feat(marker): support page-range conversion in /convert

ConvertRequest.start_page/end_page (1-based inclusive); per-request PdfConverter with config page_range, reuses loaded models. 1-based->0-based contained in marker adapter. PR-DocSrv-LargeDoc-Split-Markdown-1 commit 2.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/marker/server.py

@@ -78,6 +78,10 @@ async def startup():
 class ConvertRequest(BaseModel):
     file_path: str
     max_pages: int | None = None
+    # page range (1-based inclusive) — LargeDoc split 변환용. marker 내부 0-based 변환은
+    # convert() 에 격리 (page numbering invariant: DB/API=1-based, marker=0-based).
+    start_page: int | None = None
+    end_page: int | None = None
 
 
 class ConvertImage(BaseModel):
@@ -139,8 +143,22 @@ async def convert(req: ConvertRequest):
         raise HTTPException(404, detail={"code": "file_not_found", "message": str(p)})
 
     start = time.monotonic()
+    # page range 지정 시 per-request converter (모델 _models 재사용 → reload 없음).
+    # invariant: req.start_page/end_page = 1-based inclusive → marker 0-based 로 변환.
+    converter = _converter
+    if req.start_page is not None and req.end_page is not None:
+        if req.start_page < 1 or req.end_page < req.start_page:
+            raise HTTPException(
+                422,
+                detail={
+                    "code": "bad_page_range",
+                    "message": f"start_page={req.start_page} end_page={req.end_page}",
+                },
+            )
+        page_range = list(range(req.start_page - 1, req.end_page))  # 0-based inclusive
+        converter = PdfConverter(artifact_dict=_models, config={"page_range": page_range})
     try:
-        rendered = _converter(str(p))
+        rendered = converter(str(p))
     except Exception as exc:
         logger.exception(f"[marker-service] conversion failed path={p}: {exc}")
         raise HTTPException(