diff --git a/experiments/preconditioner_confirmation_2026-09-18.json b/experiments/preconditioner_confirmation_2026-09-18.json
new file mode 100644
index 0000000..6b4e4bc
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+++ b/experiments/preconditioner_confirmation_2026-09-18.json
@@ -0,0 +1,56 @@
+[
+  {
+    "id": "n1p5_gravity_schur_equal_gate",
+    "arguments": [
+      "--index",
+      "1.5",
+      "--angular-momentum",
+      "0",
+      "--no-central",
+      "--max-newton",
+      "0",
+      "--restart",
+      "160",
+      "--max-linear",
+      "600",
+      "--linear-tol",
+      "0.03",
+      "--probe-state",
+      "/Users/tboudreaux/.codex/.chatgpt-projects/g-p-6a6b3f2194ec8191bebcd59075897f1d/diagnostics/numerical_strategies_2026-09-17/models_v2/n1p5_J0_curvature/accepted_state.txt",
+      "--preconditioner-probe",
+      "--preconditioner-variant",
+      "gravity-schur",
+      "--schur-sweeps",
+      "1",
+      "--schur-relaxation",
+      "0.5"
+    ]
+  },
+  {
+    "id": "n1_rotating_gravity_schur_equal_gate",
+    "arguments": [
+      "--index",
+      "1",
+      "--angular-momentum",
+      "0.1",
+      "--no-central",
+      "--max-newton",
+      "0",
+      "--restart",
+      "160",
+      "--max-linear",
+      "600",
+      "--linear-tol",
+      "0.03",
+      "--probe-state",
+      "/Users/tboudreaux/.codex/.chatgpt-projects/g-p-6a6b3f2194ec8191bebcd59075897f1d/diagnostics/numerical_strategies_2026-09-17/models_v2_rotation/n1_J0p10_positivity_curvature/accepted_state.txt",
+      "--preconditioner-probe",
+      "--preconditioner-variant",
+      "gravity-schur",
+      "--schur-sweeps",
+      "1",
+      "--schur-relaxation",
+      "0.5"
+    ]
+  }
+]