Staggers are scaled by 17/19 to keep their proportion to the key pitch. The mirror distance is negative because the axis is offset from the origin and the keys sit at positive x.

Assisted-by: Claude Opus 5.5 via Claude Code

diff --git a/layout.yml b/layout.yml
index 30e0b4b..d4bdbca 100644
--- a/layout.yml
+++ b/layout.yml
@@ -2,9 +2,9 @@ meta:
   engine: 4.2.1
   name: alpheus
 units:
-  # Matches key_size in the original OpenSCAD.
-  kx: 19
-  ky: 19
+  # Choc spacing, using ergogen's built-in units.
+  kx: cx
+  ky: cy
 points:
   zones:
     matrix:
@@ -18,10 +18,10 @@ points:
       columns:
         col0:
           rows.mod.skip: true
-        col1.key.stagger: 5
-        col2.key.stagger: 6
-        col3.key.stagger: -5
-        col4.key.stagger: -6
+        col1.key.stagger: 4.5
+        col2.key.stagger: 5.5
+        col3.key.stagger: -4.5
+        col4.key.stagger: -5.5
       rows:
         mod:
         bottom:
@@ -33,19 +33,19 @@ points:
         shift: [-kx, -ky]
       key:
         spread: kx
-        height: 1.5ky-1
+        height: 1.5ky-0.5
       columns:
         inner:
         outer.key.stagger: -0.25ky
       rows:
         cluster:
   mirror:
-    distance: 0
+    distance: -5
 outlines:
   caps:
     - what: rectangle
       where: /matrix/
-      size: [kx-1, ky-1]
+      size: [kx-0.5, ky-0.5]
     - what: rectangle
       where: /thumb/
-      size: [kx-1, 1.5ky-1]
\ No newline at end of file
+      size: [kx-0.5, 1.5ky-0.5]
\ No newline at end of file