test: freeze rising-crossing DFG reassessment plan

tests/validation/cycle_v2/PLAN.md

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+# Frozen CPU-only cycle-assessor v2 plan
+
+Predeclared before evaluating v2 acceptance on archived flows, 2026-10-18.
+
+Cycle boundaries are every ascending lift Cl=0 crossing, found by linear interpolation between consecutive samples with Cl<0 then Cl>=0. Direction and zero level are fixed. No smoothing, optimized window, fitted phase, or alternative-method selection. Exact sampled zeros count once. Existing period2..5, lift amplitude>=.2, five recent consecutive cycles, period variation<=.005, extrema variation<=.005, mass/flux gates and official-reference tolerances remain unchanged.
+
+Complete cycles are resampled on257 evenly spaced phase points with the existing linear interpolation, extrema and trapezoidal integration. Force timing remains interval midpoint; pressure/mass/flux use their end-sample times. Partial cycles are excluded; implausible periods are rejected, and missing cycles must still fail consecutiveness. No density, collision, geometry, initialization, outlet or flow-data change.
+
+Official reference is rebuilt from the same pinned archive, lv6/dt4 line forces and pressure values, selecting its last complete ascending-crossing cycle. It uses the same v2 phase convention for scalar and waveform comparison. Original trough-phase reference and frozen422e549 assessment remain unchanged.
+
+Qualification order:
+1. Independent review of this definition and plan.
+2. Synthetic constant-period sinusoidal/harmonic signals sampled at dt*=.02, with fixed deterministic small perturbations confined to extrema; false local extrema must not create cycles. Test exact-zero ties, zero offset phase, genuine period drift above.005, low amplitude, insufficient cycles, invalid/nonfinite/nonmonotone input, and missing/extra crossings. No fitted noise parameters.
+3. Reanalyse official source waveform, archived full9 uniform data, and archived MRT uniform/refined data. Report every case and every gate, old and v2 side by side, including failures. No favorable-window selection.
+4. Independent code/result review. Write versioned reanalysis receipts with input hashes, assessor hash/version, reference construction and gates. Do not overwrite original results or alter the original failed exit2.
+
+Scope: DFG shedding signals with recurrent sign-changing lift. This does not define a universal cycle detector for signals without zero crossings. New acceptance is a separately identified measurement, never a claim that the historical frozen assessor passed.