Merge branch gaze-games (PR #13, narrowed) into experimental

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

gaze/ft-gaze.cpp

@@ -479,9 +479,24 @@ int main(int argc, char **argv) {
     double lastEmit = 0;
     int actionErrors = 0;
     vr::EVRInputError lastActionError = vr::VRInputError_None;
+    // During a VR game, SteamVR's gaze action is left alone. With ft-gaze reading the eyes, SteamVR
+    // restarted its eye tracker every 10 s or so in a game, as if the headset came off, and each
+    // restart took input focus from the game: Beat Saber paused (PR #13). Of what ft-gaze reads,
+    // only the action reaches SteamVR (the mmap and our tracker are files), so gaze still works
+    // over the dashboard. Games are told apart the way ft-screens does it, by the scene app.
+    bool inGame = false;
+    double nextGameCheck = 0;
 
     while (true) {
         const double now = NowRaw();
+        if (now >= nextGameCheck) {
+            nextGameCheck = now + 0.5;
+            const bool game = vr::VRApplications()->GetCurrentSceneProcessId() != 0;
+            if (game != inGame)
+                std::fprintf(stderr, "ft-gaze: %s\n",
+                             game ? "a VR game is running: SteamVR's gaze action left alone" : "the VR game ended");
+            inGame = game;
+        }
         vr::TrackedDevicePose_t hp;
         sys->GetDeviceToAbsoluteTrackingPose(vr::TrackingUniverseStanding, 0, &hp, 1);
         if (hp.bPoseIsValid) history.Add(now, hp.mDeviceToAbsoluteTracking);
@@ -502,6 +517,7 @@ int main(int argc, char **argv) {
             // SteamVR's action: a room-space origin and fixation point, turned into the head
             // frame so every source reports the same kind of angles.
             std::string action = "{\"ok\":0}";
+            if (!inGame) {
                 vr::VRActiveActionSet_t active{};
                 active.ulActionSet = set;
                 active.nPriority = vr::k_nActionSetOverlayGlobalPriorityMin;
@@ -521,6 +537,7 @@ int main(int argc, char **argv) {
                                  int(e.bValid));
                     lastActionError = ae;
                 }
+            }
 
             std::string m1 = "{\"ok\":0}", m2 = m1, left = m1, right = m1, eye = "null";
             if (haveMmap) {