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

modules/capabilities/handy.nix

@@ -1,30 +1,16 @@
 {
+  flake.modules.nixos.handy = { pkgs, ... }: {
+    services.udev.packages = [
+      (pkgs.writeTextDir "lib/udev/rules.d/70-handy-keyboard.rules" ''
+        SUBSYSTEM=="input", KERNEL=="event*", ENV{ID_INPUT_KEYBOARD}=="1", TAG+="uaccess"
+      '')
+    ];
+  };
+
   flake.modules.homeManager.handy =
-    { config, pkgs, ... }:
+    { pkgs, ... }:
     let
-      settings = (pkgs.formats.json { }).generate "handy-settings.json" {
-        settings = {
-          settings_schema_version = 1;
-          selected_model = "handy-computer/nemotron-3.5-asr-streaming-0.6b-gguf/nemotron-3.5-asr-streaming-0.6b-Q8_0.gguf";
-          selected_language = "auto";
-          translate_to_english = false;
-          selected_microphone = null;
-          always_on_microphone = false;
-          push_to_talk = true;
-          paste_method = "ctrl_shift_v";
-          typing_tool = "wtype";
-          clipboard_handling = "dont_modify";
-          auto_submit = false;
-          overlay_style = "live";
-          overlay_position = "bottom";
-          post_process_enabled = false;
-          start_hidden = true;
-          autostart_enabled = false;
-          update_checks_enabled = false;
-          show_whats_new_on_update = false;
-          onboarding_completed = true;
-        };
-      };
+      python = pkgs.python3.withPackages (ps: [ ps.evdev ]);
     in
     {
       home.packages = [ pkgs.handy ];
@@ -37,10 +23,18 @@
         };
         Install.WantedBy = [ "graphical-session.target" ];
         Service = {
-          # Handy writes migrations and runtime preferences: restore the Nix baseline on start.
-          ExecStartPre = "${pkgs.coreutils}/bin/install -Dm600 ${settings} ${config.xdg.dataHome}/com.pais.handy/settings_store.json";
           ExecStart = "${pkgs.handy}/bin/handy --start-hidden";
         };
       };
+
+      systemd.user.services.handy-ptt = {
+        Unit = {
+          Description = "Handy push-to-talk key release listener";
+          PartOf = [ "graphical-session.target" ];
+          Requisite = [ "handy.service" ];
+          After = [ "handy.service" ];
+        };
+        Service.ExecStart = "${python}/bin/python ${./handy/_push_to_talk.py} ${pkgs.handy}/bin/handy";
+      };
     };
 }

modules/capabilities/handy/_push_to_talk.py

@@ -0,0 +1,48 @@
+"""Wait for release of the physical Super+D chord that launched this service."""
+
+import signal
+import subprocess
+import sys
+from contextlib import closing
+
+from evdev import InputDevice, ecodes as key, list_devices
+
+
+def held(keys):
+    return key.KEY_D in keys and bool({key.KEY_LEFTMETA, key.KEY_RIGHTMETA} & set(keys))
+
+
+def interrupted(signum, frame):
+    raise KeyboardInterrupt
+
+
+def main(handy):
+    signal.signal(signal.SIGTERM, interrupted)
+    for path in list_devices():
+        try:
+            device = InputDevice(path)
+        except OSError:
+            continue  # Devices can disappear between enumeration and opening.
+        with closing(device):
+            if not held(device.active_keys()):
+                continue
+            action = "--cancel"
+            try:
+                subprocess.run([handy, "--toggle-transcription"], check=True)
+                # A quick release may already be queued while the CLI starts.
+                if held(device.active_keys()):
+                    for event in device.read_loop():
+                        if not held(device.active_keys()):
+                            break
+                action = "--toggle-transcription"
+            finally:
+                # Disconnects, cancellation and service shutdown discard the recording.
+                subprocess.run([handy, action], check=True)
+            return
+
+
+if __name__ == "__main__":
+    try:
+        main(sys.argv[1])
+    except KeyboardInterrupt:
+        pass

modules/capabilities/handy/_push_to_talk_test.py

@@ -0,0 +1,37 @@
+"""Synthetic key-state checks; never reads a keyboard or records audio."""
+
+from unittest.mock import Mock, patch
+
+import _push_to_talk as ptt
+
+down = [ptt.key.KEY_LEFTMETA, ptt.key.KEY_D]
+
+
+def check(states, expected, error=None):
+    device = Mock()
+    device.active_keys.side_effect = states
+    device.read_loop.return_value = iter([object(), object()])
+    if error:
+        device.read_loop.side_effect = error
+    with (
+        patch.object(ptt, "list_devices", return_value=["keyboard"]),
+        patch.object(ptt, "InputDevice", return_value=device),
+        patch.object(ptt.signal, "signal"),
+        patch.object(ptt.subprocess, "run") as run,
+    ):
+        try:
+            ptt.main("handy")
+        except (OSError, KeyboardInterrupt):
+            assert error is not None
+        assert [call.args[0][1] for call in run.call_args_list] == expected
+    device.close.assert_called_once()
+
+
+check([[]], [])  # Released before the listener starts: do not record.
+check([down, []], ["--toggle-transcription", "--toggle-transcription"])
+check([down, down, down, [ptt.key.KEY_D]], ["--toggle-transcription"] * 2)
+check([down, down], ["--toggle-transcription", "--cancel"], OSError("unplugged"))
+check([down, down], ["--toggle-transcription", "--cancel"], KeyboardInterrupt())
+assert ptt.held([ptt.key.KEY_RIGHTMETA, ptt.key.KEY_D])
+assert not ptt.held([ptt.key.KEY_LEFTMETA])
+print("Push-to-talk release, repeat, disconnect and cancellation checks passed")

modules/capabilities/niri/_bindings.nix

@@ -36,19 +36,23 @@ in
   };
 
   # Dictation
-  "Mod+Shift+D" = {
+  "Mod+D" = {
     spawn = [
-      handy
-      "--toggle-transcription"
+      "systemctl"
+      "--user"
+      "start"
+      "handy-ptt.service"
     ];
     _props.repeat = false;
+    _props.hotkey-overlay-title = "Hold to Dictate";
+  };
+  "Mod+Shift+D" = {
+    spawn-sh = "systemctl --user stop handy-ptt.service && ${handy} --toggle-transcription";
+    _props.repeat = false;
     _props.hotkey-overlay-title = "Toggle Dictation";
   };
   "Mod+Ctrl+D" = {
-    spawn = [
-      handy
-      "--cancel"
-    ];
+    spawn-sh = "systemctl --user stop handy-ptt.service && ${handy} --cancel";
     _props.repeat = false;
     _props.hotkey-overlay-title = "Cancel Dictation";
   };

modules/profiles/workstation-base.nix

@@ -17,6 +17,7 @@ in
       nixosModules.network-manager
       nixosModules.nftables-firewall
       nixosModules.niri
+      nixosModules.handy
       nixosModules.notes
       nixosModules.plymouth
       nixosModules.printing