rtx-fsi: pin FSI3's release response and settled cycle

Two tiers in the FSI2 pattern. The committed default (t_end 4.2) pins
the deterministic release response at the digit-stable measurement
(uy 10.7684 +- 23.5726 mm, ux -2.8982; +-35% bands, 2x onset-growth
floor against a measured 4.6x). The sticky-mask study configuration
(HYST>0, subcycle 2, t_end >= 8.4, ny 62 or 82) pins the settled
flapping cycle measured across two grids at t_end 8.5 / window(2.0):
uy amp in [38, 72] mm (measured 50.2 / 57.6; the un-flapped release
and every pre-hysteresis dead march sit far below, and the reference
+-34.9 sits OUTSIDE — landing inside the reference band is a loud
finding, not a regression), mids, crossing-frequency in [4.4, 6.8]
(covers the estimator's measured beat-scatter — the DFT puts both
grids at 5.4-5.6 vs ref 5.46), and drag MEDIAN in [380, 530]
(measured 454.0 vs ref 460.2). WindowStats gains drag/lift medians —
the honest central loads (the extreme-based mids are noise-dominated
at large deformation).

Band anchors computed exactly as the test computes them, replayed
offline against the run 7/8/10 CSVs (deterministic trajectories).
Verified: both committed defaults green with the release pins live,
trajectories digit-identical (FSI3's loads line gains the medians,
FSI2's output byte-identical). The t_end 8.5 study pin runs at both
grids are in flight.

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01X2GmJXeQ2njUecEKiJZ1G2

crates/specialized/rtx-fsi/tests/turek_hron_fsi3.rs

@@ -23,9 +23,14 @@
 //! # What is pinned
 //!
 //! Machinery invariants every run (conservation, finite state, coupling
-//! bookkeeping). Physics bands arrive with the measurements — this
-//! file's first commits carry the harness through the release response
-//! only; the study record lives in omni-cortex `solver_status.md`.
+//! bookkeeping). The committed default (t_end = 4.2) pins the
+//! deterministic release response (uy 10.77 ± 23.57 mm, ±35% bands).
+//! Study horizons under the sticky mask (`RTX_FSI3_HYST=0.25
+//! RTX_FSI3_STALLX=10 RTX_FSI3_T_END=8.5`, ny 62 or 82) pin the
+//! settled flapping cycle measured 2026-08-27/28 — uy amp 50–58 mm
+//! across the grids (reference 34.90; two-grid agreement 2.3% by p95,
+//! the gap grid-converged), honest drag median 454 vs reference 460.2.
+//! The full study record lives in omni-cortex `solver_status.md`.
 //!
 //! Environment knobs: `RTX_FSI3_*` — the same set as `RTX_FSI2_*` (see
 //! `turek_hron_fsi2.rs`) plus `RTX_FSI3_OMEGA0`, `RTX_FSI3_TRACE`,
@@ -148,9 +153,9 @@ fn fsi3_added_mass_flag() {
     let w = result.window(2.0);
 
     println!(
-        "  loads over the window: drag {:.2} ± {:.2} (ref {REF_DRAG_MEAN} ± {REF_DRAG_AMP}), \
-         lift {:.2} ± {:.2} (ref {REF_LIFT_MEAN} ± {REF_LIFT_AMP})",
-        w.drag_mid, w.drag_amp, w.lift_mid, w.lift_amp
+        "  loads over the window: drag {:.2} ± {:.2} median {:.2} (ref {REF_DRAG_MEAN} ± \
+         {REF_DRAG_AMP}), lift {:.2} ± {:.2} median {:.2} (ref {REF_LIFT_MEAN} ± {REF_LIFT_AMP})",
+        w.drag_mid, w.drag_amp, w.drag_median, w.lift_mid, w.lift_amp, w.lift_median
     );
     println!(
         "  FSI3 (fluid ny = {ny}, flag {flag_nx}x2 Quad8, dt = {:.2e}, {}): coupled {} \
@@ -206,4 +211,97 @@ fn fsi3_added_mass_flag() {
         result.coupled_steps,
         result.worst_stall
     );
+
+    // Physics bands, by horizon and configuration (the FSI2 pattern:
+    // the march is deterministic, so the short committed horizon
+    // carries tight regression bands on the release response; study
+    // horizons pin the MEASURED settled cycle, band-generous across
+    // the two grids that measured it. If a change moves any of these
+    // numbers, that is a finding either way and must be loud.)
+    let default_release = config.subcycle == 2
+        && config.mask_hysteresis == 0.0
+        && config.coupler == "iqn"
+        && ny == 62
+        && flag_nx == 35
+        && (t_end - 4.2).abs() < 1e-9;
+    let hyst_cycle = config.subcycle == 2
+        && config.mask_hysteresis > 0.0
+        && config.coupler == "iqn"
+        && flag_nx == 35
+        && (ny == 62 || ny == 82)
+        && t_end >= 8.4;
+    if default_release {
+        // The committed default: the release response over [4.0, 4.2],
+        // measured 2026-08-26 and digit-stable across four bit-identity
+        // re-verifications: uy 10.7684 ± 23.5726 mm, ux -2.8982 mm,
+        // onset amp 3.698e-3 -> 1.716e-2 (4.6x growth). Bands are ±35%
+        // for cross-platform floating-point drift in a growing
+        // transient (the FSI2 default's margin), not an accuracy claim.
+        assert!(
+            (7.0e-3..=14.6e-3).contains(&w.uy_mid),
+            "release uy mid {:.4e} left [7.0e-3, 14.6e-3] (measured 1.0768e-2)",
+            w.uy_mid
+        );
+        assert!(
+            (15.3e-3..=31.9e-3).contains(&w.uy_amp),
+            "release uy amp {:.4e} left [15.3e-3, 31.9e-3] (measured 2.3573e-2)",
+            w.uy_amp
+        );
+        assert!(
+            (-3.92e-3..=-1.88e-3).contains(&w.ux_mid),
+            "release ux mid {:.4e} left [-3.92e-3, -1.88e-3] (measured -2.8982e-3)",
+            w.ux_mid
+        );
+        assert!(
+            w.amp_late > 2.0 * w.amp_early,
+            "the release is not growing: onset amp {:.3e} -> {:.3e} (measured 4.6x)",
+            w.amp_early,
+            w.amp_late
+        );
+    } else if hyst_cycle {
+        // Study horizons, the sticky-mask configuration (band 0.25h,
+        // STALLX 10): the settled flapping cycle, measured 2026-08-27/28
+        // at t_end = 8.5 / window(2.0) — ny 62: uy 3.07 ± 50.25 mm
+        // (run 7), ny 82: 8.13 ± 57.55 mm (run 8); reference
+        // 1.45 ± 34.90. The AMPLITUDE discriminates: the un-flapped
+        // release and every pre-hysteresis dead march sit far below
+        // 38 mm, and the reference itself sits outside the band — a
+        // change landing INSIDE the reference band is a loud finding,
+        // not a regression.
+        assert!(
+            (38.0e-3..=72.0e-3).contains(&w.uy_amp),
+            "cycle uy amp {:.4e} left [38e-3, 72e-3] (measured 50.2e-3 / 57.6e-3 at ny 62/82)",
+            w.uy_amp
+        );
+        assert!(
+            (-8.0e-3..=22.0e-3).contains(&w.uy_mid),
+            "cycle uy mid {:.4e} left [-8e-3, 22e-3] (measured 3.1e-3 / 8.1e-3)",
+            w.uy_mid
+        );
+        assert!(
+            (-14.0e-3..=-2.0e-3).contains(&w.ux_mid),
+            "cycle ux mid {:.4e} left [-14e-3, -2e-3] (measured -4.9e-3 / -9.4e-3)",
+            w.ux_mid
+        );
+        // The crossing estimator is beat-biased on 2 s windows (it read
+        // 4.87 / 6.25 Hz where the DFT puts both grids at 5.4-5.6, ref
+        // 5.46); its band covers the estimator's measured scatter, not
+        // the physics.
+        if let Some(f) = w.frequency {
+            assert!(
+                (4.4..=6.8).contains(&f),
+                "cycle crossing-frequency {f:.3} left [4.4, 6.8] (measured 4.87 / 6.25)"
+            );
+        }
+        // The honest central drag (window median of the interval-median
+        // record): 454.0 at ny 62 (run 10) vs reference 460.2 — a loud
+        // tripwire on the load path, not an amplitude claim (the
+        // oscillation amplitudes are surface-route-unmeasurable; see
+        // omni-cortex solver_status.md).
+        assert!(
+            (380.0..=530.0).contains(&w.drag_median),
+            "cycle drag median {:.1} left [380, 530] (measured 454.0, ref 460.2)",
+            w.drag_median
+        );
+    }
 }