模型限制: 系统配置全局开放/禁止 + 用户级限制 + 网关拦截

- User 新增 allowed_models/denied_models(用户级模型限制)
- 系统配置 model_allowlist/model_denylist 全局策略, 保存即时失效网关缓存
- 网关 checkModelAllowed: 用户级 > 全局(禁止命中→403, 白名单非空→仅白名单)
- 三个协议处理器均校验, 错误按客户端协议格式返回
- 配置页"模型限制"卡片(全局允许/禁止多选); 用户编辑支持允许/禁止模型

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

server/internal/proxy/gateway.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/gin-gonic/gin"
@@ -35,6 +36,76 @@ type Gateway struct {
 	lim     *ratelimit.Limiter
 	userRPS int
 	hc      *http.Client
+
+	policyMu sync.Mutex
+	policy   modelPolicy
+}
+
+// modelPolicy 全局模型限制策略（来自系统配置，短时缓存）。
+type modelPolicy struct {
+	allow []string
+	deny  []string
+	at    time.Time
+}
+
+const modelPolicyTTL = 5 * time.Second
+
+// ResetModelPolicy 清空全局模型限制缓存（系统配置保存后调用）。
+func (g *Gateway) ResetModelPolicy() {
+	g.policyMu.Lock()
+	g.policy = modelPolicy{}
+	g.policyMu.Unlock()
+}
+
+// globalModelRestrictions 读取全局模型允许/禁止列表（缓存 30s）。
+func (g *Gateway) globalModelRestrictions() (allow, deny []string) {
+	g.policyMu.Lock()
+	defer g.policyMu.Unlock()
+	if time.Since(g.policy.at) < modelPolicyTTL {
+		return g.policy.allow, g.policy.deny
+	}
+	var raw string
+	g.db.Model(&store.SystemConfig{}).Where("key = ?", "model_allowlist").Pluck("value", &raw)
+	_ = json.Unmarshal([]byte(raw), &allow)
+	raw = ""
+	g.db.Model(&store.SystemConfig{}).Where("key = ?", "model_denylist").Pluck("value", &raw)
+	_ = json.Unmarshal([]byte(raw), &deny)
+	g.policy = modelPolicy{allow: allow, deny: deny, at: time.Now()}
+	return
+}
+
+// checkModelAllowed 模型访问控制：用户级 > 全局。
+//  1. 用户禁止列表命中 → 拒绝
+//  2. 用户允许列表非空 → 仅列表内可访问（不再看全局）
+//  3. 全局禁止命中 → 拒绝
+//  4. 全局允许列表非空 → 仅列表内可访问
+func (g *Gateway) checkModelAllowed(u *store.User, model string) bool {
+	if model == "" {
+		return true
+	}
+	if contains(u.DeniedModels, model) {
+		return false
+	}
+	if len(u.AllowedModels) > 0 {
+		return contains(u.AllowedModels, model)
+	}
+	allow, deny := g.globalModelRestrictions()
+	if contains(deny, model) {
+		return false
+	}
+	if len(allow) > 0 {
+		return contains(allow, model)
+	}
+	return true
+}
+
+func contains(list []string, s string) bool {
+	for _, v := range list {
+		if v == s {
+			return true
+		}
+	}
+	return false
 }
 
 func NewGateway(db *gorm.DB, enc *crypto.Encryptor, rec *usage.Recorder, lim *ratelimit.Limiter, userRPS int) *Gateway {

server/internal/proxy/handlers.go

@@ -23,6 +23,10 @@ func (g *Gateway) chatCompletions(c *gin.Context) {
 	}
 	c.Set("protocol", convert.ProtoChat)
 	c.Set("model_name", br.Model)
+	if !g.checkModelAllowed(u, br.Model) {
+		apiError(c, http.StatusForbidden, "model_not_allowed", "模型未对你开放，请联系管理员")
+		return
+	}
 
 	cands := g.candidateChannels(br.Model)
 	if len(cands) == 0 {
@@ -51,6 +55,10 @@ func (g *Gateway) responses(c *gin.Context) {
 	}
 	c.Set("protocol", convert.ProtoResponses)
 	c.Set("model_name", br.Model)
+	if !g.checkModelAllowed(u, br.Model) {
+		apiError(c, http.StatusForbidden, "model_not_allowed", "模型未对你开放，请联系管理员")
+		return
+	}
 
 	cands := g.candidateChannels(br.Model)
 	if len(cands) == 0 {
@@ -79,6 +87,10 @@ func (g *Gateway) messages(c *gin.Context) {
 	}
 	c.Set("protocol", convert.ProtoMessages)
 	c.Set("model_name", br.Model)
+	if !g.checkModelAllowed(u, br.Model) {
+		apiError(c, http.StatusForbidden, "model_not_allowed", "模型未对你开放，请联系管理员")
+		return
+	}
 
 	cands := g.candidateChannels(br.Model)
 	if len(cands) == 0 {