docs: use S4-only MITC4 reference gate

docs/formulations/mitc4-shell-formulation.md

@@ -8,7 +8,7 @@
 - source_numerical_review: `docs/numerical-reviews/linear-static-mitc4-shell-review.md`
 - status: `approved-for-implementation-planning`
 - owner_agent: `formulation-agent`
-- date: `2026-08-12`
+- date: `2026-08-13`
 - revision_basis: approved independent-reference policy, fixed drilling rule, and
   removal of calibration gates `NR-O01` through `NR-O04`
 - revision_state: `numerical-review-passed`
@@ -1540,13 +1540,15 @@ or drilling-energy warning is part of this check.
 
 ### 17.5 Reference-comparison boundary
 
-Abaqus comparisons block only on matched global `U1/U2/U3` rows under
+Abaqus comparison uses only the declared full-integration S4 case and blocks only
+on matched global `U1/U2/U3` rows under
 `tolerance_c=1e-9+1e-6*reference_scale_c`, where `reference_scale_c` is the maximum
 absolute finite Abaqus value for the same component. `UR1/UR2/UR3` uses the same
 formula but an exceedance emits only a deterministic nonblocking warning.
 FESA `S4` and `S4R` inputs must produce the same internal numerical rows for identical
-supported models while preserving distinct source metadata. Abaqus S4 and S4R are
-not expected to be numerically identical on finite meshes.
+supported models while preserving distinct source metadata. This common-path property
+is verified without consuming an S4R Abaqus artifact; Abaqus S4R is not an acceptance
+reference for this full-integration FESA formulation.
 
 ### 17.6 Future nonlinear tangent verification
 
@@ -1628,9 +1630,9 @@ research brief remain the project source of truth.
 | `017-020` | global 24-DOF virtual work; `rho_M <= 1e-12`; distributed loads excluded | I/O diagnostic/schema |
 | `024-029` | deterministic element buffers, partitioned linear lifecycle, full-residual reaction | planning |
 | `039-048` | nodal/global and shell/local recovery inventory, units, identities, physical shell energy | I/O schema |
-| `049-057` | normalized invariants, patches, fixed drilling, declared references and equilibrium | Numerical Review/reference/physics |
+| `049-057` | normalized invariants, patches, fixed drilling, declared S4 reference and equilibrium | Numerical Review/reference/physics |
 | `058-064` | exact B33 mixed tolerance; U blocking and UR warning-only | reference verification |
-| `065-072` | exact existing S4/S4R paths, immutability and displacement-only boundary | reference model |
+| `065-072` | exact existing S4 paths, S4R reference non-consumption, immutability and displacement-only boundary | reference model |
 
 ### 20.1 Numerical Review revision traceability
 
@@ -1678,9 +1680,11 @@ items or an expanded reference portfolio as missing evidence.
 
 ### 21.3 Reference Model handoff
 
-- Record the existing `reference/shell/` S4 and `reference/shellR/` S4R input and
-  displacement CSV paths, but compare only formulation-independent global displacement
-  evidence rather than claiming element equivalence.
+- Record only the existing `reference/shell/` S4 input and displacement CSV as the
+  acceptance pair and compare formulation-independent global displacement evidence
+  without claiming element equivalence.
+- Do not consume `reference/shellR/` in acceptance comparison; preserve S4R support
+  through source-mapping/common-kernel/metadata tests.
 - Use the exact B33 mixed tolerance; do not add administrative metadata or portfolio gates.
 - Do not create, repair, rename, or run reference artifacts during this formulation
   gate.