test: onboard quad02 reaction reference

references/quad_02_notes.md

@@ -6,6 +6,7 @@
 The original Abaqus input remains preserved as provenance:
 - `quad_02.inp`
 - `quad_02_displacements.csv`
+- `quad_02_reactionforces.csv`
 
 The Phase 1 parser-compatible derivative input is:
 - `quad_02_phase1.inp`
@@ -69,6 +70,29 @@ with component order:
 UX, UY, UZ, RX, RY, RZ
 ```
 
+`quad_02_reactionforces.csv` is an Abaqus-exported nodal reaction force/moment table with 121 rows.
+
+Required columns:
+- `Node Label`
+- `RF-RF1`
+- `RF-RF2`
+- `RF-RF3`
+- `RM-RM1`
+- `RM-RM2`
+- `RM-RM3`
+
+It maps to FESA field output:
+
+```text
+/results/steps/Step-1/frames/0/fieldOutputs/RF
+```
+
+with component order:
+
+```text
+RFX, RFY, RFZ, RMX, RMY, RMZ
+```
+
 ## Initial Tolerance
 The active automated displacement regression uses:
 
@@ -85,6 +109,19 @@ Do not tune tolerances or drilling stiffness to make this single case pass.
 
 The regression compares FESA `U` against the stored Abaqus CSV by node id and uses the tolerance above.
 
+`quad_02_phase1.inp` and `quad_02_reactionforces.csv` are also wired through the reaction CSV loader and node-wise `RF` comparator. This comparison currently records a known non-passing gap rather than an accepted pass gate:
+
+```text
+abs_tol = 1.0e-6
+rel_tol = 1.0e-5
+reference_scale = 1.0
+max_abs_error ~= 612.751347
+max_rel_error ~= 0.494032
+first_mismatch = node 1 RFZ, expected 6860.0, actual 6652.459896
+```
+
+Do not relax reaction tolerances to make this case pass. Treat the mismatch as a solver/formulation verification item.
+
 ## Current Limitations
-- `RF` has no paired Abaqus reaction CSV yet; verify `RF` by full-vector equilibrium until a `quad_02_reactions.csv` artifact is provided.
+- The stored Abaqus reaction CSV is available, but node-wise `RF` agreement is not accepted yet because the current comparison fails.
 - This is currently the only passing stored Abaqus reference regression. The PRD target still requires at least three stored reference models: one single-element case, one simple multi-element plate/shell case, and one curved shell benchmark.