fix: pdf gene

backend/app/services/report_service.py

@@ -265,6 +265,7 @@ async def _gen_pdf(case_id: UUID, report_dir: Path, body: ReportCreate, db: Asyn
     from reportlab.lib.styles import getSampleStyleSheet
     from reportlab.pdfbase import pdfmetrics
     from reportlab.pdfbase.ttfonts import TTFont
+    from reportlab.pdfbase.cidfonts import UnicodeCIDFont
     import os
 
     font_registered = False
@@ -282,7 +283,17 @@ async def _gen_pdf(case_id: UUID, report_dir: Path, body: ReportCreate, db: Asyn
             except Exception:
                 continue
 
-    font_name = "ChineseFont" if font_registered else "Helvetica"
+    if not font_registered:
+        # Docker images often do not ship Chinese system fonts.
+        # Use built-in CID font as a portable fallback.
+        try:
+            pdfmetrics.registerFont(UnicodeCIDFont("STSong-Light"))
+            font_name = "STSong-Light"
+            font_registered = True
+        except Exception:
+            font_name = "Helvetica"
+    else:
+        font_name = "ChineseFont"
     styles = getSampleStyleSheet()
     title_style = styles["Title"]
     title_style.fontName = font_name

backend/requirements.txt

@@ -11,6 +11,7 @@ Pillow==12.1.0
 httpx==0.28.1
 openpyxl==3.1.5
 python-docx==1.2.0
+reportlab
 psycopg2-binary==2.9.11
 
 # dev dependencies