feat(core): AI 生成 Agent 化 — 多模型流式脚本 agent + 可插拔 Provider + gpt-image-2 参考图 + 模特库

- 后端·可插拔 Provider 层:通用 OpenAICompatibleProvider(tokenssr 等中转站,base_url+api_key,零改代码换站)+ ModelProvider.api_key
- 后端·脚本 agent:结构化 ScriptDraft 契约 + 加载电商 skill + 出稿/改稿一体对话 agent(3模式/多模型)+ 流式 SSE 端点(DRF SSE renderer)
- 后端·图像:gpt-image-2 参考图出图 + 故事板 @图1@图2@图3 多锚点合成(锁脸锁商品);Seedance 打开 generate_audio
- 后端·模特库:gpt-image-2 生成器(9:16氛围图→16:9白底三视图)+ seed_demo_models 管理命令
- DB·迁移:tokenssr 中转站 + 多模型 seed(豆包/GPT-5.5/Gemini + gpt-image-2);ScriptSegment 结构化字段
- 前端·脚本趴:接真 SSE(工具卡 + 思考流)+ 模型下拉 + 3模式 + 改稿;agentScriptStream
- skills/ecommerce-video-script 电商脚本技能(运行时依赖)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/backend/apps/projects/views.py

@@ -3,13 +3,17 @@ from pathlib import Path
 import uuid
 
 from django.db import transaction
+from django.http import JsonResponse, StreamingHttpResponse
 from rest_framework import status
 from rest_framework.decorators import action
 from rest_framework.parsers import FormParser, MultiPartParser
+from rest_framework.renderers import BaseRenderer
 from rest_framework.response import Response
 from rest_framework.viewsets import ModelViewSet
 
+from apps.ai.models import ModelConfig
 from apps.ai.providers import TtsNotConfigured
+from apps.ai.script_agent import stream_script_agent
 from apps.ai.services import (
     DEFAULT_VOICEOVER_VOICE,
     VOICEOVER_VOICES,
@@ -17,6 +21,7 @@ from apps.ai.services import (
     generate_base_asset,
     generate_project_script,
     generate_storyboard_frame,
+    get_default_model,
     poll_video_segment,
     regenerate_script_segment,
     submit_storyboard,
@@ -58,6 +63,18 @@ from .tasks import poll_video_segment_task
 logger = logging.getLogger(__name__)
 
 
+class ServerSentEventRenderer(BaseRenderer):
+    """让 DRF 内容协商接受 Accept: text/event-stream(否则流式端点直接 406)。
+    实际响应由视图返回 StreamingHttpResponse 直接下发,这个 renderer 只用于通过协商。"""
+
+    media_type = "text/event-stream"
+    format = "event-stream"
+    charset = None
+
+    def render(self, data, accepted_media_type=None, renderer_context=None):
+        return data
+
+
 def _store_uploaded_asset(*, team, user, upload, asset_type: str, category: str, name: str) -> Asset:
     """把上传的文件落到 TOS,建 Asset+AssetFile(主文件)。供上传视频段 / 上传 BGM 复用。"""
     suffix = Path(upload.name).suffix.lower() or (".mp4" if asset_type == Asset.Type.VIDEO else ".mp3")
@@ -133,6 +150,53 @@ class ProjectViewSet(TeamScopedViewSetMixin, ModelViewSet):
         )
         return Response(ScriptVersionSerializer(script).data, status=status.HTTP_201_CREATED)
 
+    @action(detail=True, methods=["post"], url_path="script-agent-stream", renderer_classes=[ServerSentEventRenderer])
+    def script_agent_stream(self, request, pk=None):
+        """对话式脚本 agent · 流式(SSE)。出稿 + 改稿一体,多模型可选。
+        请求体:mode(auto|theme|revise)、prompt、model_config_id、selling_point_ids、
+        base_version_id(改稿)、aspect_ratio、total_duration。
+        响应:text/event-stream,逐帧吐 tool/delta/draft/saved/done/error。"""
+        project = self.get_object()
+        mode = str(request.data.get("mode") or "auto")
+        prompt = str(request.data.get("prompt") or "")
+        selling_point_ids = request.data.get("selling_point_ids") or []
+        base_version_id = request.data.get("base_version_id") or None
+        aspect_ratio = str(request.data.get("aspect_ratio") or "9:16")
+        try:
+            total_duration = int(request.data.get("total_duration") or 60)
+        except (TypeError, ValueError):
+            total_duration = 60
+
+        model_config = None
+        requested = request.data.get("model_config_id")
+        if requested:
+            model_config = (
+                ModelConfig.objects.select_related("provider")
+                .filter(id=requested, capability=ModelConfig.Capability.TEXT, status=ModelConfig.Status.ACTIVE)
+                .first()
+            )
+        if model_config is None:
+            model_config = get_default_model(ModelConfig.Capability.TEXT)
+        if model_config is None:
+            # 纯 Django 响应:绕开 DRF 渲染(此 action 只挂了 SSE renderer)
+            return JsonResponse({"detail": "没有可用的文本模型,请先在模型库配置"}, status=400)
+
+        stream = stream_script_agent(
+            project=project,
+            user=request.user,
+            model_config=model_config,
+            mode=mode,
+            user_prompt=prompt,
+            selling_point_ids=selling_point_ids,
+            base_version_id=base_version_id,
+            aspect_ratio=aspect_ratio,
+            total_duration=total_duration,
+        )
+        response = StreamingHttpResponse(stream, content_type="text/event-stream")
+        response["Cache-Control"] = "no-cache"
+        response["X-Accel-Buffering"] = "no"  # 关 nginx 缓冲,保证逐帧下发
+        return response
+
     @action(detail=True, methods=["post"], url_path="adopt-script")
     @transaction.atomic
     def adopt_script(self, request, pk=None):