初始提交：岩美 pay 收款服务（支付宝当面付 + 多商户多渠道架构）

- Go/Gin/GORM + 纯 Go SQLite（无 cgo）
- Channel 多渠道接口：支付宝当面付(precreate)/电脑网站支付(page.pay) 已实现，微信占位
- 多商户 merchants 表，回调验签+金额核对+幂等+查单兜底
- 收款页/结果页/二维码端点；docs/ 设计文档与部署 Runbook
- 密钥走环境变量/Bitwarden，不入库

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

internal/channel/alipay.go

@@ -0,0 +1,103 @@
+package channel
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/smartwalle/alipay/v3"
+
+	"github.com/wangjia/pay/internal/model"
+)
+
+type alipayChannel struct {
+	client *alipay.Client
+}
+
+func newAlipay(m *model.Merchant) (Channel, error) {
+	if m.AppID == "" || m.AppPrivateKey == "" || m.AlipayPublicKey == "" {
+		return nil, fmt.Errorf("商户 %s 的支付宝凭证不完整（app_id/app_private_key/alipay_public_key）", m.Code)
+	}
+	client, err := alipay.New(m.AppID, m.AppPrivateKey, m.Production)
+	if err != nil {
+		return nil, fmt.Errorf("初始化支付宝客户端失败: %w", err)
+	}
+	// 公钥模式（沙箱常用）。若改用证书模式，这里换成 LoadAppCertPublicKey 等。
+	if err := client.LoadAliPayPublicKey(m.AlipayPublicKey); err != nil {
+		return nil, fmt.Errorf("加载支付宝公钥失败: %w", err)
+	}
+	return &alipayChannel{client: client}, nil
+}
+
+func (a *alipayChannel) Name() string { return "alipay" }
+
+func (a *alipayChannel) PagePay(_ context.Context, req CreateReq) (string, error) {
+	var p = alipay.TradePagePay{}
+	p.OutTradeNo = req.OutTradeNo
+	p.Subject = req.Subject
+	p.TotalAmount = req.Amount
+	p.ProductCode = "FAST_INSTANT_TRADE_PAY"
+	p.NotifyURL = req.NotifyURL
+	p.ReturnURL = req.ReturnURL
+	u, err := a.client.TradePagePay(p)
+	if err != nil {
+		return "", fmt.Errorf("支付宝下单失败: %w", err)
+	}
+	return u.String(), nil
+}
+
+func (a *alipayChannel) PreCreate(ctx context.Context, req CreateReq) (string, error) {
+	var p = alipay.TradePreCreate{}
+	p.OutTradeNo = req.OutTradeNo
+	p.Subject = req.Subject
+	p.TotalAmount = req.Amount
+	p.NotifyURL = req.NotifyURL
+	rsp, err := a.client.TradePreCreate(ctx, p)
+	if err != nil {
+		return "", fmt.Errorf("支付宝预下单调用失败: %w", err)
+	}
+	if rsp.IsFailure() {
+		return "", fmt.Errorf("支付宝预下单失败: %s / %s", rsp.Msg, rsp.SubMsg)
+	}
+	return rsp.QRCode, nil
+}
+
+func (a *alipayChannel) VerifyNotify(ctx context.Context, r *http.Request) (*NotifyResult, error) {
+	if err := r.ParseForm(); err != nil {
+		return nil, fmt.Errorf("解析回调表单失败: %w", err)
+	}
+	// DecodeNotification 内部用已加载的支付宝公钥验签，验签不过会返回错误。
+	noti, err := a.client.DecodeNotification(ctx, r.Form)
+	if err != nil {
+		return nil, fmt.Errorf("回调验签失败: %w", err)
+	}
+	paid := noti.TradeStatus == alipay.TradeStatusSuccess || noti.TradeStatus == alipay.TradeStatusFinished
+	return &NotifyResult{
+		OutTradeNo:   noti.OutTradeNo,
+		TradeNo:      noti.TradeNo,
+		Amount:       noti.TotalAmount,
+		BuyerLogonID: noti.BuyerLogonId,
+		Paid:         paid,
+		Raw:          r.Form.Encode(),
+	}, nil
+}
+
+func (a *alipayChannel) Query(ctx context.Context, outTradeNo string) (*QueryResult, error) {
+	var p = alipay.TradeQuery{OutTradeNo: outTradeNo}
+	rsp, err := a.client.TradeQuery(ctx, p)
+	if err != nil {
+		return nil, fmt.Errorf("支付宝查单调用失败: %w", err)
+	}
+	if rsp.IsFailure() {
+		// 交易不存在（TRADE_NOT_EXIST）等：视为未找到，不报错，交由上层决定。
+		return &QueryResult{Found: false}, nil
+	}
+	paid := rsp.TradeStatus == alipay.TradeStatusSuccess || rsp.TradeStatus == alipay.TradeStatusFinished
+	return &QueryResult{
+		Found:      true,
+		OutTradeNo: rsp.OutTradeNo,
+		TradeNo:    rsp.TradeNo,
+		Amount:     rsp.TotalAmount,
+		Paid:       paid,
+	}, nil
+}