Wispr Flow + MX Ergo Push-to-Talk

Goal: press and hold the top-front button (▲) on the MX Ergo trackball to push-to-talk in Wispr Flow.

Current state: Not working. Karabiner is set up correctly, but Logi Options+ still owns the front button and won't release it. See findings doc for next-session options.

Files

• 2026-04-29-session-findings.md — most recent session. What the prior debug log got wrong, real root cause, what's still broken, options to try next.
• wispr-mouse-button-debug-log.md — original chain-of-attempts log (10 attempts). Some claims in here turned out to be wrong; cross-check against the findings doc.
• wispr-mouse-button-setup.md — original handoff doc. Diagnosis was incomplete — DriverKit was already activated, the real issue was BTM background-item state.

Key facts

• Karabiner v15 grabber lives inside Karabiner-Elements Privileged Daemons v2.app, NOT a standalone karabiner_grabber binary.
• macOS BTM toggles can desync from System Settings UI. The fix is OFF→ON cycle on System Settings → General → Login Items & Extensions → App Background Activity items.
• Wispr Flow's shortcut field is keyboard-only despite docs claiming Mouse 4–10 support.
• Logi Options+ on MX Ergo: "Forward" sends Logi pipeline (not raw HID); "Do nothing" silently consumes event; "Keyboard shortcut" rejects synthesized keystrokes.
• The only proven way to get raw HID button5 from the front button is to kill logioptionsplus_agent entirely.