fix(screen): compile the MUI mirror out unless it is opted into

setMirror cleared muiOwner outside any guard, so every board without a
TFT failed to compile — the member only exists on the MUI path. The
assignment was redundant anyway: freeSnapshotLocked() releases the pool
and the ownership claim together.

The guards were also drawn on HAS_TFT while the code they protect needs
a device-ui carrying the flush observer, so a color build that never
opts in still carried the rect queue in .bss. Replaces the ad-hoc
HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR) pairs with a single
derived HAS_MUI_MIRROR next to HAS_SCREEN_MIRROR, and gates the queue,
the pool, the input seam and their declarations on it.

Verified on all three build shapes: t-deck-tft with the opt-in,
picomputer-s3 (TFT, opted out) and heltec-v3 (no TFT).

src/configuration.h

@@ -681,6 +681,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define HAS_SCREEN_MIRROR 0
 #endif
 
+// Mirroring MUI (device-ui/LVGL) streams RGB565 dirty rects instead of the
+// 1bpp framebuffer, and needs a device-ui carrying the flush observer. Until
+// that lands upstream the whole path - queue, pool and input seam - compiles
+// out, so a color build that does not opt in carries none of it.
+#if HAS_SCREEN_MIRROR && HAS_TFT && defined(MESHTASTIC_MUI_MIRROR)
+#define HAS_MUI_MIRROR 1
+#else
+#define HAS_MUI_MIRROR 0
+#endif
+
 #ifndef USE_ETHERNET_DEFAULT
 #define USE_ETHERNET_DEFAULT 0
 #endif

src/graphics/ScreenMirror.cpp

@@ -40,7 +40,7 @@ void ScreenMirror::freeSnapshotLocked()
     }
     paletteSig = 0;
     paletteCount = 0;
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     if (muiPool) {
         memaudit::add("display", -(int32_t)MUI_POOL_BYTES);
         free(muiPool);
@@ -64,14 +64,13 @@ void ScreenMirror::setMirror(bool enabled)
         // Force an immediate frame so the client doesn't wait for the next
         // on-screen change.
         oneShot = true;
-#if HAS_TFT
+#if HAS_MUI_MIRROR
         if (muiRefresh)
             muiRefresh(); // MUI delivers "a frame" as a full-repaint rect burst
 #endif
     } else {
         oneShot = false;
-        freeSnapshotLocked();
-        muiOwner = nullptr;
+        freeSnapshotLocked(); // also releases the MUI pool and rect ownership
     }
     if (changed)
         LOG_INFO("Screen mirror %s", enabled ? "enabled" : "disabled");
@@ -81,7 +80,7 @@ void ScreenMirror::requestFrame()
 {
     concurrency::LockGuard g(&lock);
     oneShot = true;
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     if (muiRefresh)
         muiRefresh();
 #endif
@@ -212,7 +211,7 @@ bool ScreenMirror::copyPaletteChunk(uint32_t &clientPaletteSig, uint8_t &clientR
     return true;
 }
 
-#if HAS_TFT
+#if HAS_MUI_MIRROR
 void ScreenMirror::onMuiRect(int16_t x, int16_t y, uint16_t w, uint16_t h, const uint16_t *pixels)
 {
     uint32_t readyId = 0;
@@ -309,7 +308,7 @@ bool ScreenMirror::copyMuiChunkLocked(meshtastic_DisplayFrame &out)
 bool ScreenMirror::hasChunkFor(const void *client, uint32_t clientFrameId, uint16_t clientOffset)
 {
     concurrency::LockGuard g(&lock);
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     // One shared rect cursor means one consumer; another connection simply
     // sees no rects rather than stealing half of each frame.
     if (muiCount && (muiOwner == nullptr || muiOwner == client))
@@ -321,7 +320,7 @@ bool ScreenMirror::hasChunkFor(const void *client, uint32_t clientFrameId, uint1
 bool ScreenMirror::copyChunk(const void *client, uint32_t &clientFrameId, uint16_t &clientOffset, meshtastic_DisplayFrame &out)
 {
     concurrency::LockGuard g(&lock);
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     // MUI rects drain ahead of (and on MUI builds, instead of) mono snapshots.
     // Spike scope: the rect queue has a single consumer, not per-client cursors.
     if (muiCount) {

src/graphics/ScreenMirror.h

@@ -58,7 +58,7 @@ class ScreenMirror
     /// when the client holds the full current palette (or coloring is off).
     bool copyPaletteChunk(uint32_t &clientPaletteSig, uint8_t &clientRegionOffset, meshtastic_DisplayPalette &out);
 
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     /// MUI path: queues one LVGL dirty rect (native little-endian RGB565).
     /// Called on the LVGL thread via the device-ui flush observer; copies and returns.
     void onMuiRect(int16_t x, int16_t y, uint16_t w, uint16_t h, const uint16_t *pixels);
@@ -101,7 +101,7 @@ class ScreenMirror
     uint16_t paletteDefaultOn = 0;
     uint16_t paletteDefaultOff = 0;
 
-#if HAS_TFT
+#if HAS_MUI_MIRROR
     // MUI dirty-rect queue: FIFO rect headers over a linear pixel pool,
     // compacted whenever it drains. Spike scope: single consumer.
     struct MuiRect {
@@ -131,7 +131,7 @@ class ScreenMirror
 
 extern ScreenMirror screenMirror;
 
-#if HAS_TFT
+#if HAS_MUI_MIRROR
 /**
  * Routes a remote input event straight into device-ui's injection seam.
  * MUI builds never construct an InputBroker (Modules.cpp skips it when

src/graphics/tftSetup.cpp

@@ -12,7 +12,7 @@
 #include "graphics/driver/DisplayDriver.h"
 #include "graphics/driver/DisplayDriverConfig.h"
 #include "input/InputBroker.h"
-#if defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
 #include "input/InputDriver.h"
 #endif
 #include "util/ISpiLock.h"
@@ -321,12 +321,9 @@ class ReentrantSpiLock : public ISpiLock
 
 static ReentrantSpiLock reentrantSpiLock;
 
-#if HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
 namespace graphics
 {
-// Maps a remote input event onto device-ui's virtual LVGL devices. Note the
-// LEFT/RIGHT cross-map: the broker's codes were modeled on LVGL keys but
-// those two are swapped.
 // Reports MUI's logical panel geometry for DeviceMetadata.display. The BaseUI
 // `screen` object does not exist on MUI builds, so the dimensions come from
 // LVGL itself (already rotated to the logical orientation).
@@ -347,6 +344,9 @@ bool muiDisplayInfo(uint16_t &width, uint16_t &height, bool &hasTouch)
     return width > 0 && height > 0;
 }
 
+// Maps a remote input event onto device-ui's virtual LVGL devices. Note the
+// LEFT/RIGHT cross-map: the broker's codes were modeled on LVGL keys but
+// those two are swapped.
 bool muiInjectInputEvent(uint32_t eventCode, uint32_t kbChar, uint32_t touchX, uint32_t touchY)
 {
     if (config.display.displaymode != meshtastic_Config_DisplayConfig_DisplayMode_COLOR)
@@ -412,7 +412,7 @@ void tftSetup(void)
     I2CKeyboardScanner::setSecondaryBus(i2cProxy);
 #endif
 #ifndef ARCH_PORTDUINO
-#if HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
     // Must precede DeviceScreen::init: device-ui only builds its virtual input
     // devices (and the default focus group they need) when injection is asked for.
     InputDriver::enableInjection();
@@ -420,7 +420,7 @@ void tftSetup(void)
     deviceScreen = &DeviceScreen::create(reentrantSpiLock);
     PacketAPI::create(PacketServer::init());
     deviceScreen->init(new PacketClient);
-#if HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
     // Stream MUI's dirty rects to local clients (see graphics::ScreenMirror).
     // Gated on MESHTASTIC_MUI_MIRROR until the device-ui flush observer merges
     // (jamesarich/device-ui screen-mirror-poc); the vendored pin lacks it.

src/main.cpp

@@ -1394,7 +1394,7 @@ extern meshtastic_DeviceMetadata getDeviceMetadata()
     deviceMetadata.has_xeddsa = true;
 #endif
 
-#if HAS_TFT && HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
     // MUI owns the panel and leaves `screen` null, so ask LVGL instead.
     uint16_t muiW = 0, muiH = 0;
     bool muiTouch = false;

src/modules/AdminModule.cpp

@@ -2186,7 +2186,7 @@ void AdminModule::handleSendInputEvent(const meshtastic_AdminMessage_InputEvent
     // Wake the device if asleep
     powerFSM.trigger(EVENT_INPUT);
 
-#if HAS_SCREEN_MIRROR && defined(MESHTASTIC_MUI_MIRROR)
+#if HAS_MUI_MIRROR
     // MUI builds never construct an InputBroker (Modules.cpp skips it when
     // displaymode is COLOR), so remote input reaches the LVGL UI directly.
     if (graphics::muiInjectInputEvent(inputEvent.event_code, inputEvent.kb_char, inputEvent.touch_x, inputEvent.touch_y))