diff --git a/src/gesim/server/dashboard.py b/src/gesim/server/dashboard.py
index a03ffe4..f24cc90 100644
--- a/src/gesim/server/dashboard.py
+++ b/src/gesim/server/dashboard.py
@@ -99,7 +99,7 @@
   </section>
 
   <section class="panel">
-    <h2>Action vs predicted state &nbsp;<span style="color:var(--muted);text-transform:none;letter-spacing:0;font-weight:400">(commanded action vs world-model prediction, last frame)</span></h2>
+    <h2>Action vs predicted state &nbsp;<span style="color:var(--muted);text-transform:none;letter-spacing:0;font-weight:400">(commanded action vs PE prediction, last frame; grippers in mm)</span></h2>
     <div class="cmp" id="cmp"><div class="empty">waiting for a step…</div></div>
   </section>
 
@@ -117,12 +117,19 @@
 }
 
 const LABELS = ["L1","L2","L3","L4","L5","L6","L7","L grip","R1","R2","R3","R4","R5","R6","R7","R grip"];
+// Match gesim.types GRIPPER_APERTURE_* — WM action grippers are [0,1], PE state is mm.
+const GRIP_MIN = 35, GRIP_SPAN = 120 - 35, GRIP_DIMS = new Set([7, 15]);
+
+function actionForCompare(i, v) {
+  return GRIP_DIMS.has(i) ? v * GRIP_SPAN + GRIP_MIN : v;
+}
 
 function tableFor(title, action, state, lo, hi) {
   let rows = "";
   for (let i = lo; i < hi; i++) {
-    const a = action[i], p = state[i], d = p - a;
-    const cls = Math.abs(d) < 1e-4 ? "" : (d > 0 ? "pos" : "neg");
+    const a = actionForCompare(i, action[i]), p = state[i], d = p - a;
+    const tol = GRIP_DIMS.has(i) ? 2.0 : 1e-4;
+    const cls = Math.abs(d) < tol ? "" : (d > 0 ? "pos" : "neg");
     rows += "<tr><td class='dim'>" + LABELS[i] + "</td><td>" + a.toFixed(3) +
             "</td><td>" + p.toFixed(3) + "</td><td class='" + cls + "'>" +
             (d >= 0 ? "+" : "") + d.toFixed(3) + "</td></tr>";
diff --git a/src/gesim/types.py b/src/gesim/types.py
index c2146b5..a1a2060 100644
--- a/src/gesim/types.py
+++ b/src/gesim/types.py
@@ -18,6 +18,26 @@
 STATE_DIM = 16
 ACTION_DIM = 16
 
+# Genie-01 OmniPicker: WM actions use normalised gripper commands in [0, 1]; PE
+# state uses physical aperture in mm.  Keep in sync with conditioning/band.py.
+GRIPPER_APERTURE_MIN_MM = 35.0
+GRIPPER_APERTURE_MAX_MM = 120.0
+WM_GRIPPER_DIMS = (7, 15)
+
+
+def wm_action_gripper_to_mm(norm: float) -> float:
+    """Map a normalised WM gripper command to OmniPicker aperture in mm."""
+    span = GRIPPER_APERTURE_MAX_MM - GRIPPER_APERTURE_MIN_MM
+    return float(norm) * span + GRIPPER_APERTURE_MIN_MM
+
+
+def wm_action_row_for_state_compare(action: np.ndarray) -> np.ndarray:
+    """Return a WM action row with gripper channels converted to mm for PE comparison."""
+    out = np.asarray(action, dtype=np.float32).reshape(-1).copy()
+    for dim in WM_GRIPPER_DIMS:
+        out[dim] = wm_action_gripper_to_mm(out[dim])
+    return out
+
 
 @dataclass(frozen=True)
 class Observation:
diff --git a/src/gesim/video.py b/src/gesim/video.py
index f23fdf0..3f3afbe 100644
--- a/src/gesim/video.py
+++ b/src/gesim/video.py
@@ -10,6 +10,18 @@
 logger = logging.getLogger("gesim.video")
 
 
+def _resolve_ffmpeg() -> str | None:
+    """Return an ffmpeg binary, preferring PATH then optional imageio-ffmpeg."""
+    ffmpeg = shutil.which("ffmpeg")
+    if ffmpeg:
+        return ffmpeg
+    try:
+        import imageio_ffmpeg
+    except ImportError:
+        return None
+    return imageio_ffmpeg.get_ffmpeg_exe()
+
+
 def save_video(frames: np.ndarray, path: str, fps: int = 16):
     """Save ``(T, 3, V, H, W)`` float video to mp4. Views are tiled horizontally."""
     T, C, V, H, W = frames.shape
@@ -22,7 +34,7 @@ def save_video(frames: np.ndarray, path: str, fps: int = 16):
     rows = np.ascontiguousarray(rows)
 
     height, width = rows.shape[1], rows.shape[2]
-    ffmpeg = shutil.which("ffmpeg")
+    ffmpeg = _resolve_ffmpeg()
     if ffmpeg:
         cmd = [
             ffmpeg,
diff --git a/tests/test_gripper_units.py b/tests/test_gripper_units.py
new file mode 100644
index 0000000..d13e90a
--- /dev/null
+++ b/tests/test_gripper_units.py
@@ -0,0 +1,23 @@
+import numpy as np
+import pytest
+
+from gesim.types import (
+    GRIPPER_APERTURE_MAX_MM,
+    GRIPPER_APERTURE_MIN_MM,
+    wm_action_gripper_to_mm,
+    wm_action_row_for_state_compare,
+)
+
+
+def test_wm_action_gripper_to_mm_endpoints():
+    assert wm_action_gripper_to_mm(0.0) == pytest.approx(GRIPPER_APERTURE_MIN_MM)
+    assert wm_action_gripper_to_mm(1.0) == pytest.approx(GRIPPER_APERTURE_MAX_MM)
+
+
+def test_wm_action_row_for_state_compare_only_touches_grippers():
+    row = np.arange(16, dtype=np.float32)
+    out = wm_action_row_for_state_compare(row)
+    assert np.array_equal(out[:7], row[:7])
+    assert np.array_equal(out[8:15], row[8:15])
+    assert out[7] == pytest.approx(wm_action_gripper_to_mm(row[7]))
+    assert out[15] == pytest.approx(wm_action_gripper_to_mm(row[15]))