Guard genlocke data integrity edge cases

Block deletion of runs linked to a genlocke leg, prevent reactivating
completed/failed genlocke-linked runs, and guard encounter deletion
against genlocke transfer references with clear 400 errors.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/app/api/encounters.py

@@ -159,6 +159,19 @@ async def delete_encounter(
     if encounter is None:
         raise HTTPException(status_code=404, detail="Encounter not found")
 
+    # Block deletion if encounter is referenced by a genlocke transfer
+    transfer_result = await session.execute(
+        select(GenlockeTransfer.id).where(
+            (GenlockeTransfer.source_encounter_id == encounter_id)
+            | (GenlockeTransfer.target_encounter_id == encounter_id)
+        )
+    )
+    if transfer_result.scalar_one_or_none() is not None:
+        raise HTTPException(
+            status_code=400,
+            detail="Cannot delete an encounter that is part of a genlocke transfer.",
+        )
+
     await session.delete(encounter)
     await session.commit()
     return Response(status_code=204)

backend/src/app/api/runs.py

@@ -173,6 +173,17 @@ async def update_run(
             )
         update_data["completed_at"] = datetime.now(timezone.utc)
 
+    # Block reactivating a completed/failed run that belongs to a genlocke
+    if "status" in update_data and update_data["status"] == "active" and run.status != "active":
+        leg_result = await session.execute(
+            select(GenlockeLeg).where(GenlockeLeg.run_id == run_id)
+        )
+        if leg_result.scalar_one_or_none() is not None:
+            raise HTTPException(
+                status_code=400,
+                detail="Cannot reactivate a genlocke-linked run. The genlocke controls leg progression.",
+            )
+
     for field, value in update_data.items():
         setattr(run, field, value)
 
@@ -211,6 +222,16 @@ async def delete_run(
     if run is None:
         raise HTTPException(status_code=404, detail="Run not found")
 
+    # Block deletion if run is linked to a genlocke leg
+    leg_result = await session.execute(
+        select(GenlockeLeg).where(GenlockeLeg.run_id == run_id)
+    )
+    if leg_result.scalar_one_or_none() is not None:
+        raise HTTPException(
+            status_code=400,
+            detail="Cannot delete a run that belongs to a genlocke. Remove the leg or delete the genlocke first.",
+        )
+
     # Delete associated boss results first
     boss_results = await session.execute(
         select(BossResult).where(BossResult.run_id == run_id)