Improve tie-net heuristics and destructive edit safeguards

frontend/app.js

@@ -1633,7 +1633,7 @@ async function compileModel(model, opts = {}) {
 
     const m = result.layout_metrics;
     setStatus(
-      `Compiled (${result.errors.length}E, ${result.warnings.length}W | ${m.crossings} crossings, ${m.overlap_edges} overlaps, ${m.total_bends ?? 0} bends, ${(m.detour_ratio ?? 1).toFixed(2)}x detour)`
+      `Compiled (${result.errors.length}E, ${result.warnings.length}W | ${m.crossings} crossings, ${m.overlap_edges} overlaps, ${m.total_bends ?? 0} bends, ${m.label_tie_routes ?? 0} tie-nets, ${(m.detour_ratio ?? 1).toFixed(2)}x detour)`
     );
   } catch (err) {
     setStatus(`Compile failed: ${err.message}`, false);
@@ -2120,7 +2120,7 @@ async function runLayoutAction(path) {
     fitView(out.compile.layout);
     saveSnapshot();
     setStatus(
-      `Compiled (${out.compile.errors.length}E, ${out.compile.warnings.length}W | ${out.compile.layout_metrics.crossings} crossings, ${out.compile.layout_metrics.overlap_edges} overlaps, ${out.compile.layout_metrics.total_bends ?? 0} bends)`
+      `Compiled (${out.compile.errors.length}E, ${out.compile.warnings.length}W | ${out.compile.layout_metrics.crossings} crossings, ${out.compile.layout_metrics.overlap_edges} overlaps, ${out.compile.layout_metrics.total_bends ?? 0} bends, ${out.compile.layout_metrics.label_tie_routes ?? 0} tie-nets)`
     );
   } catch (err) {
     setStatus(`Layout action failed: ${err.message}`, false);

src/compile.js

@@ -260,7 +260,8 @@ export function compile(payload, options = {}) {
         total_length: 0,
         direct_length: 0,
         detour_ratio: 1,
-        label_tie_fallbacks: 0
+        label_tie_fallbacks: 0,
+        label_tie_routes: 0
       },
       bus_groups: [],
       focus_map: {},

src/layout.js

@@ -1366,6 +1366,15 @@ function detectBusGroups(nets) {
 }
 
 function shouldUseLabelTie(net, pinNodes, context) {
+  if (!pinNodes.length) {
+    return false;
+  }
+  const minX = Math.min(...pinNodes.map((p) => p.exit.x), 0);
+  const maxX = Math.max(...pinNodes.map((p) => p.exit.x), 0);
+  const minY = Math.min(...pinNodes.map((p) => p.exit.y), 0);
+  const maxY = Math.max(...pinNodes.map((p) => p.exit.y), 0);
+  const span = Math.abs(maxX - minX) + Math.abs(maxY - minY);
+
   if (context.renderMode === "explicit") {
     return LABEL_TIE_CLASSES.has(net.class) && pinNodes.length > 2;
   }
@@ -1378,6 +1387,16 @@ function shouldUseLabelTie(net, pinNodes, context) {
     return true;
   }
 
+  // Prefer readable schematic stubs for dense multi-node nets.
+  if (pinNodes.length >= 5) {
+    return true;
+  }
+
+  // Long-distributed analog/signal nets become noisy when fully routed.
+  if ((net.class === "analog" || net.class === "signal") && pinNodes.length >= 3 && span > GRID * 56) {
+    return true;
+  }
+
   return false;
 }
 
@@ -1577,6 +1596,7 @@ function computeLayoutMetrics(routed, busGroups) {
     (total, rn) => total + (rn.route_stats?.used_label_tie && rn.route_stats?.fallback_reason ? 1 : 0),
     0
   );
+  const labelTieRoutes = routed.reduce((total, rn) => total + (rn.route_stats?.used_label_tie ? 1 : 0), 0);
 
   return {
     segment_count: segmentCount,
@@ -1589,7 +1609,8 @@ function computeLayoutMetrics(routed, busGroups) {
     total_length: totalLength,
     direct_length: totalDirect,
     detour_ratio: totalDirect > 0 ? totalLength / totalDirect : 1,
-    label_tie_fallbacks: labelTieFallbacks
+    label_tie_fallbacks: labelTieFallbacks,
+    label_tie_routes: labelTieRoutes
   };
 }
 

tests/compile.test.js

@@ -15,6 +15,7 @@ test("compile returns svg and topology for valid model", () => {
   assert.equal(typeof result.layout_metrics.total_bends, "number");
   assert.equal(typeof result.layout_metrics.detour_ratio, "number");
   assert.equal(typeof result.layout_metrics.label_tie_fallbacks, "number");
+  assert.equal(typeof result.layout_metrics.label_tie_routes, "number");
   assert.ok(Array.isArray(result.bus_groups));
   assert.ok(result.render_mode_used);
 });
@@ -26,6 +27,7 @@ test("compile fails on invalid model", () => {
   assert.ok(result.errors.length > 0);
   assert.equal(result.layout_metrics.total_bends, 0);
   assert.equal(result.layout_metrics.detour_ratio, 1);
+  assert.equal(result.layout_metrics.label_tie_routes, 0);
 });
 
 test("compile accepts render mode options", () => {