{
  "name": "self-loop",
  "_description": "Single-atom query with a repeated variable across two columns: edge(x, x, _). Exercises evalAtom's equality-enforcement path; the planner emits one PlanEvalAtom node and no joins.",
  "schema": {
    "edge": { "columns": [{"entity": "node"}, {"entity": "node"}, {"entity": "edge"}] }
  },
  "facts": {
    "edge": [
      [{"entity": ["node", 1]}, {"entity": ["node", 2]}, {"entity": ["edge", 1]}],
      [{"entity": ["node", 2]}, {"entity": ["node", 2]}, {"entity": ["edge", 2]}],
      [{"entity": ["node", 3]}, {"entity": ["node", 3]}, {"entity": ["edge", 3]}]
    ]
  },
  "atoms": [
    {"table": "edge", "values": {"0": {"var": "x"}, "1": {"var": "x"}}}
  ],
  "expected_bindings": {
    "columns": ["x"],
    "rows": [
      [{"entity": ["node", 2]}],
      [{"entity": ["node", 3]}]
    ]
  }
}