渠道: 模型名称映射(网关生效 + 渠道侧管理)

- 候选渠道携带 upstream_model, prepareUpstream 改写请求体 model 字段为上游名
- 新增渠道视角绑定 CRUD: GET/POST/PATCH/DELETE /admin/channels/:id/models
- 前端渠道页新增"模型映射": 列出绑定、内联改上游名、解除、添加
- rewriteModel 三种协议通用(model 均在顶层)

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

server/internal/proxy/gateway.go

@@ -3,6 +3,7 @@
 package proxy
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
@@ -148,8 +149,8 @@ func (g *Gateway) models(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"object": "list", "data": data})
 }
 
-// candidateChannels 返回可用渠道候选（按模型绑定优先，退化全局）。
-func (g *Gateway) candidateChannels(model string) []*store.Channel {
+// candidateChannels 返回可用渠道候选（按模型绑定优先，退化全局；携带模型映射）。
+func (g *Gateway) candidateChannels(model string) []channel.Candidate {
 	return g.ch.Candidates(model)
 }
 
@@ -213,8 +214,9 @@ func conversionTarget(formats []string, clientProto string) string {
 	return ""
 }
 
-// prepareUpstream 计算上游访问计划：渠道声明支持客户端协议则直通，否则转换。
-func prepareUpstream(ch *store.Channel, clientProto string, body []byte) (*upstreamPlan, error) {
+// prepareUpstream 计算上游访问计划：渠道声明支持客户端协议则直通，否则转换；
+// 应用模型名称映射（upstream_model）。
+func prepareUpstream(ch *store.Channel, clientProto string, body []byte, upstreamModel string) (*upstreamPlan, error) {
 	target := conversionTarget(ch.FormatsEffective(), clientProto)
 	if target == "" {
 		return nil, fmt.Errorf("channel %q declares no supported protocol format", ch.Name)
@@ -229,7 +231,26 @@ func prepareUpstream(ch *store.Channel, clientProto string, body []byte) (*upstr
 		plan.lineConv = convert.NewStreamTransformer(target, clientProto)
 		plan.bodyConv = func(b []byte) ([]byte, error) { return convert.ConvertResponse(b, target, clientProto) }
 	}
+	// 模型名称映射：把请求体 model 字段改写为渠道侧的 upstream_model
+	if upstreamModel != "" {
+		if out, err := rewriteModel(plan.body, upstreamModel); err == nil {
+			plan.body = out
+		}
+	}
 	return plan, nil
 }
 
+// rewriteModel 改写请求体中的 model 字段（三种协议 model 都在顶层）。
+func rewriteModel(body []byte, model string) ([]byte, error) {
+	var m map[string]any
+	if err := json.Unmarshal(body, &m); err != nil {
+		return body, nil
+	}
+	if cur, _ := m["model"].(string); cur == model {
+		return body, nil
+	}
+	m["model"] = model
+	return json.Marshal(m)
+}
+
 var errNoChannel = errors.New("no available channel")

server/internal/proxy/passthrough.go

@@ -44,19 +44,28 @@ func parseBody(c *gin.Context) (*bodyReq, []byte, error) {
 	return br, body, nil
 }
 
-// upstreamURL 组装上游地址：base_url + 路径。
-// 兼容用户填完整 base（含 /v1）：去掉尾部 /v1，避免与请求路径重复。
+// upstreamURL 组装上游地址，智能识别用户填写的 Base URL 形式：
+//  - 完整端点(以目标资源路径结尾) → 直接使用
+//  - 已含版本前缀(如 /v1) → 只拼资源路径(/chat/completions 等)
+//  - 纯域名/地址前缀 → 拼完整路径(/v1/chat/completions 等)
 func upstreamURL(ch *store.Channel, path string) string {
 	base := strings.TrimRight(ch.BaseURL, "/")
-	return strings.TrimSuffix(base, "/v1") + path
+	if strings.HasSuffix(base, path) {
+		return base
+	}
+	if strings.HasSuffix(base, "/v1") {
+		return base + strings.TrimPrefix(path, "/v1")
+	}
+	return base + path
 }
 
 // doProxy 通用代理（M5）：遍历候选渠道，按需转换；可安全重试的失败自动故障转移。
-func (g *Gateway) doProxy(c *gin.Context, cands []*store.Channel, clientProto string, body []byte, stream bool, sink *usageSink) {
+func (g *Gateway) doProxy(c *gin.Context, cands []channel.Candidate, clientProto string, body []byte, stream bool, sink *usageSink) {
 	var lastStatus = http.StatusBadGateway
 	var lastBody = []byte("all upstream channels failed")
-	for _, ch := range cands {
-		plan, err := prepareUpstream(ch, clientProto, body)
+	for _, cand := range cands {
+		ch := cand.Channel
+		plan, err := prepareUpstream(ch, clientProto, body, cand.UpstreamModel)
 		if err != nil {
 			lastStatus, lastBody = http.StatusInternalServerError, []byte("conversion error: "+err.Error())
 			continue