feat(cpp-object-oriented-modular-refactoring): step 4 - model-element-google-style

include/fesa/model/shell_geometry.h

@@ -0,0 +1,53 @@
+#ifndef FESA_MODEL_SHELL_GEOMETRY_H_
+#define FESA_MODEL_SHELL_GEOMETRY_H_
+
+#include <array>
+#include <cstddef>
+#include <vector>
+
+#include "fesa/core/status.h"
+#include "fesa/model/model_types.h"
+
+namespace fesa {
+
+/// @brief Classifies a mandatory shell-geometry validation location.
+enum class ShellGeometryPointKind { kCenter, kStiffness, kTying, kRecovery };
+
+/// @brief Identifies one deterministic shell-geometry validation point.
+struct ShellGeometryValidationPoint {
+  ShellGeometryPointKind kind;
+  std::size_t location_index;
+  std::array<double, 3> natural_coordinates;
+};
+
+/// @brief Stores deterministic preprocessing data for one shell element.
+struct ShellElementGeometryData {
+  EntityIndex element_index;
+  std::array<double, 3> normal_candidate;
+  double surface_area_weight;
+};
+
+/// @brief Owns preprocessed shell node frames and element geometry data.
+struct ShellGeometry {
+  std::vector<ShellNodeInitialFrame> nodal_frames;
+  std::vector<ShellElementGeometryData> element_data;
+};
+
+/// @brief Returns the complete fixed validation-point inventory.
+/// @note Ordering is center, stiffness, tying, then recovery identity.
+const std::array<ShellGeometryValidationPoint, 17>&
+ShellGeometryValidationPoints() noexcept;
+
+/// @brief Builds deterministic nodal frames and validates shell geometry.
+/// @param nodes Source nodes indexed by stable EntityIndex.
+/// @param elements Shell definitions in stable source order.
+/// @param sections Shell sections used for thickness validation.
+/// @return Validated geometry or a structured model failure.
+Result<ShellGeometry> PreprocessShellGeometry(
+    const std::vector<Node>& nodes,
+    const std::vector<Mitc4ShellDefinition>& elements,
+    const std::vector<ShellSection>& sections);
+
+}  // namespace fesa
+
+#endif  // FESA_MODEL_SHELL_GEOMETRY_H_