COSMIC WEB: AN INDEPENDENT SMALL-WAVE REPLAY
Python 3.12.12; numpy==2.3.5; scipy==1.17.1.

Run after installing the pinned requirements in your own environment:
  python replay.py small-wave-current.json --out my-new-result
No network, browser, Engine or TNG data is used by the replay.

The JSON fixture was produced by actual Node execution of the frozen Lab model
and canonical current-state serializer, not downloaded from a browser. It uses
the sheet preset at amplitude 0.02 and native frame 116, a=1.0904635200240378.
The complete browser record integrates a=0.05 to 1.5 in 1024 logarithmic steps;
frame 116 is step 928. The reference integrates the EXACT exported initial F64
positions/momenta to the exported epoch with independent NumPy CIC scatter,
Fourier-space fourth-order gradient, and SciPy DOP853. Coordinates in the export
are unwrapped; periodic wrapping is used only for force assignment and phases.

Use your own current-state JSON instead of the fixture if desired. The script
validates the fixed N16 EdS model. Arbitrary nonlinear states may cost much more;
the following small-wave accuracy gates are only commissioned for this fixture.
Position RMS <5e-4 box; momentum RMS <0.002; raw mass error <2e-13;
integer-period force change <2e-12; initial mean force <2e-13;
reference power-growth error from EdS <1%; native/reference power error <0.1%.
Compare result.json with expected-result.json. Runtime and environment fields
can differ; numerical differences should be judged against the stated gates.
No Poisson shot-noise subtraction is appropriate to this quiet lattice.

This reduced collisionless EdS PM is not TreePM, a halo finder, gas dynamics,
a precision LCDM spectrum, or an IllustrisTNG reproduction. Original methods:
Springel 2005 https://arxiv.org/abs/astro-ph/0505010
Zeldovich 1970 https://www.giss.nasa.gov/staff/mway/cluster/zeldovich.pdf
TNG clustering conventions https://arxiv.org/abs/1707.03397
Teaching derivation and guided exercises: /stories/cosmic-web/
Fixture/scientific commissioning 2026-11-12. All source papers remain external.
