diff --git a/notes.md b/notes.md
index a9bc6529..9cc78127 100644
--- a/notes.md
+++ b/notes.md
@@ -23,24 +23,21 @@
 
 * `F` 2D image import
 * `F` detect and report slow framerates
-* `F` implement an in-app bug reporting system. add workspace to export option.
+* `F` implement an in-app bug reporting system
 * `P` improve decimation speed by avoiding in/out of Point?
 * `P` duplicate objects should share same slice data unless rotated or scaled
 * `P` worker state cache cleanup and organization
 * `P` client/worker interface normalization and cleanup
-* `C` improve path line caps
 
 # FDM
 
-* `B` dwell / extrude engage reversed?
 * `B` fix adaptive slicing with multi-extruder
 * `B` fix supports with grouped parts
-* `B` sparse infill should follow polys it intersects
+* `B` sparse infill should follow polys between intersect points
 * `B` multi-extruder rendering of raft fails to offset the rest of the print
 * `B` multi-extruder purge blocks fail to generate properly for rafts
 * `F` control for size of purge block (with 0=disabled)
 * `F` add separate fill speed control
-* `F` control shell order (in/out or out/in)
 * `F` manual support addition / control
 * `F` control layer start position
 * `F` polishing and other non-planar work
diff --git a/src/mode/fdm/prepare.js b/src/mode/fdm/prepare.js
index 76fdff6b..2fa080f1 100644
--- a/src/mode/fdm/prepare.js
+++ b/src/mode/fdm/prepare.js
@@ -444,6 +444,7 @@
         let lastEnd = null;
         let lastOut = null;
         let current = null;
+        let retracted = false;
 
         function color(point) {
             return FDM.rateToColor(point.speed, maxspd);
@@ -454,6 +455,7 @@
             const moves = [];
             const heads = [];
             const retracts = [];
+            const engages = [];
             const output = new KIRI.Render();
             layers.push(output);
 
@@ -471,8 +473,13 @@
             let emits = 0;
 
             level.forEach((out,oi) => {
+                if (retracted && out.emit) {
+                    retracted = false;
+                    engages.push(lastOut.point);
+                }
                 if (out.retract) {
                     retracts.push(out.point);
+                    retracted = true;
                 }
                 if (!out.point) {
                     // in cam mode, these are drilling or dwell ops
@@ -526,6 +533,13 @@
                         return newPolygon().centerCircle(point, 0.2, 16).setZ(point.z + 0.01);
                     }), { outline: true });
             }
+            if (engages.length) {
+                output
+                    .setLayer('engage', { line: 0x005500, face: 0x00ff00, opacity: 0.5 }, true)
+                    .addAreas(engages.map(point => {
+                        return newPolygon().centerCircle(point, 0.2, 16).setZ(point.z + 0.01);
+                    }), { outline: true });
+            }
             if (heads.length) {
                 output
                     .setLayer('arrows', { face: moveColor, line: 0x555555, opacity: 0.5 }, true)