diff --git a/experiments/PRECONDITIONER_IMPROVEMENT_2026-09-18.md b/experiments/PRECONDITIONER_IMPROVEMENT_2026-09-18.md
index 0f3bf36..623272b 100644
--- a/experiments/PRECONDITIONER_IMPROVEMENT_2026-09-18.md
+++ b/experiments/PRECONDITIONER_IMPROVEMENT_2026-09-18.md
@@ -247,7 +247,46 @@ numbers alone do not make this an acceptable physical model. The independent
 audit records these failures separately from successful linear solves and
 artifact verification.
 
-The hard rotating nonlinear case and the targeted rotating coupling
-follow-up are still running or pending. Production defaults remain unchanged:
-the stronger inverse is an optional typed policy, and the coarse candidate
-remains an experiment.
+## Rotating nonlinear follow-through
+
+The n = 1, J = 0.1 positivity-curvature run accepts one full Newton step after
+an initial positivity repair. Its first linear solve passes in thirteen
+iterations with relative true defect 0.023583. The second reaches 200
+iterations with defect 0.0315391 and fails the unchanged 0.03 gate, before a
+second trial can be tested. There are no line-search rejections. This case
+therefore retains a linear obstruction as well as an unconverged nonlinear
+state.
+
+The final nonlinear residual is 0.00896796 against a target of 8.58812e-10.
+Summed Newton time is 139.198 s, including 113.338 s in outer linear solves
+and 18.544 s in preparation; full diagnostic-run wall time is 201.245 s.
+Enthalpy-pressure virials are approximately 0.0108 and fail the physical
+milestone. Density-pressure virials are undefined, with sampled density
+minimum -0.00692627 and 2015 negative samples at quadrature order 18. The
+enthalpy positivity policy passes its checks, but does not establish density
+admissibility.
+
+The historical rotating run starts from matching physical diagnostics and
+uses matching physics and linear controls, but permits eight Newton steps
+instead of twelve. Its endpoint is not used for a controlled timing claim.
+All 67 full-campaign provenance checks pass; physical and solver failures are
+retained as experimental outcomes, not treated as successful convergence.
+
+## Complementary rotating coupling
+
+`rotation_coupling_v1`, built from `5298d88`, combines cached stellar LDU with
+one consistent gravity Schur correction at relaxation 0.5. On the saved
+rotating plateau state it passes the unchanged 0.03 gate in 142 iterations,
+with relative true defect 0.0299068971 and complete verified cost 96.8236 s.
+Its fresh independent control reproduces the original 200-iteration defect
+0.0826534298794 and costs 85.8991 s. The earlier independent control still
+failed at 600 iterations, so there is no measured finite baseline
+time-to-convergence with which to form a speedup ratio.
+
+This combination succeeds where either isolated change failed on this frozen
+rotating problem. It does not establish nonlinear convergence. One bounded
+eight-step positivity-curvature run is pending to check that distinction;
+its budget matches the historical rotating run.
+
+Production defaults remain unchanged: the stronger inverse is an optional
+typed policy, and the coarse candidate remains an experiment.
diff --git a/experiments/preconditioner_rotation_newton_2026-09-18.json b/experiments/preconditioner_rotation_newton_2026-09-18.json
new file mode 100644
index 0000000..77f8d3e
--- /dev/null
+++ b/experiments/preconditioner_rotation_newton_2026-09-18.json
@@ -0,0 +1,20 @@
+[
+  {
+    "id": "n1_J0p1_positivity_curvature_stellar_ldu_gravity_schur",
+    "arguments": [
+      "--index", "1",
+      "--angular-momentum", "0.1",
+      "--strategy", "positivity-curvature",
+      "--no-central",
+      "--max-newton", "8",
+      "--restart", "160",
+      "--max-linear", "200",
+      "--linear-tol", "0.03",
+      "--rtol", "1e-8",
+      "--atol", "0",
+      "--preconditioner-variant", "stellar-ldu-gravity-schur",
+      "--schur-sweeps", "1",
+      "--schur-relaxation", "0.5"
+    ]
+  }
+]