A lane chip clears the card above its run: running downwards ELK keeps runs half a chip and a border (14px) from nodes, so House history's feedback chip no longer covers the node border at 390 (crossings and node order unchanged, Demo house 178px taller); an empty string reads "" on its chip

frontend/src/components/Flow/LiveEdge.tsx

@@ -174,7 +174,8 @@ function formatValue(value: unknown): string {
   if (typeof value === "number") {
     return Number.isInteger(value) ? String(value) : value.toFixed(2)
   }
-  if (typeof value === "string") return value
+  // An empty string reads the way `null` and `[]` do, not as an empty pill.
+  if (typeof value === "string") return value || '""'
   // A media reference serialised whole is a line of hash: what belongs in a
   // chip this size is what kind of bytes crossed the edge.
   if (isRef(value)) return describeArtifact(value as Record<string, unknown>)

frontend/src/components/Flow/layout.ts

@@ -294,6 +294,17 @@ function graphOf(
         RANK_GAP[direction],
       ),
       "org.eclipse.elk.padding": `[top=${MARGIN},left=${MARGIN},bottom=${MARGIN},right=${MARGIN}]`,
+      // Running downwards, a chip moved onto a run across the flow (see
+      // `longestRun`) is centred on it, so a run keeps half a chip and a
+      // node's border clear of the nodes it passes. ELK's default of 10px
+      // put such a chip over the border of the card above it.
+      ...(across
+        ? {}
+        : {
+            "org.eclipse.elk.layered.spacing.edgeNodeBetweenLayers": String(
+              LABEL_H / 2 + 2,
+            ),
+          }),
       // What decides a tie is the order the document lists things in, so the
       // graph reads the way the flow is written rather than however the
       // algorithm happened to land.