Ask for one look at a centre dot after the headset was off

With the Own tracker, the probe polls its status each second. After the headset was off
(or the tracker restarted), it shows one dot at the centre until you look at it and press
(S skips): that click resets both eyes' shifts, so the first real clicks aren't 10-17
degrees off. The screen-to-direction geometry the calibration used is shared with it.

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

gaze/probe/ft-gazeprobe

@@ -458,6 +458,8 @@ class Probe(Adw.ApplicationWindow):
 
         self.models = {s: Correction() for s in SOURCES}
         self.own = OwnTracker()
+        self.reseat_check = False    # showing the one-dot check after the headset was off
+        self.reseat_skipped = False  # S skipped this one
         self.live = {s: LiveCorrection() for s in SOURCES}
         self.steam = SteamEyeLog()
         self.steam.poll()
@@ -988,6 +990,10 @@ class Probe(Adw.ApplicationWindow):
         if keyval in (Gdk.KEY_s, Gdk.KEY_S) and self.calib:
             self.calib_skip()
             return True
+        if keyval in (Gdk.KEY_s, Gdk.KEY_S) and self.reseat_check:
+            self.reseat_check, self.reseat_skipped = False, True
+            self.area.queue_draw()
+            return True
         if keyval == Gdk.KEY_Escape:
             if self.calib or self.test:
                 self.calib = self.test = None
@@ -1029,9 +1035,60 @@ class Probe(Adw.ApplicationWindow):
         if self.steam.poll():
             self.on_status("SteamVR's eye tracker just started again: its own calibration started over, "
                            "so the raw gaze may have moved")
+        self.poll_own()
         self.update_stats()
         return True
 
+    def poll_own(self):
+        """With the Own tracker: after the headset was off (or the tracker restarted), its
+        next click starts each eye's shift over, and until then the first clicks can be
+        10-17 degrees off (frame-eyes, session 5). So ask for one look at a centre dot first,
+        as Varjo's headsets do each time they're put on."""
+        if self.source != "own" or self.calib or self.capture:
+            return
+        reply = self.own.ask("status")
+        if reply.startswith("fail"):
+            return
+        st = json.loads(reply)
+        pending = bool(st.get("calibration")) and any(e.get("reseat") for e in st["eyes"].values())
+        if not pending:
+            self.reseat_skipped = False
+        check = pending and not self.reseat_skipped
+        if check != self.reseat_check:
+            self.reseat_check = check
+            self.area.queue_draw()
+
+    def reseat_press(self):
+        """The press on the check dot: a click there teaches both eyes' shifts at once."""
+        if not self.recent:
+            return
+        t_end = self.recent[-1]["t"]
+        w, h = self.canvas_size()
+        d = self.screen_direction([smp for smp in self.recent if smp["t"] >= t_end - 0.6], (w / 2, h / 2))
+        if d is None:
+            self.on_status("no gaze samples on this screen: look at the dot and press again")
+            return
+        reply = self.own.ask(f"click {t_end:.6f} {d[0]:.4f} {d[1]:.4f}")
+        if reply.startswith("ok"):
+            self.reseat_check = False
+            self.on_status("Own tracker: checked after the headset was off")
+        else:
+            self.on_status(reply[5:] if reply.startswith("fail") else reply)
+        self.area.queue_draw()
+
+    def draw_reseat(self, cr, w, h):
+        cx, cy = w / 2, h / 2
+        cr.set_source_rgb(1, 1, 1)
+        cr.arc(cx, cy, 10, 0, 2 * math.pi)
+        cr.fill()
+        cr.set_source_rgb(0.1, 0.1, 0.1)
+        cr.arc(cx, cy, 3, 0, 2 * math.pi)
+        cr.fill()
+        ink = (0.9, 0.9, 0.9)
+        self.text(cr, 60, 70, "Own tracker: the headset was off, so it may sit differently now", ink, 26)
+        self.text(cr, 60, 108, self.status if self.status.startswith("no gaze") else
+                  "Look at the dot and press (Enter, Space, or click). S skips.", ink, 20)
+
     def on_sample(self, s):
         self.sample = s
         self.recent.append(s)
@@ -1220,6 +1277,9 @@ class Probe(Adw.ApplicationWindow):
         if self.calib:
             self.calib_press()
             return
+        if self.reseat_check:
+            self.reseat_press()
+            return
         if self.mode == "test":
             self.test_press()
             return
@@ -1961,9 +2021,19 @@ class Probe(Adw.ApplicationWindow):
 
     def own_calib_point(self, samples, target):
         """Send one calibration dot to the Own tracker: the time you looked at it and its
-        direction. The direction comes from the screen geometry around it, through SteamVR's
-        nearby gaze and its pixels-per-degree there (only the geometry is used, not where
-        SteamVR thinks you looked). None if accepted, else why not."""
+        direction. None if accepted, else why not."""
+        d = self.screen_direction(samples, target)
+        if d is None or len(samples) < 2:
+            return "no gaze samples on this screen: look at the dot and press again"
+        reply = self.own.ask(f"calib-point {samples[0]['t']:.6f} {samples[-1]['t']:.6f} {d[0]:.4f} {d[1]:.4f}")
+        if reply.startswith("ok"):
+            return None
+        return reply[5:] + ": look at the dot and press again"
+
+    def screen_direction(self, samples, target):
+        """The head-relative direction (yaw, pitch) of a point on the canvas, from the screen
+        geometry around it: SteamVR's nearby gaze and its pixels-per-degree there (only the
+        geometry is used, not where SteamVR thinks you looked). None without samples."""
         pts = []
         ox, oy = self.origin or (0, 0)
         for smp in samples:
@@ -1973,18 +2043,13 @@ class Probe(Adw.ApplicationWindow):
                 if hit and hit["s"] == self.screen:
                     pts.append((hit["x"] - ox, hit["y"] - oy, hit["j"], src["hy"], src["hp"]))
                     break
-        if len(pts) < 5 or len(samples) < 2:
-            return "no gaze samples on this screen: look at the dot and press again"
+        if len(pts) < 5:
+            return None
         x = statistics.median(q[0] for q in pts)
         y = statistics.median(q[1] for q in pts)
         j = [statistics.fmean(q[2][k] for q in pts) for k in range(4)]
         oy_, op_ = deg_from_px(j, target[0] - x, target[1] - y)
-        yaw = statistics.median(q[3] for q in pts) + oy_
-        pitch = statistics.median(q[4] for q in pts) + op_
-        reply = self.own.ask(f"calib-point {samples[0]['t']:.6f} {samples[-1]['t']:.6f} {yaw:.4f} {pitch:.4f}")
-        if reply.startswith("ok"):
-            return None
-        return reply[5:] + ": look at the dot and press again"
+        return statistics.median(q[3] for q in pts) + oy_, statistics.median(q[4] for q in pts) + op_
 
     def other_dot(self, c, g):
         """Was the gaze on another dot of this round rather than the current one?
@@ -2488,6 +2553,9 @@ class Probe(Adw.ApplicationWindow):
         if self.calib:
             self.draw_calib(cr, w, h)
             return
+        if self.reseat_check:
+            self.draw_reseat(cr, w, h)
+            return
         m = self.monitors.get(self.screen)
         if m and self.is_fullscreen():
             g = m.get_geometry()