Bring up the USB gadget link (package 0b, Pi side and talos side)

The Pi presents NCM Ethernet and ACM serial from a configfs gadget, started by
robot-usb-gadget.service before networking. usb0 gets 10.55.0.2/30 with no
gateway through netplan, matched by interface name: a MAC match turns into
PermanentMACAddress= in networkd, which a gadget interface does not have, so it
stayed unmanaged. talos reaches the Pi at 10.55.0.2 (ping ~2.4 ms, SSH works)
through a NetworkManager profile, host/omarchy/robot-usb-link.sh, matched by the
gadget's fixed host MAC.

Also clamp the face's tunable parameters (focus sets a blur radius, persistence
divides) and fps, after a review flagged unvalidated node parameters.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AFN8nRRCiDiMN7ChBpHJhs

ros/hermes_face/hermes_face/face_node.py

@@ -20,7 +20,7 @@ class FaceNode(Node):
     def __init__(self):
         super().__init__('hermes_face')
         param = lambda name, default: self.declare_parameter(name, default).value  # noqa: E731
-        self.fps = float(param('fps', 30.0))
+        self.fps = min(60.0, max(1.0, float(param('fps', 30.0))))   # a timer period of 1/fps
         output = param('output', 'st7789')              # 'st7789' or 'none' (render only)
         self.pan_joint = param('pan_joint', 'pan_joint')
         self.tilt_joint = param('tilt_joint', 'tilt_joint')

ros/hermes_face/hermes_face/render.py

@@ -125,12 +125,16 @@ class FaceRenderer:
         if rotation not in (0, 90, 180, 270):
             raise ValueError(f'rotation must be 0, 90, 180 or 270, not {rotation!r}')
         self.rotation = rotation   # output turned this many degrees counter-clockwise
+        if phosphor not in PHOSPHORS:
+            raise ValueError(f'unknown phosphor {phosphor!r}; known: {", ".join(PHOSPHORS)}')
         self.rgb = PHOSPHORS[phosphor]
         self.style = style
-        self.persist_ms = persist_ms
-        self.intensity = intensity
-        self.focus = focus
-        self.jitter = jitter
+        # Clamped, because these arrive as node parameters: focus sets a blur radius, and
+        # persistence divides.
+        self.persist_ms = min(5000.0, max(5.0, float(persist_ms)))
+        self.intensity = min(4.0, max(0.0, float(intensity)))
+        self.focus = min(1.0, max(0.0, float(focus)))
+        self.jitter = min(5.0, max(0.0, float(jitter)))
         self.rng = np.random.default_rng(seed)
 
         self.buf = np.zeros((H, W), np.float32)

ros/hermes_face/test/test_render.py

@@ -99,3 +99,14 @@ def test_rotation_turns_the_frame_counter_clockwise(rotation):
 def test_bad_rotation_rejected():
     with pytest.raises(ValueError):
         FaceRenderer(rotation=45)
+
+
+def test_wild_parameters_are_clamped():
+    r = FaceRenderer(focus=1e9, persist_ms=0, intensity=-3, jitter=1e6, seed=0)
+    assert (r.focus, r.persist_ms, r.intensity, r.jitter) == (1.0, 5.0, 0.0, 5.0)
+    assert run(r, 1)[0].shape == (H, W, 3)
+
+
+def test_unknown_phosphor_rejected():
+    with pytest.raises(ValueError):
+        FaceRenderer(phosphor='P99')