fix: ptt auto-detect falls back to toggle mode

Textual does not expose key-release events, so KittyPtt
hold-mode never received key_up and stayed transmitting.
Auto-detect now tries evdev first, then falls back to
toggle (press-on/press-off). Default mode changed to toggle.

docs/USAGE.md

@@ -18,8 +18,8 @@ tuimble --host mumble.example.com --user myname
 
 ## Push-to-Talk Modes
 
-- **hold** — hold key to transmit, release to stop (default)
-- **toggle** — press to start, press again to stop
+- **toggle** — press to start, press again to stop (default)
+- **hold** — hold key to transmit, release to stop (requires evdev)
 
 ## Configuration
 

src/tuimble/app.py

@@ -410,18 +410,15 @@ class TuimbleApp(App):
 
     def on_key(self, event: events.Key) -> None:
         """Handle PTT key events."""
-        ptt_key = self._config.ptt.key
+        if event.key != self._config.ptt.key:
+            return
 
-        if isinstance(self._ptt, KittyPtt):
-            if event.key == ptt_key:
-                is_release = getattr(event, "key_type", None)
-                if is_release == "release":
-                    self._ptt.key_up()
-                else:
-                    self._ptt.key_down()
-        elif isinstance(self._ptt, TogglePtt):
-            if event.key == ptt_key:
-                self._ptt.toggle()
+        if isinstance(self._ptt, TogglePtt):
+            self._ptt.toggle()
+        elif isinstance(self._ptt, KittyPtt):
+            # Kitty hold-mode requires key-release events that Textual
+            # does not expose; kept for explicit backend="kitty" only.
+            self._ptt.key_down()
 
     def _on_ptt_change(self, transmitting: bool) -> None:
         self._audio.capturing = transmitting

src/tuimble/config.py

@@ -29,7 +29,7 @@ class AudioConfig:
 @dataclass
 class PttConfig:
     key: str = "f4"
-    mode: str = "hold"  # hold | toggle
+    mode: str = "toggle"  # toggle | hold (hold requires evdev)
     backend: str = "auto"  # auto | kitty | evdev | toggle
 
 

src/tuimble/ptt.py

@@ -139,6 +139,12 @@ def detect_backend(callback: Callback, preference: str = "auto") -> PttBackend:
     if preference == "toggle":
         return TogglePtt(callback)
 
-    # auto: try kitty first (will be validated at runtime by the app),
-    # then evdev, then toggle
-    return KittyPtt(callback)
+    # auto: Textual does not expose key-release events, so kitty
+    # hold-mode is not viable.  Try evdev, fall back to toggle.
+    try:
+        import evdev as _evdev  # noqa: F811
+
+        _ = _evdev.list_devices()
+        return EvdevPtt(callback)
+    except Exception:
+        return TogglePtt(callback)

tests/test_config.py

@@ -8,7 +8,7 @@ def test_default_config():
     assert cfg.server.host == "localhost"
     assert cfg.server.port == 64738
     assert cfg.audio.sample_rate == 48000
-    assert cfg.ptt.mode == "hold"
+    assert cfg.ptt.mode == "toggle"
 
 
 def test_server_config():