From d3286ef3b850570c2bf71f8bb5e62ac1b8ac5c0a Mon Sep 17 00:00:00 2001
From: Hermes Agent <hermes@local>
Date: Fri, 18 Sep 2026 13:02:58 +0200
Subject: [PATCH] Block all keyboard (except ESC) and all mouse input via
 WH_MOUSE_LL; tagged idle nudge passes through own hook; hint updated

---
 black_screen_dim.py | 47 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 7 deletions(-)

diff --git a/black_screen_dim.py b/black_screen_dim.py
index 3d04745..0298f19 100644
--- a/black_screen_dim.py
+++ b/black_screen_dim.py
@@ -245,6 +245,8 @@ if sys.platform == "win32":
     WM_KEYDOWN_LL = 0x0100
     VK_ESCAPE = 0x1B
     WH_KEYBOARD_LL = 13
+    WH_MOUSE_LL = 14
+    MOUSE_NUDGE_TAG = 0x42424242
     DT_CENTER = 0x00000001
     DT_VCENTER = 0x00000004
     DT_SINGLELINE = 0x00000020
@@ -302,6 +304,15 @@ if sys.platform == "win32":
             ("dwExtraInfo", ULONG_PTR),
         ]
 
+    class MSLLHOOKSTRUCT(ctypes.Structure):
+        _fields_ = [
+            ("pt", wt.POINT),
+            ("mouseData", wt.DWORD),
+            ("flags", wt.DWORD),
+            ("time", wt.DWORD),
+            ("dwExtraInfo", ULONG_PTR),
+        ]
+
     # --- prototypes (64-bit safe) ---
     user32.EnumDisplayMonitors.argtypes = [wt.HDC, ctypes.POINTER(wt.RECT), MONITORENUMPROC, wt.LPARAM]
     user32.EnumDisplayMonitors.restype = wt.BOOL
@@ -401,7 +412,7 @@ if sys.platform == "win32":
     _hwnds = []
     _hint_active = True
     _hook_id = None
-    _hint_text = "ESC - exit"
+    _hint_text = "ESC - exit  |  mouse/keyboard locked"
 
     def enum_monitor_rects():
         rects = []
@@ -456,15 +467,28 @@ if sys.platform == "win32":
         return user32.DefWindowProcW(hwnd, msg, wparam, lparam)
 
     def _low_level_keyboard_proc(nCode, wParam, lParam):
-        if nCode >= 0 and wParam == WM_KEYDOWN_LL:
+        if nCode >= 0:
             kb = ctypes.cast(lParam, ctypes.POINTER(KBDLLHOOKSTRUCT)).contents
-            if kb.vkCode == VK_ESCAPE:
+            if kb.vkCode == VK_ESCAPE and wParam == WM_KEYDOWN_LL:
                 LOG.info("ESC pressed -> exit")
                 user32.PostQuitMessage(0)
+            return 1  # block ALL keyboard input while the overlay is up
         return user32.CallNextHookEx(_hook_id, nCode, wParam, lParam)
 
+    _mouse_hook_id = None
+
+    def _low_level_mouse_proc(nCode, wParam, lParam):
+        if nCode >= 0:
+            ms = ctypes.cast(lParam, ctypes.POINTER(MSLLHOOKSTRUCT)).contents
+            # allow only our own idle-keepalive nudge (tagged dwExtraInfo);
+            # block every real mouse event (moves, clicks, wheel)
+            if int(ms.dwExtraInfo) == MOUSE_NUDGE_TAG:
+                return user32.CallNextHookEx(_mouse_hook_id, nCode, wParam, lParam)
+            return 1
+        return user32.CallNextHookEx(_mouse_hook_id, nCode, wParam, lParam)
+
     def run_overlay():
-        global _hwnds, _hook_id
+        global _hwnds, _hook_id, _mouse_hook_id
         # Per-monitor V2 DPI awareness: device-coord rects map 1:1 to each
         # monitor regardless of mixed DPI / where the primary sits.
         if shcore is not None:
@@ -522,11 +546,16 @@ if sys.platform == "win32":
         for _ in range(12):
             if user32.ShowCursor(False) < 0:
                 break
-        # global ESC hook
+        # global ESC hook (also blocks all other keyboard input)
         kb_proc = HOOKPROC(_low_level_keyboard_proc)
         _hook_id = user32.SetWindowsHookExW(WH_KEYBOARD_LL, kb_proc, hinst, 0)
         if not _hook_id:
             LOG.warning("SetWindowsHookExW failed: %d", kernel32.GetLastError())
+        # global mouse hook: block all real mouse input
+        mouse_proc = HOOKPROC(_low_level_mouse_proc)
+        _mouse_hook_id = user32.SetWindowsHookExW(WH_MOUSE_LL, mouse_proc, hinst, 0)
+        if not _mouse_hook_id:
+            LOG.warning("mouse hook failed: %d", kernel32.GetLastError())
 
         # keep display awake while running (prevents monitor standby, which would
         # make ESC's first press get swallowed by the wake and a ~30s DDC hang)
@@ -542,8 +571,9 @@ if sys.platform == "win32":
         def _activity():
             while not _activity_stop.wait(30):
                 try:
-                    user32.mouse_event(0x0001, 1, 0, 0, None)
-                    user32.mouse_event(0x0001, 0xFFFFFFFF, 0, 0, None)
+                    tag = ctypes.c_void_p(MOUSE_NUDGE_TAG)
+                    user32.mouse_event(0x0001, 1, 0, 0, tag)
+                    user32.mouse_event(0x0001, 0xFFFFFFFF, 0, 0, tag)
                 except Exception:
                     pass
 
@@ -557,6 +587,9 @@ if sys.platform == "win32":
 
         if _hook_id:
             user32.UnhookWindowsHookEx(_hook_id)
+        if _mouse_hook_id:
+            user32.UnhookWindowsHookEx(_mouse_hook_id)
+            _mouse_hook_id = None
         _activity_stop.set()
         at.join(timeout=1)
         kernel32.SetThreadExecutionState(ES_CONTINUOUS)  # allow display sleep again