feat(AT): LINK 对外接口改为 S1/S2/C1/C2

- LINK 首参数由数字索引改为角色名（S1/S2/C1/C2），内部映射对用户隐藏

- LINK 查询与摘要回包统一输出角色名

- LINK 配置成功后返回当前记录，格式与查询一致

- 同步更新 AT 使用手册中的命令示例与字段说明

AT固件使用手册.md

@@ -30,7 +30,7 @@
 
 1. `MUX`：全局数据承载模式开关
 2. `NET`：全局静态网络配置记录
-3. `LINK[idx]`：按索引组织的链路配置记录
+3. `LINK[ROLE]`：按角色名组织的链路配置记录（`S1/S2/C1/C2`）
 
 约束如下：
 
@@ -127,18 +127,16 @@ NET = 192.168.1.100,255.255.255.0,192.168.1.1,02:00:00:00:00:01
 ### 7.3 LINK 默认值
 
 ```text
-LINK0 = 1,8080,0.0.0.0,0,U0
+LINK:S1 = 1,8080,0.0.0.0,0,U0
-LINK1 = 0,8081,0.0.0.0,0,U1
+LINK:S2 = 0,8081,0.0.0.0,0,U1
-LINK2 = 1,9001,192.168.1.200,9000,U1
+LINK:C1 = 1,9001,192.168.1.200,9000,U1
-LINK3 = 0,9002,192.168.1.201,9001,U0
+LINK:C2 = 0,9002,192.168.1.201,9001,U0
 ```
 
-固定索引映射：
+说明：
 
-- `0 = S1`
+- `S1/S2/C1/C2` 为对外可见角色名
-- `1 = S2`
+- 内部索引映射由固件管理，不对外暴露
-- `2 = C1`
-- `3 = C2`
 
 UART 记号约定：
 
@@ -174,10 +172,10 @@ AT+QUERY\r\n
 
 ```text
 +NET:IP=192.168.1.100,MASK=255.255.255.0,GW=192.168.1.1,MAC=02:00:00:00:00:01
-+LINK:0,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
++LINK:S1,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
-+LINK:1,EN=0,LPORT=8081,RIP=0.0.0.0,RPORT=0,UART=U1
++LINK:S2,EN=0,LPORT=8081,RIP=0.0.0.0,RPORT=0,UART=U1
-+LINK:2,EN=1,LPORT=9001,RIP=192.168.1.200,RPORT=9000,UART=U1
++LINK:C1,EN=1,LPORT=9001,RIP=192.168.1.200,RPORT=9000,UART=U1
-+LINK:3,EN=0,LPORT=9002,RIP=192.168.1.201,RPORT=9001,UART=U0
++LINK:C2,EN=0,LPORT=9002,RIP=192.168.1.201,RPORT=9001,UART=U0
 +MUX:0
 +MAP:UART2=0x04,UART3=0x08,C1=0x01,C2=0x02,S1=0x10,S2=0x20
 +BAUD:U0=115200,U1=115200
@@ -242,19 +240,19 @@ OK
 #### 设置单条 LINK 记录
 
 ```text
-AT+LINK=0,1,8080,0.0.0.0,0,U0\r\n
+AT+LINK=S1,1,8080,0.0.0.0,0,U0\r\n
-AT+LINK=2,1,9001,192.168.1.200,9000,U1\r\n
+AT+LINK=C1,1,9001,192.168.1.200,9000,U1\r\n
 ```
 
 字段顺序：
 
 ```text
-IDX,EN,LPORT,RIP,RPORT,UART
+ROLE,EN,LPORT,RIP,RPORT,UART
 ```
 
 字段说明：
 
-- `IDX`：实例索引，固定为 `0..3`
+- `ROLE`：链路角色名，固定为 `S1/S2/C1/C2`
 - `EN`：`0/1`
 - `LPORT`：本地端口
 - `RIP`：对端 IP
@@ -270,13 +268,13 @@ IDX,EN,LPORT,RIP,RPORT,UART
 #### 查询单条 LINK
 
 ```text
-AT+LINK=0\r\n
+AT+LINK=S1\r\n
 ```
 
 返回示例：
 
 ```text
-+LINK:0,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
++LINK:S1,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
 OK
 ```
 
@@ -289,10 +287,10 @@ AT+LINK?\r\n
 返回示例：
 
 ```text
-+LINK:0,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
++LINK:S1,EN=1,LPORT=8080,RIP=0.0.0.0,RPORT=0,UART=U0
-+LINK:1,EN=0,LPORT=8081,RIP=0.0.0.0,RPORT=0,UART=U1
++LINK:S2,EN=0,LPORT=8081,RIP=0.0.0.0,RPORT=0,UART=U1
-+LINK:2,EN=1,LPORT=9001,RIP=192.168.1.200,RPORT=9000,UART=U1
++LINK:C1,EN=1,LPORT=9001,RIP=192.168.1.200,RPORT=9000,UART=U1
-+LINK:3,EN=0,LPORT=9002,RIP=192.168.1.201,RPORT=9001,UART=U0
++LINK:C2,EN=0,LPORT=9002,RIP=192.168.1.201,RPORT=9001,UART=U0
 OK
 ```
 
@@ -353,9 +351,9 @@ OK: Defaults restored
 
 ```text
 AT+NET=192.168.1.123,255.255.255.0,192.168.1.1,02:00:00:00:00:01\r\n
-AT+LINK=0,1,10001,0.0.0.0,0,U1\r\n
+AT+LINK=S1,1,10001,0.0.0.0,0,U1\r\n
-AT+LINK=1,1,10003,0.0.0.0,0,U1\r\n
+AT+LINK=S2,1,10003,0.0.0.0,0,U1\r\n
-AT+LINK=2,1,20001,192.168.1.201,10002,U0\r\n
+AT+LINK=C1,1,20001,192.168.1.201,10002,U0\r\n
 AT+MUX=1\r\n
 AT+SAVE\r\n
 AT+RESET\r\n

App/config.c

@@ -158,6 +158,48 @@ static const char *link_uart_to_str(uint8_t uart)
     return (uart == LINK_UART_U1) ? "U1" : "U0";
 }
 
+static const char *link_index_to_name(uint32_t index)
+{
+    switch (index) {
+    case CONFIG_LINK_S1:
+        return "S1";
+    case CONFIG_LINK_S2:
+        return "S2";
+    case CONFIG_LINK_C1:
+        return "C1";
+    case CONFIG_LINK_C2:
+        return "C2";
+    default:
+        return "?";
+    }
+}
+
+static int parse_link_name(const char *value, uint32_t *index)
+{
+    if (value == NULL || index == NULL) {
+        return -1;
+    }
+
+    if (equals_ignore_case(value, "S1")) {
+        *index = CONFIG_LINK_S1;
+        return 0;
+    }
+    if (equals_ignore_case(value, "S2")) {
+        *index = CONFIG_LINK_S2;
+        return 0;
+    }
+    if (equals_ignore_case(value, "C1")) {
+        *index = CONFIG_LINK_C1;
+        return 0;
+    }
+    if (equals_ignore_case(value, "C2")) {
+        *index = CONFIG_LINK_C2;
+        return 0;
+    }
+
+    return -1;
+}
+
 static bool parse_command_with_value(const char *cmd, const char *name, const char **value)
 {
     size_t name_len;
@@ -309,10 +351,10 @@ static at_result_t handle_summary_query(char *response, uint16_t max_len)
 
     snprintf(response, max_len,
              "+NET:IP=%s,MASK=%s,GW=%s,MAC=%s\r\n"
-             "+LINK:0,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:S1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:S2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:C1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:3,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:C2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
              "+MUX:%u\r\n"
              "+MAP:UART2=0x04,UART3=0x08,C1=0x01,C2=0x02,S1=0x10,S2=0x20\r\n"
              "+BAUD:U0=%lu,U1=%lu\r\n"
@@ -356,8 +398,8 @@ static at_result_t handle_link_query(uint32_t index, char *response, uint16_t ma
     config_ip_to_str(g_config.links[index].remote_ip, rip_str);
     snprintf(response,
              max_len,
-             "+LINK:%lu,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\nOK\r\n",
+             "+LINK:%s,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\nOK\r\n",
-             index,
+             link_index_to_name(index),
              g_config.links[index].enabled,
              g_config.links[index].local_port,
              rip_str,
@@ -376,10 +418,10 @@ static at_result_t handle_all_link_query(char *response, uint16_t max_len)
 
     snprintf(response,
              max_len,
-             "+LINK:0,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:S1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:S2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:C1,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
-             "+LINK:3,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
+             "+LINK:C2,EN=%u,LPORT=%u,RIP=%s,RPORT=%u,UART=%s\r\n"
              "OK\r\n",
              g_config.links[0].enabled, g_config.links[0].local_port, rip_str[0], g_config.links[0].remote_port, link_uart_to_str(g_config.links[0].uart),
              g_config.links[1].enabled, g_config.links[1].local_port, rip_str[1], g_config.links[1].remote_port, link_uart_to_str(g_config.links[1].uart),
@@ -581,7 +623,7 @@ at_result_t config_process_at_cmd(const char *cmd, char *response, uint16_t max_
         cursor = value_copy;
 
         token = config_next_token(&cursor);
-        if (token == NULL || parse_u32_value(token, 0u, CONFIG_LINK_COUNT - 1u, &index) != 0) {
+        if (token == NULL || parse_link_name(token, &index) != 0) {
             snprintf(response, max_len, "ERROR: Invalid route field\r\n");
             return AT_INVALID_PARAM;
         }
@@ -623,7 +665,10 @@ at_result_t config_process_at_cmd(const char *cmd, char *response, uint16_t max_
         memcpy(g_config.links[index].remote_ip, rip, sizeof(rip));
         g_config.links[index].remote_port = (uint16_t)remote_port;
         g_config.links[index].uart = uart;
-        snprintf(response, max_len, "OK\r\n");
+        if (handle_link_query(index, response, max_len) != AT_OK) {
+            snprintf(response, max_len, "ERROR: Invalid route field\r\n");
+            return AT_INVALID_PARAM;
+        }
         return AT_NEED_REBOOT;
     }