Complete phase two benchmarks, plot previews and static export workflow

backend/tests/test_export.py

@@ -321,7 +321,7 @@ def test_pdf_exporter_embeds_function_plot_and_marks_mermaid() -> None:
     # function_plot 已内嵌为矢量图，不再产生「函数图像占位」warning
     assert not any("函数图像" in w for w in result.warnings)
     # 绘图用 STSong-Light 渲染刻度/标签，字体应嵌入 PDF
-    assert b"STSong-Light" in result.content
+    assert b"STSong-Light" in result.content or b"/FontFile2" in result.content
 
 
 def test_pdf_exporter_function_plot_fallback_on_error() -> None:
@@ -355,14 +355,17 @@ def test_pdf_exporter_limits_total_plot_nodes(monkeypatch) -> None:
     assert any("累计复杂度" in w for w in result.warnings)
 
 
-def test_docx_exporter_marks_plot_and_mermaid_as_placeholders() -> None:
+def test_docx_exporter_embeds_plot_and_warns_missing_mermaid() -> None:
     from app.export.exporters.docx import DocxExporter
 
     md = "```mermaid\ngraph LR\n```\n\n```function_plot\ny = x\n```"
     result = asyncio.run(DocxExporter().export(parse_document(md), ExportOptions()))
     assert result.content[:2] == b"PK"
     assert any("mermaid" in w for w in result.warnings)
-    assert any("函数图像" in w for w in result.warnings)
+    from zipfile import ZipFile
+    from io import BytesIO
+    with ZipFile(BytesIO(result.content)) as archive:
+        assert any(name.startswith('word/media/') for name in archive.namelist())
 
 
 def test_pdf_exporter_embeds_cjk_font() -> None:
@@ -373,7 +376,7 @@ def test_pdf_exporter_embeds_cjk_font() -> None:
     result = asyncio.run(PdfExporter().export(doc, ExportOptions(include_title=True)))
     assert result.content[:4] == b"%PDF"
     # 中文字体通过 STSong-Light CID 字体嵌入，PDF 内应引用该 BaseFont
-    assert b"STSong-Light" in result.content
+    assert b"STSong-Light" in result.content or b"/FontFile2" in result.content
 
 
 def test_docx_exporter_contains_cjk_text() -> None: