Repurposed 2026-06-20. This issue originally proposed a native BLE-GATT
dial backend to work around a BlueZ HID-over-GATT (HoG) attach failure. That
failure is no longer reproducible — on current hardware BlueZ bridges the
Ulanzi Dial cleanly (it creates /dev/input/event* nodes with a valid
keyboard descriptor), most likely fixed by a BlueZ/kernel update since the
original report (2026-06-14). With HoG working, the real remaining blocker
turned out to be evdev access + the disabled enable-toggle, which is what
this issue now tracks. The original BLE-GATT diagnosis is preserved at the
bottom as a contingency record.

Problem

On Linux the Ulanzi Dial shows "disconnected" in the mapper even though the
device is paired, connected, and presenting input nodes. Two compounding causes,
both verified on hardware:

1. The feature is off by default. UlanziDialEnabled defaults to False
   (intentionally, to avoid the macOS Input-Monitoring prompt — privacy(hid): UlanziDialMacOSManager unconditionally requests Input Monitoring permission on every macOS launch #3257), so the
   Linux backend never even scans unless the user ticks Settings → Serial →
   USB Control Surfaces → "Enable Ulanzi Dial".
2. The evdev node isn't accessible. BlueZ HoG creates the dial's
   /dev/input/event* nodes as root:input 0660. A normal AetherSDR process
   (not root, not in the input group, no uaccess ACL) cannot open()
   them. EvdevEncoderManager::findMatchingDevice() hit EACCES and
   silently continued — so even with the feature enabled and the name
   matching exactly, the dial read as disconnected with no diagnostic.

Verified on hardware

• BlueZ HoG bridges fine: the dial enumerates as Ulanzi Dial Keyboard
  (event25) + Mouse + two Ulanzi Dial nodes (HID 0005:FFF1:0082).
• It emits exactly the keycodes the decoder expects: rotation =
  KEY_VOLUMEUP/KEY_VOLUMEDOWN, buttons = KEY_PLAYPAUSE/MUTE/
  PREVIOUSSONG/NEXTSONG, chords = Ctrl+Y/Z/V/C.
• Before the fix: open("/dev/input/event25") → EACCES (user not in input,
  no uaccess). After installing a uaccess udev rule: logind applies a
  user:<me>:rw ACL automatically on connect, open() succeeds, and turning
  the dial tunes the radio (source=ulanzi-dial intent=IncrementalTune).

Fix

Linux-specific (this is a Linux-specific access defect — the cross-platform
exception; Windows/macOS HID paths unchanged):

• Detect a present-but-inaccessible dial. EvdevEncoderManager now reads the
  device name from sysfs (/sys/class/input/event*/device/name, always
  world-readable), so it recognizes the dial even when it can't open the node.
  On EACCES it emits a new accessRequired(name) signal and logs a clear
  warning instead of failing silently.
• One-click, on-demand access grant. When accessRequired fires, the Ulanzi
  Dial mapper shows a "Grant access" button that installs a uaccess udev
  rule via polkit/pkexec (KDE/GNOME auth prompt), reloads udev, and
  re-scans. Gated on actual device detection + user consent — nothing is
  installed on machines that don't have the dial.
• packaging/linux/70-ulanzi-dial.rules — the canonical rule, committed as a
  reference and for distro packagers who prefer to ship it unconditionally; it
  is not installed by the build.

Constitution

• Cross-platform principle — Linux-only code is justified (Linux-specific
  evdev access defect); Windows/macOS unchanged.
• Principle XI (demonstrate) — verified live: dial detected → permission
  granted → rotation tunes the radio.

Related

• ULANZI H100 DIAL NO CONNECT #3670 — Windows H100 "no connect" is a different root cause (the Windows
  matcher hardcodes the product string "Ulanzi Dial"; the H100 may report a
  different name). Separate matcher-broadening task, still awaiting the
  reporter's exact device string.

05 01 09 06 A1 01 85 01 05 07 19 E0 29 E7 15 00 25 01 75 01 95 08 81 02 95 01 75 08 81 03
95 05 75 01 05 08 19 01 29 05 91 02 95 01 75 03 91 03 95 06 75 08 15 00 25 FF 05 07 19 00
29 FF 81 00 C0 05 01 09 02 A1 01 85 03 09 01 A1 00 05 09 19 01 29 05 15 00 25 01 95 05 75
01 81 02 95 01 75 03 81 03 05 01 09 30 09 31 09 38 15 80 25 7F 75 08 95 03 81 06 05 0C 0A
38 02 75 08 95 01 81 06 C0 C0 05 0C 09 01 A1 01 85 02 75 10 95 01 15 01 26 FF 03 19 01 2A
FF 03 81 60 C0 06 F1 FF 09 01 A1 01 85 FC 09 02 15 00 26 FF 00 75 08 95 40 81 02 C0 06 FD
FF 09 01 A1 01 85 FB 09 02 15 00 26 FF 00 75 08 95 40 81 02 09 03 15 00 26 FF 00 75 08 95
40 91 02 C0