Gaze checks: the headset going on is eyes coming back

Steam's eyetracking.txt writes "HMD on" every minute or so with nobody in the
headset, and SteamVR said it was worn for 12 hours straight, so the quick check
opened about 40 times an hour at an empty headset. It now opens when SteamVR's
tracker sees eyes for 3 s after none for 3 s, and closes when they're gone 2 s.

The log reader also drops repeated "HMD on" lines and sub-second offs, so
lessons stop counting as from an older wear every minute.

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

gaze/gazecheck.py

@@ -2,12 +2,14 @@
 (gaze/panel/ft-gazepanel; ft-gazed runs it). Every kind is made of dots shown at head-relative
 directions: look at each one.
 
-  quick   one dot in the middle of your view. It opens DON_DELAY after the headset goes on
-          (SteamVR's eye tracking log says when), when our own tracker asks for a click (its
-          "reseat": the headset may sit differently on your face now), at most once every
-          QUICK_COOLDOWN, and on "quickcal" (Frametop Input Settings, or a mouse button or key
-          combination mapped to Gaze quick check). Ignored, it closes after QUICK_TIMEOUT and
-          changes nothing.
+  quick   one dot in the middle of your view. It opens when the headset goes on: eyes seen
+          for DON_DELAY after none for AWAY_MIN (SteamVR's tracker's variance for an eye under
+          EYE_LOST). SteamVR's "HMD on" can't say: it repeats every minute or so, and it can
+          stay on for hours with nobody in the headset. It also opens when our own tracker asks
+          for a click (its "reseat": the headset may sit differently on your face now), at most
+          once every QUICK_COOLDOWN, and on "quickcal" (Frametop Input Settings, or a mouse
+          button or key combination mapped to Gaze quick check). Ignored, it closes after
+          QUICK_TIMEOUT and changes nothing.
   five    the middle and four around it, when the first FIVE_COUNT lessons after a quick check
           were all over FIVE_LIMIT degrees off: the quick check didn't fix it.
   full    the calibration, as the gaze probe's: three rounds, dark, medium and bright (pupil
@@ -46,7 +48,7 @@ import sys
 import time
 from pathlib import Path
 
-from gazecal import DEFAULT_MODEL, STATE, steady_samples
+from gazecal import DEFAULT_MODEL, EYE_LOST, STATE, steady_samples
 
 REPO = Path(__file__).resolve().parents[1]
 PANEL_PROG = REPO / "gaze" / "build" / "ft-gazepanel"
@@ -66,7 +68,9 @@ ACCEPT_SPREAD = 2.5    # degrees: a capture asked for (calaccept) takes this muc
 DOT_TIMEOUT = 8.0      # seconds a dot of five or full waits; then it's skipped
 QUICK_TIMEOUT = 6.0
 QUICK_COOLDOWN = 120.0
-DON_DELAY = 3.0
+DON_DELAY = 3.0        # seconds of eyes after AWAY_MIN without: the headset went on
+AWAY_MIN = 3.0
+EYES_GONE = 2.0        # seconds without eyes that close a check: the headset came off
 FIVE_LIMIT = 2.0
 FIVE_COUNT = 3
 DONE_PAUSE = 0.35      # seconds the filled dot shows before the next
@@ -151,8 +155,9 @@ class Checks:
         self.gaze_heard = 0.0
         self.want_full_until = 0.0  # gaze mode came on before the tracker said whether it's calibrated
         self.last_quick = 0.0
-        self.worn_seen = svc.steam.worn()
-        self.don_at = None
+        self.seen_at = 0.0       # eyes last seen (SteamVR's tracker's variance for them, "unc")
+        self.away = True         # no eyes for AWAY_MIN: their coming back is the headset going on
+        self.back_since = None
         self.reseat_seen = False
         self.after_quick = None
         self.panel_proc = None
@@ -254,9 +259,12 @@ class Checks:
             return True
         return svc.models[svc.source].samples > 0
 
+    def eyes_seen(self, within=1.0):
+        return time.monotonic() - self.seen_at < within
+
     def can_run(self):
-        """The headset is on and the tracker is sending."""
-        return self.svc.steam.wearing() is not False and time.monotonic() - self.svc.last_sample < 2
+        """Someone's in the headset and the tracker is sending."""
+        return self.eyes_seen() and time.monotonic() - self.svc.last_sample < 2
 
     def on_gaze_on(self):
         cal = self.calibrated()
@@ -323,6 +331,11 @@ class Checks:
         c["run"], c["accept"], c["done_at"] = [], False, None
 
     def on_sample(self, s):
+        unc = (s["src"].get("mmap1") or {}).get("unc")
+        if unc and min(unc) <= EYE_LOST:
+            self.seen_at = time.monotonic()
+            if self.away and self.back_since is None:
+                self.back_since = self.seen_at
         c = self.check
         if not c or c["done_at"]:
             return
@@ -575,7 +588,7 @@ class Checks:
             else:
                 self.advance()
             return
-        if self.svc.steam.wearing() is False:
+        if not self.eyes_seen(EYES_GONE):
             self.close("the headset came off")
             return
         if c["done_at"]:
@@ -602,17 +615,13 @@ class Checks:
                 self.want_full_until = 0.0
                 if cal is False and self.gaze_on:
                     self.start("full", "gaze mode came on without a calibration")
-        worn = svc.steam.worn()
-        if worn and worn != self.worn_seen:
-            self.worn_seen = worn
-            self.don_at = worn + DON_DELAY
-        # Both wait for the tracker to send (it takes a moment after the headset goes on).
-        if self.don_at and time.time() >= self.don_at:
-            if self.can_run():
-                self.don_at = None
-                self.auto_quick("the headset went on")
-            elif time.time() > self.don_at + 20:
-                self.don_at = None
+        if not self.eyes_seen(AWAY_MIN):
+            self.away, self.back_since = True, None
+        elif self.back_since is not None and not self.eyes_seen():
+            self.back_since = None  # gone again before DON_DELAY
+        elif self.back_since is not None and now - self.back_since >= DON_DELAY:
+            self.away, self.back_since = False, None
+            self.auto_quick("the headset went on")
         if svc.kind == "own" and now - svc.own_at < 5:
             reseat = any(e.get("reseat") for e in (svc.own.get("eyes") or {}).values())
             if not reseat:
@@ -623,7 +632,7 @@ class Checks:
 
     def status(self):
         c = self.check
-        st = {"check": None, "gaze_mode": self.gaze_on, "calibrated": self.calibrated(),
+        st = {"check": None, "gaze_mode": self.gaze_on, "calibrated": self.calibrated(), "eyes": self.eyes_seen(),
               "panel": self.panel_proc is not None,
               "last_quick_s": round(time.monotonic() - self.last_quick) if self.last_quick else None}
         if c: