world_json.h

#pragma once
#include "gaia/config/config.h"
 
#if GAIA_JSON_ENABLED
 
  #include <cstdio>
  #include <cstring>
 
  #include "gaia/ser/ser_json.h"
 
namespace gaia {
  namespace ecs {
    namespace detail {
      static constexpr uint32_t RuntimeJsonMaxDepth = 32;
 
      GAIA_NODISCARD inline bool
      runtime_type_json_type(const ComponentCacheItem& typeItem, ser::serialization_type_id& out) noexcept {
        const auto primitiveType = typeItem.primitive_type();
        if (primitiveType != EntityBad)
          return runtime_primitive_serialization_type(primitiveType, out);
        out = ser::serialization_type_id::ignore;
        return false;
      }
 
      GAIA_NODISCARD inline bool
      runtime_json_is_char8_type(const ComponentCacheItem* pType, Entity typeEntity) noexcept {
        ser::serialization_type_id type = ser::serialization_type_id::ignore;
        if (pType != nullptr)
          return runtime_type_json_type(*pType, type) && type == ser::serialization_type_id::c8;
        return runtime_primitive_serialization_type(typeEntity, type) && type == ser::serialization_type_id::c8;
      }
 
      GAIA_NODISCARD inline const ComponentCacheItem*
      find_runtime_json_type(const ComponentCache* pCache, Entity typeEntity) noexcept {
        return pCache != nullptr ? pCache->find(typeEntity) : nullptr;
      }
 
      GAIA_NODISCARD inline bool
      runtime_json_type_size(const ComponentCacheItem* pType, Entity typeEntity, uint32_t& outSize) noexcept {
        if (pType != nullptr) {
          outSize = pType->comp.size();
          return true;
        }
        outSize = ComponentCacheItem::primitive_type_size(typeEntity);
        return outSize != 0;
      }
 
      struct RuntimeJsonFieldLayout final {
        const ComponentCacheItem* pType = nullptr;
        Entity type = EntityBad;
        uint32_t elemSize = 0;
        uint32_t elemCount = 0;
      };
 
      GAIA_NODISCARD inline bool resolve_runtime_json_field_layout(
          const ComponentCache* pCache, const RuntimeFieldDesc& field, RuntimeJsonFieldLayout& out) noexcept {
        out = {};
        const auto* pFieldType = find_runtime_json_type(pCache, field.type);
        out.type = field.type;
        out.pType = pFieldType;
        out.elemCount = ComponentCacheItem::field_element_count(field);
 
        if (pFieldType != nullptr && pFieldType->typeKind == RuntimeTypeKind::Array) {
          if (field.count != 0)
            return false;
          out.type = pFieldType->element_type();
          out.elemCount = pFieldType->element_count();
          out.pType = find_runtime_json_type(pCache, out.type);
        }
 
        return out.elemCount != 0 && runtime_json_type_size(out.pType, out.type, out.elemSize);
      }
 
      GAIA_NODISCARD inline bool runtime_json_integer_bits(
          const uint8_t* pData, ser::serialization_type_id type, uint32_t valueSize, uint64_t& out) noexcept {
        switch (type) {
          case ser::serialization_type_id::s8:
          case ser::serialization_type_id::u8: {
            if (valueSize != sizeof(uint8_t))
              return false;
            uint8_t value = 0;
            memcpy(&value, pData, sizeof(value));
            out = value;
            return true;
          }
          case ser::serialization_type_id::s16:
          case ser::serialization_type_id::u16: {
            if (valueSize != sizeof(uint16_t))
              return false;
            uint16_t value = 0;
            memcpy(&value, pData, sizeof(value));
            out = value;
            return true;
          }
          case ser::serialization_type_id::s32:
          case ser::serialization_type_id::u32: {
            if (valueSize != sizeof(uint32_t))
              return false;
            uint32_t value = 0;
            memcpy(&value, pData, sizeof(value));
            out = value;
            return true;
          }
          case ser::serialization_type_id::s64:
          case ser::serialization_type_id::u64: {
            if (valueSize != sizeof(uint64_t))
              return false;
            memcpy(&out, pData, sizeof(out));
            return true;
          }
          default:
            return false;
        }
      }
 
      GAIA_NODISCARD inline bool
      runtime_json_constant_bits(ser::serialization_type_id type, int64_t value, uint64_t& out) noexcept {
        switch (type) {
          case ser::serialization_type_id::s8:
            if (value < INT8_MIN || value > INT8_MAX)
              return false;
            out = (uint8_t)value;
            return true;
          case ser::serialization_type_id::u8:
            if (value < 0 || value > UINT8_MAX)
              return false;
            out = (uint8_t)value;
            return true;
          case ser::serialization_type_id::s16:
            if (value < INT16_MIN || value > INT16_MAX)
              return false;
            out = (uint16_t)value;
            return true;
          case ser::serialization_type_id::u16:
            if (value < 0 || value > UINT16_MAX)
              return false;
            out = (uint16_t)value;
            return true;
          case ser::serialization_type_id::s32:
            if (value < INT32_MIN || value > INT32_MAX)
              return false;
            out = (uint32_t)value;
            return true;
          case ser::serialization_type_id::u32:
            if (value < 0 || (uint64_t)value > UINT32_MAX)
              return false;
            out = (uint32_t)value;
            return true;
          case ser::serialization_type_id::s64:
            out = (uint64_t)value;
            return true;
          case ser::serialization_type_id::u64:
            if (value < 0)
              return false;
            out = (uint64_t)value;
            return true;
          default:
            return false;
        }
      }
 
      GAIA_NODISCARD inline bool runtime_json_write_integer_bits(
          uint8_t* pData, ser::serialization_type_id type, uint32_t valueSize, uint64_t value) noexcept {
        switch (type) {
          case ser::serialization_type_id::s8:
          case ser::serialization_type_id::u8: {
            if (valueSize != sizeof(uint8_t))
              return false;
            const auto narrowed = (uint8_t)value;
            memcpy(pData, &narrowed, sizeof(narrowed));
            return true;
          }
          case ser::serialization_type_id::s16:
          case ser::serialization_type_id::u16: {
            if (valueSize != sizeof(uint16_t))
              return false;
            const auto narrowed = (uint16_t)value;
            memcpy(pData, &narrowed, sizeof(narrowed));
            return true;
          }
          case ser::serialization_type_id::s32:
          case ser::serialization_type_id::u32: {
            if (valueSize != sizeof(uint32_t))
              return false;
            const auto narrowed = (uint32_t)value;
            memcpy(pData, &narrowed, sizeof(narrowed));
            return true;
          }
          case ser::serialization_type_id::s64:
          case ser::serialization_type_id::u64:
            if (valueSize != sizeof(uint64_t))
              return false;
            memcpy(pData, &value, sizeof(value));
            return true;
          default:
            return false;
        }
      }
 
      GAIA_NODISCARD inline bool runtime_json_is_direct_value(const ComponentCacheItem& item) noexcept {
        switch (item.typeKind) {
          case RuntimeTypeKind::Primitive:
          case RuntimeTypeKind::Enum:
          case RuntimeTypeKind::Bitmask:
          case RuntimeTypeKind::Array:
          case RuntimeTypeKind::Vector:
            return true;
          case RuntimeTypeKind::Opaque:
            return item.opaque_adapter() != nullptr;
          default:
            return false;
        }
      }
 
      GAIA_NODISCARD inline bool runtime_json_leaf_editable(const ComponentCacheItem& item) noexcept {
        return item.typeKind == RuntimeTypeKind::Primitive || item.typeKind == RuntimeTypeKind::Enum ||
               item.typeKind == RuntimeTypeKind::Bitmask;
      }
 
      GAIA_NODISCARD inline ser::json_str
      make_runtime_json_child_path(ser::json_str_view parent, ser::json_str_view child) {
        if (parent.empty())
          return ser::json_str(child);
        if (child.empty())
          return ser::json_str(parent);
 
        ser::json_str path;
        path.reserve(parent.size() + 1 + child.size());
        path.append(parent.data(), parent.size());
        path.append('.');
        path.append(child.data(), child.size());
        return path;
      }
 
      GAIA_NODISCARD inline ser::json_str make_runtime_json_element_path(ser::json_str_view parent, uint32_t index) {
        ser::json_str path(parent);
        path.append('[');
        char idx[16]{};
        const auto len = (uint32_t)snprintf(idx, sizeof(idx), "%u", index);
        path.append(idx, len);
        path.append(']');
        return path;
      }
 
      GAIA_NODISCARD inline bool count_runtime_json_array_elements(ser::ser_json& reader, uint32_t& outCount) {
        outCount = 0;
        reader.ws();
        const auto* start = reader.pos();
        const auto* end = reader.end();
        if (start == nullptr || end == nullptr || start > end)
          return false;
 
        ser::ser_json counter(start, (uint32_t)(end - start));
        if (!counter.expect('['))
          return false;
        counter.ws();
        if (counter.consume(']'))
          return true;
 
        while (true) {
          if (!counter.skip_value())
            return false;
          ++outCount;
          if (counter.consume(','))
            continue;
          return counter.consume(']');
        }
      }
 
      inline bool write_runtime_json_value(
          const ComponentCache* pCache, const ComponentCacheItem* pType, Entity typeEntity, const uint8_t* pData,
          uint32_t valueSize, ser::ser_json& writer, const ser::RuntimeJsonPolicy& policy, uint32_t depth);
 
      inline bool write_runtime_json_field(
          const ComponentCache* pCache, const ComponentCacheItem& owner, const RuntimeFieldDesc& field,
          const uint8_t* pBase, ser::ser_json& writer, const ser::RuntimeJsonPolicy& policy, uint32_t depth) {
        RuntimeJsonFieldLayout layout{};
        if (!resolve_runtime_json_field_layout(pCache, field, layout)) {
          writer.value_null();
          return false;
        }
 
        const auto fieldSize64 = (uint64_t)layout.elemSize * (uint64_t)layout.elemCount;
        const auto end = (uint64_t)field.offset + fieldSize64;
        if (layout.elemSize == 0 || fieldSize64 > UINT32_MAX || end > owner.comp.size()) {
          writer.value_null();
          return false;
        }
 
        const auto* pFieldData = pBase + field.offset;
        if (layout.elemCount == 1 || field.jsonEncoding == RuntimeJsonEncoding::Utf8String ||
            runtime_json_is_char8_type(layout.pType, layout.type))
          return write_runtime_json_value(
              pCache, layout.pType, layout.type, pFieldData, (uint32_t)fieldSize64, writer, policy, depth + 1);
 
        bool ok = true;
        writer.begin_array();
        GAIA_FOR(layout.elemCount) {
          const auto* pElemData = pFieldData + (uintptr_t)layout.elemSize * i;
          ok = write_runtime_json_value(
                   pCache, layout.pType, layout.type, pElemData, layout.elemSize, writer, policy, depth + 1) &&
               ok;
        }
        writer.end_array();
        return ok;
      }
 
      inline bool write_runtime_json_struct(
          const ComponentCache* pCache, const ComponentCacheItem& item, const uint8_t* pData, ser::ser_json& writer,
          const ser::RuntimeJsonPolicy& policy, uint32_t depth) {
        if (depth >= RuntimeJsonMaxDepth) {
          writer.value_null();
          return false;
        }
 
        bool ok = true;
        writer.begin_object();
        GAIA_FOR(item.field_count()) {
          const auto* pField = item.field(i);
          GAIA_ASSERT(pField != nullptr);
          const auto& field = *pField;
          const auto fieldName = item.field_name(field);
          writer.key(fieldName.data(), fieldName.size());
          ok = write_runtime_json_field(pCache, item, field, pData, writer, policy, depth + 1) && ok;
        }
        writer.end_object();
        return ok;
      }
 
      inline bool write_runtime_json_value(
          const ComponentCache* pCache, const ComponentCacheItem* pType, Entity typeEntity, const uint8_t* pData,
          uint32_t valueSize, ser::ser_json& writer, const ser::RuntimeJsonPolicy& policy, uint32_t depth) {
        if (depth >= RuntimeJsonMaxDepth) {
          writer.value_null();
          return false;
        }
 
        if (pType != nullptr && pType->typeKind == RuntimeTypeKind::Array) {
          const auto elemCount = pType->element_count();
          const auto elementType = pType->element_type();
          const auto* pElementType = find_runtime_json_type(pCache, elementType);
          uint32_t elemSize = 0;
          if (elemCount == 0 || !runtime_json_type_size(pElementType, elementType, elemSize) ||
              (uint64_t)elemSize * elemCount != valueSize) {
            writer.value_null();
            return false;
          }
 
          bool ok = true;
          writer.begin_array();
          GAIA_FOR(elemCount) {
            const auto* pElemData = pData + (uintptr_t)elemSize * i;
            ok = write_runtime_json_value(
                     pCache, pElementType, elementType, pElemData, elemSize, writer, policy, depth + 1) &&
                 ok;
          }
          writer.end_array();
          return ok;
        }
 
        if (pType != nullptr && pType->typeKind == RuntimeTypeKind::Vector) {
          const auto* adapter = pType->sequence_adapter();
          const auto elementType = pType->element_type();
          const auto* pElementType = find_runtime_json_type(pCache, elementType);
          if (adapter == nullptr || adapter->count == nullptr || adapter->element == nullptr) {
            writer.value_null();
            return false;
          }
          RuntimeSequenceScope sequence{typeEntity, pData, nullptr, valueSize};
          uint32_t elemCount = 0;
          if (!adapter->count(adapter->ctx, sequence, elemCount)) {
            writer.value_null();
            return false;
          }
          if (pType->jsonEncoding == RuntimeJsonEncoding::Utf8String) {
            if (elementType != Char8) {
              writer.value_null();
              return false;
            }
 
            ser::json_str text;
            text.reserve(elemCount);
            GAIA_FOR(elemCount) {
              RuntimeSequenceElement element{};
              element.type = elementType;
              if (!adapter->element(adapter->ctx, sequence, i, element) || element.data == nullptr ||
                  element.size != sizeof(char) || (element.type != EntityBad && element.type != Char8)) {
                writer.value_null();
                return false;
              }
              text.append(*(const char*)element.data);
            }
            writer.value_string(text.empty() ? "" : text.data(), text.size());
            return true;
          }
 
          bool ok = true;
          writer.begin_array();
          GAIA_FOR(elemCount) {
            RuntimeSequenceElement element{};
            element.type = elementType;
            if (!adapter->element(adapter->ctx, sequence, i, element)) {
              writer.value_null();
              ok = false;
              continue;
            }
            if (element.type == EntityBad)
              element.type = elementType;
            ok = write_runtime_json_value(
                     pCache, pElementType, element.type, (const uint8_t*)element.data, element.size, writer, policy,
                     depth + 1) &&
                 ok;
          }
          writer.end_array();
          return ok;
        }
 
        if (pType != nullptr && pType->typeKind == RuntimeTypeKind::Opaque) {
          const auto* adapter = pType->opaque_adapter();
          const auto semanticType = pType->opaque_as_type();
          const auto* pSemanticType = find_runtime_json_type(pCache, semanticType);
          if (adapter == nullptr || adapter->project == nullptr || pSemanticType == nullptr) {
            writer.value_null();
            return false;
          }
          RuntimeOpaqueScope opaque{typeEntity, pData, nullptr, valueSize};
          RuntimeOpaqueValue projected{};
          projected.type = semanticType;
          if (!adapter->project(adapter->ctx, opaque, projected)) {
            writer.value_null();
            return false;
          }
          if (projected.type == EntityBad)
            projected.type = semanticType;
          if (projected.type != semanticType || projected.data == nullptr) {
            writer.value_null();
            return false;
          }
          return write_runtime_json_value(
              pCache, pSemanticType, projected.type, (const uint8_t*)projected.data, projected.size, writer, policy,
              depth + 1);
        }
 
        if (pType != nullptr && pType->typeKind == RuntimeTypeKind::Struct)
          return write_runtime_json_struct(pCache, *pType, pData, writer, policy, depth + 1);
 
        ser::serialization_type_id type = ser::serialization_type_id::ignore;
        if (pType != nullptr) {
          if (!runtime_type_json_type(*pType, type)) {
            writer.value_null();
            return false;
          }
        } else if (!runtime_primitive_serialization_type(typeEntity, type)) {
          writer.value_null();
          return false;
        }
 
        uint64_t valueBits = 0;
        if (pType != nullptr && policy.symbolicEnums && pType->typeKind == RuntimeTypeKind::Enum &&
            runtime_json_integer_bits(pData, type, valueSize, valueBits)) {
          GAIA_FOR(pType->constant_count()) {
            const auto* pConstant = pType->constant(i);
            GAIA_ASSERT(pConstant != nullptr);
            uint64_t constantBits = 0;
            if (runtime_json_constant_bits(type, pConstant->value, constantBits) && constantBits == valueBits) {
              const auto constantName = pType->constant_name(*pConstant);
              writer.value_string(constantName.data(), constantName.size());
              return true;
            }
          }
        }
 
        if (pType != nullptr && policy.symbolicBitmasks && pType->typeKind == RuntimeTypeKind::Bitmask &&
            runtime_json_integer_bits(pData, type, valueSize, valueBits)) {
          uint64_t remaining = valueBits;
          GAIA_FOR(pType->constant_count()) {
            const auto* pConstant = pType->constant(i);
            GAIA_ASSERT(pConstant != nullptr);
            uint64_t flagBits = 0;
            if (runtime_json_constant_bits(type, pConstant->value, flagBits) && flagBits != 0 &&
                (flagBits & (flagBits - 1)) == 0 && (remaining & flagBits) == flagBits)
              remaining &= ~flagBits;
          }
 
          if (remaining == 0) {
            writer.begin_array();
            remaining = valueBits;
            GAIA_FOR(pType->constant_count()) {
              const auto* pConstant = pType->constant(i);
              GAIA_ASSERT(pConstant != nullptr);
              uint64_t flagBits = 0;
              if (runtime_json_constant_bits(type, pConstant->value, flagBits) && flagBits != 0 &&
                  (flagBits & (flagBits - 1)) == 0 && (remaining & flagBits) == flagBits) {
                const auto constantName = pType->constant_name(*pConstant);
                writer.value_string(constantName.data(), constantName.size());
                remaining &= ~flagBits;
              }
            }
            writer.end_array();
            return true;
          }
        }
 
        return ser::detail::write_runtime_field_json(writer, pData, type, valueSize);
      }
 
      struct RuntimeJsonReadContext final {
        const ComponentCache* pCache;
        ser::ser_json& reader;
        ser::JsonDiagnostics& diagnostics;
        const ser::RuntimeJsonPolicy& policy;
        bool& ok;
      };
 
      inline bool read_runtime_json_value(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem* pType, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path, uint32_t depth);
 
      inline bool read_runtime_json_elements(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem* pType, Entity typeEntity, uint8_t* pData,
          uint32_t elemSize, uint32_t elemCount, ser::json_str_view path, uint32_t depth) {
        auto& reader = ctx.reader;
        if (!reader.expect('['))
          return false;
 
        GAIA_FOR(elemCount) {
          if (i > 0 && !reader.expect(','))
            return false;
 
          const auto elemPath = make_runtime_json_element_path(path, i);
          auto* pElemData = pData + (uintptr_t)elemSize * i;
 
          if (!read_runtime_json_value(ctx, pType, typeEntity, pElemData, elemSize, elemPath, depth))
            return false;
        }
 
        return reader.expect(']');
      }
 
      inline void warn_runtime_json(
          ser::JsonDiagnostics& diagnostics, ser::JsonDiagReason reason, ser::json_str_view path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Warning, reason, path, message);
      }
 
      inline bool read_runtime_json_field(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& owner, const RuntimeFieldDesc& field, uint8_t* pBase,
          ser::json_str_view path, uint32_t depth) {
        auto& reader = ctx.reader;
        RuntimeJsonFieldLayout layout{};
 
        if (!resolve_runtime_json_field_layout(ctx.pCache, field, layout)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime field uses an unknown reflected type.");
          return reader.skip_value();
        }
 
        const auto fieldSize64 = (uint64_t)layout.elemSize * (uint64_t)layout.elemCount;
        const auto end = (uint64_t)field.offset + fieldSize64;
 
        if (layout.elemSize == 0 || fieldSize64 > UINT32_MAX || end > owner.comp.size()) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime field points outside component size or uses an unsupported type.");
          return reader.skip_value();
        }
 
        auto* pFieldData = pBase + field.offset;
 
        if (layout.elemCount == 1 || field.jsonEncoding == RuntimeJsonEncoding::Utf8String ||
            runtime_json_is_char8_type(layout.pType, layout.type))
          return read_runtime_json_value(
              ctx, layout.pType, layout.type, pFieldData, (uint32_t)fieldSize64, path, depth + 1);
 
        return read_runtime_json_elements(
            ctx, layout.pType, layout.type, pFieldData, layout.elemSize, layout.elemCount, path, depth + 1);
      }
 
      inline bool read_runtime_json_struct(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, uint8_t* pData, ser::json_str_view path,
          uint32_t depth) {
        auto& reader = ctx.reader;
 
        if (depth >= RuntimeJsonMaxDepth) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path, "Runtime JSON nesting is too deep.");
          return reader.skip_value();
        }
 
        if (reader.parse_null()) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::NullComponentPayload, path, "Runtime object payload is null.");
          return true;
        }
 
        if (!reader.expect('{'))
          return false;
 
        reader.ws();
        if (reader.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view key;
          bool keyFromScratch = false;
          if (!reader.parse_string_view(key, &keyFromScratch))
            return false;
 
          // Escaped names are temporary, so keep a copy while reading the field value.
          ser::json_str keyStorage;
          if (keyFromScratch) {
            keyStorage.assign(key.data(), key.size());
            key = keyStorage;
          }
 
          if (!reader.expect(':'))
            return false;
 
          const auto* pField = item.field(util::str_view(key.data(), (uint32_t)key.size()));
          const auto fieldPath = make_runtime_json_child_path(path, key);
 
          if (pField == nullptr) {
            ctx.ok = false;
            warn_runtime_json(ctx.diagnostics, ser::JsonDiagReason::UnknownField, fieldPath, "Unknown runtime field.");
            if (!reader.skip_value())
              return false;
          } else if (!read_runtime_json_field(ctx, item, *pField, pData, fieldPath, depth + 1))
            return false;
 
          reader.ws();
          if (reader.consume(','))
            continue;
          if (reader.consume('}'))
            break;
          return false;
        }
 
        return true;
      }
 
      inline bool read_runtime_json_array(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, uint8_t* pData, uint32_t valueSize,
          ser::json_str_view path, uint32_t depth) {
        const auto elemCount = item.element_count();
        const auto elementType = item.element_type();
        const auto* pElementType = find_runtime_json_type(ctx.pCache, elementType);
        uint32_t elemSize = 0;
 
        if (elemCount == 0 || !runtime_json_type_size(pElementType, elementType, elemSize) ||
            (uint64_t)elemSize * elemCount != valueSize) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime array payload uses an invalid reflected element type.");
          return ctx.reader.skip_value();
        }
 
        return read_runtime_json_elements(ctx, pElementType, elementType, pData, elemSize, elemCount, path, depth + 1);
      }
 
      inline bool read_runtime_json_utf8_vector(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path) {
        const auto* adapter = item.sequence_adapter();
        ser::json_str_view text;
 
        if (item.element_type() != Char8 || adapter == nullptr || adapter->resize == nullptr ||
            adapter->element == nullptr || !ctx.reader.parse_string_view(text)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime UTF-8 string cannot be resized or traversed.");
          return false;
        }
 
        RuntimeSequenceScope sequence{typeEntity, pData, pData, valueSize};
 
        if (!adapter->resize(adapter->ctx, sequence, text.size())) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime UTF-8 string adapter rejected the requested byte count.");
          return true;
        }
 
        // Escaped text is temporary, so copy its bytes before reading anything else.
        // Each byte is stored as one Char8 element.
        GAIA_FOR(text.size()) {
          RuntimeSequenceElement element{};
          element.type = Char8;
 
          if (!adapter->element(adapter->ctx, sequence, i, element) || element.mutData == nullptr ||
              element.size != sizeof(char) || (element.type != EntityBad && element.type != Char8)) {
            ctx.ok = false;
            warn_runtime_json(
                ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
                "Runtime UTF-8 string adapter rejected an element.");
            return true;
          }
 
          *(char*)element.mutData = text.data()[i];
 
          if (adapter->commitElement != nullptr && !adapter->commitElement(adapter->ctx, sequence, element)) {
            ctx.ok = false;
            warn_runtime_json(
                ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
                "Runtime UTF-8 string adapter rejected element commit.");
            return true;
          }
        }
 
        return true;
      }
 
      inline bool read_runtime_json_vector(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path, uint32_t depth) {
        if (item.jsonEncoding == RuntimeJsonEncoding::Utf8String)
          return read_runtime_json_utf8_vector(ctx, item, typeEntity, pData, valueSize, path);
 
        const auto* adapter = item.sequence_adapter();
        const auto elementType = item.element_type();
        const auto* pElementType = find_runtime_json_type(ctx.pCache, elementType);
        uint32_t elemCount = 0;
 
        // Count first because the adapter must resize the sequence before it can return its elements.
        if (adapter == nullptr || adapter->resize == nullptr || adapter->element == nullptr ||
            !count_runtime_json_array_elements(ctx.reader, elemCount)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime vector payload cannot be resized or traversed.");
          return ctx.reader.skip_value();
        }
 
        RuntimeSequenceScope sequence{typeEntity, pData, pData, valueSize};
 
        if (!adapter->resize(adapter->ctx, sequence, elemCount)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime vector adapter rejected the requested element count.");
          return ctx.reader.skip_value();
        }
 
        if (!ctx.reader.expect('['))
          return false;
 
        GAIA_FOR(elemCount) {
          if (i > 0 && !ctx.reader.expect(','))
            return false;
 
          RuntimeSequenceElement element{};
          element.type = elementType;
 
          if (!adapter->element(adapter->ctx, sequence, i, element) || element.mutData == nullptr) {
            ctx.ok = false;
            warn_runtime_json(
                ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
                "Runtime vector adapter rejected an element.");
            return ctx.reader.skip_value();
          }
 
          if (element.type == EntityBad)
            element.type = elementType;
 
          const auto elemPath = make_runtime_json_element_path(path, i);
 
          if (!read_runtime_json_value(
                  ctx, pElementType, element.type, (uint8_t*)element.mutData, element.size, elemPath, depth + 1))
            return false;
        }
 
        return ctx.reader.expect(']');
      }
 
      inline bool read_runtime_json_opaque(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path, uint32_t depth) {
        const auto* adapter = item.opaque_adapter();
        const auto semanticType = item.opaque_as_type();
        const auto* pSemanticType = find_runtime_json_type(ctx.pCache, semanticType);
 
        if (adapter == nullptr || adapter->project == nullptr || pSemanticType == nullptr) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime opaque payload cannot be projected.");
          return ctx.reader.skip_value();
        }
 
        RuntimeOpaqueScope opaque{typeEntity, pData, pData, valueSize};
        RuntimeOpaqueValue projected{};
        projected.type = semanticType;
 
        if (!adapter->project(adapter->ctx, opaque, projected) || projected.mutData == nullptr) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime opaque adapter rejected projection.");
          return ctx.reader.skip_value();
        }
 
        // EntityBad means "use the type from the schema."
        if (projected.type == EntityBad)
          projected.type = semanticType;
 
        if (projected.type != semanticType) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime opaque adapter projected an unexpected semantic type.");
          return ctx.reader.skip_value();
        }
 
        const bool parsed = read_runtime_json_value(
            ctx, pSemanticType, projected.type, (uint8_t*)projected.mutData, projected.size, path, depth + 1);
 
        // The adapter may be using a temporary value. Commit it only if the whole read succeeded.
        if (parsed && adapter->commit != nullptr && ctx.ok && !adapter->commit(adapter->ctx, opaque, projected)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path, "Runtime opaque adapter rejected commit.");
        }
 
        return parsed;
      }
 
      inline bool read_runtime_json_enum_symbol(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, ser::serialization_type_id type, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path) {
        ser::json_str_view symbol;
        if (!ctx.reader.parse_string_view(symbol))
          return false;
 
        const auto* pConstant = item.constant(util::str_view(symbol.data(), (uint32_t)symbol.size()));
        uint64_t constantBits = 0;
 
        if (pConstant == nullptr || !runtime_json_constant_bits(type, pConstant->value, constantBits) ||
            !runtime_json_write_integer_bits(pData, type, valueSize, constantBits)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::UnknownRuntimeConstant, path,
              "Runtime enum symbol is unknown or incompatible with its underlying type.");
        }
 
        return true;
      }
 
      inline bool read_runtime_json_bitmask_symbols(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem& item, ser::serialization_type_id type, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path) {
        auto& reader = ctx.reader;
 
        if (!reader.expect('['))
          return false;
 
        uint64_t valueBits = 0;
        bool symbolsOk = true;
 
        reader.ws();
        if (!reader.consume(']')) {
          while (true) {
            ser::json_str_view symbol;
            if (!reader.parse_string_view(symbol))
              return false;
 
            // Keep reading after a bad name so the next JSON value starts in the right place.
            if (symbolsOk) {
              const auto* pConstant = item.constant(util::str_view(symbol.data(), (uint32_t)symbol.size()));
              uint64_t flagBits = 0;
 
              if (pConstant == nullptr) {
                symbolsOk = false;
                ctx.ok = false;
                warn_runtime_json(
                    ctx.diagnostics, ser::JsonDiagReason::UnknownRuntimeConstant, path,
                    "Runtime bitmask symbol is unknown.");
              } else if (
                  !runtime_json_constant_bits(type, pConstant->value, flagBits) || flagBits == 0 ||
                  (flagBits & (flagBits - 1)) != 0 || (valueBits & flagBits) != 0) {
                symbolsOk = false;
                ctx.ok = false;
                warn_runtime_json(
                    ctx.diagnostics, ser::JsonDiagReason::InvalidRuntimeConstant, path,
                    "Runtime bitmask symbol is not a distinct one-bit flag.");
              } else {
                valueBits |= flagBits;
              }
            }
 
            reader.ws();
            if (reader.consume(','))
              continue;
            if (reader.consume(']'))
              break;
            return false;
          }
        }
 
        // Leave the old value alone if any name is invalid.
        if (symbolsOk && !runtime_json_write_integer_bits(pData, type, valueSize, valueBits)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
              "Runtime bitmask symbols are incompatible with the underlying field size.");
        }
 
        return true;
      }
 
      inline bool read_runtime_json_scalar(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem* pType, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path) {
        ser::serialization_type_id type = ser::serialization_type_id::ignore;
 
        if (pType != nullptr) {
          if (!runtime_type_json_type(*pType, type)) {
            ctx.ok = false;
            warn_runtime_json(
                ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path,
                "Runtime field uses an unsupported reflected type.");
            return ctx.reader.skip_value();
          }
        } else if (!runtime_primitive_serialization_type(typeEntity, type)) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path, "Runtime field type is unknown.");
          return ctx.reader.skip_value();
        }
 
        ctx.reader.ws();
        // Names are optional. Numbers still work for enum and bitmask values.
        if (pType != nullptr && ctx.policy.symbolicEnums && pType->typeKind == RuntimeTypeKind::Enum &&
            !ctx.reader.eof() && ctx.reader.peek() == '"')
          return read_runtime_json_enum_symbol(ctx, *pType, type, pData, valueSize, path);
        if (pType != nullptr && ctx.policy.symbolicBitmasks && pType->typeKind == RuntimeTypeKind::Bitmask &&
            !ctx.reader.eof() && ctx.reader.peek() == '[')
          return read_runtime_json_bitmask_symbols(ctx, *pType, type, pData, valueSize, path);
 
        // Valid JSON can still lose data when it is converted to the field's type.
        bool fieldOk = true;
        if (!ser::detail::read_runtime_field_json(ctx.reader, pData, type, valueSize, fieldOk))
          return false;
 
        if (!fieldOk) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldValueAdjusted, path,
              "Field value was lossy, truncated, or unsupported for the target runtime field type.");
        }
 
        return true;
      }
 
      inline bool read_runtime_json_value(
          RuntimeJsonReadContext& ctx, const ComponentCacheItem* pType, Entity typeEntity, uint8_t* pData,
          uint32_t valueSize, ser::json_str_view path, uint32_t depth) {
        if (depth >= RuntimeJsonMaxDepth) {
          ctx.ok = false;
          warn_runtime_json(
              ctx.diagnostics, ser::JsonDiagReason::FieldOutOfBounds, path, "Runtime JSON nesting is too deep.");
          return ctx.reader.skip_value();
        }
 
        if (pType != nullptr) {
          switch (pType->typeKind) {
            case RuntimeTypeKind::Array:
              return read_runtime_json_array(ctx, *pType, pData, valueSize, path, depth);
            case RuntimeTypeKind::Vector:
              return read_runtime_json_vector(ctx, *pType, typeEntity, pData, valueSize, path, depth);
            case RuntimeTypeKind::Opaque:
              return read_runtime_json_opaque(ctx, *pType, typeEntity, pData, valueSize, path, depth);
            case RuntimeTypeKind::Struct:
              return read_runtime_json_struct(ctx, *pType, pData, path, depth + 1);
            default:
              break;
          }
        }
 
        return read_runtime_json_scalar(ctx, pType, typeEntity, pData, valueSize, path);
      }
    } // namespace detail
 
    inline bool component_to_json(
        const ComponentCacheItem& item, const void* pComponentData, ser::ser_json& writer,
        const ser::RuntimeJsonPolicy& policy = {}) {
      GAIA_ASSERT(pComponentData != nullptr);
      if (pComponentData == nullptr)
        return false;
 
      return detail::write_runtime_json_value(
          item.owner_cache(), &item, item.entity, reinterpret_cast<const uint8_t*>(pComponentData), item.comp.size(),
          writer, policy, 0);
    }
 
    inline ser::json_str component_to_json(const ComponentCacheItem& item, const void* pComponentData, bool& ok) {
      ser::ser_json writer;
      ok = component_to_json(item, pComponentData, writer);
      return writer.str();
    }
 
    inline bool json_to_component(
        const ComponentCacheItem& item, void* pComponentData, ser::ser_json& reader, ser::JsonDiagnostics& diagnostics,
        const ser::RuntimeJsonPolicy& policy = {}, ser::json_str_view componentPath = {}) {
      GAIA_ASSERT(pComponentData != nullptr);
      if (pComponentData == nullptr)
        return false;
 
      if (reader.parse_null()) {
        detail::warn_runtime_json(
            diagnostics, ser::JsonDiagReason::NullComponentPayload, componentPath, "Component payload is null.");
        return true;
      }
 
      if (detail::runtime_json_is_direct_value(item)) {
        bool ok = true;
        detail::RuntimeJsonReadContext ctx{item.owner_cache(), reader, diagnostics, policy, ok};
        return detail::read_runtime_json_value(
            ctx, &item, item.entity, reinterpret_cast<uint8_t*>(pComponentData), item.comp.size(), componentPath, 0);
      }
 
      bool rawFound = false;
      bool fieldFound = false;
      bool ok = true;
 
      detail::RuntimeJsonReadContext ctx{item.owner_cache(), reader, diagnostics, policy, ok};
      ser::ser_buffer_binary rawPayload;
      auto* pBase = reinterpret_cast<uint8_t*>(pComponentData);
 
      if (!reader.expect('{'))
        return false;
 
      reader.ws();
      if (reader.consume('}')) {
        detail::warn_runtime_json(
            diagnostics, ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, componentPath,
            "Component object is empty and contains no runtime fields or $raw payload.");
        return true;
      }
 
      while (true) {
        ser::json_str_view key;
        bool keyFromScratch = false;
        if (!reader.parse_string_view(key, &keyFromScratch))
          return false;
 
        // Escaped names are temporary, so keep a copy while reading the component value.
        ser::json_str keyStorage;
        if (keyFromScratch) {
          keyStorage.assign(key.data(), key.size());
          key = keyStorage;
        }
 
        if (!reader.expect(':'))
          return false;
 
        const auto fieldPath = detail::make_runtime_json_child_path(componentPath, key);
 
        if (key == "$raw") {
          rawFound = true;
          if (!ser::detail::parse_json_byte_array(reader, rawPayload))
            return false;
        } else if (item.field_count() != 0 && item.comp.soa() == 0) {
          const auto* pField = item.field(util::str_view(key.data(), (uint32_t)key.size()));
          if (pField == nullptr) {
            ok = false;
            detail::warn_runtime_json(
                diagnostics, ser::JsonDiagReason::UnknownField, fieldPath, "Unknown runtime field.");
            if (!reader.skip_value())
              return false;
          } else {
            fieldFound = true;
            if (!detail::read_runtime_json_field(ctx, item, *pField, pBase, fieldPath, 0))
              return false;
          }
        } else {
          ok = false;
          detail::warn_runtime_json(
              diagnostics, ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, fieldPath,
              "Runtime field metadata is unavailable for keyed field payloads.");
          if (!reader.skip_value())
            return false;
        }
 
        reader.ws();
        if (reader.consume(','))
          continue;
        if (reader.consume('}'))
          break;
        return false;
      }
 
      if (rawFound) {
        if (item.comp.soa() != 0) {
          detail::warn_runtime_json(
              diagnostics, ser::JsonDiagReason::SoaRawUnsupported,
              detail::make_runtime_json_child_path(componentPath, "$raw"),
              "$raw payload is not supported for SoA components.");
          return true;
        }
 
        // Apply $raw last. If both forms are present, $raw wins regardless of key order.
        auto s = ser::make_serializer(rawPayload);
        s.seek(0);
        item.load(s, pBase, 0, 1, 1);
      }
 
      if (!rawFound && !fieldFound)
        detail::warn_runtime_json(
            diagnostics, ser::JsonDiagReason::MissingRuntimeFieldsOrRawPayload, componentPath,
            "Component payload contains neither recognized runtime fields nor $raw data.");
 
      return true;
    }
 
    inline bool
    json_to_component(const ComponentCacheItem& item, void* pComponentData, ser::ser_json& reader, bool& ok) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = json_to_component(item, pComponentData, reader, diagnostics);
 
      ok = !diagnostics.has_issues();
      return parsed;
    }
 
    inline bool
    World::save_json(ser::ser_json& writer, ser::JsonSaveFlags flags, const ser::RuntimeJsonPolicy& policy) const {
      auto write_component_key = [&](Entity component, const ComponentCacheItem& item) {
        if (!component.pair()) {
          const auto componentName = comp_cache().symbol_name(item);
          if (componentName.empty())
            return false;
          writer.key(componentName.data(), componentName.size());
          return true;
        }
 
        const auto relation = pair_rel(*this, component);
        auto relationName = symbol(relation);
        if (relationName.empty())
          relationName = name(relation);
        const auto target = pair_tgt(*this, component);
        auto targetName = symbol(target);
        if (targetName.empty())
          targetName = name(target);
        if (relationName.empty() || targetName.empty())
          return false;
 
        util::str pairName;
        pairName.append("(");
        pairName.append(relationName.data(), relationName.size());
        pairName.append(",");
        pairName.append(targetName.data(), targetName.size());
        pairName.append(")");
        writer.key(pairName.data(), pairName.size());
        return true;
      };
 
      auto write_raw_component = [&](const ComponentCacheItem& item, const uint8_t* pData, uint32_t from, uint32_t to,
                                     uint32_t cap) {
        ser::ser_buffer_binary raw;
        auto s = ser::make_serializer(raw);
        item.save(s, pData, from, to, cap);
 
        writer.begin_object();
        writer.key("$raw");
        writer.begin_array();
        const auto* pRaw = raw.data();
        GAIA_FOR(raw.bytes()) writer.value_int(pRaw[i]);
        writer.end_array();
        writer.end_object();
      };
 
      bool ok = true;
      const bool includeBinarySnapshot = (flags & ser::JsonSaveFlags::BinarySnapshot) != 0;
      const bool allowRawFallback = (flags & ser::JsonSaveFlags::RawFallback) != 0;
      ser::bin_stream binarySnapshot;
      if (includeBinarySnapshot) {
        auto s = ser::make_serializer(binarySnapshot);
        s.reset();
        save_to(s);
      }
 
      writer.clear();
      writer.begin_object();
      writer.key("format");
      writer.value_int(WorldSerializerJSONVersion);
      writer.key("worldVersion");
      writer.value_int(m_worldVersion);
      if (includeBinarySnapshot) {
        writer.key("binary");
        writer.begin_array();
        {
          const auto* pData = (const uint8_t*)binarySnapshot.data();
          GAIA_FOR(binarySnapshot.bytes()) writer.value_int(pData[i]);
        }
        writer.end_array();
      }
      writer.key("archetypes");
      writer.begin_array();
 
      for (const auto* pArchetype: m_archetypes) {
        if (pArchetype == nullptr || pArchetype->chunks().empty())
          continue;
 
        writer.begin_object();
        writer.key("id");
        writer.value_int((uint32_t)pArchetype->id());
        writer.key("hash");
        writer.value_int((uint64_t)pArchetype->lookup_hash().hash);
 
        writer.key("components");
        writer.begin_array();
        {
          for (const auto entity: pArchetype->ids_view()) {
            const auto itemName = name(entity);
            if (!itemName.empty())
              writer.value_string(itemName.data(), itemName.size());
            else
              writer.value_string("<unnamed>");
          }
        }
        writer.end_array();
 
        writer.key("entities");
        writer.begin_array();
        {
          for (const auto* pChunk: pArchetype->chunks()) {
            if (pChunk == nullptr || pChunk->empty())
              continue;
 
            const auto ents = pChunk->entity_view();
            const auto recs = pChunk->comp_rec_view();
            GAIA_FOR((uint32_t)ents.size()) {
              const auto entity = ents[i];
 
              writer.begin_object();
              {
                writer.key("entity");
                {
                  writer.begin_object();
                  writer.key("id");
                  writer.value_int(entity.id());
                  writer.key("gen");
                  writer.value_int(entity.gen());
                  writer.key("pair");
                  writer.value_bool(entity.pair());
                  writer.key("kind");
                  writer.value_string(EntityKindString[entity.kind()]);
                  const auto entityName = name(entity);
                  if (!entityName.empty()) {
                    writer.key("name");
                    writer.value_string(entityName.data(), entityName.size());
                  }
                  writer.end_object();
                }
 
                writer.key("components");
                writer.begin_object();
                {
                  GAIA_FOR_((uint32_t)recs.size(), j) {
                    const auto& rec = recs[j];
                    const auto& item = *rec.pItem;
                    const auto component = pChunk->ids_view()[j];
                    if (!write_component_key(component, item)) {
                      writer.key("<unnamed>");
                      if (component.pair() && !includeBinarySnapshot)
                        ok = false;
                    }
 
                    // Tags have no associated payload.
                    if (rec.comp.size() == 0) {
                      writer.value_bool(true);
                      continue;
                    }
 
                    const auto row = component.kind() == EntityKind::EK_Uni ? 0U : i;
 
                    if ((item.field_count() != 0 || detail::runtime_json_is_direct_value(item)) &&
                        rec.comp.soa() == 0) {
                      const auto* pCompData = pChunk->comp_ptr(j, row);
                      ok = ecs::component_to_json(item, pCompData, writer, policy) && ok;
                    } else {
                      if (allowRawFallback)
                        write_raw_component(item, rec.pData, row, row + 1, pChunk->capacity());
                      else {
                        writer.value_null();
                        ok = false;
                      }
                    }
                  }
                  writer.end_object();
                }
              }
              writer.end_object();
            }
          }
        }
 
        writer.end_array();
        writer.end_object();
      }
 
      writer.end_array();
      writer.end_object();
      return ok;
    }
 
    inline ser::json_str World::save_json(bool& ok, ser::JsonSaveFlags flags) const {
      ser::ser_json writer;
      ok = save_json(writer, flags);
      return writer.str();
    }
 
    inline bool World::load_json(
        const char* json, uint32_t len, ser::JsonDiagnostics& diagnostics, const ser::RuntimeJsonPolicy& policy) {
      diagnostics.clear();
      if (json == nullptr)
        return false;
      if (len == 0) {
        diagnostics.add(
            ser::JsonDiagSeverity::Error, ser::JsonDiagReason::InvalidJson, "$",
            "Input JSON length must be provided and non-zero.");
        return false;
      }
 
      const auto dataLen = len;
      const auto* p = json;
      const auto* end = json + dataLen;
      auto warn = [&](ser::JsonDiagReason reason, ser::json_str_view path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Warning, reason, path, message);
      };
      auto error = [&](ser::JsonDiagReason reason, ser::json_str_view path, const char* message) {
        diagnostics.add(ser::JsonDiagSeverity::Error, reason, path, message);
      };
 
      // Validate top-level format version first.
      {
        ser::ser_json header(json, dataLen);
        if (!header.expect('{')) {
          error(ser::JsonDiagReason::InvalidJson, "$", "Root JSON value must be an object.");
          return false;
        }
 
        bool hasFormat = false;
        uint32_t formatValue = 0;
 
        header.ws();
        if (!header.consume('}')) {
          while (true) {
            ser::json_str_view key;
            if (!header.parse_string_view(key))
              return false;
            if (!header.expect(':'))
              return false;
 
            if (key == "format") {
              double d = 0.0;
              if (!header.parse_number(d))
                return false;
              if (d < 0.0 || d > 4294967295.0)
                return false;
              const auto v = (uint32_t)d;
              if ((double)v != d)
                return false;
              formatValue = v;
              hasFormat = true;
            } else {
              if (!header.skip_value())
                return false;
            }
 
            header.ws();
            if (header.consume(','))
              continue;
            if (header.consume('}'))
              break;
            return false;
          }
        }
 
        header.ws();
        if (!header.eof())
          return false;
 
        if (!hasFormat) {
          error(ser::JsonDiagReason::MissingFormatField, "$.format", "Missing required 'format' field.");
          return false;
        }
 
        if (formatValue != WorldSerializerJSONVersion) {
          error(
              ser::JsonDiagReason::UnsupportedFormatVersion, "$.format",
              "Unsupported format version. Expected numeric value 1.");
          return false;
        }
      }
 
      // Prefer fast-path: binary snapshot payload.
      {
        const char key[] = "\"binary\"";
        const uint32_t keyLen = (uint32_t)(sizeof(key) - 1);
        const char* keyPos = nullptr;
        for (const char* it = p; it + keyLen <= end; ++it) {
          if (memcmp(it, key, keyLen) == 0) {
            keyPos = it;
            break;
          }
        }
        if (keyPos != nullptr) {
          const char* arr = nullptr;
          for (const char* it = keyPos + keyLen; it < end; ++it) {
            if (*it == '[') {
              arr = it;
              break;
            }
          }
          if (arr != nullptr) {
            ser::bin_stream serializer;
            ser::ser_json binaryReader(arr, (uint32_t)(end - arr));
            if (!ser::detail::parse_json_byte_array(binaryReader, serializer))
              return false;
 
            return load(serializer);
          }
        }
      }
 
      // Fallback: semantic world JSON parser.
      ser::ser_json jp(json, dataLen);
 
      struct CompDataLoc {
        uint8_t* pBase = nullptr;
        uint32_t row = 0;
      };
 
      auto locate_component_data = [&](Entity entity, Entity component) {
        CompDataLoc loc{};
        auto& ec = fetch(entity);
        const auto compIdx = core::get_index(ec.pChunk->ids_view(), component);
        if (compIdx == BadIndex)
          return loc;
 
        loc.pBase = ec.pChunk->comp_ptr_mut(compIdx, 0);
        loc.row = component.kind() == EntityKind::EK_Uni ? 0U : ec.row;
        return loc;
      };
 
      auto parse_and_apply_component_value = [&](Entity entity, Entity component, const ComponentCacheItem& item,
                                                 ser::json_str_view compPath) -> bool {
        jp.ws();
        if (jp.eof())
          return false;
 
        if (jp.parse_null()) {
          warn(
              ser::JsonDiagReason::NullComponentPayload, compPath,
              "Null component payload is ignored in semantic mode.");
          return true;
        }
 
        if (!has_direct(entity, component)) {
          if (component.pair())
            add(entity, Pair(pair_rel(*this, component), pair_tgt(*this, component)));
          else
            add(entity, component);
        }
 
        const auto loc = locate_component_data(entity, component);
        if (loc.pBase == nullptr) {
          warn(
              ser::JsonDiagReason::MissingComponentStorage, compPath,
              "Component storage is unavailable on the target entity.");
          return jp.skip_value();
        }
 
        auto* pRowData = loc.pBase + (uintptr_t)item.comp.size() * loc.row;
 
        if (!ecs::json_to_component(item, pRowData, jp, diagnostics, policy, compPath))
          return false;
 
        return true;
      };
 
      auto parse_entity_meta = [&](bool& isPair, ser::json_str& nameOut) -> bool {
        if (!jp.expect('{'))
          return false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "pair") {
            if (!jp.parse_bool(isPair))
              return false;
          } else if (key == "name") {
            if (!jp.parse_string(nameOut))
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_components_for_entity = [&](Entity& entity, bool& created, bool isPair,
                                             const ser::json_str& entityName) -> bool {
        if (!jp.expect('{'))
          return false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view compName;
          bool compNameFromScratch = false;
          if (!jp.parse_string_view(compName, &compNameFromScratch))
            return false;
 
          // Escaped names are temporary, so keep a copy while reading the component value.
          ser::json_str compNameStorage;
          if (compNameFromScratch) {
            compNameStorage.assign(compName.data(), compName.size());
            compName = compNameStorage;
          }
 
          if (!jp.expect(':'))
            return false;
 
          const auto componentName = util::str_view(compName.data(), compName.size());
          const bool nameIsInternal = ComponentCache::is_internal_symbol(componentName);
          const auto componentEntity = nameIsInternal ? EntityBad : name_to_entity({compName.data(), compName.size()});
 
          const ComponentCacheItem* pItem = nullptr;
          if (componentEntity.pair())
            pItem = comp_cache().find_pair_payload(componentEntity);
          else if (componentEntity != EntityBad)
            pItem = comp_cache().find(componentEntity);
 
          const auto itemName = pItem != nullptr ? comp_cache().symbol_name(*pItem) : util::str_view{};
          const bool itemIsInternal = ComponentCache::is_internal_symbol(itemName);
          const auto relationName =
              componentEntity.pair() ? symbol(pair_rel(*this, componentEntity)) : util::str_view{};
          const bool relationIsInternal = ComponentCache::is_internal_symbol(relationName);
 
          if (isPair || nameIsInternal || itemIsInternal || relationIsInternal) {
            if (!jp.skip_value())
              return false;
          } else {
            if (pItem == nullptr) {
              warn(
                  ser::JsonDiagReason::UnknownComponent, compName,
                  "Component is not registered in the component cache.");
              if (!jp.skip_value())
                return false;
            } else if (pItem->comp.size() == 0) {
              // Ignore tag-only components in semantic mode for now.
              warn(
                  ser::JsonDiagReason::TagComponentUnsupported, compName,
                  "Tag-only component semantic JSON loading is currently unsupported.");
              if (!jp.skip_value())
                return false;
            } else {
              if (!created) {
                entity = add();
                created = true;
 
                if (!entityName.empty()) {
                  const auto existing = get(entityName.data(), (uint32_t)entityName.size());
                  if (existing == EntityBad)
                    name(entity, entityName.data(), (uint32_t)entityName.size());
                  else
                    warn(
                        ser::JsonDiagReason::DuplicateEntityName, "entity.name",
                        "Entity name already exists; keeping existing mapping.");
                }
              }
 
              if (!parse_and_apply_component_value(entity, componentEntity, *pItem, compName))
                return false;
            }
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_entity_entry = [&]() -> bool {
        if (!jp.expect('{')) {
          error(ser::JsonDiagReason::InvalidJson, "$", "Root JSON value must be an object.");
          return false;
        }
 
        bool isPair = false;
        ser::json_str entityName;
        Entity entity = EntityBad;
        bool created = false;
 
        jp.ws();
        if (jp.consume('}'))
          return true;
 
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "entity") {
            if (!parse_entity_meta(isPair, entityName))
              return false;
          } else if (key == "components") {
            if (!parse_components_for_entity(entity, created, isPair, entityName))
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
 
        return true;
      };
 
      auto parse_archetypes = [&]() -> bool {
        if (!jp.expect('['))
          return false;
 
        jp.ws();
        if (jp.consume(']'))
          return true;
 
        while (true) {
          if (!jp.expect('{'))
            return false;
 
          jp.ws();
          if (!jp.consume('}')) {
            while (true) {
              ser::json_str_view key;
              if (!jp.parse_string_view(key))
                return false;
              if (!jp.expect(':'))
                return false;
 
              if (key == "entities") {
                if (!jp.expect('['))
                  return false;
 
                jp.ws();
                if (!jp.consume(']')) {
                  while (true) {
                    if (!parse_entity_entry())
                      return false;
 
                    jp.ws();
                    if (jp.consume(','))
                      continue;
                    if (jp.consume(']'))
                      break;
                    return false;
                  }
                }
              } else {
                if (!jp.skip_value())
                  return false;
              }
 
              jp.ws();
              if (jp.consume(','))
                continue;
              if (jp.consume('}'))
                break;
              return false;
            }
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume(']'))
            break;
          return false;
        }
 
        return true;
      };
 
      if (!jp.expect('{'))
        return false;
 
      bool hasArchetypes = false;
      jp.ws();
      if (!jp.consume('}')) {
        while (true) {
          ser::json_str_view key;
          if (!jp.parse_string_view(key))
            return false;
          if (!jp.expect(':'))
            return false;
 
          if (key == "archetypes") {
            hasArchetypes = true;
            if (!parse_archetypes())
              return false;
          } else {
            if (!jp.skip_value())
              return false;
          }
 
          jp.ws();
          if (jp.consume(','))
            continue;
          if (jp.consume('}'))
            break;
          return false;
        }
      }
 
      jp.ws();
      if (!jp.eof())
        return false;
      if (!hasArchetypes) {
        error(ser::JsonDiagReason::MissingArchetypesSection, "$.archetypes", "Missing required 'archetypes' section.");
        return false;
      }
 
      return true;
    }
 
    inline bool World::load_json(const char* json, uint32_t len) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = load_json(json, len, diagnostics);
      return parsed && !diagnostics.has_issues();
    }
 
    inline bool
    World::load_json(ser::json_str_view json, ser::JsonDiagnostics& diagnostics, const ser::RuntimeJsonPolicy& policy) {
      return load_json(json.data(), json.size(), diagnostics, policy);
    }
 
    inline bool World::load_json(ser::json_str_view json) {
      ser::JsonDiagnostics diagnostics;
      const bool parsed = load_json(json.data(), json.size(), diagnostics);
      return parsed && !diagnostics.has_issues();
    }
  } // namespace ecs
} // namespace gaia
 
#endif