fix: 统一AI生成失败提示

core/backend/apps/ai/script_agent.py

@@ -14,7 +14,7 @@ SSE 事件(每帧 `data: {json}\n\n`,json 带 type):
   saved  {script_version_id, version}             —— 已落库的 ScriptVersion(含 segments/metadata)
   summary {text}                                  —— 模型自己写的收尾交付语(当 AI 回复气泡,替代写死的「已生成」)
   done   {}                                       —— 结束
-  error  {detail}                                 —— 失败(已回滚额度)
+  error  {detail,error}                           —— 失败(已回滚额度；error 为安全业务错误对象)
 """
 from __future__ import annotations
 
@@ -26,6 +26,7 @@ from pathlib import Path
 from django.conf import settings
 from django.utils import timezone
 
+from apps.ai.generation_errors import classify_generation_error
 from apps.ai.models import AITask, ModelConfig
 from apps.billing.services.ledger import charge_reserved_credit, release_credit
 
@@ -621,7 +622,8 @@ def stream_script_agent(
             },
         )
     except Exception as exc:  # noqa: BLE001 — 多为额度不足
-        yield _sse({"type": "error", "detail": f"任务创建失败(可能额度不足):{exc}"})
+        internal_kind = "user_credit_insufficient" if str(exc).strip().lower() == "insufficient credit" else ""
+        yield _sse(_script_error_event(exc, internal_kind=internal_kind))
         return
     reservation = task.credit_reservation
     # 额度是否已结算(charge 成功 / release 失败)。客户端中途断连时,生成器被 .close() 抛
@@ -676,7 +678,7 @@ def stream_script_agent(
             _fail_task(task, reservation, str(exc))
             settled = True
             yield _sse({"type": "tool", "id": "generate", "status": "error"})
-            yield _sse({"type": "error", "detail": f"脚本生成失败:{exc}"})
+            yield _sse(_script_error_event(exc, reference_id=str(task.id)))
             return
 
         yield _sse({"type": "tool", "id": "generate", "status": "done"})
@@ -707,7 +709,7 @@ def stream_script_agent(
         except Exception as exc:  # noqa: BLE001 — 落库失败:atomic 已回滚 charge,补释放预留
             _fail_task(task, reservation, f"保存脚本失败:{exc}")
             settled = True
-            yield _sse({"type": "error", "detail": f"保存脚本失败:{exc}"})
+            yield _sse(_script_error_event(exc, reference_id=str(task.id), internal_kind="processing_failed"))
             return
 
         from apps.projects.serializers import ScriptVersionSerializer
@@ -743,6 +745,26 @@ def _fail_task(task, reservation, message: str) -> None:
             pass
 
 
+def _script_error_event(
+    exc: Exception,
+    *,
+    reference_id: str | None = None,
+    internal_kind: str = "",
+) -> dict:
+    """脚本 SSE 的安全失败帧；原始异常只落任务记录/日志，不回传普通用户。"""
+    public_error = classify_generation_error(
+        exc,
+        operation="script_generate",
+        internal_kind=internal_kind,
+        reference_id=reference_id,
+    )
+    return {
+        "type": "error",
+        "detail": public_error.fallback_message,
+        "error": public_error.as_dict(),
+    }
+
+
 def _load_base_draft(project, base_version_id: str) -> dict | None:
     from apps.projects.models import ScriptVersion