feat(48-02): auto-detect loop edges with magenta visual styling

- Import wouldCreateCycle from executionUtils in WorkflowCanvas
- Add cycle detection in handleConnect for batch and single connections
- Mark backward connections as loop edges (isLoop: true, loopCount: 3)
- Add setLoopCount store action with 1-100 clamping
- Add loop color (#d946ef magenta) to EDGE_COLORS in both files
- Loop edges render in magenta before pause edges
- Add loop indicator overlay (↻ N×) at edge midpoint using foreignObject
- Loop gradient defined in SharedEdgeGradients

src/components/WorkflowCanvas.tsx

@@ -70,6 +70,7 @@ import { stripBinaryData } from "@/lib/chat/contextBuilder";
 import { PromptEditorModal } from "./modals/PromptEditorModal";
 import { PromptConstructorEditorModal } from "./modals/PromptConstructorEditorModal";
 import { resolveTextSourcesThroughRouters } from "@/store/utils/connectedInputs";
+import { wouldCreateCycle } from "@/store/utils/executionUtils";
 import { parseVarTags } from "@/utils/parseVarTags";
 import { AnnotationModal } from "./AnnotationModal";
 import { browseRegistry } from "@/utils/browseRegistry";
@@ -664,7 +665,12 @@ export function WorkflowCanvas() {
               }
             }
             if (resolved.targetHandle) batchUsed.add(resolved.targetHandle);
+            // Check for cycle and mark as loop edge if detected
+            if (wouldCreateCycle(resolved.source!, resolved.target!, edges)) {
+              onConnect(resolved, { isLoop: true, loopCount: 3 });
+            } else {
               onConnect(resolved);
+            }
             return;
           }
 
@@ -705,8 +711,13 @@ export function WorkflowCanvas() {
           resolved = resolveSwitchHandle(resolved);
           if (resolved.targetHandle) batchUsed.add(resolved.targetHandle);
           if (isValidConnection(resolved)) {
+            // Check for cycle and mark as loop edge if detected
+            if (wouldCreateCycle(resolved.source!, resolved.target!, edges)) {
+              onConnect(resolved, { isLoop: true, loopCount: 3 });
+            } else {
               onConnect(resolved);
             }
+          }
         });
       } else {
         // Single connection
@@ -714,8 +725,13 @@ export function WorkflowCanvas() {
         resolved = resolveRouterHandle(resolved);
         resolved = resolveRouterSourceHandle(resolved);
         resolved = resolveSwitchHandle(resolved);
+        // Check for cycle and mark as loop edge if detected
+        if (wouldCreateCycle(resolved.source!, resolved.target!, edges)) {
+          onConnect(resolved, { isLoop: true, loopCount: 3 });
+        } else {
           onConnect(resolved);
         }
+      }
     },
     [onConnect, nodes, edges]
   );

src/components/edges/EditableEdge.tsx

@@ -29,6 +29,7 @@ const EDGE_COLORS: Record<string, string> = {
   text: "#2563eb", // Blue for text connections
   "3d": "#06b6d4", // Cyan for 3D connections
   easeCurve: "#f59e0b", // Amber for ease curve connections
+  loop: "#d946ef", // Magenta for loop edges
 };
 
 export function EditableEdge({
@@ -71,18 +72,23 @@ export function EditableEdge({
     return (targetNode.data as NanoBananaNodeData).status === "loading";
   });
 
-  // Determine edge color based on handle type (orange if paused)
+  // Determine edge color based on handle type (magenta for loop edges, orange if paused)
   const edgeColor = useMemo(() => {
+    if (edgeData?.isLoop) return EDGE_COLORS.loop;
     if (hasPause) return EDGE_COLORS.pause;
     // Use source handle to determine color (or target if source is not available)
     // Strip numeric suffixes (e.g., "image-0" -> "image") for lookup
     const handleType = sourceHandleId || targetHandleId || "";
     const normalizedType = handleType.replace(/-\d+$/, "");
     return EDGE_COLORS[normalizedType] || EDGE_COLORS.default;
-  }, [hasPause, sourceHandleId, targetHandleId]);
+  }, [edgeData?.isLoop, hasPause, sourceHandleId, targetHandleId]);
 
   // Reference shared gradient by color key + selection state
   const gradientId = useMemo(() => {
+    if (edgeData?.isLoop) {
+      const selectionKey = isConnectedToSelection ? "active" : "dimmed";
+      return getSharedGradientId("loop", selectionKey);
+    }
     if (hasPause) {
       const selectionKey = isConnectedToSelection ? "active" : "dimmed";
       return getSharedGradientId("pause", selectionKey);
@@ -93,7 +99,7 @@ export function EditableEdge({
     const colorKey = normalizedType in EDGE_COLORS ? normalizedType : "default";
     const selectionKey = isConnectedToSelection ? "active" : "dimmed";
     return getSharedGradientId(colorKey, selectionKey);
-  }, [hasPause, sourceHandleId, targetHandleId, isConnectedToSelection]);
+  }, [edgeData?.isLoop, hasPause, sourceHandleId, targetHandleId, isConnectedToSelection]);
 
   // Calculate the path based on edge style
   const [edgePath, labelX, labelY] = useMemo(() => {
@@ -265,6 +271,22 @@ export function EditableEdge({
         </g>
       )}
 
+      {/* Loop indicator at edge midpoint */}
+      {edgeData?.isLoop && (
+        <foreignObject
+          x={labelX - 28}
+          y={labelY - 12}
+          width={56}
+          height={24}
+          className="pointer-events-none"
+        >
+          <div className="flex items-center justify-center gap-1 px-2 py-0.5 bg-neutral-800/90 border border-fuchsia-500/60 rounded-full text-[10px] font-medium">
+            <span className="text-fuchsia-300">↻</span>
+            <span className="text-fuchsia-100">{edgeData.loopCount || 3}×</span>
+          </div>
+        </foreignObject>
+      )}
+
       {/* Draggable handles on segments */}
       {(selected || isDragging) &&
         handlePositions.map((handle, index) => (

src/components/edges/SharedEdgeGradients.tsx

@@ -15,6 +15,7 @@ const EDGE_COLORS: Record<string, string> = {
   text: "#2563eb",
   "3d": "#06b6d4",
   easeCurve: "#f59e0b",
+  loop: "#d946ef",
 };
 
 const SELECTION_STATES = ["active", "dimmed"] as const;

src/store/workflowStore.ts

@@ -235,6 +235,7 @@ interface WorkflowStore {
   addEdgeWithType: (connection: Connection, edgeType: string, edgeDataOverrides?: Record<string, unknown>) => void;
   removeEdge: (edgeId: string) => void;
   toggleEdgePause: (edgeId: string) => void;
+  setLoopCount: (edgeId: string, count: number) => void;
 
   // Copy/Paste operations
   copySelectedNodes: () => void;
@@ -893,6 +894,19 @@ const workflowStoreImpl: StateCreator<WorkflowStore> = (set, get) => ({
     }));
   },
 
+  setLoopCount: (edgeId: string, count: number) => {
+    const clamped = Math.max(1, Math.min(100, count));
+    pushUndoCheckpoint(get, set);
+    set((state) => ({
+      edges: state.edges.map((edge) =>
+        edge.id === edgeId
+          ? { ...edge, data: { ...edge.data, loopCount: clamped } }
+          : edge
+      ),
+      hasUnsavedChanges: true,
+    }));
+  },
+
   copySelectedNodes: () => {
     const { nodes, edges } = get();
     const selectedNodes = nodes.filter((node) => node.selected);