Open the app with the Predator key, bump to 1.3.0

The Predator key sends keyboard usage 0xC9, which lies outside the
logical range the keyboard declares, so the kernel never emits an input
event for it. It is also reported on vendor report 4 of USB interface 2
(04 81 ff on press). predatord now listens there and opens the app in
the active graphical session via the user's systemd manager.

The action is configurable on the System page: open the app, switch to
the next performance mode, or do nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

predator_control/__init__.py

@@ -2,7 +2,7 @@
 
 import os
 
-__version__ = "1.2.0"
+__version__ = "1.3.0"
 
 APP_NAME = "Predator Control"
 RUN_DIR = os.environ.get("PREDATOR_CONTROL_RUN_DIR", "/run/predator-control")

predator_control/daemon.py

@@ -25,6 +25,7 @@ import traceback
 from . import CONFIG_DIR, CONFIG_PATH, SOCKET_PATH, STATE_PATH, __version__
 from . import hardware as hw
 from . import updater
+from .hotkey import HotkeyListener, launch_in_session
 from .keyboard import EFFECTS, NUM_CELLS, Keyboard
 
 DEFAULT_CONFIG = {
@@ -49,6 +50,7 @@ DEFAULT_CONFIG = {
     "battery": {"limit": None},   # None = leave the firmware state alone
     "keyboard_presets": {},
     "updates": {"auto_check": True, "interval_hours": 6},
+    "predator_key": "open",       # open | cycle_profile | none
 }
 
 
@@ -277,6 +279,18 @@ class Daemon:
             self._last_try = time.time()
             self.check_update_async()
 
+    def predator_key(self):
+        action = self.config.get("predator_key", "open")
+        if action == "open":
+            if not launch_in_session(["predator-control"]):
+                log("Predator key: no active graphical session to open the app in")
+        elif action == "cycle_profile":
+            with self.lock:
+                ch = hw.profile_choices()
+                cur = hw.get_profile()
+                nxt = ch[(ch.index(cur) + 1) % len(ch)] if cur in ch else ch[0]
+                self._try("profile", hw.set_profile, nxt)
+
     def loop(self):
         while True:
             try:
@@ -328,6 +342,12 @@ class Daemon:
                 merge(self.config["updates"], {k: a[k] for k in ("auto_check", "interval_hours") if k in a})
                 self.save_config()
                 return {}
+            if cmd == "set_predator_key":
+                if a["action"] not in ("open", "cycle_profile", "none"):
+                    raise ValueError("unknown action")
+                self.config["predator_key"] = a["action"]
+                self.save_config()
+                return {}
             if cmd == "restore":
                 self.restore()
                 return {}
@@ -511,6 +531,7 @@ def main():
     signal.signal(signal.SIGTERM, lambda *_: (server.server_close(), sys.exit(0)))
     signal.signal(signal.SIGUSR1, lambda *_: threading.Thread(target=lambda: (d.lock.acquire(), d.restore(), d.lock.release())).start())
     threading.Thread(target=d.loop, daemon=True).start()
+    HotkeyListener(d.predator_key, log).start()
     server.serve_forever()
 
 

predator_control/gui/app.py

@@ -674,6 +674,19 @@ class SystemPage(Page):
         self.fw_card.body.addWidget(_muted("Values are stored in the laptop firmware (EC/BIOS)."))
         self.lay.addWidget(self.fw_card)
 
+        key = Card("Predator key")
+        kr = QHBoxLayout()
+        kr.addWidget(QLabel("When the Predator key is pressed"))
+        self.key_action = QComboBox()
+        for val, text in (("open", "Open Predator Control"), ("cycle_profile", "Switch to the next performance mode"),
+                          ("none", "Do nothing")):
+            self.key_action.addItem(text, val)
+        self.key_action.activated.connect(lambda: win.backend.run("set_predator_key", action=self.key_action.currentData()))
+        kr.addWidget(self.key_action)
+        kr.addStretch(1)
+        key.body.addLayout(kr)
+        self.lay.addWidget(key)
+
         upd = Card("Updates")
         self.upd_head = QLabel("")
         self.upd_head.setObjectName("big")
@@ -782,6 +795,8 @@ class SystemPage(Page):
             err = ("\n\n⚠ %s" % st["update_error"]) if st.get("update_error") else ""
             self.upd_text.setText("Installed version %s · last check %s%s%s" % (st.get("version"), when, err, extra))
             self.upd_install.hide()
+        if not self.key_action.view().isVisible():
+            self.key_action.setCurrentIndex(max(0, self.key_action.findData(st["config"].get("predator_key", "open"))))
         self.upd_auto.setChecked(st["config"].get("updates", {}).get("auto_check", True))
         a = st["available"]
         yes = lambda v: "✔" if v else "✘"

predator_control/hotkey.py

@@ -0,0 +1,83 @@
+"""Predator key listener.
+
+The PH16-71 Predator key produces no input event: its keyboard usage (0xC9) is outside the
+range the keyboard declares, so the kernel drops it. The key is also reported on the
+vendor report 4 of USB interface 2: `04 81 ff` on press, `04 00 00` on release.
+"""
+
+import os
+import pwd
+import select
+import subprocess
+import threading
+import time
+
+from .keyboard import HOTKEY_INTERFACE, find_hidraw
+
+PRESS_PREFIX = b"\x04\x81"
+
+
+def active_session_user():
+    """(uid, name) of the active graphical session, or None."""
+    out = subprocess.run(["loginctl", "list-sessions", "--no-legend"],
+                         capture_output=True, text=True).stdout
+    for line in out.splitlines():
+        sid = line.split()[0] if line.split() else None
+        if not sid:
+            continue
+        props = dict(l.split("=", 1) for l in subprocess.run(
+            ["loginctl", "show-session", sid, "-p", "Active", "-p", "Type", "-p", "User", "-p", "Name"],
+            capture_output=True, text=True).stdout.splitlines() if "=" in l)
+        if props.get("Active") == "yes" and props.get("Type") in ("wayland", "x11"):
+            return int(props["User"]), props["Name"]
+    return None
+
+
+def launch_in_session(args):
+    sess = active_session_user()
+    if not sess:
+        return False
+    uid, name = sess
+    # runs in the user's systemd manager, which carries WAYLAND_DISPLAY/DISPLAY on Plasma
+    r = subprocess.run(["systemd-run", "--quiet", "--user", "--machine=%s@.host" % name, "--collect",
+                        "--unit=predator-control-launch-%d" % int(time.time() * 1000)] + args,
+                       capture_output=True, text=True)
+    return r.returncode == 0
+
+
+class HotkeyListener(threading.Thread):
+    def __init__(self, on_press, log):
+        super().__init__(daemon=True)
+        self.on_press = on_press
+        self.log = log
+
+    def run(self):
+        while True:
+            path = find_hidraw(HOTKEY_INTERFACE)
+            if not path:
+                time.sleep(5)
+                continue
+            try:
+                fd = os.open(path, os.O_RDONLY)
+            except OSError as e:
+                self.log("hotkey: cannot open %s: %s" % (path, e))
+                time.sleep(5)
+                continue
+            last = 0.0
+            try:
+                while True:
+                    select.select([fd], [], [])
+                    data = os.read(fd, 64)
+                    if not data:
+                        break
+                    if data.startswith(PRESS_PREFIX) and time.monotonic() - last > 0.4:
+                        last = time.monotonic()
+                        try:
+                            self.on_press()
+                        except Exception as e:
+                            self.log("hotkey: %s" % e)
+            except OSError:
+                pass  # device vanished (suspend/replug) – reopen
+            finally:
+                os.close(fd)
+            time.sleep(1)

predator_control/keyboard.py

@@ -13,6 +13,7 @@ import threading
 ACER_VID = 0x04F2
 KNOWN_PIDS = (0x0117, 0x011A)
 LED_INTERFACE = 3
+HOTKEY_INTERFACE = 2   # vendor report 4 carries the Predator key
 NUM_CELLS = 128
 
 OP_BEGIN = 0x88
@@ -57,7 +58,7 @@ def checksum(body7):
     return (0xFF - (sum(body7) & 0xFF)) & 0xFF
 
 
-def find_hidraw():
+def find_hidraw(interface=LED_INTERFACE):
     """Path of the hidraw node of the LED interface, or None."""
     for node in sorted(glob.glob("/sys/class/hidraw/hidraw*")):
         try:
@@ -76,7 +77,7 @@ def find_hidraw():
         devpath = os.path.realpath(os.path.join(node, "device"))
         # .../1-7:1.3/0003:04F2:011A.0004  -> interface number from the parent
         iface = os.path.basename(os.path.dirname(devpath)).rsplit(".", 1)[-1]
-        if iface == str(LED_INTERFACE):
+        if iface == str(interface):
             return "/dev/" + os.path.basename(node)
     return None