underworldcode · lmoresi · Jul 16, 2026 · Jul 16, 2026
@@ -64,8 +64,9 @@ uw.meshing.smooth_mesh_interior(mesh, metric=M, method="mmpde",
     slip_surfaces=True, skip_threshold=None)     # tensor metric: do the skip check yourself
 ```
 
-Pitfalls that make it "not work": `method="anisotropic"`/`"ot"` (shred/sliver — use
-mmpde); injecting `relax`/`n_outer` (starves mmpde's CG); `strategy=` instead of
+Pitfalls that make it "not work": `method="anisotropic"`/`"ot"`/`"spring"`/`"ma"`
+(RETIRED 2026-07 — they now raise ValueError; mmpde is the default and only
+metric mover); injecting `relax`/`n_outer` (starves mmpde's CG); `strategy=` instead of
 `refinement=R` (under-grades); a scalar bump for a fault (refines a fat corridor,
 leaves the centre coarse); signed `Surface.distance.sym` for `d` (bleeds along the
 line extension — use a direct unsigned distance). Full rationale + the rest of the

@@ -65,7 +65,7 @@ for each edge vector $\mathbf{e}$. Edges that are too long get subdivided; regio
 UW3 offers **two complementary** ways to put resolution where it is
 needed:
 
-| | `mesh.remesh(...)` (this page) | `smooth_mesh_interior(method="anisotropic")` |
+| | `mesh.remesh(...)` (this page) | `smooth_mesh_interior(method="mmpde")` |
 |---|---|---|
 | Mechanism | **Re-mesh** (MMG): insert/remove/retriangulate | **Redistribute** the existing nodes (move only) |
 | Node budget | *Changes* — targets an **absolute** edge length `h` | **Fixed** — relative redistribution to a target *density* |
@@ -405,9 +405,10 @@ smooth_mesh_interior(mesh, metric=rho, method="mmpde",
 ```{tip}
 **`method="mmpde"` is the default mover** (since this release): the
 variational moving-mesh adaptation of Huang & Kamenski. It is
-dimension-general (2D/3D), matrix-free (no PETSc solve — small
-per-cell dense algebra plus a parallel `Vec` assembly), provably
-non-folding, and — uniquely among the movers here — genuinely
+matrix-free (no PETSc solve — small per-cell dense algebra plus a
+parallel `Vec` assembly), provably non-folding, currently 2D
+(triangle meshes; the method itself is dimension-general but the
+3D discretization is not implemented), and genuinely
 *clusters and aligns* to an **anisotropic tensor** metric. It is
 both the most capable and the most straightforward to reason about,
 which is why it is now the default. Pass a **scalar** density (as
@@ -417,13 +418,13 @@ above; it is promoted to the isotropic tensor `ρ·I`) or a `d×d`
 long-along refinement. Full design + derivation:
 {doc}`/developer/design/anisotropic-mmpde-mover`.
 
-The earlier movers remain available via `method=`:
-`"spring"` (fast volumetric equant-cell smoother), `"ma"`
-(isotropic Monge–Ampère), `"ot"` (linear OT-improvement step),
-`"anisotropic"` (decoupled-Winslow tensor smoother — reshapes but
-does not cluster). Use them only when you specifically need their
-behaviour; `"mmpde"` supersedes `"anisotropic"` for fault / front
-refinement.
+The earlier movers — `"spring"` (volumetric equant-cell smoother),
+`"ma"` (isotropic Monge–Ampère), `"ot"` (linear OT-improvement
+step) and `"anisotropic"` (decoupled-Winslow tensor smoother) —
+were **retired in 2026-07**: `"mmpde"` with a scalar metric
+reproduces their isotropic equidistribution, and with a tensor
+metric it clusters and aligns where they could not. The retired
+spellings now raise a `ValueError` pointing here.
 
 Key `mmpde` knobs (via `method_kwargs`): `p` (functional exponent,
 1.5–2), `theta` (Huang alignment/equidistribution balance, 1/3),
@@ -439,9 +440,6 @@ T| - g_{lo})/(g_{hi}-g_{lo}),0,1\big)$ with $g_{lo},g_{hi}$ the
 lo/hi percentiles of $|\nabla T|$ — deliberately the same shape as
 {py:func}`underworld3.adaptivity.metric_from_gradient`, so the
 *intent* you express is identical whichever family you choose.
-The mover then builds a gradient-derived **anisotropic tensor**
-metric internally and solves an M-weighted Laplace (Winslow)
-coordinate map.
 
 ```{important}
 This is a **gradient** metric: it resolves where the field
@@ -455,13 +453,8 @@ on general non-separable features and on cell-alignment / quality
 (it never produces slivers).
 ```
 
-Key knobs (via `method_kwargs`): `aniso_cap` (max cell anisotropy
-— the binding stability lever; ≈2 robust, ≳6 folds), `relax`
-(damping), `n_outer` (composed damped steps), `linear_solver`
-(`"direct"` MUMPS, or `"gamg"` for the parallel-scalable path —
-validated bit-parity). The full mathematical derivation (OT /
-Monge–Ampère, the metric-tensor / Winslow mover, dynamic field
-handling, Nusselt) is in
+The full mathematical derivation (including the retired OT /
+Monge–Ampère and Winslow movers, kept as an R&D record) is in
 {doc}`/developer/design/mesh-adaptation-formulation`; operational
 detail in {doc}`/developer/subsystems/mesh-metric-redistribution`;
 the dated R&D log in

@@ -83,8 +83,8 @@ re-discretising on the coarse mesh. `pc_mg_galerkin = both` does this.
 
 This is the key reason to prefer FMG when you adapt:
 
-- The coordinate-deforming adaptation movers (Winslow / anisotropic /
-  `OT_adapt` / `follow_metric`) **preserve mesh topology**. The refinement
+- The coordinate-deforming adaptation movers (the MMPDE mover /
+  `follow_metric`) **preserve mesh topology**. The refinement
   hierarchy survives them, so geometric multigrid keeps working as the mesh
   deforms — precisely where GAMG struggles with the resulting anisotropy.
 - A **true remesh** (a topology change) collapses the hierarchy to a single

@@ -6,6 +6,30 @@ This log tracks significant development work at a conceptual level, suitable for
 
 ## 2026 Q3 (July – September)
 
+### Retired Interior Movers — MMPDE Is the Mover (July 2026)
+
+**The superseded fixed-topology interior movers were retired** (maintainer
+ruling 2026-07): the spring-equilibrium, Monge–Ampère, OT-improvement-step
+and anisotropic-Winslow movers were deleted, together with `mesh.OT_adapt()`
+(built on the OT step; closes #346, whose latent MPI deadlock dies with the
+spring mover, and #353, whose `strategy=` TypeError dies with the dispatch).
+
+- `smooth_mesh_interior(method=...)` now defaults to **`"mmpde"`** (was
+  `"spring"`) — a sanctioned behaviour change: with a scalar metric the
+  MMPDE mover reproduces the retired movers' isotropic equidistribution
+  (the isotropic-metric equivalence), and with a tensor metric it clusters
+  and aligns where they could not. Retired spellings raise a `ValueError`
+  naming the replacement.
+- `follow_metric(...)` (the two-knob adapter) now drives the MMPDE mover;
+  `mesh.OT_adapt()` raises a `RuntimeError` tombstone pointing at
+  `follow_metric` / `smooth_mesh_interior` / `mesh.adapt`.
+- The graph-Laplacian Jacobi smoother and the Taubin surface-field smoother
+  (`smooth_surface_field`) are separate, current tools and are unchanged.
+- The boundary-facet / boundary-slip primitives shared with surviving code
+  moved from `meshing/_ot_adapt.py` into `meshing/smoothing/graph.py`;
+  the style-gate allowlist shrank by the deleted files' entries.
+
+
 ### July 2026 Quality Campaign — Audit, Style Charter, Remediation Waves (July 2026)
 
 **A systematic post-development-burst quality campaign**: six adversarially

@@ -1,5 +1,10 @@
 # Monge–Ampère mesh redistribution: Newton/cofactor linearisation
 
+> **RETIRED movers note (2026-07):** the spring / Monge-Ampère / OT-step /
+> anisotropic-Winslow interior movers this document discusses were retired
+> (superseded by `method="mmpde"`, the default). Kept as the R&D record;
+> the code lives in git history before the retirement commit.
+
 > **Status**: exploration (Phase 0), `feature/winslow-mesh-smoother`,
 > 2026-05-17. Companion to
 > `docs/developer/subsystems/mesh-metric-redistribution.md` (the

@@ -1,5 +1,10 @@
 # Mesh adaptation by metric-driven node redistribution — mathematical formulation
 
+> **RETIRED movers note (2026-07):** the spring / Monge-Ampère / OT-step /
+> anisotropic-Winslow interior movers this document discusses were retired
+> (superseded by `method="mmpde"`, the default). Kept as the R&D record;
+> the code lives in git history before the retirement commit.
+
 **Status**: Reference (current, 2026-05) — the mathematical formulation for the implemented `smooth_mesh_interior` family (`meshing/smoothing.py`).
 
 > **Scope.** This is the self-contained *mathematical* reference for the

@@ -1,9 +1,14 @@
 ---
 title: "Mesh.OT_adapt() — public API proposal"
 date: 2026-05-24
-status: proposal
+status: retired (2026-07 — OT_adapt removed; superseded by the MMPDE mover)
 ---
 
+> **RETIRED movers note (2026-07):** the spring / Monge-Ampère / OT-step /
+> anisotropic-Winslow interior movers this document discusses were retired
+> (superseded by `method="mmpde"`, the default). Kept as the R&D record;
+> the code lives in git history before the retirement commit.
+
 # `mesh.OT_adapt()` — public API proposal
 
 ## Background

@@ -7,18 +7,25 @@ which remeshes / changes topology).
 
 > **Mathematics:** the full derivations (optimal-transport /
 > Monge–Ampère, the volumetric spring, the anisotropic
-> metric-tensor / Winslow mover, the gradient-metric construction,
-> dynamic field handling, and the Nusselt diagnostic) are in
+> metric-tensor / Winslow mover — all retired 2026-07 — the
+> gradient-metric construction, dynamic field handling, and the
+> Nusselt diagnostic) are in
 > {doc}`/developer/design/mesh-adaptation-formulation`. This page is
 > the operational guide.
 
+> **Retirement note (2026-07):** the `spring`, `ma`, `ot` and
+> `anisotropic` movers described in the historical sections below
+> were retired — superseded by `method="mmpde"` (the default),
+> whose scalar-metric behaviour reproduces their isotropic
+> equidistribution. The retired spellings raise a `ValueError`.
+> Sections describing them are kept as the R&D record.
+
 ```python
 import underworld3 as uw
 from underworld3.meshing import smooth_mesh_interior
 
-smooth_mesh_interior(mesh, metric=f, method="spring")       # fast
-smooth_mesh_interior(mesh, metric=f, method="ma")           # robust
-smooth_mesh_interior(mesh, metric=f, method="anisotropic")  # cleanest, aligned
+smooth_mesh_interior(mesh, metric=f)                  # mmpde (default)
+smooth_mesh_interior(mesh, metric=M_tensor)           # tensor metric: aligned
 ```
 
 ## When to use it

@@ -64,8 +64,8 @@ This section needs:
 
 - [Metric-driven mesh redistribution](mesh-metric-redistribution.md)
   — topology-preserving node redistribution toward a target
-  size/density field (`smooth_mesh_interior`; spring &
-  Monge–Ampère methods). Restores the grading of a deformed
+  size/density field (`smooth_mesh_interior`; the variational
+  MMPDE mover). Restores the grading of a deformed
   adapted mesh or bunches nodes ~2× at a feature; contrast
   `mesh.adapt()` which remeshes.
 

@@ -27,9 +27,8 @@ src/underworld3/tests/test_adaptivity_metrics.py:access-context
 src/underworld3/discretisation/discretisation_mesh.py:mesh-data
 
 # --- hedging-name (Charter S3) ---------------------------------------------
-# Four `_do_move()` local closures in the mesh-mover machinery.
+# `_do_move()` local closures in the mesh-mover machinery (three sites).
 src/underworld3/discretisation/discretisation_mesh.py:hedging-name
-src/underworld3/meshing/_ot_adapt.py:hedging-name
 src/underworld3/meshing/smoothing/api.py:hedging-name
 
 # --- except-pass (Charter S4) ----------------------------------------------
@@ -46,9 +45,6 @@ src/underworld3/function/_function.pyx:except-pass
 src/underworld3/function/expressions.py:except-pass
 src/underworld3/function/quantities.py:except-pass
 src/underworld3/function/unit_conversion.py:except-pass
-src/underworld3/meshing/_ot_adapt.py:except-pass
-src/underworld3/meshing/smoothing/anisotropic.py:except-pass
-src/underworld3/meshing/smoothing/monge_ampere.py:except-pass
 src/underworld3/meshing/surfaces.py:except-pass
 src/underworld3/model.py:except-pass
 src/underworld3/scaling/_scaling.py:except-pass