Target the combined rotation stall and its physical slice refinement

experiments/COUPLED_CONVERGENCE_STUDY_2026-09-19.md

@@ -122,6 +122,11 @@ alpha falls below .001 by update six, with pressure-preparation rejections.
 Add a combined inverse benchmark at its update-seven capture and eta=.003,
 including the same raw trial grid. This separates the rotation obstruction
 from n=2's gravity-dominated merit rejection without changing admissibility.
+The n=1.5,J=.1 control reaches 7.60e-5 after eight updates, then needs alpha
+1/512 with both pressure and metric rejections. Also compare the combined
+inverse at its final saved state, once its original twelve-update budget is
+complete. This is the combined higher-index/rotation obstruction; it is not
+assumed to be a failed linear solve, since its update-eight linear gate passes.
 
 The small Schur block contains all 25 surface parameters and every generated
 scalar. Its field inverse is the unbordered structure inverse; restricting an

experiments/convergence_linear_cases_2026-09-19.json

@@ -193,5 +193,38 @@
       "--no-central",
       "--benchmark-trials"
     ]
+  },
+  {
+    "id": "n1p5_rotating_late_combined",
+    "arguments": [
+      "--index",
+      "1.5",
+      "--angular-momentum",
+      "0.1",
+      "--surface-prescription",
+      "harmonics",
+      "--surface-degree",
+      "4",
+      "--restart",
+      "160",
+      "--max-linear",
+      "300",
+      "--rtol",
+      "0",
+      "--atol",
+      "1e-12",
+      "--max-newton",
+      "0",
+      "--linear-tol",
+      ".003",
+      "--preconditioner-probe",
+      "--preconditioner-variant",
+      "gravity-schur-surface-border-schur",
+      "--restart-snapshot",
+      "../../diagnostics/coupled_convergence_2026-09-19/screen_v1/n1p5_J0p1/accepted_state.txt",
+      "--allow-unconverged-restart",
+      "--no-central",
+      "--benchmark-trials"
+    ]
   }
 ]

experiments/convergence_slice_cases_2026-09-19.json

@@ -42,10 +42,10 @@
     ]
   },
   {
-    "id": "n1_rotating_s4",
+    "id": "n1p5_rotating_s4",
     "arguments": [
       "--index",
-      "1",
+      "1.5",
       "--angular-momentum",
       "0.1",
       "--no-central",
@@ -56,17 +56,17 @@
       "--max-newton",
       "0",
       "--density-snapshot",
-      "../../diagnostics/coupled_convergence_2026-09-19/screen_v1/n1_J0p1",
+      "../../diagnostics/coupled_convergence_2026-09-19/screen_v1/n1p5_J0p1",
       "--model-slices-only",
       "--slice-subdivisions",
       "4"
     ]
   },
   {
-    "id": "n1_rotating_s8",
+    "id": "n1p5_rotating_s8",
     "arguments": [
       "--index",
-      "1",
+      "1.5",
       "--angular-momentum",
       "0.1",
       "--no-central",
@@ -77,7 +77,7 @@
       "--max-newton",
       "0",
       "--density-snapshot",
-      "../../diagnostics/coupled_convergence_2026-09-19/screen_v1/n1_J0p1",
+      "../../diagnostics/coupled_convergence_2026-09-19/screen_v1/n1p5_J0p1",
       "--model-slices-only",
       "--slice-subdivisions",
       "8"