feat(worker): ffmpeg渲染失败时捕获stderr写入error_detail，增强排障能力

- RenderAdapterResult新增error_detail字段存完整stderr
- render_adapter单独捕获CalledProcessError，把stderr写入error_message和error_detail
- edit_plan_generation失败时把error_detail拼进gen_task.error_message
- 新增test_ffmpeg_error_captures_stderr测试
- 35个render_adapter测试全绿

apps/worker/video_processing/render_adapter.py

@@ -16,6 +16,7 @@
 from __future__ import annotations
 
 import logging
+import subprocess
 import tempfile
 from dataclasses import dataclass
 from pathlib import Path
@@ -70,6 +71,7 @@ class RenderAdapterResult:
     rendered_clip_ids: list[str] = None  # 成功渲染的 clip id 列表
     failed_clip_ids: list[str] = None  # 失败的 clip id 列表
     error_message: str = ""
+    error_detail: str = ""  # 详细错误信息（如 ffmpeg stderr），用于排查
 
     def __post_init__(self):
         if self.rendered_clip_ids is None:
@@ -249,6 +251,20 @@ class RenderAdapter:
                 failed_clip_ids=failed_clip_ids,
             )
 
+        except subprocess.CalledProcessError as exc:
+            stderr_text = (exc.stderr or "").strip()
+            logger.error(
+                "[render-adapter] ffmpeg渲染失败: plan_id=%s job_id=%s exit_code=%d\nstderr:\n%s",
+                plan_id,
+                job_id,
+                exc.returncode,
+                stderr_text[:3000],
+            )
+            return RenderAdapterResult(
+                success=False,
+                error_message=f"FFmpeg渲染失败(exit={exc.returncode}): {stderr_text[:200]}",
+                error_detail=stderr_text[:3000],
+            )
         except Exception as exc:
             logger.exception(
                 "[render-adapter] render failed: plan_id=%s job_id=%s engine=unified error=%s",

apps/worker/worker_app/tasks/edit_plan_generation.py

@@ -265,8 +265,11 @@ def _render_with_unified(
         return {"status": "error", "message": f"渲染失败: {render_err}"}
 
     if not result.success:
+        full_error = result.error_message or "渲染失败"
+        if result.error_detail:
+            full_error = f"{full_error}\n--- stderr ---\n{result.error_detail}"
         logger.error("渲染失败(unified): %s — %s", plan_id, result.error_message)
-        _mark_plan_failed(plan_repo, plan_id, gen_task_repo, generation_task_id, result.error_message or "渲染失败")
+        _mark_plan_failed(plan_repo, plan_id, gen_task_repo, generation_task_id, full_error)
         return {"status": "error", "message": result.error_message or "渲染失败"}
 
     output_path = result.output_path or Path("")

tests/unit/test_render_adapter.py

@@ -393,6 +393,40 @@ class TestRenderPlan:
         assert call_kwargs.kwargs["output_width"] == 1080
         assert call_kwargs.kwargs["output_height"] == 1920
 
+    @patch("video_processing.render_adapter.UnifiedRenderService")
+    @patch("video_processing.render_adapter.download_asset")
+    def test_ffmpeg_error_captures_stderr(self, mock_download, mock_render_cls, tmp_path):
+        """ffmpeg CalledProcessError 时 stderr 写入 error_detail 和 error_message。"""
+        import subprocess
+
+        def _fake_download(storage_key, local_path):
+            local_path.parent.mkdir(parents=True, exist_ok=True)
+            local_path.write_bytes(b"fake data")
+            return True
+
+        mock_download.side_effect = _fake_download
+
+        mock_render = MagicMock()
+        mock_render.render.side_effect = subprocess.CalledProcessError(
+            returncode=1,
+            cmd=["ffmpeg", "-i", "input.mp4", "output.mp4"],
+            stderr="Invalid data found when processing input\nLast message repeated 3 times",
+        )
+        mock_render_cls.return_value = mock_render
+
+        plan = FakePlan(id="plan_001", status="editing")
+        clips = [_make_clip("c1", order=0, duration=5.0)]
+        asset_url_map = {"asset_c1.mp4": "https://test-bucket.oss.com/assets/asset_c1.mp4"}
+        adapter, _, _ = _make_adapter(plan=plan, clips=clips, asset_url_map=asset_url_map)
+
+        result = adapter.render_plan("plan_001", job_id="job_001", work_dir=tmp_path / "work")
+
+        assert not result.success
+        assert "FFmpeg渲染失败" in result.error_message
+        assert "exit=1" in result.error_message
+        assert "Invalid data found" in result.error_detail
+        assert "Invalid data found" in result.error_message
+
     @patch("video_processing.render_adapter.download_asset")
     def test_progress_callback(self, mock_download, tmp_path):
         """进度回调被正确触发。"""