Notes: dual-mode ELM327 adapter, optimized-GIF transparency issue

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -89,7 +89,12 @@ Note: `scr_lvgl_init()` already calls `lv_init()`; the demo `.ino` calls it agai
 AIDA64 secondary screen (18 styles), mic spectrum, MP3 player (`/music` on SD), photo frame (`/pic`, 360×360 JPEG), MJPEG player (`/mjpeg`), weather, theme clocks, WiFi provisioning AP "My App"/12345678 + web config at device IP.
 Re-flash it with Flash Download Tool: ESP32-S3, `1.85_demo.bin` @ 0x0.
 
+## OBD adapter (user's)
+AliExpress "ELM327 Mini V2.1 Bluetooth OBD **Dual Mode** 5.1" — dual mode = Bluetooth Classic SPP **and BLE**, so the ESP32-S3 should be able to connect directly over BLE (no bridge ESP32).
+Cheap dual-mode clones typically expose BLE service `FFF0` (notify `FFF1`, write `FFF2`) — **not yet verified** on this adapter; scan it first. Adapter is powered from the car's OBD port (pin 16, 12 V).
+
 ## Gotchas / observations
+- **GIF transparency → black background:** almost all GIFs in `10-OBD-Display-2024/assets/gifs` are *optimized* (frames mark unchanged pixels transparent, disposal 1/2). LVGL 8.3's gifdec shows the screen background (black in the sketches) wherever no frame has painted yet. Fix by using un-optimized GIFs (full frames, no transparency) or a non-black screen background.
 - Display is round: corners of the 360×360 framebuffer are not visible — design UI within a 360 px circle.
 - Compiling a 13.9 MB GIF into the firmware will not fit "Huge APP" (3 MB); large media should live on SD (or in a custom partition).
 - The top-level demo `setup()` returns early if no SD card is present, before showing anything.