research: VIV driver — fail closed on any non-finite recorded output

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

research/viv_re150/run.py

@@ -96,12 +96,13 @@ def main():
             d = sim.moving_diagnostics()[0]
             f_obs = sim.read_force(body)[1]
             f_rhs = float(d[1] + d[3])             # CME + Wen (y)
-            if not math.isfinite(f_rhs):
+            row = (n, y1, v1, f_rhs, float(d[1]), float(d[3]), float(f_obs),
-                status = "fail_nonfinite_force"
+                   float(d[7] - d[10]), float(d[13]))
+            if not viv.finite(row):                # every recorded output, not only the RHS
+                status = "fail_nonfinite_output"
                 break
             s.y, s.v, f_last = y1, v1, f_rhs       # commit only after a successful step
-            rows.append((n, s.y, s.v, f_rhs, float(d[1]), float(d[3]), float(f_obs),
+            rows.append(row)
-                         float(d[7] - d[10]), float(d[13])))
             if args.smoke:
                 continue                           # no settle / score in the plumbing smoke
             if cyc.update(s.y) == "scored":

research/viv_re150/viv.py

@@ -16,6 +16,11 @@ WINDOW_TOL, LAST5_TOL = 0.02, 0.01
 CYCLE_CAP, STEP_CAP_TN, SEED_TN, Y_LIMIT = 150, 200, 40, 1.0
 
 
+def finite(values):
+    """True iff every recorded value is finite (fail-closed output check)."""
+    return all(math.isfinite(float(v)) for v in values)
+
+
 class Structure:
     """Undamped spring-mass, exact harmonic update over dt = 1 with constant force."""
 

tests/unit/test_viv_logic.py

@@ -86,3 +86,11 @@ def test_viv_config_passes_the_real_loader(tmp_path):
     assert (cfg.nx, cfg.ny) == (nx, ny) == (3000, 2400)
     assert cfg.collision == "MRT" and cfg.y_wall_bc == "free_slip" and cfg.velocity == .04
     assert math.isclose(cfg.viscosity, .04 * 40 / 150)
+
+
+def test_finite_rejects_any_nonfinite_recorded_output():
+    row = (3, .1, .2, .3, .4, .5, .6, .7, 0.0)
+    assert viv.finite(row)
+    for i in range(len(row)):
+        for bad in (float("nan"), float("inf"), -float("inf")):
+            assert not viv.finite(row[:i] + (bad,) + row[i + 1:])