docs: redefine phase 1 rebaseline steps

phases/1-linear-static-mitc4-rebaseline/step10.md

@@ -0,0 +1,54 @@
+# Sprint Contract: MITC4 Stiffness Drilling
+
+## Objective
+Assemble the MITC4 element stiffness and internal force kernel using the documented strain, material, integration, six-DOF transform, and drilling stabilization.
+
+## Required Reading
+- /AGENTS.md
+- /docs/MITC4_FORMULATION.md
+- /docs/NUMERICAL_CONVENTIONS.md
+- /docs/ADR.md
+
+## Scope
+- Accumulate `K_e = integral B^T D B dV`.
+- Add local drilling stabilization with `drilling_stiffness_scale = 1.0e-3`.
+- Transform local element stiffness/internal force to global 24-DOF order.
+- Preserve parameterization and diagnostics for drilling scale.
+
+## Allowed Files
+- `include/`
+- `src/`
+- `tests/`
+- `PLAN.md`
+- `PROGRESS.md`
+
+## Explicit Non-Goals
+- Do not add assembly/global solve.
+- Do not tune drilling scale to match one reference case.
+- Do not output stresses/resultants as mandatory fields.
+
+## Tests To Write First
+- Stiffness dimension and symmetry tests.
+- Drilling diagonal reference tests using minimum positive physical local stiffness diagonal.
+- Zero/invalid reference diagonal diagnostic tests.
+- Rigid body physical strain-energy tests with documented drilling effects.
+- Internal force consistency test `f_int_e = K_e u_e` for linear elastic Phase 1.
+
+## Reference Artifacts
+- None.
+
+## Acceptance Commands
+```bash
+python scripts/validate_workspace.py
+```
+
+## Evaluator Checklist
+- Old `1.0e-6 * E * thickness` drilling rule is gone.
+- Global 24-DOF ordering matches `UX,UY,UZ,RX,RY,RZ` per node.
+- Stiffness remains linear elastic and symmetric.
+
+## Handoff Requirements
+- Record element kernel readiness in `PROGRESS.md`.
+
+## Do Not
+- Do not optimize or parallelize before element tests pass.