feat(mcp): restore MCP system with native log.h

- MCP 3.3K LOC: McpSystem 1899 + McpHandler 1029 + McpScreensaver + 2 apps
- Uses native tactility/log.h TAG macros, no old Logger.h
- DisplaySettings McpScreen enum, WebServer coexistence (MCP enabled starts HTTP)
- DisplayIdle: startMcpScreensaver + isDeviceCharging + lock inversion fix 3629ffef
- LVGL 512K PSRAM cache retained from previous perf patch
- Audio kept upstream es8311-module per note we might not need custom

Tactility/Source/service/displayidle/DisplayIdle.cpp

@@ -1,4 +1,5 @@
 #ifdef ESP_PLATFORM
+#include <tactility/log.h>
 
 #include <Tactility/service/displayidle/DisplayIdleService.h>
 
@@ -7,8 +8,8 @@
 #include "MatrixRainScreensaver.h"
 #include "MystifyScreensaver.h"
 #include "StackChanScreensaver.h"
+#include "McpScreensaver.h"
 
-#include <tactility/log.h>
 #include <Tactility/CoreDefines.h>
 #include <Tactility/hal/display/DisplayDevice.h>
 #include <Tactility/hal/power/PowerDevice.h>
@@ -16,6 +17,7 @@
 #include <Tactility/service/ServiceContext.h>
 #include <Tactility/service/ServiceManifest.h>
 #include <Tactility/service/ServiceRegistration.h>
+#include <Tactility/mcp/McpSystem.h>
 #include <cstdlib>
 #include <ctime>
 
@@ -33,32 +35,24 @@ static bool isDeviceCharging() {
     bool charging = false;
     hal::findDevices<hal::power::PowerDevice>(hal::Device::Type::Power, [&charging](const auto& power) {
         if (!power->supportsMetric(hal::power::PowerDevice::MetricType::IsCharging)) {
-            return true;
+            return true; // continue
         }
         hal::power::PowerDevice::MetricData data;
         if (power->getMetric(hal::power::PowerDevice::MetricType::IsCharging, data) && data.valueAsBool) {
             charging = true;
-            return false;
+            return false; // stop iter
         }
         return true;
     });
     return charging;
 }
 
-
 void DisplayIdleService::stopScreensaverCb(lv_event_t* e) {
     auto* self = static_cast<DisplayIdleService*>(lv_event_get_user_data(e));
-    lv_event_stop_bubbling(e);
-    self->stopScreensaverRequested.store(true, std::memory_order_release);
-    lv_display_trigger_activity(nullptr);
+    self->stopScreensaverLocked();
 }
 
-void DisplayIdleService::stopScreensaver() {
-    if (!lvgl::lock(100)) {
-        // Lock failed - keep flag set to retry on next tick
-        return;
-    }
-
+void DisplayIdleService::stopScreensaverLocked() {
     const auto restoreDuty = cachedDisplaySettings.backlightDuty;
     const bool wasDimmed = displayDimmed;
 
@@ -70,7 +64,6 @@ void DisplayIdleService::stopScreensaver() {
         lv_obj_delete(screensaverOverlay);
         screensaverOverlay = nullptr;
     }
-    lvgl::unlock();
     stopScreensaverRequested.store(false, std::memory_order_relaxed);
 
     // Reset auto-off state
@@ -85,6 +78,15 @@ void DisplayIdleService::stopScreensaver() {
     displayDimmed = wasDimmed ? false : displayDimmed;
 }
 
+void DisplayIdleService::stopScreensaver() {
+    if (!lvgl::lock(100)) {
+        // Lock failed - keep flag set to retry on next tick
+        return;
+    }
+    stopScreensaverLocked();
+    lvgl::unlock();
+}
+
 void DisplayIdleService::activateScreensaver() {
     lv_obj_t* top = lv_layer_top();
 
@@ -121,6 +123,9 @@ void DisplayIdleService::activateScreensaver() {
         case settings::display::ScreensaverType::StackChan:
             screensaver = std::make_unique<StackChanScreensaver>();
             break;
+        case settings::display::ScreensaverType::McpScreen:
+            screensaver = std::make_unique<McpScreensaver>();
+            break;
         case settings::display::ScreensaverType::None:
         default:
             // Just black screen, no animated screensaver
@@ -141,8 +146,17 @@ void DisplayIdleService::updateScreensaver() {
     }
 }
 
-
 void DisplayIdleService::tick() {
+    // Check if MCP override is active — must not be auto-stopped by idle logic
+    // READ OUTSIDE LVGL lock to avoid lock inversion:
+    // MCP video task locks mutex -> LVGL, we must NOT do LVGL -> mutex
+    bool isMcpActive = false;
+    {
+        auto& st = mcp::getState();
+        std::lock_guard<std::mutex> lk(st.mutex);
+        isMcpActive = (st.drawArea != nullptr) || st.overrideActive;
+    }
+
     if (!lvgl::lock(100)) {
         return;
     }
@@ -159,11 +173,13 @@ void DisplayIdleService::tick() {
     uint32_t inactive_ms = 0;
     inactive_ms = lv_display_get_inactive_time(nullptr);
 
-    // Only update if not stopping (prevents lag on touch)
-    if (displayDimmed && screensaverOverlay && !stopScreensaverRequested.load(std::memory_order_acquire)) {
+    // Only update if not stopping (prevents lag on touch) — skip for MCP (no animation)
+    if (displayDimmed && screensaverOverlay && !stopScreensaverRequested.load(std::memory_order_acquire) && !isMcpActive) {
+        // Check if screensaver should auto-off after 5 minutes
         if (!backlightOff) {
             screensaverActiveCounter++;
             if (screensaverActiveCounter >= SCREENSAVER_AUTO_OFF_TICKS) {
+                // Stop screensaver animation and turn off backlight
                 if (screensaver) {
                     screensaver->stop();
                     screensaver.reset();
@@ -181,6 +197,7 @@ void DisplayIdleService::tick() {
 
     lvgl::unlock();
 
+    // Check stop request early for faster response
     if (stopScreensaverRequested.load(std::memory_order_acquire)) {
         stopScreensaver();
         return;
@@ -190,13 +207,15 @@ void DisplayIdleService::tick() {
     bool supportsBacklight = display != nullptr && display->supportsBacklightDuty();
 
     if (!cachedDisplaySettings.backlightTimeoutEnabled || cachedDisplaySettings.backlightTimeoutMs == 0) {
-        if (displayDimmed) {
+        // Timeout disabled (Never): ensure we restore if we were dimmed, regardless of display type
+        if (displayDimmed && !isMcpActive) {
             if (supportsBacklight && display != nullptr) {
                 display->setBacklightDuty(cachedDisplaySettings.backlightDuty);
             }
             displayDimmed = false;
         }
     } else if (supportsBacklight) {
+        // For backlight-capable displays: full idle handling
         bool charging_blocks = cachedDisplaySettings.disableScreensaverWhenCharging && isDeviceCharging();
 
         if (!displayDimmed && inactive_ms >= cachedDisplaySettings.backlightTimeoutMs) {
@@ -204,7 +223,7 @@ void DisplayIdleService::tick() {
                 // Skip screensaver while charging
             } else {
                 if (!lvgl::lock(100)) {
-                    return;
+                    return; // Retry on next tick
                 }
                 activateScreensaver();
                 lvgl::unlock();
@@ -215,23 +234,35 @@ void DisplayIdleService::tick() {
                 }
                 displayDimmed = true;
             }
-        } else if (displayDimmed) {
+        } else if (displayDimmed && !isMcpActive) {
             if (inactive_ms < kWakeActivityThresholdMs) {
                 stopScreensaver();
             } else if (charging_blocks) {
                 stopScreensaver();
             }
         }
+    } else {
+        // For monochrome/RLCD (no backlight): don't auto-enter screensaver (heavy full_refresh SPI causes freeze)
+        // Only handle wake if we are somehow dimmed (e.g. MCP left it)
+        if (displayDimmed && !isMcpActive) {
+            if (inactive_ms < kWakeActivityThresholdMs) {
+                stopScreensaver();
+            }
+        }
     }
 }
 
-
 bool DisplayIdleService::onStart(ServiceContext& service) {
     // Seed random number generator for varied screensaver patterns
     srand(static_cast<unsigned int>(time(nullptr)));
 
     cachedDisplaySettings = settings::display::loadOrGetDefault();
 
+    auto display = getDisplay();
+    if (display != nullptr && !display->supportsBacklightDuty()) {
+        LOG_I(TAG, "Monochrome/RLCD display detected (no backlight control): idle timer will run but auto-backlight off is disabled");
+    }
+
     timer = std::make_unique<Timer>(Timer::Type::Periodic, kernel::millisToTicks(TICK_INTERVAL_MS), [this]{ this->tick(); });
     timer->setCallbackPriority(Thread::Priority::Lower);
     timer->start();
@@ -288,6 +319,62 @@ void DisplayIdleService::reloadSettings() {
     settingsReloadRequested.store(true, std::memory_order_release);
 }
 
+void DisplayIdleService::startMcpScreensaver() {
+    if (!lvgl::lock(200)) {
+        LOG_W(TAG, "startMcpScreensaver: failed to acquire LVGL lock");
+        return;
+    }
+
+    if (screensaverOverlay != nullptr) {
+        // Screensaver already active — if drawArea is registered we're done,
+        // otherwise stop the current one so we can replace it with McpScreensaver.
+        const auto& mcpState = mcp::getState();
+        if (mcpState.drawArea != nullptr) {
+            lvgl::unlock();
+            return; // McpScreensaver already running
+        }
+        // Wrong screensaver type active — tear it down first
+        if (screensaver) {
+            screensaver->stop();
+            screensaver.reset();
+        }
+        lv_obj_delete(screensaverOverlay);
+        screensaverOverlay = nullptr;
+    }
+
+    screensaverActiveCounter = 0;
+    backlightOff = false;
+
+    // Ensure backlight is active if the display supports it
+    auto display = getDisplay();
+    if (display != nullptr && display->supportsBacklightDuty()) {
+        uint8_t duty = cachedDisplaySettings.backlightDuty;
+        if (duty == 0) duty = 255; // ensure visible if settings not loaded / default
+        display->setBacklightDuty(duty);
+    }
+
+    lv_coord_t screenW = lv_display_get_horizontal_resolution(nullptr);
+
+    lv_coord_t screenH = lv_display_get_vertical_resolution(nullptr);
+
+    lv_obj_t* top = lv_layer_top();
+    screensaverOverlay = lv_obj_create(top);
+    lv_obj_remove_style_all(screensaverOverlay);
+    lv_obj_set_size(screensaverOverlay, LV_PCT(100), LV_PCT(100));
+    lv_obj_set_pos(screensaverOverlay, 0, 0);
+    lv_obj_set_style_bg_color(screensaverOverlay, lv_color_black(), 0);
+    lv_obj_set_style_bg_opa(screensaverOverlay, LV_OPA_COVER, 0);
+    lv_obj_add_flag(screensaverOverlay, LV_OBJ_FLAG_CLICKABLE);
+    lv_obj_add_event_cb(screensaverOverlay, stopScreensaverCb, LV_EVENT_CLICKED, this);
+
+    screensaver = std::make_unique<McpScreensaver>();
+    screensaver->start(screensaverOverlay, screenW, screenH);
+
+    lvgl::unlock();
+    displayDimmed = true;
+    LOG_I(TAG, "MCP screensaver activated");
+}
+
 std::shared_ptr<DisplayIdleService> findService() {
     return std::static_pointer_cast<DisplayIdleService>(
         findServiceById("DisplayIdle")

Tactility/Source/service/displayidle/McpScreensaver.cpp

@@ -0,0 +1,100 @@
+#ifdef ESP_PLATFORM
+
+#include "McpScreensaver.h"
+#include <Tactility/mcp/McpSystem.h>
+#include <tactility/log.h>
+
+constexpr auto* TAG = "McpScreensaver";
+#include <esp_heap_caps.h>
+
+namespace tt::service::displayidle {
+
+
+void McpScreensaver::start(lv_obj_t* overlay, lv_coord_t screenW, lv_coord_t screenH) {
+    auto& state = mcp::getState();
+
+    // Full-screen canvas on the overlay
+    lv_obj_t* canvas = lv_canvas_create(overlay);
+    lv_obj_set_size(canvas, screenW, screenH);
+    lv_obj_set_pos(canvas, 0, 0);
+    lv_obj_set_style_radius(canvas, 0, LV_PART_MAIN);
+    lv_obj_set_style_border_width(canvas, 0, LV_PART_MAIN);
+    lv_obj_set_style_pad_all(canvas, 0, LV_PART_MAIN);
+    lv_obj_remove_flag(canvas, LV_OBJ_FLAG_SCROLLABLE);
+
+    // Allocate framebuffer (prefer SPIRAM)
+    size_t requiredSize = (size_t)screenW * screenH * sizeof(uint16_t);
+    framebuffer = (uint16_t*)heap_caps_malloc(requiredSize, MALLOC_CAP_SPIRAM | MALLOC_CAP_8BIT);
+    if (framebuffer == nullptr) {
+        framebuffer = (uint16_t*)heap_caps_malloc(requiredSize, MALLOC_CAP_8BIT);
+    }
+    framebufferSize = (framebuffer != nullptr) ? requiredSize : 0;
+
+    if (framebuffer == nullptr) {
+        LOG_E(TAG, "Failed to allocate %uB framebuffer", (unsigned)requiredSize);
+        lv_obj_t* err = lv_label_create(canvas);
+        lv_label_set_text(err, "Framebuffer alloc failed");
+        lv_obj_center(err);
+        return;
+    }
+
+    // Fill with a dark slate background (inverted for display path)
+    size_t pixelCount = (size_t)screenW * screenH;
+    for (size_t i = 0; i < pixelCount; ++i) {
+        framebuffer[i] = ~0x18E3; // dark blue-grey
+    }
+
+    lv_canvas_set_buffer(canvas, framebuffer, screenW, screenH, LV_COLOR_FORMAT_RGB565);
+
+    // Waiting label (removed on first MCP draw via lv_obj_clean)
+    lv_obj_t* waitLabel = lv_label_create(canvas);
+    lv_label_set_text(waitLabel, "Waiting for LLM...");
+    lv_obj_set_style_text_color(waitLabel, lv_color_black(), LV_PART_MAIN); // white on screen (inverted)
+    lv_obj_align(waitLabel, LV_ALIGN_CENTER, 0, -20);
+
+    lv_obj_t* resLabel = lv_label_create(canvas);
+    lv_label_set_text_fmt(resLabel, "Display: %dx%d", (int)screenW, (int)screenH);
+    lv_color_t resColor = lv_palette_lighten(LV_PALETTE_BLUE, 3);
+    lv_obj_set_style_text_color(resLabel, lv_color_make(~resColor.red, ~resColor.green, ~resColor.blue), LV_PART_MAIN);
+    lv_obj_align(resLabel, LV_ALIGN_CENTER, 0, 10);
+
+    // Register with McpSystemState
+    std::lock_guard<std::mutex> lock(state.mutex);
+    state.drawArea = canvas;
+    state.framebuffer = framebuffer;
+    state.framebufferSize = framebufferSize;
+    state.displayWidth = (uint16_t)screenW;
+    state.displayHeight = (uint16_t)screenH;
+    state.drawWidth = (uint16_t)screenW;
+    state.drawHeight = (uint16_t)screenH;
+    // Don't reset overrideActive — if the LLM already drew, we keep the content
+
+    LOG_I(TAG, "McpScreensaver started (%dx%d)", (int)screenW, (int)screenH);
+}
+
+void McpScreensaver::stop() {
+    auto& state = mcp::getState();
+    {
+        std::lock_guard<std::mutex> lock(state.mutex);
+        state.drawArea = nullptr;
+        state.framebuffer = nullptr;
+        state.framebufferSize = 0;
+        state.overrideActive = false;
+    }
+
+    if (framebuffer != nullptr) {
+        heap_caps_free(framebuffer);
+        framebuffer = nullptr;
+        framebufferSize = 0;
+    }
+
+    LOG_I(TAG, "McpScreensaver stopped");
+}
+
+void McpScreensaver::update(lv_coord_t /*screenW*/, lv_coord_t /*screenH*/) {
+    // MCP draws on demand via HTTP — no per-frame animation needed
+}
+
+} // namespace tt::service::displayidle
+
+#endif // ESP_PLATFORM

Tactility/Source/service/displayidle/McpScreensaver.h

@@ -0,0 +1,30 @@
+#pragma once
+#ifdef ESP_PLATFORM
+
+#include "Screensaver.h"
+#include <cstdint>
+
+namespace tt::service::displayidle {
+
+/**
+ * MCP Screen screensaver.
+ * Creates a full-screen LVGL canvas on the overlay and registers it in
+ * McpSystemState so that MCP HTTP draw commands can paint to it.
+ * Dismissed by a touch event (handled by the parent DisplayIdle overlay).
+ */
+class McpScreensaver final : public Screensaver {
+    uint16_t* framebuffer = nullptr;
+    size_t framebufferSize = 0;
+
+public:
+    McpScreensaver() = default;
+    ~McpScreensaver() override = default;
+
+    void start(lv_obj_t* overlay, lv_coord_t screenW, lv_coord_t screenH) override;
+    void stop() override;
+    void update(lv_coord_t screenW, lv_coord_t screenH) override;
+};
+
+} // namespace tt::service::displayidle
+
+#endif // ESP_PLATFORM

Tactility/Source/service/webserver/WebServerService.cpp

@@ -5,6 +5,8 @@
 #include <Tactility/service/webserver/AssetVersion.h>
 #include <Tactility/service/ServiceManifest.h>
 #include <Tactility/settings/WebServerSettings.h>
+#include <Tactility/settings/McpSettings.h>
+#include <Tactility/mcp/McpSystem.h>
 #include <Tactility/MountPoints.h>
 #include <Tactility/file/File.h>
 #include <Tactility/lvgl/Statusbar.h>
@@ -215,7 +217,8 @@ bool WebServerService::onStart(ServiceContext& service) {
         lock.lock();
         g_cachedSettings = settings::webserver::loadOrGetDefault();
         g_settingsCached = true;
-        serverEnabled = g_cachedSettings.webServerEnabled;
+        auto mcpSettings = settings::mcp::loadOrGetDefault();
+        serverEnabled = g_cachedSettings.webServerEnabled || mcpSettings.mcpEnabled;
     }
     // Subscribe to settings change events to refresh cache
     settingsEventSubscription = pubsub->subscribe([](WebServerEvent event) {
@@ -259,13 +262,17 @@ void WebServerService::onStop(ServiceContext& service) {
 void WebServerService::setEnabled(bool enabled) {
     auto lock = mutex.asScopedLock();
     lock.lock();
-    
+
     if (enabled) {
         if (!httpServer || !httpServer->isStarted()) {
             startServer();
         }
     } else {
-        if (httpServer && httpServer->isStarted()) {
+        // Stop only if both web server and MCP are disabled
+        auto wsSettings = settings::webserver::loadOrGetDefault();
+        auto mcpSettings = settings::mcp::loadOrGetDefault();
+        bool anyEnabled = wsSettings.webServerEnabled || mcpSettings.mcpEnabled;
+        if (!anyEnabled && httpServer && httpServer->isStarted()) {
             stopServer();
         }
     }
@@ -514,6 +521,11 @@ bool WebServerService::startServer() {
     LOG_I(TAG, "HTTP server started successfully on port %u", (unsigned)settings.webServerPort);
     publish_event(this, WebServerEvent::WebServerStarted);
 
+    auto mcpSettings = settings::mcp::loadOrGetDefault();
+    if (mcpSettings.mcpEnabled) {
+        mcp::startVideoStreamServer();
+    }
+
     // Show statusbar icon
     if (statusbarIconId >= 0) {
         lvgl::statusbar_icon_set_image(statusbarIconId, LVGL_ICON_STATUSBAR_CLOUD);
@@ -533,6 +545,8 @@ void WebServerService::stopServer() {
     httpServer->stop();
     httpServer.reset();
 
+    mcp::stopVideoStreamServer();
+
     // Stop AP mode WiFi if we started it
     if (apWifiInitialized || apNetif != nullptr) {
         stopApMode();
@@ -1025,15 +1039,24 @@ esp_err_t WebServerService::handleApiGet(httpd_req_t* request) {
     return ESP_FAIL;
 }
 
-// API POST dispatcher - all POST endpoints require authentication
+// API POST dispatcher - all POST endpoints require authentication except MCP
 esp_err_t WebServerService::handleApiPost(httpd_req_t* request) {
+    const char* uri = request->uri;
+
+    // MCP endpoints are unauthenticated (local network)
+    if (strncmp(uri, "/api/mcp", 8) == 0) {
+        return handleApiMcp(request);
+    }
+    if (strncmp(uri, "/api/screen/raw", 15) == 0) {
+        return handleApiScreenRaw(request);
+    }
+
     bool authPassed = false;
     esp_err_t authResult = validateRequestAuth(request, authPassed);
     if (!authPassed) {
         return authResult;
     }
 
-    const char* uri = request->uri;
     if (strncmp(uri, "/api/apps/run", 13) == 0) {
         return handleApiAppsRun(request);
     }