From 9f879a4bf94462b7d64b6b697816afc50bc5ebd7 Mon Sep 17 00:00:00 2001
From: Nickolas Oliveira <nickolas.oliveira02@gmail.com>
Date: Thu, 18 Jun 2026 16:04:18 -0300
Subject: [PATCH] fix(evo-flow): route split node to the selected variant edge
 (EVO-1828)

The Split (A/B) node computed the target handle but dropped it: its `.then()`
called createSuccessResult without nextNodeHandle, so the executor fell back to
the first edge and every contact took variant A regardless of percentages.
Carry nextNodeHandle in the result (mirroring ConditionalNode) and declare it
on NodeExecutionResult. Adds unit specs for the handle + per-contact selection.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../temporal/activities/nodes/base.node.ts    |  1 +
 .../activities/nodes/split.node.spec.ts       | 55 +++++++++++++++++++
 .../temporal/activities/nodes/split.node.ts   | 16 ++++--
 3 files changed, 67 insertions(+), 5 deletions(-)
 create mode 100644 src/modules/temporal/activities/nodes/split.node.spec.ts

diff --git a/src/modules/temporal/activities/nodes/base.node.ts b/src/modules/temporal/activities/nodes/base.node.ts
index 0359f6b..eb8abc7 100644
--- a/src/modules/temporal/activities/nodes/base.node.ts
+++ b/src/modules/temporal/activities/nodes/base.node.ts
@@ -8,6 +8,7 @@ import {
 export interface NodeExecutionResult {
   success: boolean;
   nextNodeId?: string;
+  nextNodeHandle?: string; // Branch routing: the edge.sourceHandle the executor should follow (conditional/split nodes)
   error?: string;
   variables?: Record<string, any>;
   executionTime?: number;
diff --git a/src/modules/temporal/activities/nodes/split.node.spec.ts b/src/modules/temporal/activities/nodes/split.node.spec.ts
new file mode 100644
index 0000000..d8223bd
--- /dev/null
+++ b/src/modules/temporal/activities/nodes/split.node.spec.ts
@@ -0,0 +1,55 @@
+import { SplitNode } from './split.node';
+
+describe('SplitNode (EVO-1828)', () => {
+  let node: SplitNode;
+
+  const make = (
+    variants?: Array<{ id: string; name: string; percentage: number }>,
+    contactId = 'contact-1',
+  ) => ({
+    nodeId: 'split-1',
+    contactId,
+    sessionId: 'session-1',
+    nodeData: { variants },
+  });
+
+  beforeEach(() => {
+    node = new SplitNode();
+    const logger = (node as any).logger;
+    for (const m of ['log', 'debug', 'warn', 'error']) {
+      jest.spyOn(logger, m).mockImplementation(() => undefined);
+    }
+  });
+
+  it('returns a nextNodeHandle pointing at the selected variant (was dropped before the fix)', async () => {
+    const res = await node.execute(make());
+    expect(res.success).toBe(true);
+    expect(res.nextNodeHandle).toMatch(/^split-variant-(variant-a|variant-b)$/);
+  });
+
+  it('routes every contact to variant A when A is 100%', async () => {
+    const variants = [
+      { id: 'variant-a', name: 'A', percentage: 100 },
+      { id: 'variant-b', name: 'B', percentage: 0 },
+    ];
+    for (const c of ['c1', 'c2', 'whatever']) {
+      const res = await node.execute(make(variants, c));
+      expect(res.nextNodeHandle).toBe('split-variant-variant-a');
+    }
+  });
+
+  it('routes every contact to variant B when B is 100%', async () => {
+    const variants = [
+      { id: 'variant-a', name: 'A', percentage: 0 },
+      { id: 'variant-b', name: 'B', percentage: 100 },
+    ];
+    const res = await node.execute(make(variants, 'c1'));
+    expect(res.nextNodeHandle).toBe('split-variant-variant-b');
+  });
+
+  it('selects deterministically per contactId', async () => {
+    const a = await node.execute(make(undefined, 'same-contact'));
+    const b = await node.execute(make(undefined, 'same-contact'));
+    expect(a.nextNodeHandle).toBe(b.nextNodeHandle);
+  });
+});
diff --git a/src/modules/temporal/activities/nodes/split.node.ts b/src/modules/temporal/activities/nodes/split.node.ts
index 585fbec..67d162e 100644
--- a/src/modules/temporal/activities/nodes/split.node.ts
+++ b/src/modules/temporal/activities/nodes/split.node.ts
@@ -79,11 +79,17 @@ export class SplitNode extends BaseNode {
       };
     })
       .then(({ result, executionTime }) => {
-        return this.createSuccessResult(input, executionTime, {
-          [`node_${input.nodeId}_selected_variant`]: result.selectedVariant,
-          [`node_${input.nodeId}_variant_id`]: result.variantId,
-          [`node_${input.nodeId}_random_value`]: result.random,
-        });
+        // EVO-1828: carry the routing decision so the executor branches to the
+        // selected variant's edge (sourceHandle = split-variant-<id>) instead of
+        // always falling back to the first edge.
+        return {
+          ...this.createSuccessResult(input, executionTime, {
+            [`node_${input.nodeId}_selected_variant`]: result.selectedVariant,
+            [`node_${input.nodeId}_variant_id`]: result.variantId,
+            [`node_${input.nodeId}_random_value`]: result.random,
+          }),
+          nextNodeHandle: result.nextNodeHandle,
+        };
       })
       .catch((error) => {
         const executionTime = Date.now();