include/ling3/decoder_state.h

#pragma once

#include "ling3/gdn_step.h"
#include <array>
#include <filesystem>
#include <string>
#include <string_view>
#include <vector>

namespace ling3 {
// Complete, portable numerical state, independent of a decoder's live buffers.
// Not a chat history or a suspended sampler. Treat published states as immutable.
struct AttentionState {
    GdnState gdn;
    std::array<std::vector<float>, 3> conv;
    std::vector<std::uint16_t> keys, values;
    std::size_t bytes() const;
};
struct DecoderState {
    std::string signature;
    std::size_t position = 0;
    std::vector<AttentionState> layers;
    std::size_t bytes() const;
};

// Versioned little-endian format, per-buffer CRC, bounded allocations. Loading
// validates every layer before the engine can mutate any live numerical state.
void ValidateDecoderState(const DecoderState & state, std::string_view signature,
                          std::size_t capacity);
void WriteDecoderState(const DecoderState & state, const std::filesystem::path & path);
DecoderState ReadDecoderState(const std::filesystem::path & path,
                              std::string_view signature, std::size_t capacity);
} // namespace ling3