port = listener.Addr().(*net.TCPAddr).Port
+	listener.Close()
+	box, err := proxy.Start(ctx, raw, s.port)
+	clear(raw)
+	if err != nil {
+		return err
+	}
+	defer box.Close()
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /{$}", s.asset("index.html", "text/html; charset=utf-8"))
+	mux.HandleFunc("GET /favicon.svg", s.asset("favicon.svg", "image/svg+xml"))
+	mux.HandleFunc("GET /style.css", s.asset("style.css", "text/css; charset=utf-8"))
+	mux.HandleFunc("GET /app.js", s.asset("app.js", "application/javascript; charset=utf-8"))
+	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
+		if s.db.PingContext(r.Context()) != nil {
+			reply(w, 503, map[string]any{"ok": false})
+			return
+		}
+		reply(w, 200, map[string]any{"ok": true, "payments_enabled": s.payments})
+	})
+	mux.HandleFunc("POST /api/redeem", s.redeem)
+	mux.HandleFunc("POST /api/status", s.status)
+	mux.HandleFunc("GET /admin", s.admin(s.asset("admin.html", "text/html; charset=utf-8")))
+	mux.HandleFunc("GET /admin.js", s.admin(s.asset("admin.js", "application/javascript; charset=utf-8")))
+	mux.HandleFunc("GET /api/admin/codes", s.admin(s.list))
+	mux.HandleFunc("POST /api/admin/codes", s.admin(s.generate))
+	mux.HandleFunc("POST /api/admin/revoke", s.admin(s.revoke))
+	addr := os.Getenv("XGIFT_LISTEN")
+	if addr == "" {
+		addr = "127.0.0.1:8787"
+	}
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil || net.ParseIP(host) == nil || !net.ParseIP(host).IsLoopback() {
+		return errors.New("listen address must use a loopback IP")
+	}
+	h := &http.Server{Addr: addr, Handler: s.middleware(mux), ReadHeaderTimeout: 5 * time.Second, ReadTimeout: 10 * time.Second, WriteTimeout: 50 * time.Second, IdleTimeout: 60 * time.Second, MaxHeaderBytes: 16 << 10}
+	done := make(chan error, 1)
+	go func() { done <- h.ListenAndServe() }()
+	log.Printf("xgift-web listening on %s; payments enabled=%t", addr, s.payments)
+	select {
+	case err = <-done:
+	case <-ctx.Done():
+	}
+	shutdown, cancel := context.WithTimeout(context.Background(), 55*time.Second)
+	defer cancel()
+	if e := h.Shutdown(shutdown); e != nil {
+		h.Close()
+	}
+	s.jobs.Wait()
+	if errors.Is(err, http.ErrServerClosed) {
+		return nil
+	}
+	return err
+}
+func privateFile(path string) ([]byte, error) {
+	i, e := os.Lstat(path)
+	if e != nil {
+		return nil, e
+	}
+	if !i.Mode().IsRegular() || i.Mode().Perm()&0077 != 0 {
+		return nil, errors.New("secret file must be regular and owner-only")
+	}
+	return os.ReadFile(path)
+}
+func token(n int) string {
+	b := make([]byte, n)
+	if _, e := rand.Read(b); e != nil {
+		panic(e)
+	}
+	return hex.EncodeToString(b)
+}
+func hash(code string) string { b := sha256.Sum256([]byte(code)); return hex.EncodeToString(b[:]) }
+func reply(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(v)
+}
+func message(w http.ResponseWriter, status int, msg string) {
+	reply(w, status, map[string]any{"message": msg})
+}
+func decode(w http.ResponseWriter, r *http.Request, v any) bool {
+	if r.Header.Get("Content-Type") != "application/json" {
+		message(w, 415, "请使用 JSON 请求。")
+		return false
+	}
+	d := json.NewDecoder(http.MaxBytesReader(w, r.Body, 4096))
+	d.DisallowUnknownFields()
+	if d.Decode(v) != nil {
+		message(w, 400, "请求格式不正确。")
+		return false
+	}
+	if d.Decode(new(any)) != io.EOF {
+		message(w, 400, "请求格式不正确。")
+		return false
+	}
+	return true
+}
+func (s *server) asset(name, kind string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		b, err := assets.ReadFile("assets/" + name)
+		if err != nil {
+			http.NotFound(w, r)
+			return
+		}
+		w.Header().Set("Content-Type", kind)
+		w.Write(b)
+	}
+}
+func (s *server) allow(key string, max int) bool {
+	s.limitsMu.Lock()
+	defer s.limitsMu.Unlock()
+	now := time.Now()
+	if len(s.limits) > 10000 {
+		for k, v := range s.limits {
+			if now.Sub(v.start) > time.Minute {
+				delete(s.limits, k)
+			}
+		}
+		if len(s.limits) > 10000 {
+			return false
+		}
+	}
+	l := s.limits[key]
+	if now.Sub(l.start) > time.Minute {
+		l = limit{start: now}
+	}
+	l.count++
+	s.limits[key] = l
+	return l.count <= max
+}
+func (s *server) middleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store")
+		w.Header().Set("Content-Security-Policy", "default-src 'none'; script-src 'self'; style-src 'self'; connect-src 'self'; img-src 'self'; base-uri 'none'; form-action 'self'; frame-ancestors 'none'")
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		w.Header().Set("Referrer-Policy", "no-referrer")
+		w.Header().Set("X-Frame-Options", "DENY")
+		w.Header().Set("Permissions-Policy", "camera=(), microphone=(), geolocation=()")
+		if r.Method == "POST" && r.Header.Get("Origin") != s.origin {
+			message(w, 403, "请求来源不正确，请从本站页面重试。")
+			return
+		}
+		if strings.HasPrefix(r.URL.Path, "/api/") || strings.HasPrefix(r.URL.Path, "/admin") {
+			// Caddy overwrites X-Real-IP, and this server accepts loopback traffic only.
+			ip := r.Header.Get("X-Real-IP")
+			if net.ParseIP(ip) == nil {
+				ip, _, _ = net.SplitHostPort(r.RemoteAddr)
+			}
+			max := 60
+			bucket := "api:"
+			if r.URL.Path == "/api/redeem" {
+				max = 8
+				bucket = "redeem:"
+			}
+			if !s.allow(bucket+ip, max) {
+				w.Header().Set("Retry-After", "60")
+				message(w, 429, "操作太频繁，请稍后重试。")
+				return
+			}
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+func (s *server) admin(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		user, password, ok := r.BasicAuth()
+		sum := sha256.Sum256([]byte(password))
+		if !ok || subtle.ConstantTimeCompare(sum[:], s.adminHash[:]) != 1 || user != "admin" {
+			w.Header().Set("WWW-Authenticate", `Basic realm="XGift Admin", charset="UTF-8"`)
+			message(w, 401, "需要管理员登录。")
+			return
+		}
+		next(w, r)
+	}
+}
+func (s *server) find(code string) (codeRow, error) {
+	var c codeRow
+	e := s.db.QueryRow("SELECT id,hint,batch,months,status,username,message,created,updated FROM codes WHERE hash=?", hash(code)).Scan(&c.ID, &c.Hint, &c.Batch, &c.Months, &c.Status, &c.Username, &c.Message, &c.Created, &c.Updated)
+	return c, e
+}
+func readInput(w http.ResponseWriter, r *http.Request) (string, string, bool) {
+	var q struct {
+		Code     string `json:"code"`
+		Username string `json:"username"`
+	}
+	if !decode(w, r, &q) {
+		return "", "", false
+	}
+	q.Code = strings.ToUpper(strings.TrimSpace(q.Code))
+	q.Username = strings.ToLower(strings.TrimPrefix(strings.TrimSpace(q.Username), "@"))
+	if !codePattern.MatchString(q.Code) || !usernamePattern.MatchString(q.Username) {
+		message(w, 400, "请填写完整兑换码和正确的 X 用户名（不是显示名称）。")
+		return "", "", false
+	}
+	return q.Code, q.Username, true
+}
+func (s *server) status(w http.ResponseWriter, r *http.Request) {
+	code, user, ok := readInput(w, r)
+	if !ok {
+		return
+	}
+	c, e := s.find(code)
+	if e != nil || c.Username != "" && c.Username != user {
+		message(w, 404, "兑换码或用户名不匹配。")
+		return
+	}
+	reply(w, 200, map[string]any{"status": c.Status, "months": c.Months, "message": c.Message})
+}
+func (s *server) redeem(w http.ResponseWriter, r *http.Request) {
+	code, user, ok := readInput(w, r)
+	if !ok {
+		return
+	}
+	c, e := s.find(code)
+	if errors.Is(e, sql.ErrNoRows) {
+		message(w, 404, "兑换码不存在，请检查后重试。")
+		return
+	}
+	if e != nil {
+		message(w, 503, "服务暂时不可用，兑换码未使用。")
+		return
+	}
+	if c.Status != "active" {
+		if c.Username == user && (c.Status == "processing" || c.Status == "review" || c.Status == "succeeded") {
+			reply(w, 200, map[string]any{"status": c.Status, "message": c.Message, "months": c.Months})
+			return
+		}
+		message(w, 409, "兑换码已使用或已停用，请联系提供方。")
+		return
+	}
+	select {
+	case s.work <- struct{}{}:
+	default:
+		message(w, 503, "正在处理其他请求，请稍后重试。兑换码未使用。")
+		return
+	}
+	handedOff := false
+	defer func() {
+		if !handedOff {
+			<-s.work
+		}
+	}()
+	ctx, cancel := context.WithTimeout(r.Context(), 35*time.Second)
+	defer cancel()
+	recipient, e := checkout.Eligibility(ctx, s.vault, user, s.port)
+	if e != nil {
+		switch {
+		case errors.Is(e, checkout.ErrNotEligible):
+			message(w, 422, "X 当前不允许向这个账号赠送 Premium。兑换码未使用，可换一个符合条件的账号。")
+		case errors.Is(e, checkout.ErrUserNotFound):
+			message(w, 422, "未能找到这个 X 账号，请检查用户名。兑换码未使用。")
+		default:
+			message(w, 503, "暂时无法向 X 核实赠送资格，请稍后重试。兑换码未使用。")
+		}
+		return
+	}
+	if !s.payments {
+		reply(w, 503, map[string]any{"status": "paused", "eligible": true, "months": c.Months, "message": "这个账号可以接收赠送，但充值服务暂未开放。兑换码未使用，请稍后再来。"})
+		return
+	}
+	// The same lock is used by the CLI. Keep it until the final database write.
+	lock, e := os.OpenFile(s.lockPath, os.O_CREATE|os.O_RDWR, 0600)
+	if e != nil {
+		message(w, 503, "订单服务暂时不可用，兑换码未使用。")
+		return
+	}
+	if e = syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); e != nil {
+		lock.Close()
+		message(w, 503, "订单处理中，请稍后重试。兑换码未使用。")
+		return
+	}
+	release := func() { syscall.Flock(int(lock.Fd()), syscall.LOCK_UN); lock.Close() }
+	// A prior CLI order must not be counted as fulfillment of a new redemption code.
+	for _, key := range []string{"checkout:" + recipient, "checkout:" + user} {
+		if _, e = s.vault.Get(key); !errors.Is(e, sql.ErrNoRows) {
+			release()
+			message(w, 409, "这个账号已有订单记录，需要管理员核实后处理。兑换码未使用。")
+			return
+		}
+	}
+	result, e := s.db.Exec("UPDATE codes SET status='processing',username=?,recipient_id=?,message=?,updated=? WHERE id=? AND status='active'", user, recipient, "正在处理，请不要重复提交。", time.Now().Unix(), c.ID)
+	if e != nil {
+		release()
+		message(w, 409, "无法创建订单；该账号可能已有兑换记录。兑换码未使用。")
+		return
+	}
+	n, e := result.RowsAffected()
+	if e != nil || n != 1 {
+		release()
+		message(w, 409, "兑换码状态已改变，请刷新后查询。")
+		return
+	}
+	handedOff = true
+	s.jobs.Add(1)
+	go func() {
+		defer s.jobs.Done()
+		defer func() { <-s.work }()
+		defer release()
+		ctx, cancel := context.WithTimeout(s.ctx, 150*time.Second)
+		defer cancel()
+		record, err := checkout.RunForRecipient(ctx, s.vault, user, recipient, true, s.port, c.Months)
+		status, msg := "review", "订单需要人工核实，请联系管理员；请勿重复兑换。"
+		if err == nil && record != nil && record.Status == "succeeded" && record.RecipientID == recipient && record.Months == c.Months && record.Amount == c.Months*10000 && record.Currency == "BDT" {
+			status, msg = "succeeded", fmt.Sprintf("已为 @%s 完成 %d 个月 Premium 赠送。", user, c.Months)
+		}
+		updated, e := s.db.Exec("UPDATE codes SET status=?,message=?,updated=? WHERE id=? AND status='processing'", status, msg, time.Now().Unix(), c.ID)
+		if e != nil {
+			log.Printf("order %s requires database reconciliation", c.ID)
+			return
+		}
+		n, e := updated.RowsAffected()
+		if e != nil || n != 1 {
+			log.Printf("order %s requires database reconciliation", c.ID)
+			return
+		}
+		// Never log the checkout URL, credentials or upstream payloads.
+		log.Printf("order %s finished: %s", c.ID, status)
+	}()
+	reply(w, 202, map[string]any{"status": "processing", "months": c.Months, "message": "正在处理，请保留本页并等待结果。"})
+}
+func (s *server) generate(w http.ResponseWriter, r *http.Request) {
+	var q struct {
+		Months int    `json:"months"`
+		Count  int    `json:"count"`
+		Batch  string `json:"batch"`
+	}
+	if !decode(w, r, &q) {
+		return
+	}
+	q.Batch = strings.TrimSpace(q.Batch)
+	if (q.Months != 3 && q.Months != 6) || q.Count < 1 || q.Count > 500 || len(q.Batch) > 120 {
+		message(w, 400, "请选择 3 或 6 个月，数量 1–500，批次名称不超过 120 字节。")
+		return
+	}
+	if q.Batch == "" {
+		q.Batch = time.Now().UTC().Format("20060102-150405") + "-" + token(3)
+	}
+	tx, e := s.db.BeginTx(r.Context(), nil)
+	if e != nil {
+		message(w, 503, "暂时无法生成兑换码。")
+		return
+	}
+	defer tx.Rollback()
+	codes := make([]string, 0, q.Count)
+	now := time.Now().Unix()
+	for i := 0; i < q.Count; i++ {
+		code := "XG-" + strings.ToUpper(token(24))
+		_, e = tx.Exec("INSERT INTO codes(id,hash,hint,batch,months,status,created,updated) VALUES(?,?,?,?,?,'active',?,?)", token(16), hash(code), code[len(code)-8:], q.Batch, q.Months, now, now)
+		if e != nil {
+			message(w, 503, "生成失败，没有保存本批兑换码。")
+			return
+		}
+		codes = append(codes, code)
+	}
+	if e = tx.Commit(); e != nil {
+		message(w, 503, "保存结果不确定，请在后台核实批次后再操作。")
+		return
+	}
+	reply(w, 201, map[string]any{"codes": codes, "batch": q.Batch, "months": q.Months})
+}
+func (s *server) list(w http.ResponseWriter, r *http.Request) {
+	page := 0
+	if raw := r.URL.Query().Get("page"); raw != "" {
+		n, err := strconv.Atoi(raw)
+		if err != nil || n < 0 || n > 100000 {
+			message(w, 400, "页码不正确。")
+			return
+		}
+		page = n
+	}
+	rows, e := s.db.Query("SELECT id,hint,batch,months,status,username,message,created,updated FROM codes ORDER BY created DESC,rowid DESC LIMIT 101 OFFSET ?", page*100)
+	if e != nil {
+		message(w, 503, "无法读取兑换码。")
+		return
+	}
+	defer rows.Close()
+	codes := []codeRow{}
+	for rows.Next() {
+		var c codeRow
+		if e = rows.Scan(&c.ID, &c.Hint, &c.Batch, &c.Months, &c.Status, &c.Username, &c.Message, &c.Created, &c.Updated); e != nil {
+			message(w, 503, "无法读取兑换码。")
+			return
+		}
+		codes = append(codes, c)
+	}
+	if rows.Err() != nil {
+		message(w, 503, "无法读取兑换码。")
+		return
+	}
+	hasMore := len(codes) > 100
+	if hasMore {
+		codes = codes[:100]
+	}
+	reply(w, 200, map[string]any{"codes": codes, "payments_enabled": s.payments, "page": page, "has_more": hasMore})
+}
+func (s *server) revoke(w http.ResponseWriter, r *http.Request) {
+	var q struct {
+		ID string `json:"id"`
+	}
+	if !decode(w, r, &q) {
+		return
+	}
+	res, e := s.db.Exec("UPDATE codes SET status='revoked',message='兑换码已停用',updated=? WHERE id=? AND status='active'", time.Now().Unix(), q.ID)
+	if e != nil {
+		message(w, 503, "停用失败。")
+		return
+	}
+	n, e := res.RowsAffected()
+	if e != nil || n != 1 {
+		message(w, 409, "只能停用尚未使用的兑换码。")
+		return
+	}
+	message(w, 200, "兑换码已停用。")
+}
diff --git a/internal/vault/vault.go b/internal/vault/vault.go
new file mode 100644
index 0000000..732c763
--- /dev/null
+++ b/internal/vault/vault.go
@@ -0,0 +1,165 @@
+package vault
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"database/sql"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	_ "github.com/mattn/go-sqlite3"
+	"golang.org/x/crypto/scrypt"
+)
+
+type Vault struct {
+	db   *sql.DB
+	aead cipher.AEAD
+}
+
+func NewPassword() (string, error) {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	f, err := os.CreateTemp("/tmp", "xgift-password-*")
+	if err != nil {
+		return "", err
+	}
+	path := f.Name()
+	if _, err = f.WriteString(base64.RawURLEncoding.EncodeToString(b) + "\n"); err != nil {
+		f.Close()
+		os.Remove(path)
+		return "", err
+	}
+	if err = f.Close(); err != nil {
+		return "", err
+	}
+	return path, nil
+}
+
+func Open(path, passwordFile string, create bool) (*Vault, error) {
+	info, err := os.Lstat(passwordFile)
+	if err != nil {
+		return nil, err
+	}
+	if !info.Mode().IsRegular() || info.Mode().Perm()&0077 != 0 {
+		return nil, errors.New("password file must be a regular owner-only file (0600)")
+	}
+	password, err := os.ReadFile(passwordFile)
+	if err != nil {
+		return nil, err
+	}
+	password = []byte(strings.TrimSpace(string(password)))
+	defer clear(password)
+	if len(password) < 32 {
+		return nil, errors.New("password is too short")
+	}
+	if create {
+		if err = os.MkdirAll(filepath.Dir(path), 0700); err != nil {
+			return nil, err
+		}
+		if err = os.Chmod(filepath.Dir(path), 0700); err != nil {
+			return nil, err
+		}
+		f, e := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)
+		if e != nil {
+			return nil, e
+		}
+		f.Close()
+	}
+	info, err = os.Lstat(path)
+	if err != nil {
+		return nil, err
+	}
+	if !info.Mode().IsRegular() || info.Mode().Perm()&0077 != 0 {
+		return nil, errors.New("database must be a regular owner-only file")
+	}
+	db, err := sql.Open("sqlite3", path+"?_busy_timeout=5000&_journal_mode=DELETE&_secure_delete=on&_synchronous=FULL")
+	if err != nil {
+		return nil, err
+	}
+	db.SetMaxOpenConns(1)
+	ok := false
+	defer func() {
+		if !ok {
+			db.Close()
+		}
+	}()
+	var salt []byte
+	if create {
+		_, err = db.Exec(`CREATE TABLE metadata (key TEXT PRIMARY KEY, value BLOB NOT NULL); CREATE TABLE secrets (name TEXT PRIMARY KEY, payload BLOB NOT NULL);`)
+		if err != nil {
+			return nil, err
+		}
+		salt = make([]byte, 32)
+		if _, err = rand.Read(salt); err != nil {
+			return nil, err
+		}
+		_, err = db.Exec("INSERT INTO metadata VALUES ('salt', ?)", salt)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		if err = db.QueryRow("SELECT value FROM metadata WHERE key='salt'").Scan(&salt); err != nil {
+			return nil, err
+		}
+	}
+	if len(salt) != 32 {
+		return nil, errors.New("invalid vault salt")
+	}
+	key, err := scrypt.Key(password, salt, 32768, 8, 1, 32)
+	if err != nil {
+		return nil, err
+	}
+	defer clear(key)
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	aead, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	v := &Vault{db, aead}
+	if create {
+		err = v.Put("vault-check", []byte("xgift-v1"))
+	} else {
+		var b []byte
+		b, err = v.Get("vault-check")
+		if err == nil && string(b) != "xgift-v1" {
+			err = errors.New("invalid vault version")
+		}
+	}
+	if err != nil {
+		return nil, errors.New("vault authentication failed (wrong password or corrupted database)")
+	}
+	ok = true
+	return v, nil
+}
+
+func (v *Vault) Put(name string, plain []byte) error {
+	nonce := make([]byte, v.aead.NonceSize())
+	if _, err := rand.Read(nonce); err != nil {
+		return err
+	}
+	encrypted := v.aead.Seal(nonce, nonce, plain, []byte("xgift-v1:"+name))
+	_, err := v.db.Exec("INSERT INTO secrets(name,payload) VALUES (?,?) ON CONFLICT(name) DO UPDATE SET payload=excluded.payload", name, encrypted)
+	return err
+}
+func (v *Vault) Get(name string) ([]byte, error) {
+	var b []byte
+	if err := v.db.QueryRow("SELECT payload FROM secrets WHERE name=?", name).Scan(&b); err != nil {
+		return nil, fmt.Errorf("secret %s unavailable: %w", name, err)
+	}
+	n := v.aead.NonceSize()
+	if len(b) < n {
+		return nil, errors.New("invalid encrypted record")
+	}
+	return v.aead.Open(nil, b[:n], b[n:], []byte("xgift-v1:"+name))
+}
+func (v *Vault) Close() error { return v.db.Close() }