# PRE-02 construction-invariant reproduction

This deterministic JavaScript fixture demonstrates the state model in “Invalid
State Should Be Difficult to Construct.”

It executes:

- supported legacy absence;
- one complete and arithmetically consistent snapshot;
- partial presence;
- disagreement between held and gross amounts;
- disagreement between gross and net plus tax;
- disagreement between tax amount and rounded rate calculation; and
- an unknown-field control.

Run:

```sh
node experiment.mjs
```

The amounts and tax rate are synthetic. The fixture is not private accounting
code, framework validation, a database constraint, or production evidence.