diff --git a/src/kiri/mode/cam/work/prepare.js b/src/kiri/mode/cam/work/prepare.js
index 3db3af20..c1dc7e9c 100644
--- a/src/kiri/mode/cam/work/prepare.js
+++ b/src/kiri/mode/cam/work/prepare.js
@@ -138,6 +138,7 @@ export async function prepare_one(widget, settings, print, firstPoint, update) {
         toolType,
         toolDiam,
         toolDiamMove,
+        toolDiamEpsilon,
         travelBounds,
         spindle = 0,
         spindleMax = device.spindleMax,
@@ -211,6 +212,7 @@ export async function prepare_one(widget, settings, print, firstPoint, update) {
             toolType = tool.getType();
             toolDiam = tool.fluteDiameter();
             toolDiamMove = (tool.hasTaper() ? tolerance ?? toolDiam : toolDiam) * 2;
+            toolDiamEpsilon = toolDiam * 0.01,
             lastTool = toolID;
         }
         feedRate = Math.min(camFastFeed, feed || feedRate || plunge);
@@ -593,9 +595,11 @@ export async function prepare_one(widget, settings, print, firstPoint, update) {
             if (lastTravelBounds) check.push(...lastTravelBounds);
             let from = toWidgetCoords(printPoint);
             let to = toWidgetCoords(point);
+            let ep = toolDiamEpsilon;
             for (let poly of check) {
-                let ints = poly.intersections(from, to);
-                if (ints.length) {
+                let ints = poly.intersections(from, to) ?? [];
+                let far = ints.filter(p => p.distTo2D(to) > ep && p.distTo2D(from) > ep);
+                if (far.length) {
                     if (debug) console.log({ ints, poly, deltaXY, deltaZ });
                     upAndOver = "bounds";
                     break;
diff --git a/src/void/api/solids.js b/src/void/api/solids.js
index 56971f65..a7f221e3 100644
--- a/src/void/api/solids.js
+++ b/src/void/api/solids.js
@@ -1756,7 +1756,9 @@ function edgeKey(a, b) {
                     const mesh = new THREE.Mesh(built.render, this._material.clone());
                     mesh.userData.solidId = id;
                     mesh.userData.solid = true;
-                    const edgesGeom = new THREE.EdgesGeometry(built.render, SOLID_CREASE_ANGLE_DEG);
+                    // Derive visible hard edges from indexed manifold topology, not the
+                    // creased render geometry, to avoid triangle/split seam artifacts.
+                    const edgesGeom = new THREE.EdgesGeometry(built.indexed, SOLID_CREASE_ANGLE_DEG);
                     const edges = new THREE.LineSegments(edgesGeom, this._edgeMaterial.clone());
                     edges.userData.solidId = id;
                     edges.userData.solidEdge = true;
@@ -1807,7 +1809,7 @@ function edgeKey(a, b) {
                     const built = buildSolidGeometry(meshData);
                     view.mesh.geometry = built.render;
                     view.indexedGeometry = built.indexed;
-                    view.edges.geometry = new THREE.EdgesGeometry(built.render, SOLID_CREASE_ANGLE_DEG);
+                    view.edges.geometry = new THREE.EdgesGeometry(built.indexed, SOLID_CREASE_ANGLE_DEG);
                 }
                 // Build selectable face regions from the same geometry used for ray hits.
                 // This keeps surface-region hover/selection aligned with rendered shading.
diff --git a/src/void/solid/rebuild.js b/src/void/solid/rebuild.js
index 4736ae3e..f0df1e1d 100644
--- a/src/void/solid/rebuild.js
+++ b/src/void/solid/rebuild.js
@@ -278,6 +278,8 @@ async function rebuildGeneratedSolidsFromSnapshot(snapshot, options = {}) {
             const operation = ['new', 'add', 'subtract'].includes(String(params.operation || 'new'))
                 ? String(params.operation || 'new')
                 : 'new';
+            // Symmetric is a single extrusion whose local span is shifted to
+            // [-depth/2, +depth/2], not two opposing extrusions/union.
             const localZShift = symmetric ? (-depth / 2) : (direction === 'reverse' ? -depth : 0);
             const createdBodyIds = [];
             const bySketch = new Map();