fix: carry LED segment mask to GUI preview via FrameSent

src/trcc/core/commands/led.py

@@ -320,6 +320,7 @@ def execute(self, app: App) -> LedColorsResult:
             # device (LCD carries a surface; LED carries the colors).
             app.events.publish(FrameSent(
                 key=self.key, bytes_sent=len(colors), display_colors=colors,
+                mask=list(mask),
             ))
         return LedColorsResult(
             ok=ok, key=self.key, colors=colors,

src/trcc/core/events.py

@@ -61,6 +61,10 @@ class FrameSent(Event):
     # LCD (one render → FrameSent → handle_frame → preview), not a parallel
     # one.  Empty for LCD / pure-bytes sends.
     display_colors: list = field(default_factory=list)
+    # LED segment mask (list of bool) — determines which LEDs are
+    # lit vs off.  Carried alongside display_colors so the GUI preview
+    # accurately mirrors the physical hardware for segment-display styles.
+    mask: list = field(default_factory=list)
 
 
 @dataclass(frozen=True, slots=True)

src/trcc/ui/gui/led_handler.py

@@ -329,9 +329,10 @@ def _on_test_mode_changed(self, on: bool) -> None:
     def handle_frame(self, image: Any) -> None:
         """Receive tick result — update LED color display on the panel."""
         display_colors = image.get('display_colors') if isinstance(image, dict) else None
+        display_mask = image.get('mask') if isinstance(image, dict) else None
         log.debug("handle_frame: active=%s colors=%s",
                   self._active, len(display_colors) if display_colors else None)
         if not self._active:
             return
         if display_colors is not None:
-            self._panel.set_led_colors(display_colors)
+            self._panel.set_led_colors(display_colors, display_mask)

src/trcc/ui/gui/trcc_app.py

@@ -511,10 +511,11 @@ def _on_bus_frame_sent(self, event: Any) -> None:
         # FrameSent → handle_frame seam (the device's render IS the preview).
         surface = getattr(event, "surface", None)
         colors = getattr(event, "display_colors", None)
+        mask = getattr(event, "mask", None)
         if surface is not None:
             handler.handle_frame(surface)
         elif colors:
-            handler.handle_frame({"display_colors": list(colors)})
+            handler.handle_frame({"display_colors": list(colors), "mask": list(mask) if mask else None})
         else:
             handler.rebuild_preview()
 

src/trcc/ui/gui/uc_led_control.py

@@ -859,9 +859,11 @@ def initialize(self, style_id: int, segment_count: int,
         elif is_lf11:
             self._populate_disk_identity()
 
-    def set_led_colors(self, colors: list[tuple[int, int, int]]) -> None:
+    def set_led_colors(self, colors: list[tuple[int, int, int]], mask: list[bool] | None = None) -> None:
         """Update LED preview from controller tick."""
         self._preview.set_colors(colors)
+        if mask is not None:
+            self._preview.set_mask(mask)
 
     def set_status(self, text: str) -> None:
         """Update status text."""

src/trcc/ui/gui/uc_screen_led.py

@@ -500,6 +500,13 @@ def set_colors(self, colors: list[tuple[int, int, int]]) -> None:
             self._colors.append((0, 0, 0))
         self.update()
 
+    def set_mask(self, mask: list[bool]) -> None:
+        """Update LED on/off mask from controller tick."""
+        self._is_on = list(mask[:len(self._is_on)])
+        while len(self._is_on) < len(self._positions):
+            self._is_on.append(False)
+        self.update()
+
     def set_segment_on(self, index: int, on: bool) -> None:
         """Toggle an individual segment."""
         if 0 <= index < len(self._is_on):
@@ -637,6 +644,8 @@ def _paint_led_rects(self, painter: QPainter) -> None:
         for i, pos in enumerate(self._positions):
             if i >= len(self._colors):
                 break
+            if i < len(self._is_on) and not self._is_on[i]:
+                continue
             r, g, b = self._colors[i]
             if r == 0 and g == 0 and b == 0:
                 continue