fix(sgcr): relax source-side port spacing so fork in-line children stay straight

packages/viewer/src/client/renderers/sgcr/layout.ts

@@ -304,7 +304,12 @@ function assignCoordinates(
   // at one node can never visually stack (an "other artifact" the vision pass caught). PORT_STEP ≥
   // arrowhead width is the by-construction guarantee for arrowhead separation.
   const PORT_STEP = 16;
+  // Arrowheads sit at an edge's TARGET, so only TARGET-side ports need the full arrowhead-clearance
+  // spacing. SOURCE-side ports (no arrowhead) only need to be visually distinct — packing them tighter
+  // lets a fork keep its in-line child's port centred (straight connector) instead of shoving it off.
+  const SOURCE_STEP = 8;
   const LOOP_W = 26; // cell cross reserved on the right for a self-loop
+  const reversedOf = new Map(edgeRecs.map((er) => [er.id, er.reversed]));
 
   // Build wires (one per unit sub-edge) first so we know each channel's load + each node's port demand.
   const wires: Wire[] = [];
@@ -468,7 +473,7 @@ function assignCoordinates(
   // + arrowheads can't stack) and within the node face; an endpoint outside the face clamps to the face
   // edge (that edge must turn — it's genuinely off to the side). Ordering by neighbour cross also keeps
   // the fan from self-crossing at the node.
-  const distribute = (it: Item, list: Wire[]) => {
+  const distribute = (it: Item, list: Wire[], isFar: boolean) => {
     if (it.isDummy) { for (const w of list) setPort(w, it.id, it.cc); return; }
     if (list.length === 0) return;
     const parity = it.rank % 2 === 1 ? 0.5 : 0;
@@ -478,21 +483,25 @@ function assignCoordinates(
     it.portHi = hiI;
     const sorted = list.slice().sort((p, q) => otherCross(p, it.id) - otherCross(q, it.id) || (p.edgeId < q.edgeId ? -1 : p.edgeId > q.edgeId ? 1 : 0));
     const n = sorted.length;
-    // Forward pass: each port at its desired (clamped) col, pushed right to keep PORT_STEP spacing.
+    // A port carries an arrowhead (→ needs full PORT_STEP) iff `it` is the edge's TARGET end here: the
+    // higher-rank end of a forward edge, or the lower-rank end of a reversed one. Flat edges keep the
+    // full step (conservative). The min gap before port i is PORT_STEP if either neighbour is a target.
+    const isTarget = sorted.map((w) => w.flat || (isFar ? !!reversedOf.get(w.edgeId) : !reversedOf.get(w.edgeId)));
+    const gap = (i: number) => (isTarget[i - 1] || isTarget[i] ? PORT_STEP : SOURCE_STEP);
+    // Forward pass: each port at its desired (clamped) col, pushed right to keep the per-gap spacing.
     const cols: number[] = [];
-    let prev = -Infinity;
     for (let i = 0; i < n; i++) {
       let col = Math.max(loI, Math.min(hiI, Math.round(otherCross(sorted[i], it.id))));
-      if (col < prev + PORT_STEP) col = prev + PORT_STEP;
-      cols[i] = col; prev = col;
+      if (i > 0 && col < cols[i - 1] + gap(i)) col = cols[i - 1] + gap(i);
+      cols[i] = col;
     }
     // If the forward pass overflowed the face (cluster pushed past hiI), pull back from the right.
-    if (cols[n - 1] > hiI) { let next = hiI; for (let i = n - 1; i >= 0; i--) { if (cols[i] > next) cols[i] = next; next = cols[i] - PORT_STEP; } }
+    if (cols[n - 1] > hiI) { let next = hiI; for (let i = n - 1; i >= 0; i--) { if (cols[i] > next) cols[i] = next; next = cols[i] - (i > 0 ? gap(i) : 0); } }
     for (let i = 0; i < n; i++) setPort(sorted[i], it.id, cols[i] + parity);
   };
   for (const it of items.values()) {
-    distribute(it, farWires.get(it.id)!);
-    distribute(it, nearWires.get(it.id)!);
+    distribute(it, farWires.get(it.id)!, true);
+    distribute(it, nearWires.get(it.id)!, false);
   }
 
   // STRAIGHTEN SPINE EDGES (Brandes-Köpf-style turn minimization): each node's PRIMARY wire on a face