feat(cpp-object-oriented-modular-refactoring): step 3 - foundation-google-style

include/fesa/core/diagnostic.h

@@ -0,0 +1,31 @@
+#ifndef FESA_CORE_DIAGNOSTIC_H_
+#define FESA_CORE_DIAGNOSTIC_H_
+
+#include <string>
+#include <vector>
+
+#include "fesa/core/source_identity.h"
+
+namespace fesa {
+
+/// @brief Distinguishes recoverable warnings from operation-stopping errors.
+enum class Severity { kWarning, kError };
+
+/// @brief Carries a structured, backend-independent diagnostic record.
+struct Diagnostic {
+  Severity severity;
+  std::string code;
+  SourceLocation location;
+  std::string keyword;
+  std::string entity_identity;
+  std::string message;
+};
+
+/// @brief Orders diagnostics by their externally visible source tuple.
+/// @param diagnostics Records to reorder in place.
+/// @note Records with identical keys retain their discovery order.
+void SortDiagnostics(std::vector<Diagnostic>& diagnostics);
+
+}  // namespace fesa
+
+#endif  // FESA_CORE_DIAGNOSTIC_H_