fix: prevent repeated task creation after failures

tests/test_scanner_state.py

@@ -69,7 +69,7 @@ def test_scan_ignores_repositories_not_allowed_by_current_config(db):
     assert created == []
 
 
-def test_retry_after_terminal_task_allows_new_scan_task(db):
+def test_terminal_task_does_not_create_scan_loop(db):
     repo = db.upsert_repository(owner="acme", name="service", clone_url="x", default_branch="main", enabled=True)
     db.upsert_issue(
         repo_id=repo.id,
@@ -88,8 +88,7 @@ def test_retry_after_terminal_task_allows_new_scan_task(db):
 
     created = scan_eligible_issues(db, LabelsConfig())
 
-    assert len(created) == 1
-    assert created[0] != task_id
+    assert created == []
 
 
 def test_claim_next_task_claims_expired_lease(db):
@@ -111,6 +110,21 @@ def test_claim_next_task_claims_expired_lease(db):
     assert reclaimed.lease_owner == "worker-b"
 
 
+def test_retry_task_clears_active_lease(db):
+    repo = db.upsert_repository(owner="acme", name="service", clone_url="x", default_branch="main", enabled=True)
+    task = db.create_task(repo.id, 1)
+    claimed = db.claim_next_task("worker-a", 60)
+    assert claimed is not None
+    db.transition(claimed.id, TaskState.PLANNING, error_message="stuck")
+
+    retried = db.retry_task(task.id)
+
+    assert retried.state == TaskState.DISCOVERED
+    assert retried.lease_owner is None
+    assert retried.lease_expires_at is None
+    assert retried.error_message is None
+
+
 def test_state_transition_validation():
     validate_transition(TaskState.DISCOVERED, TaskState.CLAIMED)