fix(06.2): WR-08 delete_document defers commit so audit log writes in same transaction

backend/services/storage.py

@@ -140,7 +140,12 @@ async def list_metadata(
     return rows
 
 
-async def delete_document(session: AsyncSession, doc_id: str, skip_quota: bool = False) -> bool:
+async def delete_document(
+    session: AsyncSession,
+    doc_id: str,
+    skip_quota: bool = False,
+    auto_commit: bool = True,
+) -> bool:
     """Delete a document's MinIO object and its PostgreSQL row.
 
     Returns False if the document is not found; True on success.
@@ -149,6 +154,11 @@ async def delete_document(session: AsyncSession, doc_id: str, skip_quota: bool =
 
     skip_quota=True skips the quota decrement — used for cloud-stored documents
     that were never charged against the user's MinIO quota (T-06.2-03-01).
+
+    auto_commit=False defers the session.commit() to the caller, allowing the
+    caller to write an audit log entry in the same transaction before committing
+    (avoids the split-transaction gap where a failed audit write loses the record
+    while the document row is already gone).
     """
     try:
         uid = uuid.UUID(doc_id)
@@ -179,7 +189,8 @@ async def delete_document(session: AsyncSession, doc_id: str, skip_quota: bool =
         )
 
     await session.delete(doc)
-    await session.commit()
+    if auto_commit:
+        await session.commit()
     return True