fix: improve import, evidence indexing and material-scoped grading

Preserve document revisions and evidence, harden indexing and export behavior, add explicit material selection and direct-folder import, validate model JSON schemas with safe error messages, and retain student selection while loading scoring data.

backend/wisegrade/submissions.py

@@ -0,0 +1,85 @@
+"""Document preparation shared by scoring and indexing."""
+from contextlib import contextmanager
+import errno
+import os
+import time
+
+from sqlalchemy import select
+
+from .config import get_settings
+from .models import KnowledgeDocument, Project, SubmissionFile
+from .parsing import parse_document, text_quality
+from .rag import INDEX_VERSION, ingest
+from .storage import secure_path, sha256
+
+
+@contextmanager
+def file_index_lock(file_id: int):
+    root = get_settings().processed_path
+    root.mkdir(parents=True, exist_ok=True)
+    with (root / f"file-{file_id}.lock").open("a+b") as handle:
+        if os.name == "nt":
+            import msvcrt
+            if not handle.tell():
+                handle.write(b"0")
+                handle.flush()
+            while True:
+                handle.seek(0)
+                try:
+                    msvcrt.locking(handle.fileno(), msvcrt.LK_NBLCK, 1)
+                    break
+                except OSError as exc:
+                    if exc.errno not in (errno.EACCES, errno.EAGAIN, errno.EDEADLK):
+                        raise
+                    time.sleep(.05)
+            try:
+                yield
+            finally:
+                handle.seek(0)
+                msvcrt.locking(handle.fileno(), msvcrt.LK_UNLCK, 1)
+        else:
+            import fcntl
+            fcntl.flock(handle, fcntl.LOCK_EX)
+            try:
+                yield
+            finally:
+                fcntl.flock(handle, fcntl.LOCK_UN)
+
+
+def parse_submission(db, file: SubmissionFile, *, embedder=None):
+    with file_index_lock(file.id):
+        db.refresh(file)
+        if file.recognition_status != "recognized":
+            raise ValueError("材料已取消选择，请重新预览")
+        path = secure_path(file.relative_path)
+        if sha256(path) != file.sha256:
+            file.parse_status, file.parse_error = "changed", "源文件已变化，请重新扫描并确认导入"
+            db.commit()
+            raise ValueError(file.parse_error)
+        try:
+            # An indexing failure does not invalidate already saved parsing.
+            parsed = file.parsed if file.parsed and file.parsed.get("pages") else parse_document(
+                path, file.category, get_settings().processed_path / f"file-{file.id}" / file.sha256[:16])
+            parsed = {**parsed, "pages": [{**page, "text_quality": text_quality(page.get("text", ""))}
+                                          for page in parsed["pages"]]}
+            file.parsed = parsed
+            doc = db.scalar(select(KnowledgeDocument).where(KnowledgeDocument.submission_file_id == file.id,
+                             KnowledgeDocument.source_hash == file.sha256, KnowledgeDocument.status != "superseded"))
+            if not doc or doc.source_hash != file.sha256 or doc.index_version != INDEX_VERSION or doc.status != "ready":
+                project = db.get(Project, file.project_id)
+                kwargs = {"embedder": embedder} if embedder else {}
+                ingest(db, course_version_id=project.course_version_id, project_id=project.id,
+                       submission_file_id=file.id, title=path.name, category=file.category,
+                       source_hash=file.sha256, pages=parsed["pages"], **kwargs)
+            file.parse_status, file.parse_error = "ready", ""
+            db.commit()
+            return parsed
+        except Exception as exc:
+            db.rollback()
+            file = db.get(SubmissionFile, file.id)
+            # Preserve parse output on model/index errors for a later retry.
+            if "parsed" in locals():
+                file.parsed = parsed
+            file.parse_status, file.parse_error = "failed", str(exc)[:1000]
+            db.commit()
+            raise