docs: align payment guide with visible routing

docs/PAYMENT.md

@@ -22,11 +22,11 @@ Sub2API has a built-in payment system that enables user self-service top-up with
 | Provider | Payment Methods | Description |
 |----------|----------------|-------------|
 | **EasyPay** | Alipay, WeChat Pay | Third-party aggregation via EasyPay protocol |
-| **Alipay (Direct)** | PC Page Pay, H5 Mobile Pay | Direct integration with Alipay Open Platform, auto-switches by device |
-| **WeChat Pay (Direct)** | Native QR Code, H5 Pay | Direct integration with WeChat Pay APIv3, mobile-first H5 |
+| **Alipay (Direct)** | Desktop QR code, mobile Alipay redirect | Direct integration with Alipay Open Platform, returning desktop QR codes and mobile WAP/app launch links |
+| **WeChat Pay (Direct)** | Native QR, H5, MP/JSAPI Pay | Direct integration with WeChat Pay APIv3 with environment-aware routing |
 | **Stripe** | Card, Alipay, WeChat Pay, Link, etc. | International payments, multi-currency support |
 
-> Alipay/WeChat Pay direct and EasyPay can coexist. Direct channels connect to payment APIs directly with lower fees; EasyPay aggregates through third-party platforms with easier setup.
+> Alipay/WeChat Pay direct and EasyPay can both exist as backend provider instances, but the frontend always exposes only two visible buttons: `Alipay` and `WeChat Pay`. Admins choose exactly one source for each visible method: direct or EasyPay. Direct channels connect to payment APIs directly with lower fees; EasyPay aggregates through third-party platforms with easier setup.
 
 > **EasyPay Provider Recommendations**: Both options below are third-party aggregators compatible with the EasyPay protocol. Pick based on the funding channel and settlement currency you need:
 >
@@ -65,6 +65,15 @@ Configure the following in Admin Dashboard **Settings → Payment Settings**:
 | **Max Pending Orders** | Maximum concurrent pending orders per user | 3 |
 | **Load Balance Strategy** | Strategy for selecting provider instances | Least Amount |
 
+### Frontend Visible Method Routing
+
+The current payment UX keeps the frontend method list unified and does not expose provider brands directly:
+
+- **Alipay**: when enabled, this button must be routed to either `Alipay (Direct)` or `EasyPay Alipay`
+- **WeChat Pay**: when enabled, this button must be routed to either `WeChat Pay (Direct)` or `EasyPay WeChat`
+- Each visible method can route to only one source at a time
+- If a visible method is enabled without a selected source, the frontend will not expose that method
+
 ### Load Balance Strategies
 
 | Strategy | Description |
@@ -113,7 +122,7 @@ Compatible with any payment service that implements the EasyPay protocol.
 
 ### Alipay (Direct)
 
-Direct integration with Alipay Open Platform. Supports PC page pay and H5 mobile pay.
+Direct integration with Alipay Open Platform. Desktop flows return a QR code for in-page display, while mobile flows return an Alipay WAP/app redirect URL.
 
 | Parameter | Description | Required |
 |-----------|-------------|----------|
@@ -123,7 +132,7 @@ Direct integration with Alipay Open Platform. Supports PC page pay and H5 mobile
 
 ### WeChat Pay (Direct)
 
-Direct integration with WeChat Pay APIv3. Supports Native QR code and H5 payment.
+Direct integration with WeChat Pay APIv3. Supports Native QR code payment, H5 payment, and MP/JSAPI payment inside the WeChat environment.
 
 | Parameter | Description | Required |
 |-----------|-------------|----------|
@@ -220,8 +229,8 @@ User selects amount and payment method
        ▼
   User completes payment
   ├─ EasyPay     → QR code / H5 redirect
-  ├─ Alipay      → PC page pay / H5 mobile pay
-  ├─ WeChat Pay  → Native QR / H5 pay
+  ├─ Alipay      → Desktop QR / mobile Alipay redirect
+  ├─ WeChat Pay  → Desktop Native QR / non-WeChat H5 / in-WeChat JSAPI
   └─ Stripe      → Payment Element (card/Alipay/WeChat/etc.)
        │
        ▼