Prefer edge snaps outside corner radius

CHANGELOG.md

@@ -5,7 +5,7 @@
 - Stability: gate conversion-backed direct file views behind an explicit Load model action even when Obsidian restores them through `onLoadFile`, preventing STEP/STP workspace restore loops from freezing the vault.
 - Stability: make the direct-view load gate settings-aware for preferred OBJ conversion and keep mobile direct-format reads on Obsidian vault APIs instead of desktop Node path helpers.
 - UI: upgrade measurement calibration so users can scale the loaded model uniformly from the latest ruler distance, keep overlays anchored in model space, apply locked model-size scaling from one known axis, and verify the workflow through preview automation.
-- UI: make distance measurement lock the selected object by default and snap endpoints to its mesh vertices or visible crease/perimeter triangle edges, filtering coplanar face diagonals, with first-click target selection when needed and Alt/Option-click preserving the older free surface pick as a backup.
+- UI: make distance measurement lock the selected object by default and snap endpoints to mesh vertices or visible crease/perimeter triangle edges, filtering coplanar face diagonals and preferring edge projection outside the corner radius, with first-click target selection when needed and Alt/Option-click preserving the older free surface pick as a backup.
 - UI: restyle distance measurements as orthographic drawing-style dimension callouts with extension lines, arrowheads, and compact drafting labels instead of thick freehand ruler lines.
 - UI: remove the preview canvas native hover tooltip while preserving keyboard shortcut metadata for accessibility.
 - UI: clarify render scale versus measurement scale by showing render resolution as percentages, syncing the toolbar to the active renderer budget, and applying the configured scale to `3dgrid`.

src/render/preview/measurement.test.ts

@@ -139,6 +139,43 @@ describe("measurement helpers", () => {
     expect(snapped?.point).toEqual({ x: 0, y: 0, z: 0 });
   });
 
+  it("uses edge projection once the pointer is outside the corner radius", () => {
+    const snapped = snapMeasurementPointToGeometry(
+      { x: -0.06, y: 0, z: 0 },
+      {
+        vertices: [
+          { point: { x: 0, y: 0, z: 0 } },
+          { point: { x: 1, y: 0, z: 0 } },
+        ],
+        edges: [
+          { start: { x: 0, y: 0, z: 0 }, end: { x: 1, y: 0, z: 0 } },
+        ],
+        vertexRadius: 0.05,
+      },
+    );
+
+    expect(snapped?.kind).toBe("edge");
+    expect(snapped?.point).toEqual({ x: 0, y: 0, z: 0 });
+  });
+
+  it("rejects geometry snaps beyond the target snap distance", () => {
+    const snapped = snapMeasurementPointToGeometry(
+      { x: 3, y: 3, z: 0 },
+      {
+        vertices: [
+          { point: { x: 0, y: 0, z: 0 } },
+        ],
+        edges: [
+          { start: { x: 0, y: 0, z: 0 }, end: { x: 1, y: 0, z: 0 } },
+        ],
+        vertexRadius: 0.05,
+        maxDistance: 0.5,
+      },
+    );
+
+    expect(snapped).toBeNull();
+  });
+
   it("creates geometry snap edges from indexed and non-indexed triangles without face diagonals", () => {
     const squareVertices = [
       { x: 0, y: 0, z: 0 },

src/render/preview/measurement.ts

@@ -192,10 +192,10 @@ export function snapMeasurementPointToGeometry(
     });
   }
 
-  const vertexRadius = input.vertexRadius ?? 0;
-  const candidate = nearestVertex && (nearestVertex.distance <= vertexRadius || !nearestEdge)
+  const vertexRadius = Math.max(input.vertexRadius ?? 0, 0);
+  const candidate = nearestVertex && nearestVertex.distance <= vertexRadius
     ? nearestVertex
-    : chooseNearestMeasurementSnapResult(nearestVertex, nearestEdge);
+    : nearestEdge ?? nearestVertex;
   if (!candidate) {
     return null;
   }