Preserve bounded validation evidence and historical failures

tests/validation/multigrid/shear_v0_2_evidence/README.txt

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+Shear diagnostic v0.2 — Horsea review and single bounded run
+2026-10-13 (Asia/Shanghai); completed 13:02:45 local time.
+
+Result: exit 0; N_BOOLEAN_HARD_CHECKS=22; ALL_HARD_CHECKS_PASS=True.
+The delivered script ran exactly once: 7 runs, 32 coarse steps each. No extra
+cases, tests, retries, algorithm edits or tolerance changes were performed.
+The original script, Grok output, joint report and source manifest are retained
+byte-for-byte. The reference remains the pinned CPUREF-0.3 original.
+
+Review before execution
+Read the complete 790-line script, joint report, Grok output, input manifest
+and existing reference. Followed .github/skills/lbm-ref-architecture-guard/
+SKILL.md and its discovery/architecture checklists. No applicable AGENTS.md
+was found on the workspace/test-directory ancestor chain. No numerical issue
+blocks this fixed-scope rerun; this is Horsea's own review, not the Mac review.
+
+Reference findings (local files read only; no external package execution):
+1. ref/lbmpy/src/lbmpy/relaxationrates.py: lattice nu=(tau-1/2)/3.
+2. ref/OpenLB/src/core/unitConverter.h: physical nu=lattice nu*dx^2/dt.
+   With dx_f=dt_f=1/2, tau_c=.8 and tau_f=1.1 both give physical nu=.1;
+   the lattice velocity conversion is unchanged and B needs two fine steps.
+3. ref/lbmpy/tests/full_scenarios/shear_wave/scenario_shear_wave.py:
+   periodic modes decay as exp(-nu*|k|^2*t); log-amplitude fits estimate
+   decay. This supports the diagnostic, not an accuracy threshold here.
+4. ref/lbmpy/tests/test_shear_flow.py: the second moment needs the convective
+   contribution and relaxation correction considered before stress comparison.
+   The supplied global Pi_xy mean is not used as stress evidence.
+5. Existing cpu_reference.py: arrival_f input/output, tick advances by 2,
+   two fine hops, one coarse ghost explosion, closed-corner coalescence.
+   Reviewed full source and confirmed the unchanged hash before execution.
+
+Architecture/scope: script main -> run_uniform(B/C), run_composite(A/A_T) ->
+reference advance_coarse_once -> existing collision/hops/coalescence. Observation
+restricts rho and j to the same 16x16 coarse cells before dividing to obtain u.
+All observations are arrival_f. Exact cell-average sine velocity includes sinc
+and the patch coordinate offset; equilibrium of that velocity is not the exact
+cell average of nonlinear equilibrium populations. Fit 4..32 means coarse steps
+(reference ticks 8..64), despite the legacy PER-TICK table heading.
+Only the new script and this evidence directory are in scope. No src, existing
+test, strategy document, old evidence, reference or DynamisLab changes.
+
+Nonblocking limits: composite conservation uses the reference's _leaf_totals;
+this diagnostic is not a fresh independent conservation implementation. The
+uniform solver has an unused intermediate equilibrium calculation; it does not
+change its returned values. Retained both without cleanup to preserve delivery
+bytes. The explicit CPU_REFERENCE_PATH is required in this layout because the
+script's default filename is cpu_reference_v0.3.py.
+
+Execution evidence
+results_horsea.json records the exact complete parent/child argv, cwd, process
+environment, versions, timestamps, hard limits, exit code and measured memory.
+run_once.py is the stdlib-only recorder, not another numerical test. It refuses
+existing execution logs/results and checks the script/reference hashes and hard
+limits before launching. Both it and the child ran through existing prlimit:
+  address space 268435456 bytes (soft=hard)
+  file size 2097152 bytes (soft=hard), core 0
+OPENBLAS_NUM_THREADS=1, PYTHONDONTWRITEBYTECODE=1, PYTHONNOUSERSITE=1.
+PYTHONPATH is this exact multigrid directory; CPU_REFERENCE_PATH is its exact
+cpu_reference.py. PYTHONOPTIMIZE=0 keeps assertions enabled. No global changes.
+Existing Python 3.10.13 / NumPy 1.26.4; no dependency installation.
+Start/end UTC: 05:02:42.804589 / 05:02:45.056308 on 2026-10-13.
+Child wall time 2.237032 s; peak child RSS 37.69140625 MiB, parent 18.75 MiB.
+Combined stdout/stderr plus recorder metadata: 11421 bytes, below 2 MiB.
+No CelerisLab, Simulation or pycuda imports; no production/GPU/SSH/system work.
+
+Comparison with Grok
+HARD CHECKS and SUMMARY_LINES blocks match exactly at printed precision.
+All 22 individual Boolean values were parsed and matched, and checked against
+the printed list of 22 names. All 33 summary values match; all printed numeric
+differences in these two blocks are zero. See comparison.json for each value.
+This is not a claim of full-precision field or whole-stdout byte equality;
+reference path, runtime and recorder metadata are environment-specific.
+
+lambda per coarse step:
+  A phi0       0.0158522189
+  A phi(pi/2)  0.0158419175
+  B both       0.0153991657
+  C both       0.0155497331
+  analytic     0.0154212569
+Conservation mass drift <=8.242e-13, momentum drift <=1.690e-13, versus
+unchanged mass-scaled tolerance 2.560e-10. Transpose error 6.661338e-16
+passes 1e-15. Initial matches and all finite-state checks pass unchanged.
+
+Interpretation qualifications to the preserved joint report
+The ~2.94% / ~2.88% excess decay relative to B is a diagnostic observation
+over this fixed window, not a hard-threshold failure. A good exponential fit
+over steps 4..32 does not establish longer-time persistence or exclude all
+initialization effects. Symmetry cancels the global Pi mean; it is not stress
+transfer evidence. Time-held ghost supply and unscaled nonequilibrium copying
+are candidate explanations, not an exhaustive set or an identified mechanism.
+In particular, a negative time-interpolation result would not establish the
+other candidate by elimination. Original joint_report.md remains unchanged.
+
+Next minimal verification — specification only, not implemented or run
+First specify a phase- and unit-matched local shear observation on the same
+7-run/32-step setup: arrival_f Pi_xy^neq=sum(cx*cy*f)-rho*ux*uy, restricted
+with consistent volume weighting and the appropriate relaxation/unit conversion.
+Measure a cosine shear-mode projection and signed profiles on both sides of
+the patch faces, with B/C as controls; avoid cancellation by a domain mean.
+Keep all 22 checks, initialization and fit window fixed. Report differences
+without inventing a pass/fail stress threshold. This can test localization and
+phase structure, but does not alone prove causation.
+Before any later time-interpolated-ghost variant, jointly specify the available
+donor time levels, arrival_f/postcollision_g phase, interpolation order and flux
+accounting. Coarse g(t+1) is unavailable before the present fine hops; silently
+reordering the step or using unspecified future data would confound that test.
+No such variant, new observation code or reference continuation is part of this run.
+
+Audit
+baseline.json freezes HEAD, Git status and 281 existing file hashes before any
+input extraction. Its scope includes tracked/nonignored project files and the
+prior baseline's ignored records; excludes the read-only ref tree and bytecode.
+manifest.json records final old-file/input/reference verification and every new
+file's path, bytes and SHA256, except its own hash reported in the handoff.
+No commit or push. Stopped for joint acceptance.