diff --git a/stage0/sema.c b/stage0/sema.c
index d47c865ddc..bd3c43ef7d 100644
--- a/stage0/sema.c
+++ b/stage0/sema.c
@@ -610,6 +610,10 @@ static TypeIndex semaTypeOf(Sema* sema, AirInstRef ref) {
     case AIR_INST_BYTE_SWAP:
     case AIR_INST_BIT_REVERSE:
     case AIR_INST_ABS:
+    case AIR_INST_UNWRAP_ERRUNION_PAYLOAD:
+    case AIR_INST_UNWRAP_ERRUNION_ERR:
+    case AIR_INST_UNWRAP_ERRUNION_PAYLOAD_PTR:
+    case AIR_INST_UNWRAP_ERRUNION_ERR_PTR:
     case AIR_INST_NEG:
     case AIR_INST_NEG_OPTIMIZED:
     case AIR_INST_DBG_INLINE_BLOCK:
@@ -11926,6 +11930,44 @@ static AirInstRef zirOptionalPayload(
     return AIR_REF_FROM_IP(payload_ip);
 }
 
+// zirErrUnionPayload: extract payload from error union (unsafe path).
+// Ported from src/Sema.zig zirErrUnionPayload → analyzeErrUnionPayload.
+// Runtime: emit AIR_INST_UNWRAP_ERRUNION_PAYLOAD.
+static AirInstRef zirErrUnionPayload(
+    Sema* sema, SemaBlock* block, uint32_t inst) {
+    ZirInstRef operand_ref = sema->code.inst_datas[inst].un_node.operand;
+    AirInstRef operand = resolveInst(sema, operand_ref);
+    TypeIndex eu_ty = semaTypeOf(sema, operand);
+    // Get the payload type from the error union type.
+    TypeIndex payload_ty = IP_INDEX_VOID_TYPE;
+    if (sema->ip->items[eu_ty].tag == IP_KEY_ERROR_UNION_TYPE)
+        payload_ty = sema->ip->items[eu_ty].data.error_union_type.payload;
+    AirInstData data;
+    memset(&data, 0, sizeof(data));
+    data.ty_op.ty_ref = AIR_REF_FROM_IP(payload_ty);
+    data.ty_op.operand = operand;
+    return semaAddInst(block, AIR_INST_UNWRAP_ERRUNION_PAYLOAD, data);
+}
+
+// zirErrUnionCode: extract error code from error union.
+// Ported from src/Sema.zig zirErrUnionCode.
+// Runtime: emit AIR_INST_UNWRAP_ERRUNION_ERR.
+static AirInstRef zirErrUnionCode(
+    Sema* sema, SemaBlock* block, uint32_t inst) {
+    ZirInstRef operand_ref = sema->code.inst_datas[inst].un_node.operand;
+    AirInstRef operand = resolveInst(sema, operand_ref);
+    TypeIndex eu_ty = semaTypeOf(sema, operand);
+    // Get the error set type from the error union type.
+    TypeIndex err_ty = IP_INDEX_VOID_TYPE;
+    if (sema->ip->items[eu_ty].tag == IP_KEY_ERROR_UNION_TYPE)
+        err_ty = sema->ip->items[eu_ty].data.error_union_type.error_set;
+    AirInstData data;
+    memset(&data, 0, sizeof(data));
+    data.ty_op.ty_ref = AIR_REF_FROM_IP(err_ty);
+    data.ty_op.operand = operand;
+    return semaAddInst(block, AIR_INST_UNWRAP_ERRUNION_ERR, data);
+}
+
 // --- analyzeBodyInner ---
 // Ported from src/Sema.zig analyzeBodyInner.
 // Main dispatch loop: iterates over ZIR instructions in a body and
@@ -12742,6 +12784,22 @@ bool analyzeBodyInner(
             i++;
             continue;
 
+        // err_union_payload: extract payload from error union.
+        case ZIR_INST_ERR_UNION_PAYLOAD_UNSAFE:
+        case ZIR_INST_ERR_UNION_PAYLOAD_UNSAFE_PTR:
+            instMapPut(
+                &sema->inst_map, inst, zirErrUnionPayload(sema, block, inst));
+            i++;
+            continue;
+
+        // err_union_code: extract error code from error union.
+        case ZIR_INST_ERR_UNION_CODE:
+        case ZIR_INST_ERR_UNION_CODE_PTR:
+            instMapPut(
+                &sema->inst_map, inst, zirErrUnionCode(sema, block, inst));
+            i++;
+            continue;
+
         // Validation-only instructions: no value produced, no AIR emitted.
         // These validate preconditions but don't produce useful values.
         case ZIR_INST_VALIDATE_ARRAY_INIT_TY: