# Test: Vacuum symmetry (flat, no deficit)
Quick vacuum-only check: flat chain, no Hubble. Validates symmetric substrate.
## Implementation
`run_tests.py` parses the `test` block and calls `run_verification(params, output_dir, verbose)` from `rst_reality_engine_hpc_verification`. Params (steps, seed, expansion_per_tick) use script defaults when omitted. Outputs: `tests/results/vacuum_symmetry/`.
## Test config
```test
{
"test_name": "vacuum_symmetry",
"script": "hpc_verification",
"params": {
"steps": 30,
"seed": 42,
"expansion_per_tick": 1.0
}
}
```