fix(tomo_params): pin seed=0 in the OMNY fermat position estimate, as flomni/lamni

get_omny_fermat_spiral_pos() draws a random sub-step offset per call, so the
estimate (and its test against a second call) was not reproducible.

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

csaxs_bec/bec_widgets/widgets/tomo_params/tomo_params.py

@@ -2767,6 +2767,11 @@ def _compute_fermat_positions_omny(params: dict[str, Any]) -> tuple[int, int]:
     estimate can never drift out of sync. cenx/ceny/zshift left at their
     defaults -- they only shift the final position, never affect the count.
 
+    The real scan also draws a fresh random sub-step offset on every call
+    (see get_omny_fermat_spiral_pos()'s `seed` argument), which can shift
+    the actual scan-time count by a point or two near the threshold. A
+    fixed seed is used here only so this estimate is itself reproducible.
+
     Returns:
         (estimated_count, minimum_required)
     """
@@ -2778,7 +2783,13 @@ def _compute_fermat_positions_omny(params: dict[str, Any]) -> tuple[int, int]:
     if step <= 0:
         return 0, OmnyFermatScan.MIN_POSITIONS
     positions = OmnyFermatScan.get_omny_fermat_spiral_pos(
-        -abs(fovx / 2), abs(fovx / 2), -abs(fovy / 2), abs(fovy / 2), step=step, spiral_type=0
+        -abs(fovx / 2),
+        abs(fovx / 2),
+        -abs(fovy / 2),
+        abs(fovy / 2),
+        step=step,
+        spiral_type=0,
+        seed=0,
     )
     return len(positions), OmnyFermatScan.MIN_POSITIONS
 

tests/tests_bec_ipython_client/test_omny_tomo_params_widget_math.py

@@ -138,8 +138,10 @@ def test_compute_fermat_positions_omny_matches_scan_class_below_threshold():
     count, min_positions = _compute_fermat_positions_omny(params)
     assert min_positions == OmnyFermatScan.MIN_POSITIONS
     assert count < min_positions
+    # _compute_fermat_positions_omny() pins seed=0 for its own reproducibility --
+    # match it here rather than drawing an independent random offset.
     expected = OmnyFermatScan.get_omny_fermat_spiral_pos(
-        -1.0, 1.0, -1.0, 1.0, step=2.0, spiral_type=0
+        -1.0, 1.0, -1.0, 1.0, step=2.0, spiral_type=0, seed=0
     )
     assert count == len(expected)