search challenge: triangle marker on a crate's back face (rendered in vision, in digest), report tool with distance verification, smooth turn(duration), --free/--search autonomous modes, look_at crates; verified with gpt-5.6-luna

testbed/tests/test_world.py

@@ -131,3 +131,51 @@ def test_describe_layout():
     assert d["room"]["width"] == ROOM_SIZE
     assert len(d["obstacles"]) == 3
     assert d["beacon"]["id"] == "beacon"
+
+
+def test_marker_is_on_a_back_face():
+    """The triangle must sit on a face pointing away from the spawn corner."""
+    for _ in range(20):
+        room = Room()
+        pos = room.marker_world_pos()
+        assert pos is not None
+        box = next(b for b in room.boxes if b.id == room.marker["box"])
+        face = room.marker["face"]
+        # spawn is at (1.5, 1.5); the marker face normal must point away from it
+        to_spawn = (1.5 - box.cx, 1.5 - box.cz)
+        normal = {
+            "x0": (-1, 0), "x1": (1, 0), "z0": (0, -1), "z1": (0, 1),
+        }[face]
+        assert normal[0] * to_spawn[0] + normal[1] * to_spawn[1] < 0
+        assert pos[0] == pytest.approx(box.x_max()) if face == "x1" else True
+
+
+def test_marker_not_visible_from_spawn():
+    """Looking toward the beacon from spawn must not show the triangle."""
+    from testbed.room.render import Raycaster
+
+    room = Room()
+    # Spawn looks at the beacon; the marker is on a back face, so the anchor
+    # pixel of the marker must be occluded (different surface) or off-frame.
+    pos = room.marker_world_pos()
+    assert pos is not None
+    # Stand on the marker's side of the crate, facing it.
+    face = room.marker["face"]
+    offsets = {
+        "x0": (-1.0, 0.0, 90.0),   # west face: stand west, face +x
+        "x1": (1.0, 0.0, 270.0),   # east face: stand east, face -x
+        "z0": (0.0, -1.0, 0.0),    # south face: stand south, face +z
+        "z1": (0.0, 1.0, 180.0),   # north face: stand north, face -z
+    }[face]
+    room.capsule.x = pos[0] + offsets[0]
+    room.capsule.z = pos[2] + offsets[1]
+    room.capsule.yaw_deg = offsets[2]
+    img, _ = Raycaster().render(room)
+    px = img.load()
+    orange = 0
+    for y in range(0, 120, 2):
+        for x in range(0, 160, 2):
+            r, g, b = px[x, y]
+            if r > 200 and 100 < g < 190 and b < 90:
+                orange += 1
+    assert orange > 3, "triangle must be visible when looking at the marker face"