Add bounded paired Karman pinball VIV research driver

docs/karman_viv.md

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+# Re_D = 50 Kármán inflow: paired pinball VIV / frozen PPO demo
+
+Development experiment, frozen before results, 2026-10-31. No new production
+method, structural damping, force filter, policy training, or main merge.
+[Force-spike research index](research/moving_boundary_force_spikes.md).
+
+## Plant and structure
+
+Base `e9213dd2cc9cfed0e8487a3cf4ebdd94d23dc64d`; fixed-policy contract from
+`580397eaf83c85b233495791ecc51662a374a247`. Reuse `steady_pinball` config,
+coordinate map and exact held-force oscillator. D40, U=.005, nu=.004, MRT,
+2559 x 1022, FP32 unshifted double buffers. Regularized parabolic inlet,
+NEQ extrapolation outlet, bounce-back y walls (.5,1020.5); no BC changes.
+D20 coordinates map x'=2x, y'=.5+2(y-.5).
+Upstream cylinder (400,510.5), radius40, is static. Pinballs radius20 at
+(1200,510.5), (1252,540.5), (1252,480.5) share only transverse translation.
+Lab probes radius10 at (1600,590.5), (1600,510.5), (1600,430.5) stay fixed.
+
+One shared `Translation`, travel ±D, max wall speed .025, existing clearance
+and per-step move guards unchanged. M2: m*=2 based on all three disks,
+M=7539.8223686, fn=.000025, K=.000186037660, C=zeta=0; release y=v=0.
+Each native step uses previous-step sum(CME_y+Wen_y), then exact oscillator
+update with held force. Wall speed is interval displacement y[n+1]-y[n].
+Cover/uncover impulses are logged, never added to the selected RHS. This
+estimator remains provisional; existing spike/convergence limitations remain.
+
+## Same release state, two clocks
+
+A static precursor retains the accepted Kármán sequence: upstream+probes,
+2,048,000-step warmup, 150 x 3,200-step no-pinball target samples, add static
+pinballs/sync, second 2,048,000-step warmup. Save both DDF buffers, flags,
+clock and last instantaneous force. Construct each moving arm fresh at the
+same zero-offset geometry, check flags, copy both buffers and clock, verify
+exact copy hashes. This one-time research initialization is not a moving
+checkpoint or FSI rollback. Initial policy observation and spin are zero.
+
+Frozen model SHA256 `148240c1dcb8b11d8e5a0a9e991f6874c4e799c9744707bf0fb32a8efeb0468d`;
+normalizer `534fda818c030a56960e95d0f3ac1e350d887d03db7f80f1d6453195a502b7f0`.
+Only these explicit supplied assets are accepted. Policy is CPU deterministic.
+Native policy signals: packed CME (same `read_force` path), lab area-mean
+velocity, each averaged over SI3200. Convert to original D20 training units:
+forces x2, area-mean velocity x2 x78, then frozen force-first normalization
+and clipping. Fine-grid probe pixel footprint is not exactly identical;
+using the original78 cells avoids a hidden area-count normalization change.
+The moving plant, motion-induced force, lab-frame wake displacement and D40
+resolution remain out of training distribution. No transfer guarantee.
+
+A=(8a+(0,-4,4))*.005; EMA alpha=.9^(1/4), reset0 each SI; omega=+A_eff/20.
+This preserves historical physical actuator timescale under dt/4.
+The zero arm substitutes a=(0,.5,-.5), so all spins are identically zero.
+Policy interval averaging does **not** average the native structural RHS.
+
+## Bound, output, and interpretation
+
+One serial pair, zero then controlled: 400SI=1,280,000 native steps=160D/U
+=32Tn per arm. No retuning/automatic extension. Stop on nonfinite state,
+no_donor, travel/speed/move rejection, or four-hour whole-pair wall cap.
+A failure stops the remaining run; retain valid rows and completed intervals.
+NaN trailing rows are unexecuted, not zero-valued observations.
+
+Report first/last80D/U windows, mean offset separately from centered RMS,
+half-range, peak, frequency and drift; native versus SI-averaged force,
+CME/Wen/node/crossing terms and action/observation clipping. Last80D/U is
+the principal descriptive window, not an asserted settled window. If zero
+arm half-range <.1D there, classify weak response and do not claim vibration
+suppression. Report continuous ratios regardless. Cloaking uses retained
+canonical last30 lagged sensor DTW against this precursor's no-pinball target,
+with fixed-body D20 results contextual only. These are development criteria,
+not paper uncertainty, grid convergence, or proof of validated FSI.
+
+Save native18-column rows (~184MB/arm), small SI signals, target, config,
+release two buffers (~188MiB), hashes and terminal reports outside checkout.
+No per-step field output. Expected new data <650MB, check actual resources.
+
+```
+CUDA_VISIBLE_DEVICES=0 PYTHONPATH=src python research/karman_viv/run.py \
+  --model /tmp/celeris-karman-viv-assets/model.zip \
+  --norm /tmp/celeris-karman-viv-assets/norm.json --out /tmp/NEW_OUTPUT
+```
+
+First `--smoke`: same D40 geometry, warmup32/target2x8/warmup32,
+4x8 response steps each arm; strictly plumbing only. CPU source checks and
+independent exact-tip review precede GPU. Preserve original DynamisLab files.

docs/research/moving_boundary_force_spikes.md

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+# Moving-boundary force spikes: evidence and source index
+
+Updated 2026-10-31.
+
+This note indexes supplied audited observations and primary-source extractions.
+It does not report a newly measured cure or implement an alternative method.
+Paper details below were supplied by the parent investigation; no new source
+retrieval or independent paper verification was performed for this note.
+
+## Current implementation and interpretation
+
+- Celeris M1 reconstructs a fresh node as `feq(rho_bar, u_wall) + donor NEQ`.
+- In exact arithmetic, the donor non-equilibrium component has zero mass and
+  momentum when formed against the donor's own equilibrium moments.
+- Re-projecting that same reconstruction onto the same wall velocity therefore
+  does not, by itself, change its mass or momentum or supply a cure for spikes.
+- Floating-point residuals should be measured separately from this algebraic fact.
+- Peng's alternative differs upstream: extrapolate PDFs from three donors, then
+  replace selected moments. It is not simply another projection of current M1.
+- PPO interval-force observations and native per-step FSI right-hand-side forces
+  are distinct signals; comparisons must identify which signal is being used.
+
+## Audited run observations supplied to this note
+
+- D40 revision: `e9213dd2cc9cfed0e8487a3cf4ebdd94d23dc64d`.
+- Window: first `97.303 D/U` of physical time.
+- Maximum displacement: `max |y|/D = 0.304893`.
+- Maximum native force-coefficient increment: `max |ΔCy| = 0.66688`.
+- D20 over the same physical-time window: `max |ΔCy| = 1.80735`.
+- The largest D40 event involved 30 nodes.
+- These are supplied audited observations, not measurements made for this note.
+- Time steps and trajectories differ between runs. This comparison establishes
+  neither spatial convergence nor a unique cause for the force spikes.
+
+Evidence locations supplied by the investigation:
+
+- Horsea: `/tmp/celeris-results-pinball-resolution`.
+- Mac: `validation-evidence/pinball-force-diagnosis`.
+
+These locations index run evidence, not local copies of the cited papers.
+
+## Tao, Hu, and Guo (2016): time-step decoupling
+
+Computers & Fluids **133**, 1–14. DOI:
+[10.1016/j.compfluid.2016.04.009](https://doi.org/10.1016/j.compfluid.2016.04.009).
+[Publisher abstract](https://www.sciencedirect.com/science/article/pii/S0045793016301116).
+
+- Abstract-level support only: non-equilibrium refill reduces oscillations.
+- With local iteration, the compared refill methods give similar oscillation magnitudes.
+- Time-step decoupling reduces oscillations further in the reported sedimentation,
+  Couette, and Poiseuille examples.
+- The exact decoupling schedule and time-step ratios have not been verified.
+- This abstract does not establish equivalence to an arbitrary force filter.
+- Do not implement a claimed reproduction until the actual methods are available.
+
+## Marson et al. (2021): local iterations
+
+Physical Review E **103**, 053308. DOI:
+[10.1103/PhysRevE.103.053308](https://doi.org/10.1103/PhysRevE.103.053308).
+[Open repository record](https://archive-ouverte.unige.ch/unige:151868).
+
+- §VI, p. 18 discusses pressure waves associated with fresh nodes.
+- Appendix E.3, p. 25 and Fig. 18, p. 24 describe the local procedure.
+- Copy a local sublattice, perform local collision and streaming, write the fresh
+  nodes, and repeat before the global collision and streaming operation.
+- One to three iterations performed best in the reported tests; this is not a
+  universal iteration-count recommendation.
+- The reported smoothed torque-noise assessment is qualitative here.
+- Its thin-shell setting differs from the current moving-body configuration.
+
+## Peng (2016): extrapolation and moment replacement
+
+Computers & Mathematics with Applications **72**, 349–374. DOI:
+[10.1016/j.camwa.2015.08.027](https://doi.org/10.1016/j.camwa.2015.08.027).
+
+- §5.1.2, Eq. (50), p. 368: extrapolate PDFs along an outward normal direction:
+  `f_new(x) = 3 f(x + e) - 3 f(x + 2e) + f(x + 3e)`.
+- §5.1.3, Eq. (51): wall equilibrium plus donor non-equilibrium is the family
+  containing the current M1 reconstruction.
+- §5.1.4, Eqs. (52)–(54): in MRT space, replace momentum with `j = rho0 u_wall`,
+  preserve the other moments, then apply the inverse transform.
+- A compressible Celeris adaptation must choose the appropriate density;
+  copying the paper's `rho0` blindly is not justified.
+- Three valid donors require new eligibility checks and fallback behavior beyond
+  the current one-link shared-body clearance rule.
+- §§5.2–5.3 retain nonzero fluctuations in specific configurations; these results
+  do not promise elimination of force spikes in the present problem.
+
+## Bounded next investigation
+
+1. Retain current M1 as the baseline and compare matched prescribed trajectories
+   over matched physical-time windows.
+2. Record raw force RHS, node crossings, donor moments, mass and momentum changes,
+   impulse, spectra, and trajectory response together.
+3. Evaluate local iterations, Peng-style reconstruction, and force filtering as
+   separate interventions, with explicit definitions and diagnostics.
+4. Obtain the actual time-step-decoupling methods before implementing that method.
+
+The current task indexes evidence only; it makes no alternative-method change.