feat: add hold-to-talk listener and restore Handy-managed preferences

docs/constellation-work.md

@@ -119,15 +119,17 @@ reports are not a fresh comparison with this baseline.
 ## Open choices and next discussion
 
 Dictation: plain local transcription is selected; rambling cleanup is deferred.
-Handy preferences are Nix-owned in `modules/capabilities/handy.nix`: Nemotron
-Streaming 3.5, automatic language detection, default microphone, Live overlay at
-the bottom, Ctrl+Shift+V paste through wtype, preserved clipboard, manual submission
-and no cloud processing. Other preferences use pinned app defaults. A user service
-copies the baseline into Handy's writable store on each start, allowing migrations
-while resetting GUI edits. Models/recordings stay outside Nix; the selected model
-is already downloaded on Zenith. Other hosts still need model provisioning.
-Super+Shift+D toggles; Super+Ctrl+D cancels. Super+D push-to-talk awaits the user's
-decision about a keyboard listener: Niri 26.04 has no key-release bindings.
+Handy preferences are application-owned again: the Nix settings generator and
+startup reset are removed. The existing settings file is left untouched.
+Nix installs Handy/wtype and runs Handy as a graphical-session user service.
+Super+D launches a short-lived Python/evdev listener: hold to record, release D
+or Super to finish. Both keys must be on the same keyboard. Niri owns the shortcut
+and disables repeat; no persistent keyboard logger or exclusive input grab runs.
+A udev uaccess rule grants the active local user access to keyboard event devices.
+Super+Shift+D toggles; Super+Ctrl+D cancels. Both stop any active hold listener
+before issuing their Handy command, preventing a later release from restarting
+recording. Begin push-to-talk from idle: Handy exposes toggles, not idempotent
+start/stop commands. Niri 26.04 itself has no key-release bindings.
 Noctalia suppresses microphone activity popups/indicators; camera and screen-sharing
 indications remain. Automatic paste and live capture need interactive checks.
 
@@ -139,9 +141,11 @@ and Vulkan batch mode (156 ms inference, 420 ms load). This checks model inferen
 not live capture/stop/cancel. No new audio was recorded. Switching to CPU is not a
 confirmed fix. After activation, retry live recording and stopping, and inspect
 the service logs if it hangs.
-Verification: formatting, flake evaluation, both workstation builds and whitespace
-checks passed. Handy loaded the generated settings in an isolated data directory
-without settings parse errors. System activation remains user-owned and pending.
+Synthetic listener checks cover release during startup, repeat, modifier-first
+release, device disconnect and cancellation, without live input/audio access.
+System activation and an interactive hold/release trial remain user-owned.
+Formatting, flake evaluation, both workstation builds, synthetic listener checks
+and whitespace checking passed. No live input listener or microphone was started.
 
 The focus is the broader environment, not further API/database polish. Candidate
 areas remain places/ownership, navigation/interaction, human/agent collaboration,