diff --git a/app/src/lib/graph-interface/graph-manager.svelte.test.ts b/app/src/lib/graph-interface/graph-manager.svelte.test.ts
new file mode 100644
index 0000000..de4d88c
--- /dev/null
+++ b/app/src/lib/graph-interface/graph-manager.svelte.test.ts
@@ -0,0 +1,265 @@
+import { describe, expect, it } from 'vitest';
+import { GraphManager } from './graph-manager.svelte';
+import {
+  createMockNodeRegistry,
+  mockFloatInputNode,
+  mockFloatOutputNode,
+  mockGeometryOutputNode,
+  mockPathInputNode,
+  mockVec3OutputNode
+} from './test-utils';
+
+describe('GraphManager', () => {
+  describe('getPossibleSockets', () => {
+    describe('when dragging an output socket', () => {
+      it('should return compatible input sockets based on type', () => {
+        const registry = createMockNodeRegistry([
+          mockFloatOutputNode,
+          mockFloatInputNode,
+          mockGeometryOutputNode,
+          mockPathInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const floatInputNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        const floatOutputNode = manager.createNode({
+          type: 'test/node/output',
+          position: [0, 0],
+          props: {}
+        });
+
+        expect(floatInputNode).toBeDefined();
+        expect(floatOutputNode).toBeDefined();
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: floatOutputNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        expect(possibleSockets.length).toBe(1);
+        const socketNodeIds = possibleSockets.map(([node]) => node.id);
+        expect(socketNodeIds).toContain(floatInputNode!.id);
+      });
+
+      it('should exclude self node from possible sockets', () => {
+        const registry = createMockNodeRegistry([
+          mockFloatOutputNode,
+          mockFloatInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const floatInputNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        expect(floatInputNode).toBeDefined();
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: floatInputNode!,
+          index: 'value',
+          position: [0, 0]
+        });
+
+        const socketNodeIds = possibleSockets.map(([node]) => node.id);
+        expect(socketNodeIds).not.toContain(floatInputNode!.id);
+      });
+
+      it('should exclude parent nodes from possible sockets when dragging output', () => {
+        const registry = createMockNodeRegistry([
+          mockFloatOutputNode,
+          mockFloatInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const parentNode = manager.createNode({
+          type: 'test/node/output',
+          position: [0, 0],
+          props: {}
+        });
+
+        const childNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        expect(parentNode).toBeDefined();
+        expect(childNode).toBeDefined();
+
+        if (parentNode && childNode) {
+          manager.createEdge(parentNode, 0, childNode, 'value');
+        }
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: parentNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        const socketNodeIds = possibleSockets.map(([node]) => node.id);
+        expect(socketNodeIds).not.toContain(childNode!.id);
+      });
+
+      it('should return sockets compatible with accepts property', () => {
+        const registry = createMockNodeRegistry([
+          mockGeometryOutputNode,
+          mockPathInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const geometryOutputNode = manager.createNode({
+          type: 'test/node/geometry',
+          position: [0, 0],
+          props: {}
+        });
+
+        const pathInputNode = manager.createNode({
+          type: 'test/node/path',
+          position: [100, 100],
+          props: {}
+        });
+
+        expect(geometryOutputNode).toBeDefined();
+        expect(pathInputNode).toBeDefined();
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: geometryOutputNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        const socketNodeIds = possibleSockets.map(([node]) => node.id);
+        expect(socketNodeIds).toContain(pathInputNode!.id);
+      });
+
+      it('should return empty array when no compatible sockets exist', () => {
+        const registry = createMockNodeRegistry([
+          mockVec3OutputNode,
+          mockFloatInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const vec3OutputNode = manager.createNode({
+          type: 'test/node/vec3',
+          position: [0, 0],
+          props: {}
+        });
+
+        const floatInputNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        expect(vec3OutputNode).toBeDefined();
+        expect(floatInputNode).toBeDefined();
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: vec3OutputNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        const socketNodeIds = possibleSockets.map(([node]) => node.id);
+        expect(socketNodeIds).not.toContain(floatInputNode!.id);
+        expect(possibleSockets.length).toBe(0);
+      });
+
+      it('should return socket info with correct socket key for inputs', () => {
+        const registry = createMockNodeRegistry([
+          mockFloatOutputNode,
+          mockFloatInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const floatOutputNode = manager.createNode({
+          type: 'test/node/output',
+          position: [0, 0],
+          props: {}
+        });
+
+        const floatInputNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        expect(floatOutputNode).toBeDefined();
+        expect(floatInputNode).toBeDefined();
+
+        const possibleSockets = manager.getPossibleSockets({
+          node: floatOutputNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        const matchingSocket = possibleSockets.find(([node]) => node.id === floatInputNode!.id);
+        expect(matchingSocket).toBeDefined();
+        expect(matchingSocket![1]).toBe('value');
+      });
+
+      it('should return multiple compatible sockets', () => {
+        const registry = createMockNodeRegistry([
+          mockFloatOutputNode,
+          mockFloatInputNode,
+          mockGeometryOutputNode,
+          mockPathInputNode
+        ]);
+
+        const manager = new GraphManager(registry);
+
+        const floatOutputNode = manager.createNode({
+          type: 'test/node/output',
+          position: [0, 0],
+          props: {}
+        });
+
+        const geometryOutputNode = manager.createNode({
+          type: 'test/node/geometry',
+          position: [200, 0],
+          props: {}
+        });
+
+        const floatInputNode = manager.createNode({
+          type: 'test/node/input',
+          position: [100, 100],
+          props: {}
+        });
+
+        const pathInputNode = manager.createNode({
+          type: 'test/node/path',
+          position: [300, 100],
+          props: {}
+        });
+
+        expect(floatOutputNode).toBeDefined();
+        expect(geometryOutputNode).toBeDefined();
+        expect(floatInputNode).toBeDefined();
+        expect(pathInputNode).toBeDefined();
+
+        const possibleSocketsForFloat = manager.getPossibleSockets({
+          node: floatOutputNode!,
+          index: 0,
+          position: [0, 0]
+        });
+
+        expect(possibleSocketsForFloat.length).toBe(1);
+        expect(possibleSocketsForFloat.map(([n]) => n.id)).toContain(floatInputNode!.id);
+      });
+    });
+  });
+});
diff --git a/app/src/lib/graph-interface/graph-manager.svelte.ts b/app/src/lib/graph-interface/graph-manager.svelte.ts
index 8f9c938..6d33fd2 100644
--- a/app/src/lib/graph-interface/graph-manager.svelte.ts
+++ b/app/src/lib/graph-interface/graph-manager.svelte.ts
@@ -757,12 +757,16 @@ export class GraphManager extends EventEmitter<{
         (n) => n.id !== node.id && !parents.has(n.id)
       );
 
-      // get edges from this socket
-      const edges = new SvelteMap(
-        this.getEdgesFromNode(node)
-          .filter((e) => e[1] === index)
-          .map((e) => [e[2].id, e[3]])
-      );
+      const edges = new SvelteMap<number, string[]>();
+      this.getEdgesFromNode(node)
+        .filter((e) => e[1] === index)
+        .forEach((e) => {
+          if (edges.has(e[2].id)) {
+            edges.get(e[2].id)?.push(e[3]);
+          } else {
+            edges.set(e[2].id, [e[3]]);
+          }
+        });
 
       const ownType = nodeType.outputs?.[index];
 
@@ -775,7 +779,7 @@ export class GraphManager extends EventEmitter<{
 
           if (
             areSocketsCompatible(ownType, otherType)
-            && edges.get(node.id) !== key
+            && !edges.get(node.id)?.includes(key)
           ) {
             sockets.push([node, key]);
           }
diff --git a/app/src/lib/graph-interface/test-utils.ts b/app/src/lib/graph-interface/test-utils.ts
new file mode 100644
index 0000000..26a0a4d
--- /dev/null
+++ b/app/src/lib/graph-interface/test-utils.ts
@@ -0,0 +1,86 @@
+import type { NodeDefinition, NodeId, NodeRegistry } from '@nodarium/types';
+
+export function createMockNodeRegistry(nodes: NodeDefinition[]): NodeRegistry {
+  const nodesMap = new Map(nodes.map(n => [n.id, n]));
+  return {
+    status: 'ready' as const,
+    load: async (nodeIds: NodeId[]) => {
+      const loaded: NodeDefinition[] = [];
+      for (const id of nodeIds) {
+        if (nodesMap.has(id)) {
+          loaded.push(nodesMap.get(id)!);
+        }
+      }
+      return loaded;
+    },
+    getNode: (id: string) => nodesMap.get(id as NodeId),
+    getAllNodes: () => Array.from(nodesMap.values()),
+    register: async () => {
+      throw new Error('Not implemented in mock');
+    }
+  };
+}
+
+export const mockFloatOutputNode: NodeDefinition = {
+  id: 'test/node/output',
+  inputs: {},
+  outputs: ['float'],
+  meta: { title: 'Float Output' },
+  execute: () => new Int32Array()
+};
+
+export const mockFloatInputNode: NodeDefinition = {
+  id: 'test/node/input',
+  inputs: { value: { type: 'float' } },
+  outputs: [],
+  meta: { title: 'Float Input' },
+  execute: () => new Int32Array()
+};
+
+export const mockGeometryOutputNode: NodeDefinition = {
+  id: 'test/node/geometry',
+  inputs: {},
+  outputs: ['geometry'],
+  meta: { title: 'Geometry Output' },
+  execute: () => new Int32Array()
+};
+
+export const mockPathInputNode: NodeDefinition = {
+  id: 'test/node/path',
+  inputs: { input: { type: 'path', accepts: ['geometry'] } },
+  outputs: [],
+  meta: { title: 'Path Input' },
+  execute: () => new Int32Array()
+};
+
+export const mockVec3OutputNode: NodeDefinition = {
+  id: 'test/node/vec3',
+  inputs: {},
+  outputs: ['vec3'],
+  meta: { title: 'Vec3 Output' },
+  execute: () => new Int32Array()
+};
+
+export const mockIntegerInputNode: NodeDefinition = {
+  id: 'test/node/integer',
+  inputs: { value: { type: 'integer' } },
+  outputs: [],
+  meta: { title: 'Integer Input' },
+  execute: () => new Int32Array()
+};
+
+export const mockBooleanOutputNode: NodeDefinition = {
+  id: 'test/node/boolean',
+  inputs: {},
+  outputs: ['boolean'],
+  meta: { title: 'Boolean Output' },
+  execute: () => new Int32Array()
+};
+
+export const mockBooleanInputNode: NodeDefinition = {
+  id: 'test/node/boolean-input',
+  inputs: { value: { type: 'boolean' } },
+  outputs: [],
+  meta: { title: 'Boolean Input' },
+  execute: () => new Int32Array()
+};