Hands: label side cameras by the hands when a forced HANDS_SWAP_SIDES disagrees

With HANDS_SWAP_SIDES set to 0 or 1, ft-hands kept the forced naming as the
published truth even after the hands showed it was backwards. The hand recorder
took that as the session's decision, so the export labelled slam_left and
slam_right the wrong way round (dataset PR #4: every take swapped).

ft-hands now publishes the hands' answer once they disagree (state "forced,
disagrees"); tracking keeps the forced names. sides.read_live corrects the same
case from an ft-hands built before this, and the recorder's log says to use auto.

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

hands/rec/tests/test_sides.py

@@ -91,6 +91,29 @@ class RulesTest(unittest.TestCase):
         finally:
             shutil.rmtree(d)
 
+    def test_read_live_forced(self):
+        """HANDS_SWAP_SIDES=0 forced and the hands disagree: the hands are the truth, whether
+        ft-hands published them (built after 2026-10-06) or kept the forced value (before)."""
+        d = tempfile.mkdtemp()
+        try:
+            path = os.path.join(d, "sides.json")
+
+            def live(**kw):
+                s = dict(pid=1, ring_ino=0, mode="0", names_swapped=False,
+                         updated_ns=time.clock_gettime_ns(time.CLOCK_MONOTONIC), **kw)
+                with open(path, "w") as f:
+                    json.dump(s, f)
+                return sides.read_live(path)
+
+            self.assertEqual(live(state="forced", swapped=False, decided_by="config")["swapped"], False)
+            self.assertEqual(live(state="forced, agrees", swapped=False, decided_by="config")["swapped"], False)
+            old = live(state="forced, disagrees", swapped=False, decided_by="config")
+            self.assertEqual((old["swapped"], old["decided_by"]), (True, "auto"))
+            new = live(state="forced, disagrees", swapped=True, decided_by="auto")
+            self.assertEqual((new["swapped"], new["decided_by"]), (True, "auto"))
+        finally:
+            shutil.rmtree(d)
+
 
 class TakesTest(unittest.TestCase):
     """A swapped session: one take's parts recorded before the decision (ft-camd's names) and
@@ -226,6 +249,22 @@ class SessionSidesTest(unittest.TestCase):
         self.assertTrue(s._session_json["sides"]["reversed_from"]["swapped"])
         self.assertFalse(takes.read_json(os.path.join(self.tmp, "session.json"))["sides"]["swapped"])
 
+    def test_read_sides_forced(self):
+        """PR #4 on the dataset: HANDS_SWAP_SIDES=0 from the old example config, and the hands
+        disagree. The session takes the hands' answer, not the forced one."""
+        s = session.Session(os.path.join(self.tmp, "base"), {}, {}, "room", self.script, dry_run=True,
+                            hands_dir=self.tmp)
+        s.session_dir = self.tmp
+        s._session_json = {"sides": {"swapped": None}}
+        self.live(mode="0", state="forced", swapped=False, decided_by="config", names_swapped=False, evidence=None)
+        s._read_sides(force=True)
+        self.assertIs(s._sides_swapped(), False)
+        self.live(mode="0", state="forced, disagrees", swapped=False, decided_by="config", names_swapped=False)
+        s._read_sides(force=True)
+        self.assertIs(s._sides_swapped(), True)
+        self.assertEqual(s._session_json["sides"]["decided_by"], "auto")
+        self.assertEqual(s._session_json["sides"]["reversed_from"]["decided_by"], "config")
+
     def test_recorder_parts(self):
         calls = []