// native_bridge/src/main.cpp
// Entry point of daw_vst_bridge.exe β€” opens shared memory created by the DAW
// (Rust/Tauri side), runs the real-time MIDI->audio loop, watches the parent.
#include "INativeInstrument.h"
#include "SharedMemoryIPC.h"
#include "NativeInstrumentEngine.h"

#ifdef _WIN32
#include <windows.h>
#include <imm.h>
#include <mmsystem.h>
#include <process.h>
#include <thread>
#else
#include <unistd.h>
#include <cstdlib>
#include <thread>
#endif

#include <chrono>
#include <algorithm>
#include <atomic>
#include <cctype>
#include <condition_variable>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <mutex>
#include <set>
#include <string>
#include <vector>

// --- platform helpers -------------------------------------------------------
static bool parent_alive(uint32_t pid) {
#ifdef _WIN32
    HANDLE h = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, pid);
    if (!h) return false;
    CloseHandle(h);
    return true;
#else
    return pid == 0 || (kill(pid, 0) == 0);
#endif
}

static void sleep_ms(uint32_t ms) {
#ifdef _WIN32
    Sleep(ms);
#else
    std::this_thread::sleep_for(std::chrono::milliseconds(ms));
#endif
}

#ifdef _WIN32
// IME recursion fix (Nexus 0xC00000FD -> USER32 0xC000041D): the plugin's
// wndproc calls ImmIsUIMessageW for every message and forwards WM_IME_* to the
// IME window; with a live IMC on the editor window that bounces back to the
// same hwnd -> infinite SendMessageW recursion -> stack overflow. Removing the
// IMC (ImmAssociateContext NULL) stops the forwarding.
static void disable_ime_contexts(HWND w) {
    if (w && IsWindow(w)) {
        char cls[64] = {0};
        GetClassNameA(w, cls, 63);
        ImmAssociateContext(w, nullptr);
        for (HWND c = GetWindow(w, GW_CHILD); c; c = GetWindow(c, GW_HWNDNEXT)) {
            char cls2[64] = {0};
            GetClassNameA(c, cls2, 63);
            ImmAssociateContext(c, nullptr);
        }
    }
}

 // G1.3: bo pump gate cu (g_juceOwnerTids / g_ownerTid /
 // is_teardown_window): teardown (close/LOAD job) va message pump cung chay tren
 // 1 thread (UiThread) — job chay thi pump dung, job xong thi editor window da
 // destroy nen USER32 tu huy message toi window chet. Khong con "2 thread trong
 // 1 DLL" khi teardown (multi-worker cu).

// CBT hook: strip the IMC the moment any JUCE_* window is born (JUCE message
// window AND editor child) β€” the post-attach disable_ime_contexts runs too
// late; the recursion can start inside attachView (0xC00000FD observed, run
// 9). Runs on the window's creating thread, so the association is legal.
static HHOOK g_cbtHook = nullptr;
static LRESULT CALLBACK ImeCbtHookProc(int nCode, WPARAM wParam, LPARAM lParam) {
    if (nCode == HCBT_CREATEWND) {
        // Class name via GetClassNameA, NOT lpszClass: JUCE creates windows
        // with MAKEINTATOM class names (HIWORD(lpszClass)==0), and ANSI-created
        // windows deliver a CREATESTRUCTA β€” lpszClass is unusable in both cases.
        HWND w = (HWND)wParam;
        char cls[64] = {0};
        if (GetClassNameA(w, cls, 63) > 0 && std::strncmp(cls, "JUCE_", 5) == 0) {
            ImmAssociateContext(w, nullptr);

        }
    }
    return CallNextHookEx(g_cbtHook, nCode, wParam, lParam);
}
#endif

#ifdef _WIN32
// Native VST editor windows registry β€” global de WM_DESTROY (chay tren worker
// thread cua channel tao window) co the don map. USERDATA luu channel+1 (KHONG
// luu con tro inst truc tiep: assign() thay inst moi moi lan load β€” con tro cu
// bi huy β†’ WM_DESTROY tren con tro dangling β†’ crash/hang bridge).
class ChannelWorker;  // fwd β€” WM_DESTROY posts closeGUI() to the channel worker
static void post_close_gui(uint32_t ch, HWND hwnd);  // defined after ChannelWorker
static void post_resize_view(uint32_t ch, int w, int h);  // defined after ChannelWorker

static InstrumentEngineManager* g_engine = nullptr;
static std::mutex g_guiMutex;
static std::map<uint32_t, void*> g_guiWindows;  // channel -> HWND (keep window alive)
static std::map<HWND, uint32_t> g_hwndToCh;     // HWND -> channel (WM_DESTROY cleanup)
static ChannelWorker* g_uiWorker = nullptr;

// Same-plugin-DLL reentrancy guards: two threads inside one VST3 DLL (Nexus)
// crash or deadlock. g_attachPaths = lowercase plugin paths whose reload/
// createView is running on some worker β€” a same-path close job must not unmute
// its channel mid-attach (the attach job owns the silence state until
// attachView finishes). g_closeInFlight = channels whose close job
// (closeGUI + destroy children + reload) is still inside createInstance β€”
// unmuting them then would race the plugin teardown.
static std::mutex g_attachMutex;
static std::vector<std::string> g_attachPaths;
static bool g_closeInFlight[16] = { false };

static LRESULT CALLBACK VstWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    if (uMsg == WM_CLOSE) {
        uint32_t ch = UINT32_MAX;
        {
            std::lock_guard<std::mutex> lock(g_guiMutex);
            auto it = g_hwndToCh.find(hwnd);
            if (it != g_hwndToCh.end()) ch = it->second;
        }
        if (ch != UINT32_MAX) {
            // CRASH FIX (0xc000041d STATUS_FATAL_USER_CALLBACK_EXCEPTION /
            // 0xc0000005 trong USER32, Event Log 9:47/10:20/10:22):
            // KHONG de DefWindowProc DestroyWindow o day. Plugin editor la
            // child cua window nay, tao TREN worker thread (view->attached()
            // chay trong attach job) - DestroyWindow tren main thread pha huy
            // child cross-thread -> crash USER32. Detach view tren worker
            // (closeGUI), an window, GIU window trong registry de reuse.
            post_close_gui(ch, hwnd);
            ShowWindow(hwnd, SW_HIDE);
            return 0;
        }
        // Window khong thuoc registry (chua dang ky) - de DefWindowProc huy.
    } else if (uMsg == WM_DESTROY) {
        // Chi xay ra khi window thuc su bi huy (khong con path chu dong nao
        // DestroyWindow khi view dang attached). Xoa registry + detach view.
        uint32_t ch = UINT32_MAX;
        {
            std::lock_guard<std::mutex> lock(g_guiMutex);
            auto it = g_hwndToCh.find(hwnd);
            if (it != g_hwndToCh.end()) ch = it->second;
            g_hwndToCh.erase(hwnd);
            for (auto it = g_guiWindows.begin(); it != g_guiWindows.end();) {
                if (it->second == hwnd) it = g_guiWindows.erase(it);
                else ++it;
            }
        }
        if (ch != UINT32_MAX) post_close_gui(ch, hwnd);
    } else if (uMsg == WM_ERASEBKGND) {
        return 1; // Do not paint background to prevent white flashes
    } else if (uMsg == WM_PAINT) {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);
        EndPaint(hwnd, &ps);
        return 0;
    } else if (uMsg == WM_SIZE) {
        int w = LOWORD(lParam);
        int h = HIWORD(lParam);
        HWND child = FindWindowExA(hwnd, nullptr, nullptr, nullptr);
        if (child) {
            MoveWindow(child, 0, 0, w, h, TRUE);
        }
        uint32_t ch = UINT32_MAX;
        {
            std::lock_guard<std::mutex> lock(g_guiMutex);
            auto it = g_hwndToCh.find(hwnd);
            if (it != g_hwndToCh.end()) ch = it->second;
        }
        if (ch != UINT32_MAX) {
            post_resize_view(ch, w, h);
        }
        return 0;
    }
    return DefWindowProcA(hwnd, uMsg, wParam, lParam);
}
#endif

// Serialize plugin loads across channels: concurrent VST3 createInstance on
// separate worker threads (Nexus) deadlocks inside the SDK factory - all
// stuck forever (observed: 3 concurrent Nexus loads, zero assign returned).
// One load at a time; SF2/SFZ loads are fast, contention negligible.
static std::mutex g_loadMutex;
// Pending OPEN_GUI requests whose channel instrument was not loaded yet.
// The main loop fulfils them as soon as the load job completes (assign ok),
// so the GUI button works regardless of JS retry timing.
static std::mutex g_pendingGuiMutex;
static std::map<uint32_t, std::pair<void*, std::string>> g_pendingGui;

// B9: native Win32 window for the VST editor (replaces the WebView2 surface β€”
// the HTML window was drawn ON TOP of the plugin GUI). MUST be created on the
// ChannelWorker thread so the worker's idle message pump services its messages.
static std::once_flag registerWindowOnce;
static void* create_native_vst_window(const char* title) {
#ifdef _WIN32
    static const char* kWndClass = "SonicForge_Native_VST3_Class";
    std::call_once(registerWindowOnce, []() {
        WNDCLASSA wc = {};
        wc.lpfnWndProc = VstWindowProc;
        wc.hInstance = GetModuleHandleA(nullptr);
        wc.lpszClassName = kWndClass;
        RegisterClassA(&wc);
    });
    HWND hwnd = CreateWindowExA(0, kWndClass, title ? title : "VST",
                                WS_OVERLAPPEDWINDOW | WS_VISIBLE | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
                                CW_USEDEFAULT, CW_USEDEFAULT, 800, 600,
                                nullptr, nullptr, GetModuleHandleA(nullptr), nullptr);
    return (void*)hwnd;
#else
    (void)title;
    return nullptr;
#endif
}

// G1.2: single persistent UiThread β€” ONE thread owns the COM STA apartment for
// ALL instruments for the whole bridge lifetime. loadPlugin and openGUI MUST run
// on the same thread β€” if the loading thread exits, its apartment dies and
// VST3 plugins that marshal internally (Nexus) hang forever in
// view->attached(). Verified with gui_probe: `bridge_like` (load thread exits,
// openGUI on another) hangs; `same_thread` (load+openGUI on one alive thread)
// returns attached=OK.
class ChannelWorker {
public:
    ChannelWorker() {
#ifdef _WIN32
        jobEvent_ = CreateEvent(nullptr, FALSE, FALSE, nullptr);
#endif
        th_ = std::thread([this] {
#ifdef _WIN32
            OleInitialize(nullptr);
            OleInitialize(nullptr);
            // Default IMC = none on this thread: new editor windows get
            // no IME context (see disable_ime_contexts).
            ImmAssociateContextEx(nullptr, nullptr, IACE_DEFAULT);
            // CBT hook on this worker: strip IMC on JUCE_* windows at birth.
            // Global hooks fail from an exe module β€” install per thread, and
            // this thread creates the plugin editor windows.
            SetWindowsHookExW(WH_CBT, ImeCbtHookProc, GetModuleHandleW(nullptr), GetCurrentThreadId());

            // Elevate VST GUI thread priority to prevent throttling
            SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_ABOVE_NORMAL);
#endif
            std::unique_lock<std::mutex> lk(mu_);
            for (;;) {
                if (stop_ && jobs_.empty()) break;
                if (!jobs_.empty()) {
                    auto job = std::move(jobs_.front());
                    jobs_.pop_front();
                    lk.unlock();
                    job();
                    lk.lock();
                    continue;
                }
                lk.unlock();
                MSG msg;
                bool hadMessages = false;
                // Cap the idle pump per iteration to avoid starving the job queue,
                // but pump up to 128 messages for high GUI responsiveness.
                for (int pumped = 0; pumped < 128; ++pumped) {
                    if (!PeekMessageW(&msg, nullptr, 0, 0, PM_REMOVE)) break;
                    hadMessages = true;
                    // G1.3: bo pump gate cu — teardown (close/LOAD job)
                    // va pump cung 1 thread (UiThread): job chay thi pump dung;
                    // het job thi editor window da destroy -> message chet bi
                    // USER32 huy tu dong. Khong can drop theo close_in_flight.

                    TranslateMessage(&msg);
                    // CRASH FIX (0xc000041d STATUS_FATAL_USER_CALLBACK_EXCEPTION):
                    // a plugin window proc (Nexus throws nlohmann::json::out_of_range
                    // internally) that raises a C++ exception would otherwise escape
                    // DispatchMessageW and std::terminate this worker thread. Catch
                    // it here β€” the editor may glitch, but the bridge survives.
                    try {
                        DispatchMessageW(&msg);
                    } catch (...) {
                        std::cerr << "[NativeBridge] worker pump EXCEPTION β€” plugin window proc threw" << std::endl;
                    }
                }
                lk.lock();
                if (!hadMessages && jobs_.empty()) {
#ifdef _WIN32
                    if (jobEvent_) {
                        lk.unlock();
                        MsgWaitForMultipleObjects(1, &jobEvent_, FALSE, 10, QS_ALLINPUT);
                        lk.lock();
                    } else {
                        cv_.wait_for(lk, std::chrono::milliseconds(2));
                    }
#else
                    cv_.wait_for(lk, std::chrono::milliseconds(2));
#endif
                }
            }
#ifdef _WIN32
            OleUninitialize();
            OleUninitialize();
#endif
        });
    }
    ~ChannelWorker() {
        {
            std::lock_guard<std::mutex> lk(mu_);
            stop_ = true;
        }
#ifdef _WIN32
        if (jobEvent_) {
            SetEvent(jobEvent_);
        }
#endif
        cv_.notify_all();
        if (th_.joinable()) th_.join();
#ifdef _WIN32
        if (jobEvent_) {
            CloseHandle(jobEvent_);
            jobEvent_ = nullptr;
        }
#endif
    }
    void post(std::function<void()> job) {
        {
            std::lock_guard<std::mutex> lk(mu_);
            jobs_.push_back(std::move(job));
        }
#ifdef _WIN32
        if (jobEvent_) {
            SetEvent(jobEvent_);
        }
#endif
        cv_.notify_all();
    }


private:
    std::thread th_;
    std::mutex mu_;
    std::condition_variable cv_;
    std::deque<std::function<void()>> jobs_;
    bool stop_ = false;
#ifdef _WIN32
    HANDLE jobEvent_ = nullptr;
#endif
};

// resizeView() must run on the channel worker (the view was attached in its
// COM STA apartment), never on the main pump thread.
static void post_resize_view(uint32_t ch, int w, int h) {
    if (g_uiWorker) {
        g_uiWorker->post([ch, w, h]() {
            if (!g_engine) return;
            auto* i = g_engine->get(ch);
            if (i) i->resizeView(w, h);
        });
    }
}

// --- same-plugin-DLL silence helpers ----------------------------------------
// Two threads inside one VST3 DLL (Nexus) crash/deadlock: the audio loop's
// process() on one instance must not race createInstance/createView/terminate
// on another. Windows plugin paths are case-insensitive β€” compare lowercased.
static std::string lower_path_str(std::string p) {
    std::transform(p.begin(), p.end(), p.begin(),
                   [](unsigned char c) { return (char)::tolower(c); });
    return p;
}

static std::string lower_plugin_path(uint32_t ch) {
    return g_engine ? lower_path_str(g_engine->pathOf(ch)) : std::string();
}

// Channels (other than ch) currently assigned the same plugin DLL path.
static std::vector<uint32_t> same_plugin_channels(uint32_t ch) {
    std::vector<uint32_t> out;
    std::string p = lower_plugin_path(ch);
    if (p.empty()) return out;
    for (uint32_t y = 0; y < 16; ++y) {
        if (y == ch) continue;
        if (!g_engine->get(y)) continue;
        if (lower_plugin_path(y) == p) out.push_back(y);
    }
    return out;
}

static bool close_in_flight(uint32_t ch) {
    std::lock_guard<std::mutex> lk(g_attachMutex);
    return g_closeInFlight[ch];
}



 // G1.3: 1 UiThread — editor windows tao trong attach job (UiThread), destroy
 // chi goi tu UiThread job (close_editor_now / LOAD) -> ownerTid luon == current
 // tid -> destroy truc tiep. Neu owner khac thread (khong con xay ra) -> bo
 // (leak > crash): cross-thread DestroyWindow khong an toan.
 static void destroy_window_on_owner(HWND hwnd) {
     if (!hwnd || !IsWindow(hwnd)) return;
     DWORD ownerTid = GetWindowThreadProcessId(hwnd, nullptr);
     DWORD curTid = GetCurrentThreadId();
     if (ownerTid == 0 || ownerTid == curTid) {
         if (IsWindow(hwnd)) DestroyWindow(hwnd);
         return;
     }
     std::cerr << "[NativeBridge] destroy_window_on_owner: owner tid=" << ownerTid
               << " != current " << curTid << " - leaving window " << hwnd << std::endl;
 }


// Unmute y unless its own close job is still inside createInstance β€” that job
// performs the unmute once its fresh instance is loaded (or, if an attach for
// the same plugin is in flight, the attach job's restore does it).
static void unmute_if_not_closing(uint32_t y, const char* why) {
    (void)why;
    if (close_in_flight(y)) {
        return;
    }
    g_engine->setReloading(y, false);
}

// closeGUI() MUST run on the UiThread (its COM STA apartment) β€” the view was
// attached there. Calling view->removed() from another thread is a
// cross-apartment COM call that corrupts the plugin; Nexus then hangs on the
// NEXT view->attached(). G1.2: 1 UiThread chung β€” close chay synchronous tren
// job; goi truc tiep (Option B trong attach job) hoac qua post_close_gui
// (WM_CLOSE/WM_DESTROY).
static void close_editor_now(uint32_t ch, HWND hwnd) {
    // Guard window-replaced race: neu OPEN_GUI moi da dung window khac
    // (hoac da xoa), khong detach view cua window moi.
            {
                std::lock_guard<std::mutex> lock(g_guiMutex);
                auto it = g_guiWindows.find(ch);
                if (it == g_guiWindows.end() || it->second != hwnd) {
                    return;
                }
            }
            // Silence first: the audio loop must not process() the instance
            // while we tear its editor down on this thread.
            g_engine->setReloading(ch, true);
            // Close-in-flight: until the fresh instance is loaded, no other
            // job may unmute this channel (its plugin is being torn down).
            {
                std::lock_guard<std::mutex> lk(g_attachMutex);
                g_closeInFlight[ch] = true;
            }
            if (auto* i = g_engine->get(ch)) {
                // closeGUI() nulls the view WITHOUT view->removed() (Nexus
                // removed() deadlocks this worker - modal wait for a message
                // only its own pump can dispatch, but it is inside removed()).
                try {
                    i->closeGUI();
                } catch (...) {
                    std::cerr << "[NativeBridge] closeGUI EXCEPTION ch=" << ch
                              << " β€” plugin threw" << std::endl;
                }
                // CRASH FIX: the editor was dropped WITHOUT view->removed() β€”
                // the instance's editor state is dangling, so the audio loop
                // must NOT process() it. Rebuild a fresh instance NOW on this
                // worker (its COM STA apartment is alive); reload() ==
                // terminate + loadPlugin (createInstance). Same-plugin
                // channels are silenced so no second thread enters this DLL
                // during createInstance (2 threads in one DLL -> Nexus exits
                // silently, observed in probes). Serialized with other loads
                // by g_loadMutex.
                std::vector<uint32_t> sp = same_plugin_channels(ch);
                for (uint32_t y : sp) {
                    g_engine->setReloading(y, true);
                }
#ifdef _WIN32
                // CRASH FIX (0xc000041d): destroy the editor's child windows
                // on the thread that OWNS them (the plugin's JUCE
                // MessageManager thread - a single worker), never
                // cross-thread. Wait for each destroy to finish (owner worker
                // serializes it with its pump) BEFORE reload() - otherwise
                // reload's createInstance enters the DLL while the owner
                // thread is still inside the plugin wndproc (2 threads in one
                // DLL -> Nexus crash). Kept OUTSIDE g_loadMutex: the wait
                // must not block other loads (the owner worker may itself be
                // waiting on that lock).
                disable_ime_contexts(hwnd);
                if (hwnd && IsWindow(hwnd)) {
                    while (HWND c = FindWindowExA(hwnd, nullptr, nullptr, nullptr)) {
                        destroy_window_on_owner(c);
                    }
                }
#endif
                {
                    // reload() = terminate + loadPlugin (createInstance) β€”
                    // serialized with all other plugin-DLL entry points.
                    // Nexus may throw a C++ exception here too; catch it,
                    // treat as failed reload, and let the restore below
                    // unmute the channel (instance may be broken; next
                    // load/assign rebuilds it).
                    std::lock_guard<std::mutex> lg(g_loadMutex);
                    try {
                        // G0.4: reload() terminates + recreates the instance;
                        // capture the preset first, restore it after, so the
                        // sound survives a GUI close (reopen keeps it too).
                        i->captureState();
                        i->reload();
                        i->restoreState();
                    } catch (...) {
                        std::cerr << "[NativeBridge] closeGUI reload EXCEPTION ch=" << ch
                                  << " β€” plugin threw (createInstance)" << std::endl;
                    }
                }
                // createInstance is done: unmuting is safe again. But if an
                // attach for the SAME plugin path is still running (its
                // createView must not race process() on any same-path
                // channel), leave the silence in place β€” the attach job's
                // restore unmutes everything once attachView finished.
                {
                    std::lock_guard<std::mutex> lk(g_attachMutex);
                    g_closeInFlight[ch] = false;
                }
                bool pathBusy = false;
                {
                    std::lock_guard<std::mutex> lk(g_attachMutex);
                    std::string p = lower_plugin_path(ch);
                    pathBusy = !p.empty() &&
                               std::find(g_attachPaths.begin(), g_attachPaths.end(), p) != g_attachPaths.end();
                }
                if (!pathBusy) {
                    for (uint32_t y : sp) unmute_if_not_closing(y, "closeGUI");
                    g_engine->setReloading(ch, false);
                }
            } else {
                // Instrument already gone (unloaded) β€” nothing to rebuild.
                g_engine->setReloading(ch, false);
                std::lock_guard<std::mutex> lk(g_attachMutex);
                g_closeInFlight[ch] = false;
            }
}

static void post_close_gui(uint32_t ch, HWND hwnd) {
    if (g_uiWorker) {
        g_uiWorker->post([ch, hwnd]() { close_editor_now(ch, hwnd); });
    }
}

int main(int argc, char* argv[]) {
    std::cout << "[NativeBridge] Starting DAW Host Bridge Engine..." << std::endl;
#ifdef _WIN32
    // Disable Power Throttling (Efficiency Mode) for this background process
#ifndef PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION
#define PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION 0x00000004
#endif
#ifndef PROCESS_POWER_THROTTLING_EXECUTION_SPEED
#define PROCESS_POWER_THROTTLING_EXECUTION_SPEED         0x00000001
#endif
    PROCESS_POWER_THROTTLING_STATE powerState = {};
    powerState.Version = PROCESS_POWER_THROTTLING_CURRENT_VERSION;
    powerState.ControlMask = PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION | PROCESS_POWER_THROTTLING_EXECUTION_SPEED;
    powerState.StateMask = 0; // Turn off throttling
    SetProcessInformation(GetCurrentProcess(), ProcessPowerThrottling, &powerState, sizeof(powerState));

    // DPI: declare per-monitor v2 FIRST (before any window is created).
    // Without it, on scaled displays (125/150%) the plugin's own renderer
    // paints at 100% into an OS-scaled window -> blank/white panel with dark
    // strips (reported "GUI trαΊ―ng, khΓ΄ng load"). Runtime call works even
    // without an exe manifest. Ignore failure (already aware).
    SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
    // Default IMC = none on the main thread (IME recursion fix).
    // Default IMC = none on the main thread (IME recursion fix).
    ImmAssociateContextEx(nullptr, nullptr, IACE_DEFAULT);

#endif

    // 1. Shared memory name: argv --shm <name> | env SF_SHM_NAME | default
    std::string shmName = "SonicForge_DAW_IPC";
    for (int i = 1; i + 1 < argc; ++i) {
        if (std::strcmp(argv[i], "--shm") == 0) shmName = argv[i + 1];
    }
    if (const char* e = std::getenv("SF_SHM_NAME")) shmName = e;

    // Parent watchdog PID (set by Tauri sidecar spawner)
    uint32_t parentPid = 0;
    if (const char* e = std::getenv("SF_PARENT_PID")) parentPid = (uint32_t)std::atoi(e);

    // V8 bug 2: watchdog THREAD rieng - main loop chi check parent_alive giua
    // cac block; neu VST process() chan loop thi khong bao gio thoat -> orphan.
    // Thread nay chay doc lap, parent chet -> TerminateProcess ngay. Kem
    // start-time check chong PID reuse (OpenProcess tra handle cua process
    // khac chiem lai PID -> tuong parent con song mai).
    if (parentPid != 0) {
        std::thread([parentPid]() {
            auto proc_birth = [](HANDLE h) -> uint64_t {
                FILETIME c, e, k, u;
                if (GetProcessTimes(h, &c, &e, &k, &u))
                    return (uint64_t(c.dwHighDateTime) << 32) | c.dwLowDateTime;
                return 0;
            };
            uint64_t birth = 0;
            {
                HANDLE h = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, parentPid);
                if (h) { birth = proc_birth(h); CloseHandle(h); }
            }
            for (;;) {
                Sleep(2000);
                HANDLE h = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, FALSE, parentPid);
                if (!h) { TerminateProcess(GetCurrentProcess(), 0); return; }
                uint64_t nowBirth = proc_birth(h);
                CloseHandle(h);
                if (birth != 0 && nowBirth != 0 && nowBirth != birth) {
                    TerminateProcess(GetCurrentProcess(), 0); return;
                }
            }
        }).detach();
    }

#ifdef _WIN32
    // Real-time-ish timing: 1ms scheduler resolution
    timeBeginPeriod(1);
    HANDLE hMapFile = OpenFileMappingA(FILE_MAP_ALL_ACCESS, FALSE, shmName.c_str());
    if (!hMapFile) {
        std::cerr << "[NativeBridge] Failed to open Shared Memory mapping: " << shmName << std::endl;
        return 1;
    }
    auto* shmIPC = (SharedAudioBufferIPC*)MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, sizeof(SharedAudioBufferIPC));
    if (!shmIPC) { CloseHandle(hMapFile); return 1; }
#else
    (void)shmName; // POSIX shm mapping (shm_open) added when porting off Windows
    auto* shmIPC = (SharedAudioBufferIPC*)std::calloc(1, sizeof(SharedAudioBufferIPC));
    if (!shmIPC) return 1;
#endif

    InstrumentEngineManager instruments;
#ifdef _WIN32
    g_engine = &instruments;
#endif
    // Per-channel persistent workers: loadPlugin + openGUI run on the SAME
    // thread whose COM STA apartment stays alive for the channel's lifetime
    // (see ChannelWorker comment β€” a dead apartment hangs Nexus attached()).
    // G1.2: MOT UiThread chung (COM STA + message pump + job queue) cho moi
    // channel β€” thay 16 ChannelWorker. Verify gui_probe `shared_worker` (G1.1):
    // load + openGUI 2 instance tren 1 worker OK, khong crash/hang.
    ChannelWorker uiWorker;
    g_uiWorker = &uiWorker;
    // B9: native editor windows per channel β€” keep alive (HWND outlives the job).
    // Registry la global (g_guiWindows) β€” WM_DESTROY cleanup can tu VstWindowProc.
    // B8: sample rate from the DAW (Rust spawns us with SF_SAMPLE_RATE).
    // Block size is fixed by the SHM layout (AUDIO_BLOCK_SIZE) β€” SF_BLOCK_SIZE
    // is accepted but must match, otherwise warned and ignored.
    double sampleRate = 44100.0;
    if (const char* e = std::getenv("SF_SAMPLE_RATE")) {
        double sr = (double)std::atoi(e);
        if (sr > 0) sampleRate = sr;
    }
    if (const char* e = std::getenv("SF_BLOCK_SIZE")) {
        uint32_t b = (uint32_t)std::atoi(e);
        if (b != AUDIO_BLOCK_SIZE)
            std::cerr << "[NativeBridge] SHM block size fixed at " << AUDIO_BLOCK_SIZE
                      << " (SF_BLOCK_SIZE=" << b << " ignored)" << std::endl;
    }
    const uint32_t block = AUDIO_BLOCK_SIZE;
    uint64_t playheadSamples = 0;
    // V8 bug 3: khi STOP da xu ly, bo qua NOTE_ON (velocity>0) den sau - JS
    // note-on timer co the bay toi sau STOP (guardPlay tre do React re-render)
    // -> retrigger note -> VST loop am. Chi PLAY moi nhan note-on lai.
    bool transportStopped = false;

    auto dispatch = [&](const SharedAudioBufferIPC::MidiEventIPC& evt) {
        // Manager-level dispatch: ONE engine-mutex hold per event (get +
        // channelQuiet + instrument call) so assign()/unload() can never
        // destroy the instance mid-call β€” use-after-free when loading a new
        // VSTi while other channels keep playing. channelQuiet drops events
        // for channels mid-reload only (G1.4: bo mute-when-editor-open).
        // CRASH FIX: noteOn/noteOff/CC enter the plugin (DLL entry); a C++
        // exception from the plugin must not escape the audio loop.
        try {
        switch (evt.command) {
            case 0x9:
                // sampleOffset LUON LUON = 0 khi den day: events duoc dispatch ngay
                // truoc segment chua no (A11 splitting), nen offset tuong doi la 0.
                // Truyen offset tuyet doi truoc day lam sfizz/VST3 trigger tre.
                if (evt.velocity > 0) {
                    if (transportStopped) return; // V8 bug 3: drop note-on sau STOP
                    instruments.noteOn(evt.channel, evt.pitch, evt.velocity / 127.0f);
                } else
                    instruments.noteOff(evt.channel, evt.pitch);
                break;
            case 0x8:
                instruments.noteOff(evt.channel, evt.pitch);
                break;
            case 0xB: // CC: controller number in pitch, value in data2
                // V9 bug 4: sau STOP, drop sustain-down (CC64>0) β€” JS co the
                // gui CC64 xuong sau STOP (note-on/CC timer tre); VSTi giu
                // note khi pedal down -> am treo loop. CC64=0 (sustain-up)
                // van cho qua.
                if (transportStopped && evt.pitch == 64 && evt.data2 > 0) return;
                instruments.controlChange(evt.channel, evt.pitch, evt.data2);
                break;
            case 0xC: // program change: program in data2
                instruments.programChange(evt.channel, evt.data2);
                break;
            case 0xE: // 14-bit pitch bend: data2 = LSB, data3 = MSB
                instruments.pitchBend(evt.channel, evt.data2 | (uint32_t(evt.data3) << 7));
                break;
            default: break;
        }
        } catch (...) {
            std::cerr << "[NativeBridge] dispatch EXCEPTION ch=" << (int)evt.channel
                      << " cmd=" << std::hex << (int)evt.command << std::dec
                      << " β€” plugin threw (note/CC)" << std::endl;
        }
    };

    // Render only [from, to) of the block β€” used by sample-accurate splitting.
    auto renderSegment = [&](uint32_t from, uint32_t to) {
        if (to <= from) return;
        instruments.renderAll(shmIPC->masterLeft + from, shmIPC->masterRight + from, to - from);
    };

    double blockDurationMs = (double)block / sampleRate * 1000.0;
    auto startTime = std::chrono::steady_clock::now();
    uint64_t blockCount = 0;

    // OPEN_GUI handling - shared by the control queue and the pending-GUI
    // sweep. Gate on the MAIN thread before creating a window: instrument
    // load is ASYNC (worker thread); OPEN_GUI too early would attach to an
    // empty channel and leave a blank window. Not loaded yet => remember the
    // request; the sweep retries once the load job completes. Window MUST
    // belong to the MAIN thread (audio loop pump dispatches its messages);
    // a window on a worker whose pump is idle during jobs hangs
    // view->attached() (gui_probe: two_workers_close TIMEOUT). The attach
    // job runs on the channel worker (COM STA apartment stays alive).
    // G0.3: while an attach job is in flight, tell the Tauri watchdog via
    // SHM so a long Nexus reload/attach (can exceed 3s) is not mistaken
    // for a dead bridge and killed. RAII -> cleared on every exit path.
    struct AttachInFlightGuard {
        SharedAudioBufferIPC* ipc;
        explicit AttachInFlightGuard(SharedAudioBufferIPC* p) : ipc(p) { if (ipc) ipc->attachInFlight = 1; }
        ~AttachInFlightGuard() { if (ipc) ipc->attachInFlight = 0; }
    };
    auto handleOpenGui = [&](uint32_t guiCh, uintptr_t arg1, const std::string& pluginId) {
        if (!instruments.get(guiCh)) {
            std::cerr << "[NativeBridge] GUI deferred ch=" << guiCh
                      << " plugin=" << pluginId << " (no instrument yet) - queued" << std::endl;
            std::lock_guard<std::mutex> lock(g_pendingGuiMutex);
            g_pendingGui[guiCh] = { (void*)arg1, pluginId };
            return;
        }
        // Dedupe OPEN_GUI spam (frontend openVstGuiRetry): view dang
        // attached -> GUI da mo, khong post attach job lan nua. Re-attach
        // tren view dang attached lam plugin loi (Nexus createView null).
        if (auto* i0 = instruments.get(guiCh)) {
            if (i0->hasAttachedView()) {
                return;
            }
        }
        // G0.1 (BUG_REPORT): mo GUI khi dang PLAY -> attachView chay tren worker
        // thread trong luc audio loop process() cung DLL (2 thread 1 plugin) ->
        // Nexus throw (createView/attached) -> GUI khong load + retry spam ->
        // stall 3s -> watchdog kill bridge -> mat het instrument -> cam. Defer
        // OPEN_GUI toi khi transport STOP (sweep duoi fulfill khi loaded &&
        // transportStopped). Khong doi: tranh mat am; user STOP la GUI tu mo.
        if (!transportStopped) {
            std::cerr << "[NativeBridge] GUI deferred ch=" << guiCh
                      << " plugin=" << pluginId << " (transport PLAY) - queued" << std::endl;
            std::lock_guard<std::mutex> lock(g_pendingGuiMutex);
            g_pendingGui[guiCh] = { (void*)arg1, pluginId };
            return;
        }
        // G1.2: window + attach chay tren UiThread (1 thread chung, COM STA +
        // message pump + job queue). Window messages do UiThread pump dispatch β€”
        // audio loop khong con PeekMessageW (xoa block pump o main loop).
        // G1.1 verify: gui_probe shared_worker = 1 worker load+openGUI 2 inst OK.
        uiWorker.post([&instruments, shmIPC, guiCh, arg1, arg2 = pluginId]() {
            AttachInFlightGuard _aifGuard{shmIPC};
            if (!instruments.get(guiCh)) {
                std::cerr << "[NativeBridge] GUI attach FAILED hwnd=0"
                          << " plugin=" << arg2 << " ch=" << guiCh << " (no instrument loaded)" << std::endl;
                return;
            }
            if (auto* inst0 = instruments.get(guiCh)) {
                if (inst0->hasAttachedView()) {
                    // Dedupe race: main da silence (setReloading) truoc khi post β€”
                    // restore de channel khong cam vinh vien.
                    std::vector<uint32_t> sp = same_plugin_channels(guiCh);
                    for (uint32_t y : sp) unmute_if_not_closing(y, "openGUI-dedupe");
                    unmute_if_not_closing(guiCh, "openGUI-dedupe");
                    return;
                }
            }
            void* hwnd = (void*)arg1;
#ifdef _WIN32
            HWND nativeHwnd = nullptr;
            {
                std::lock_guard<std::mutex> lock(g_guiMutex);
                auto it = g_guiWindows.find(guiCh);
                if (it != g_guiWindows.end()) nativeHwnd = (HWND)it->second;
            }
            if (hwnd == 0) {
                if (nativeHwnd && IsWindow(nativeHwnd)) {
                    hwnd = (void*)nativeHwnd;
                    SetWindowTextA(nativeHwnd, arg2.c_str());
                    ShowWindow(nativeHwnd, SW_SHOW);
                    SetForegroundWindow(nativeHwnd);
                    // Reuse: cap nhat USERDATA (channel+1) - inst CU da bi thay
                    // the boi assign() -> WM_DESTROY sau nay lookup inst MOI.
                    SetWindowLongPtrA(nativeHwnd, GWLP_USERDATA, (LONG_PTR)(guiCh + 1));
                } else {
                    nativeHwnd = (HWND)create_native_vst_window(arg2.c_str());
                    if (!nativeHwnd) {
                        std::cerr << "[NativeBridge] GUI create window FAILED plugin=" << arg2 << std::endl;
                        std::vector<uint32_t> sp = same_plugin_channels(guiCh);
                        for (uint32_t y : sp) unmute_if_not_closing(y, "openGUI-createfail");
                        unmute_if_not_closing(guiCh, "openGUI-createfail");
                        return;
                    }
                    {
                        std::lock_guard<std::mutex> lock(g_guiMutex);
                        g_guiWindows[guiCh] = nativeHwnd;      // keep window alive
                        g_hwndToCh[nativeHwnd] = guiCh;       // WM_DESTROY cleanup
                    }
                    SetWindowLongPtrA(nativeHwnd, GWLP_USERDATA, (LONG_PTR)(guiCh + 1));
                    hwnd = (void*)nativeHwnd;
                }
            }
#endif
        // G0.1b: silence same-path instances on the MAIN thread BEFORE the
        // attach job runs - renderAll of this loop iteration (and any before
        // the worker sets reloading_) would otherwise process() another Nexus
        // while the job's reload() (createInstance/terminate) enters the DLL
        // -> 2 threads in 1 DLL -> Nexus hang -> writeIndex stall -> watchdog
        // kills the bridge (observed: defer OK, attach after STOP still
        // restarted). setReloading is a flag under the engine mutex; renderAll
        // skips reloading channels, so no process() can race the job. The job
        // keeps its own setReloading + restore logic unchanged. Dat o day (sau
        // window create) de window fail khong keo mute vinh vien.
        {
            std::string gp0 = lower_plugin_path(guiCh);
            if (!gp0.empty()) {
                for (uint32_t y = 0; y < 16; ++y) {
                    if (y == guiCh) continue;
                    if (!instruments.get(y)) continue;
                    if (lower_plugin_path(y) == gp0)
                        instruments.setReloading(y, true);
                }
                instruments.setReloading(guiCh, true);
            }
        }
#ifdef _WIN32
            // Option B: chi 1 editor VST mo tai 1 thoi diem toan bridge. Instance
            // thu 2 cua CUNG plugin (Nexus) attach view o thread khac -> treo.
            // G1.2: 1 UiThread -> dong editor cua channel khac DONG BO (goi
            // close_editor_now truc tiep). Khong the PostMessage(WM_CLOSE) cho
            // job khac nhu cu β€” job close nam sau job hien tai trong queue cua
            // CUNG thread -> khong bao gio chay -> 5s timeout -> attach abort.
            {
                std::vector<uint32_t> others;
                {
                    std::lock_guard<std::mutex> lock(g_guiMutex);
                    for (const auto& kv : g_guiWindows)
                        if (kv.first != guiCh) others.push_back(kv.first);
                }
                for (uint32_t y : others) {
                    // Skip channels whose editor already detached (close job
                    // finished): do not WM_CLOSE a hidden reused window, do
                    // not re-silence a channel that is already unmuted.
                    if (auto* yi0 = instruments.get(y)) {
                        if (!yi0->hasAttachedView()) {
                            continue;
                        }
                    }
                    HWND yHwnd = nullptr;
                    {
                        std::lock_guard<std::mutex> lock(g_guiMutex);
                        auto it = g_guiWindows.find(y);
                        if (it != g_guiWindows.end()) yHwnd = (HWND)it->second;
                    }
                    if (!yHwnd || !IsWindow(yHwnd)) continue;
                    close_editor_now(y, yHwnd);
                }
            }
#else
            (void)0;
#endif
            if (auto* inst = instruments.get(guiCh)) {
                // Reopen sau khi dong: reload() (terminate + loadPlugin)
                // PHAI chay tren worker thread nay - COM STA apartment
                // cua channel song o day. view->attached() cung chay o
                // day; window thuoc main thread nen main pump (audio
                // loop) dispatch messages cua no - khong can pump worker.
                // Chan UAF bang flag reloading_ (set/clear duoi engine
                // mutex; renderAll giu mutex khi process).
                // G1.4: bo mute-when-editor-open - channel process() binh
                // thuong khi editor mo trong PLAY (verified: writeIndex
                // advancing voi GUI open, Nexus khong crash). reloading_ giu
                // im channel chi trong luc createView/createInstance chay
                // (2 thread 1 DLL); clear ngay sau attach xong.
                // STALL/CRASH FIX (Fix C, restored): silence EVERY channel
                // assigned the SAME plugin DLL path for the reload+attach
                // duration β€” the audio loop must not process() another
                // instance of this DLL while createInstance/createView runs
                // on this worker (2 threads in one DLL -> Nexus exits
                // silently, observed in probes). Iterate ALL 16 channels, not
                // just window-owning ones: session-restore instances without
                // a window are live and renderable.
                std::vector<uint32_t> samePathSilenced;
                std::string gp = lower_plugin_path(guiCh);
                if (!gp.empty()) {
                    for (uint32_t y = 0; y < 16; ++y) {
                        if (y == guiCh) continue;
                        if (!instruments.get(y)) continue;
                        if (lower_plugin_path(y) == gp) {
                            instruments.setReloading(y, true);
                            samePathSilenced.push_back(y);
                        }
                    }
                }
                instruments.setReloading(guiCh, true);
                // Register attach-in-flight: a same-path close job must not
                // unmute its channel while createView runs here (it stays
                // silenced; this job's restore unmutes it at the end).
                {
                    std::lock_guard<std::mutex> lk(g_attachMutex);
                    if (!gp.empty()) g_attachPaths.push_back(gp);
                }
                bool ok = false;
                {
                    // Serialize ALL plugin-DLL entry (createInstance AND
                    // createView) with other loads: two threads inside one
                    // DLL (Nexus) crash. createView outside the lock raced a
                    // same-path close job's reload (createInstance) -> Nexus
                    // exited silently (observed in probes).
                    std::lock_guard<std::mutex> lg(g_loadMutex);
                    // CRASH FIX (0xc000041d): attachView -> view->attached()
                    // and reloadForGUI both enter the plugin DLL β€” a C++
                    // exception (Nexus) must not escape this job (would
                    // std::terminate the worker). Treat as attach failure;
                    // the else branch below closes the empty window.
                    try {
                        ok = inst->reloadForGUI();
                        // IME recursion fix: strip the editor's IMC before
                        // attachView creates the editor child β€” a live IMC on
                        // a JUCE_ window + plugin wndproc (ImmIsUIMessageW ->
                        // SendMessageW WM_IME_SETCONTEXT same hwnd) = infinite
                        // recursion (0xC00000FD, observed inside attachView).
                        if (ok) disable_ime_contexts((HWND)hwnd);
                        if (ok) ok = inst->attachView(hwnd);
                    } catch (...) {
                        std::cerr << "[NativeBridge] GUI attach EXCEPTION ch=" << guiCh
                                  << " β€” plugin threw (createView/attached)" << std::endl;
                        ok = false;
                    }
                }
                // Attach done (ok or failed) β€” close jobs may unmute again.
                {
                    std::lock_guard<std::mutex> lk(g_attachMutex);
                    if (!gp.empty()) {
                        auto it = std::find(g_attachPaths.begin(), g_attachPaths.end(), gp);
                        if (it != g_attachPaths.end()) g_attachPaths.erase(it);
                    }
                }
                // Restore same-path silence. Channels whose own close job is
                // still inside createInstance stay muted β€” that job owns
                // their unmute and performs it once reload finished.
                for (uint32_t y : samePathSilenced)
                    unmute_if_not_closing(y, "openGUI");
                if (ok) {

                    disable_ime_contexts((HWND)hwnd);

                    std::cout << "[NativeBridge] GUI attached hwnd=" << hwnd
                              << " plugin=" << arg2 << " ch=" << guiCh
                              << std::endl;
                    instruments.setReloading(guiCh, false);
                }
                else {
                    // Attach failed -> no editor running -> safe to process again.
                    instruments.setReloading(guiCh, false);
                    std::cerr << "[NativeBridge] GUI attach FAILED hwnd=" << hwnd
                              << " plugin=" << arg2 << std::endl;
#ifdef _WIN32
                    // Attach that β€” khong co view (VD: channel la SF2/SFZ hoac plugin
                    // loi). Dong ngay cua so vo nghia de khong con window treo trong
                    // registry; WM_CLOSE -> UiThread pump destroy (owner = UiThread).
                    // PostMessage an toan cross-thread (khong nhu DestroyWindow).

                    PostMessageA((HWND)hwnd, WM_CLOSE, 0, 0);
#endif
                }
            }
        });
    };

    // 2. REAL-TIME AUDIO PROCESSING ENGINE LOOP
    while (true) {
        // CRASH FIX (0xc000041d): last-resort net β€” any C++ exception that
        // escapes the targeted guards (e.g. inside renderAll -> process())
        // must not kill the bridge. Log and continue the loop.
        try {
        // G1.2: audio loop KHONG pump messages nua β€” moi window (native VST +
        // editor children) thuoc UiThread; UiThread pump dispatch chung.
        // A. Control events β€” non-rt safe, drained first
        for (uint32_t i = 0; i < shmIPC->controlQueueCount; ++i) {
            const auto& c = shmIPC->controlQueue[i];
            if (c.type == 2) { // LOAD_INSTRUMENT (A10: assign per MIDI channel)
                // Robust path length: do not trust arg1 (Rust passes 0 for LOAD).
                // Chay tren persistent worker thread cua channel: VST3 init
                // (loadPlugin) co the mat giay β€” chay dong bo tren audio loop
                // lam writeIndex stall > 3s -> Rust tuong bridge chet va restart
                // nham (2 bridge cung map SHM -> race control queue / double
                // load). assign() chi giu mutex khi ghi map nen renderAll khong
                // bao gio stall. openGUI sau nay chay tren CUNG thread nay
                // (ChannelWorker) β€” thread khong bao gio exit nen COM STA
                // apartment cua plugin con song (xem ChannelWorker comment).
                size_t plen = 0;
                while (plen < sizeof(c.arg2) && c.arg2[plen]) ++plen;
                std::string path(c.arg2, plen);
                InstrumentType t = (InstrumentType)c.arg0;
                uint32_t ch = c.channel & 0xF;
                uiWorker.post([&instruments, t, ch, path, sampleRate, block]() {
                    // CRASH FIX: this job enters the plugin DLL (createInstance
                    // in loadPlugin, old-instance terminate on replace) while
                    // the audio loop may process() another instance of the SAME
                    // DLL β€” 2 threads in one DLL crashes Nexus (observed with
                    // session-restore instances). Silence this channel (its old
                    // instance is being torn down / replaced) and every
                    // same-plugin channel for the whole job. Old path covers
                    // the old-instance teardown; the new path (computed BEFORE
                    // assign β€” see spNew below) covers the freshly created
                    // instance. CRASH FIX (SF→VSTi while playing): the new
                    // path must be silenced BEFORE assign() β€” assign() itself
                    // runs createInstance (loadPlugin) on this worker, and a
                    // restored channel on ANOTHER track holding the SAME DLL
                    // kept process()ing on the audio loop during that window
                    // (old code silenced spNew only AFTER assign β†’ crash).
                    instruments.setReloading(ch, true);
                    std::vector<uint32_t> spOld = same_plugin_channels(ch);
                    for (uint32_t y : spOld) {
                        g_engine->setReloading(y, true);
                    }
                    // Channels (other than ch) already assigned the NEW path β€”
                    // silence BEFORE createInstance enters that DLL.
                    std::vector<uint32_t> spNew;
                    if (t == InstrumentType::VST3) {
                        std::string np = lower_path_str(path);
                        if (!np.empty()) {
                            for (uint32_t y = 0; y < 16; ++y) {
                                if (y == ch) continue;
                                if (!g_engine->get(y)) continue;
                                if (std::find(spOld.begin(), spOld.end(), y) != spOld.end()) continue;
                                if (lower_plugin_path(y) != np) continue;
                                g_engine->setReloading(y, true);
                                spNew.push_back(y);
                            }
                        }
                    }
#ifdef _WIN32
                    // DONG cua so editor dang mo cua channel TRUOC khi assign():
                    // thay the inst (VST3 -> SF2/inst khac) ma editor con song ->
                    // old inst destructor goi view->removed() tren HWND con hoat
                    // dong -> plugin block -> treo bridge.
                    // G1.2/G1.3: window tao tren UiThread (handleOpenGui post attach
                    // job; create_native_vst_window chay trong job). LOAD job cung
                    // chay tren UiThread -> khong cross-thread destroy. An window,
                    // giu registry de reuse; editor detach + reload o duoi.

                    HWND hToHide = nullptr;
                    {
                        std::lock_guard<std::mutex> lock(g_guiMutex);
                        auto git = g_guiWindows.find(ch);
                        if (git != g_guiWindows.end()) hToHide = (HWND)git->second;
                    }
                    // CRASH FIX: detach view TRUOC khi thay inst. Plugin editor
                    // children thuoc worker thread nay (attachView chay o day);
                    // khong destroy parent window (main-owned) khi view con song
                    // -> DestroyWindow cross-thread -> USER32 0xc000041d. An
                    // window, giu trong registry de reuse (reopen ShowWindow lai).
                    if (hToHide && IsWindow(hToHide)) {
                        // CRASH FIX (0xc000041d USER32 while playing): silence
                        // the channel while the old editor detaches β€” view->removed()
                        // on this worker would race processor->process() on the
                        // audio loop (same plugin instance).
                        instruments.setReloading(ch, true);
                        // CRASH FIX: the plugin's editor window procs run on
                        // this worker; if one throws (Nexus) the exception must
                        // not escape the LOAD job (would std::terminate the
                        // worker). Detach best-effort and continue.
                        try {
                            disable_ime_contexts(hToHide);
                            if (auto* i = instruments.get(ch)) i->closeGUI();
                            // CRASH FIX (0xc000041d): destroy the old
                            // editor's child windows on the thread that OWNS
                            // them (JUCE MessageManager worker), never
                            // cross-thread - DestroyWindow from this LOAD
                            // worker raced the owner's pump dispatching
                            // WM_PAINT into the plugin wndproc -> AV. Wait
                            // for each destroy before assign() below. The
                            // parent window is hidden and kept for reuse.
                            // See post_close_gui for the same pattern.
                            while (HWND c = FindWindowExA(hToHide, nullptr, nullptr, nullptr)) {
                                destroy_window_on_owner(c);
                            }
                        } catch (...) {
                            std::cerr << "[NativeBridge] LOAD close-editor EXCEPTION ch=" << ch
                                      << " β€” plugin window proc threw" << std::endl;
                        }
                        ShowWindow(hToHide, SW_HIDE);
                    }
#endif
                    std::lock_guard<std::mutex> lg(g_loadMutex);
                    // CRASH FIX (0xc000041d): Nexus throws nlohmann::json::
                    // out_of_range inside createInstance (loadPlugin) β€” the
                    // C++ exception must not escape the LOAD job (would
                    // std::terminate the worker). Catch it, treat as failed
                    // load, keep the old instance, and let the restore below
                    // unmute the channel.
                    bool ok = false;
                    try {
                        ok = instruments.assign(ch, t, path, sampleRate, block);
                    } catch (...) {
                        std::cerr << "[NativeBridge] assign EXCEPTION ch=" << ch
                                  << " type=" << (int)t << " path=" << path
                                  << " β€” plugin threw (createInstance)" << std::endl;
                        ok = false;
                    }
                    if (ok) {
                        std::cout << "[NativeBridge] instrument loaded ch=" << ch
                                  << " type=" << (int)t << " " << path << std::endl;
                    } else {
                        std::cerr << "[NativeBridge] instrument load FAILED ch=" << ch
                                  << " type=" << (int)t << " " << path << std::endl;
                    }
                    // Restore. Failed load keeps the OLD instance β€” unmute it
                    // back (silenced at job start); a successful assign leaves
                    // the fresh instance unmuted by construction.
                    if (!ok) g_engine->setReloading(ch, false);
                    for (uint32_t y : spOld) unmute_if_not_closing(y, "load");
                    for (uint32_t y : spNew) unmute_if_not_closing(y, "load");
                });
            } else if (c.type == 1) { // PANIC
                instruments.allNotesOff();
                std::cout << "[NativeBridge] PANIC β€” all notes off" << std::endl;
            } else if (c.type == 3) { // TRANSPORT (A13)
                if (c.arg0 == 0) { // STOP β†’ flush every note immediately
                    transportStopped = true;
                    // Release sustain pedal TRUOC (CC64=0) β€” nhieu VSTi giu note
                    // khi pedal con down -> note-off cua allNotesOff bi bo qua
                    // -> am treo loop (V8 bug 3).
                    for (uint32_t ch = 0; ch < 16; ++ch) {
                        if (auto* inst = instruments.get(ch)) inst->controlChange(ch, 64, 0);
                    }
                    instruments.allNotesOff();
                    std::cout << "[NativeBridge] transport STOP β€” all notes off" << std::endl;
                } else if (c.arg0 == 1) { // PLAY
                    transportStopped = false;
                    playheadSamples = c.arg1;
                    std::cout << "[NativeBridge] transport PLAY playhead=" << playheadSamples << std::endl;
                } else if (c.arg0 == 2) { // SET_POSITION (seek while stopped)
                    playheadSamples = c.arg1;
                }
            } else if (c.type == 4) { // OPEN_GUI (A7): arg1 = parent HWND (0 β†’ bridge tα»± tαΊ‘o native window), arg2 = plugin id
                uint32_t guiCh = c.channel;
                if (guiCh >= 16) guiCh = 0;
                handleOpenGui(guiCh, (uintptr_t)c.arg1, std::string(c.arg2));
            }
        }
        shmIPC->controlQueueCount = 0;

        // Pending OPEN_GUI requests: fulfilled as soon as the channel's
        // instrument becomes available (load job completed on its worker).
        {
            std::vector<std::pair<uint32_t, std::pair<void*, std::string>>> readyGui;
            {
                std::lock_guard<std::mutex> lock(g_pendingGuiMutex);
                for (auto it = g_pendingGui.begin(); it != g_pendingGui.end(); ) {
                    // G0.1: giu entry khi dang PLAY - handleOpenGui se defer lai
                    if (transportStopped && instruments.get(it->first)) {
                        readyGui.push_back({ it->first, it->second });
                        it = g_pendingGui.erase(it);
                    } else ++it;
                }
            }
            for (auto& g : readyGui)
                handleOpenGui(g.first, (uintptr_t)g.second.first, g.second.second);
        }


        // B. Snapshot queued MIDI events (bounded copy, queue reset immediately)
        uint32_t nEvents = shmIPC->midiQueueCount > 64 ? 64 : shmIPC->midiQueueCount;
        SharedAudioBufferIPC::MidiEventIPC evts[64];
        for (uint32_t i = 0; i < nEvents; ++i) evts[i] = shmIPC->midiQueue[i];
        shmIPC->midiQueueCount = 0;

        // A11 sample-accurate: sort by sampleOffset, dispatch at each boundary,
        // render the sub-block before the boundary. Events with offset 0 (live
        // keyboard, current JS) are dispatched first and shape the whole block.
        std::stable_sort(evts, evts + nEvents,
                         [](const SharedAudioBufferIPC::MidiEventIPC& a,
                            const SharedAudioBufferIPC::MidiEventIPC& b) {
                             return a.sampleOffset < b.sampleOffset;
                         });
        uint32_t cursor = 0;
        uint32_t ei = 0;
        while (ei < nEvents && evts[ei].sampleOffset <= cursor) { dispatch(evts[ei]); ++ei; }
        for (; ei < nEvents; ++ei) {
            uint32_t off = evts[ei].sampleOffset < block ? evts[ei].sampleOffset : block;
            if (off > cursor) { renderSegment(cursor, off); cursor = off; }
            dispatch(evts[ei]);
        }
        if (cursor < block) renderSegment(cursor, block);
        shmIPC->bridgeWriteIndex++;

        // D. Parent died / window closed -> exit (no orphan process)
        if (parentPid != 0 && !parent_alive(parentPid)) {
            std::cout << "[NativeBridge] parent gone β€” exiting." << std::endl;
            break;
        }

        // E. Synchronize with real-time audio playback
        blockCount++;
        auto targetTime = startTime + std::chrono::microseconds(static_cast<int64_t>(blockCount * blockDurationMs * 1000.0));
        auto now = std::chrono::steady_clock::now();
        if (now < targetTime) {
            auto diff = std::chrono::duration_cast<std::chrono::microseconds>(targetTime - now).count();
            if (diff > 1000) {
                sleep_ms(diff / 1000);
            }
            while (std::chrono::steady_clock::now() < targetTime) {
                std::this_thread::yield();
            }
        }
        } catch (...) {
            std::cerr << "[NativeBridge] main loop EXCEPTION β€” plugin threw during render/control" << std::endl;
        }
    }

#ifdef _WIN32
    UnmapViewOfFile(shmIPC);
    CloseHandle(hMapFile);
    timeEndPeriod(1);
    CoUninitialize();
#else
    std::free(shmIPC);
#endif
    return 0;
}