fix(plugin): extend image host forward timeout

Allow image generation requests to use the five-minute host forward window while keeping regular requests on the existing timeout.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: DouDOU-start

backend/internal/plugin/host_service.go

@@ -459,7 +459,7 @@ func (h *HostService) forward(ctx context.Context, req *pb.HostForwardRequest) (
 	if err != nil {
 		return nil, err
 	}
-	fwdCtx, cancel := context.WithTimeout(ctx, 120*time.Second)
+	fwdCtx, cancel := context.WithTimeout(ctx, hostForwardTimeout(req))
 	defer cancel()
 
 	var hardExclude []int
@@ -706,7 +706,18 @@ func (h *HostService) forwardStream(ctx context.Context, req *pb.HostForwardRequ
 }
 
 // maxHostForwardAttempts 最大 failover 次数，与 Forwarder 保持一致。
-const maxHostForwardAttempts = 3
+const (
+	maxHostForwardAttempts    = 3
+	defaultHostForwardTimeout = 120 * time.Second
+	imageHostForwardTimeout   = 300 * time.Second
+)
+
+func hostForwardTimeout(req *pb.HostForwardRequest) time.Duration {
+	if req != nil && requestNeedsImage(req.Path, req.Model) {
+		return imageHostForwardTimeout
+	}
+	return defaultHostForwardTimeout
+}
 
 // failoverStreamWriter 包装 hostStreamWriter，支持 failover 重试。
 // 成功响应（StatusCode < 400）立即提交到真正的 gRPC stream，实现真流式；

backend/internal/plugin/host_service_test.go

@@ -3,15 +3,38 @@ package plugin
 import (
 	"context"
 	"testing"
+	"time"
 
 	"entgo.io/ent/dialect/sql/schema"
 	_ "github.com/mattn/go-sqlite3"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
 	"github.com/DouDOU-start/airgate-core/ent/enttest"
+	pb "github.com/DouDOU-start/airgate-sdk/proto"
 )
 
+func TestHostForwardTimeout(t *testing.T) {
+	cases := []struct {
+		name string
+		req  *pb.HostForwardRequest
+		want time.Duration
+	}{
+		{name: "nil request", req: nil, want: defaultHostForwardTimeout},
+		{name: "chat request", req: &pb.HostForwardRequest{Path: "/v1/chat/completions", Model: "gpt-4o"}, want: defaultHostForwardTimeout},
+		{name: "images API request", req: &pb.HostForwardRequest{Path: "/v1/images/generations", Model: "gpt-4o"}, want: imageHostForwardTimeout},
+		{name: "image model request", req: &pb.HostForwardRequest{Path: "/v1/responses", Model: "gpt-image-2"}, want: imageHostForwardTimeout},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := hostForwardTimeout(tc.req); got != tc.want {
+				t.Fatalf("hostForwardTimeout() = %s, want %s", got, tc.want)
+			}
+		})
+	}
+}
+
 func TestCheckHostForwardBalance(t *testing.T) {
 	ctx := context.Background()
 	db := enttest.Open(t, "sqlite3", "file:host_forward_balance?mode=memory&cache=shared&_fk=1", enttest.WithMigrateOptions(schema.WithGlobalUniqueID(false)))