M54: harden operations and demo resilience

backend/app/services/data_quality_common.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime, timedelta
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.core.errors import AppError
+from app.models.data_quality import DataQualityIssue
+
+
+def issue_due_at(detected_at: datetime, severity: str) -> datetime:
+    """Return the local operational SLA deadline for a newly detected issue."""
+    return detected_at + {
+        "high": timedelta(hours=4),
+        "medium": timedelta(days=1),
+        "low": timedelta(days=3),
+    }.get(severity, timedelta(days=1))
+
+
+def has_open_issue(
+    db: Session,
+    rule_type: str,
+    entity_type: str,
+    entity_id: uuid.UUID,
+) -> bool:
+    return (
+        db.scalar(
+            select(DataQualityIssue.id).where(
+                DataQualityIssue.rule_type == rule_type,
+                DataQualityIssue.entity_type == entity_type,
+                DataQualityIssue.entity_id == entity_id,
+                DataQualityIssue.status == "open",
+            )
+        )
+        is not None
+    )
+
+
+def new_scan_ref(prefix: str) -> str:
+    """Generate a stable human-readable prefix with a concurrent-safe suffix."""
+    return f"{prefix}-{uuid.uuid4().hex[:10].upper()}"
+
+
+def load_open_issue(db: Session, public_ref: str, *, lock: bool = True) -> DataQualityIssue:
+    statement = select(DataQualityIssue).where(DataQualityIssue.public_ref == public_ref)
+    if lock:
+        statement = statement.with_for_update().execution_options(populate_existing=True)
+    issue = db.scalar(statement)
+    if issue is None:
+        raise AppError("ISSUE_NOT_FOUND", "Data quality issue not found.", status_code=404)
+    if issue.status != "open":
+        raise AppError(
+            "ISSUE_NOT_OPEN",
+            f"Issue is '{issue.status}', not 'open'.",
+            status_code=409,
+        )
+    return issue