diff --git a/src/store/__tests__/loopEdge.integration.test.ts b/src/store/__tests__/loopEdge.integration.test.ts
new file mode 100644
index 00000000..ef421781
--- /dev/null
+++ b/src/store/__tests__/loopEdge.integration.test.ts
@@ -0,0 +1,216 @@
+/**
+ * Loop Edge Integration Tests
+ *
+ * Tests the runtime behavior of loop edges during workflow execution.
+ * These tests validate that loops execute N times with correct data flow.
+ */
+
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { useWorkflowStore } from "../workflowStore";
+import { WorkflowNode, WorkflowEdge, WorkflowNodeData } from "@/types";
+
+// Test helpers
+function makeNode(id: string, type: string, data?: Partial<WorkflowNodeData>): WorkflowNode {
+  return {
+    id,
+    type,
+    position: { x: 0, y: 0 },
+    data: data || {},
+  } as WorkflowNode;
+}
+
+function makeEdge(
+  source: string,
+  target: string,
+  opts?: { isLoop?: boolean; loopCount?: number; hasPause?: boolean }
+): WorkflowEdge {
+  return {
+    id: `${source}-${target}`,
+    source,
+    target,
+    data: opts || {},
+  } as WorkflowEdge;
+}
+
+function setupStore(nodes: WorkflowNode[], edges: WorkflowEdge[]): void {
+  useWorkflowStore.setState({ nodes, edges });
+}
+
+describe("setLoopCount", () => {
+  beforeEach(() => {
+    // Reset store to clean state
+    useWorkflowStore.setState({
+      nodes: [],
+      edges: [],
+      groups: {},
+      isRunning: false,
+      hasUnsavedChanges: false,
+    });
+  });
+
+  it("updates edge data loopCount", () => {
+    const edge = makeEdge("a", "b", { isLoop: true, loopCount: 3 });
+    setupStore([], [edge]);
+
+    useWorkflowStore.getState().setLoopCount(edge.id, 5);
+
+    const updatedEdge = useWorkflowStore.getState().edges.find((e) => e.id === edge.id);
+    expect(updatedEdge?.data?.loopCount).toBe(5);
+  });
+
+  it("clamps loop count to minimum 1", () => {
+    const edge = makeEdge("a", "b", { isLoop: true, loopCount: 3 });
+    setupStore([], [edge]);
+
+    useWorkflowStore.getState().setLoopCount(edge.id, 0);
+
+    const updatedEdge = useWorkflowStore.getState().edges.find((e) => e.id === edge.id);
+    expect(updatedEdge?.data?.loopCount).toBe(1);
+  });
+
+  it("clamps loop count to maximum 100", () => {
+    const edge = makeEdge("a", "b", { isLoop: true, loopCount: 3 });
+    setupStore([], [edge]);
+
+    useWorkflowStore.getState().setLoopCount(edge.id, 150);
+
+    const updatedEdge = useWorkflowStore.getState().edges.find((e) => e.id === edge.id);
+    expect(updatedEdge?.data?.loopCount).toBe(100);
+  });
+});
+
+describe("executeWorkflow with loop edges", () => {
+  beforeEach(() => {
+    // Reset store to clean state
+    useWorkflowStore.setState({
+      nodes: [],
+      edges: [],
+      groups: {},
+      isRunning: false,
+      hasUnsavedChanges: false,
+    });
+  });
+
+  it("executes loop subgraph exactly N times", async () => {
+    // Create A(imageInput) → B(prompt) → C(output) with loop edge C→A (loopCount: 3)
+    const nodeA = makeNode("a", "imageInput", { image: "data:image/png;base64,test" });
+    const nodeB = makeNode("b", "prompt", { prompt: "test prompt" });
+    const nodeC = makeNode("c", "output");
+
+    const edges = [
+      makeEdge("a", "b"),
+      makeEdge("b", "c"),
+      makeEdge("c", "a", { isLoop: true, loopCount: 3 }),
+    ];
+
+    setupStore([nodeA, nodeB, nodeC], edges);
+
+    // Spy on copyLoopOutput to count iterations
+    const copyLoopOutputSpy = vi.spyOn(
+      await import("../utils/executionUtils"),
+      "copyLoopOutput"
+    );
+
+    await useWorkflowStore.getState().executeWorkflow();
+
+    // copyLoopOutput should be called (loopCount - 1) times
+    // because first iteration uses original input
+    expect(copyLoopOutputSpy).toHaveBeenCalledTimes(2); // 3 iterations - 1 = 2 calls
+  });
+
+  it("executes non-loop prefix and suffix nodes once", async () => {
+    // Create PREFIX(imageInput) → A(prompt) → B(prompt) → SUFFIX(output)
+    // with loop edge B→A (loopCount: 3)
+    const prefix = makeNode("prefix", "imageInput", { image: "data:image/png;base64,test" });
+    const nodeA = makeNode("a", "prompt", { prompt: "loop start" });
+    const nodeB = makeNode("b", "prompt", { prompt: "loop end" });
+    const suffix = makeNode("suffix", "output");
+
+    const edges = [
+      makeEdge("prefix", "a"),
+      makeEdge("a", "b"),
+      makeEdge("b", "suffix"),
+      makeEdge("b", "a", { isLoop: true, loopCount: 3 }),
+    ];
+
+    setupStore([prefix, nodeA, nodeB, suffix], edges);
+
+    // Spy on updateNodeData to track execution
+    const updateNodeDataSpy = vi.spyOn(useWorkflowStore.getState(), "updateNodeData");
+
+    await useWorkflowStore.getState().executeWorkflow();
+
+    // Check that prefix and suffix nodes were updated less frequently than loop nodes
+    // (This is a simplified check - in real execution, loop nodes would be updated more)
+    const prefixUpdates = updateNodeDataSpy.mock.calls.filter((call) => call[0] === "prefix");
+    const suffixUpdates = updateNodeDataSpy.mock.calls.filter((call) => call[0] === "suffix");
+    const loopNodeUpdates = updateNodeDataSpy.mock.calls.filter(
+      (call) => call[0] === "a" || call[0] === "b"
+    );
+
+    // Prefix and suffix should have fewer updates than loop nodes
+    expect(prefixUpdates.length).toBeLessThan(loopNodeUpdates.length);
+    expect(suffixUpdates.length).toBeLessThan(loopNodeUpdates.length);
+  });
+
+  it("does not affect workflows with no loop edges", async () => {
+    // Standard A → B → C workflow
+    const nodeA = makeNode("a", "imageInput", { image: "data:image/png;base64,test" });
+    const nodeB = makeNode("b", "prompt", { prompt: "test" });
+    const nodeC = makeNode("c", "output");
+
+    const edges = [makeEdge("a", "b"), makeEdge("b", "c")];
+
+    setupStore([nodeA, nodeB, nodeC], edges);
+
+    // Should execute without errors
+    await useWorkflowStore.getState().executeWorkflow();
+
+    // Verify workflow completed
+    expect(useWorkflowStore.getState().isRunning).toBe(false);
+  });
+
+  it("treats loopCount:1 same as no loop", async () => {
+    // Create A(imageInput) → B(prompt) with loop edge B→A (loopCount: 1)
+    const nodeA = makeNode("a", "imageInput", { image: "data:image/png;base64,test" });
+    const nodeB = makeNode("b", "prompt", { prompt: "test" });
+
+    const edges = [makeEdge("a", "b"), makeEdge("b", "a", { isLoop: true, loopCount: 1 })];
+
+    setupStore([nodeA, nodeB], edges);
+
+    // Spy on copyLoopOutput
+    const copyLoopOutputSpy = vi.spyOn(
+      await import("../utils/executionUtils"),
+      "copyLoopOutput"
+    );
+
+    await useWorkflowStore.getState().executeWorkflow();
+
+    // With loopCount=1, copyLoopOutput should never be called (no iterations to feedback)
+    expect(copyLoopOutputSpy).toHaveBeenCalledTimes(0);
+  });
+
+  it("stops loop mid-iteration when aborted", async () => {
+    // Create loop with loopCount: 10
+    const nodeA = makeNode("a", "imageInput", { image: "data:image/png;base64,test" });
+    const nodeB = makeNode("b", "prompt", { prompt: "test" });
+
+    const edges = [makeEdge("a", "b"), makeEdge("b", "a", { isLoop: true, loopCount: 10 })];
+
+    setupStore([nodeA, nodeB], edges);
+
+    // Start execution (don't await)
+    const executionPromise = useWorkflowStore.getState().executeWorkflow();
+
+    // Abort after a short delay
+    setTimeout(() => {
+      useWorkflowStore.getState().stopWorkflow();
+    }, 10);
+
+    await executionPromise;
+
+    // Verify execution was stopped
+    expect(useWorkflowStore.getState().isRunning).toBe(false);
+  });
+});