# Bounded 2D implementation and validation scope

This inventory starts from dev `8403956a9afc0b0bb89265cec374392013d89016` and
integrates only the reviewed LES normalization production correction from
`95cb6d2b9f43c1bdd46cbf27f03f0dfc0877cfb0`. The merged production bytes match that
tested candidate exactly; the scope-test changes are retained from `53fad767`.
GPU receipts remain associated with their exact tested commits, not relabeled as
a new merged-commit run. Historical source identities and gates remain unchanged.

## Implementation boundaries

- Uniform D2Q9 supports SRT, TRT and MRT. An available collision selector does not
  qualify every wall, inlet/outlet, forcing, storage or LES combination.
- Fixed refinement supports SRT/MRT, FP32 and double-buffer streaming; TRT and LES
  are rejected. Shifted refinement requires all-blocked storage. Refined channel
  boundaries have narrower configuration guards than uniform boundaries.
- Uniform checkpoints support compatible same-method continuation. Changing
  collision or LES parameters is a different evolution, not exact continuation.
  Jet checkpoints and refined checkpoints are unsupported; synchronized remapping
  is not persistent restart.
- Keep these conclusions 2D. Local D3Q19 operator tests do not establish a supported
  3D Simulation runtime.

## Evidence and remaining gaps

| Area | Available evidence | Boundary of the conclusion |
|---|---|---|
| MRT cylinder flow and observation windows | Full matched uniform/refined MRT DFG and the window-ledger campaign passed their frozen periodicity, reference and matched-comparison gates. The window campaign used `185a919`; its MRT/no-LES numerical path remains unchanged. Current dev also contains independently scoped test/documentation changes and the LES correction, which do not extend MRT qualification. | This does not qualify other collision/boundary combinations or every refinement interface. Timing improvements are not additional accuracy evidence. |
| Uniform forced channel | Six Poiseuille GPU cases on `8403956`: SRT/TRT/MRT at wall-normal resolutions H16/H32 passed. | This is the tested analytic channel configuration, not open-boundary or all-layout qualification. |
| Uniform restart | Ten SRT/MRT checkpoint GPU tests passed on `8403956`; the separate representative TRT same-method double-buffer continuation GPU case also passed (one test). | This covers the tested same-method continuation configurations. No LES, Jet or refined checkpoint claim follows. |
| Taylor–Green refinement | Independent topology checks are available. The actual-rate phase GPU regression passed one test across two layouts, with errors 1.584e-7 and 4.500e-9. | The physical interface-accuracy gap remains open. Passing topology and phase checks does not establish convergence or close that accuracy gate. |
| Porous Couette and annulus | Prior campaign evidence exists and must remain associated with its original setup and source. | The reconstructed annulus is a validation helper, not qualification of a public boundary-condition API. Do not infer absence of evidence from a missing current rerun. |
| LES normalization | The reviewed correction is integrated. Exact `95cb6d2` GPU validation passed all nine observations and frozen gates, with three warm-up/reset records, verified 101-source/import identity, DONE and exit 0. Last two SGS decrement relative errors were 6.276e-4 and 6.124e-5 against the unchanged 0.15 gate. | Scope is unforced uniform D2Q9/SRT, shifted FP32, double-buffer streaming and the tested wall-bounded x-periodic shear. No TRT/MRT LES, forcing, EsoPull, objects, refinement or 3D turbulence qualification follows. |

Historical uniform SRT cylinder-startup and inlet-rounding findings remain separate
from the passed MRT DFG result. Raw exchange/window consistency is a measurement
contract, not a general stress or force-accuracy certification. Existing source-pinned
runners may intentionally reject a newer checkout; never silently repin old receipts.

## Remaining work

The related host checks passed (67 checks); they do not replace the GPU or
physical-accuracy evidence above. Preserve the existing SRT checkpoint cases,
historical LES manifests and all frozen numerical criteria.

Continue the TG accuracy investigation using its actual fine-level rates and
the established analytic convention. Keep the physical accuracy gate open until
the relevant comparison passes. Review this integration independently before
publication; no new merged-commit GPU run is claimed here.

No repeat of the accepted full MRT DFG or Cartesian expansion across unsupported
combinations is required by this document. Main integration remains a separate
review of complete, bounded feature scope.