From 3a10f1277a15d7e85dcac2b9f3b0429e755948da Mon Sep 17 00:00:00 2001
From: Noah Treuhaft <noah.treuhaft@gmail.com>
Date: Wed, 25 Mar 2026 19:01:20 -0400
Subject: [PATCH] fix defuse() bug on record field with union type

---
 runtime/sam/expr/function/defuse.go      |  2 +-
 runtime/ztests/expr/function/defuse.yaml | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/runtime/sam/expr/function/defuse.go b/runtime/sam/expr/function/defuse.go
index 08080be6f..24f272367 100644
--- a/runtime/sam/expr/function/defuse.go
+++ b/runtime/sam/expr/function/defuse.go
@@ -49,7 +49,7 @@ func (d *defuse) eval(in super.Value) super.Value {
 			fields = append(fields, super.NewField(f.Name, val.Type()))
 		}
 		b.EndContainerWithNones(typ.Opts, nones)
-		return super.NewValue(d.sctx.MustLookupTypeRecord(fields), b.Bytes())
+		return super.NewValue(d.sctx.MustLookupTypeRecord(fields), b.Bytes().Body())
 	case *super.TypeArray:
 		elems := d.parseArrayOrSet(typ.Type, in.Bytes())
 		if len(elems) == 0 {
diff --git a/runtime/ztests/expr/function/defuse.yaml b/runtime/ztests/expr/function/defuse.yaml
index 2822eee1e..0a393f993 100644
--- a/runtime/ztests/expr/function/defuse.yaml
+++ b/runtime/ztests/expr/function/defuse.yaml
@@ -34,3 +34,13 @@ input: &input |
   error(1::=er1)::=er2
 
 output: *input
+
+---
+
+spq: defuse(this)
+
+input: |
+  {a:fusion(1::(int64|string),<int64>)}
+
+output: |
+  {a:1}