diff --git a/apps/tests/phase129_if_only_join_k_as_last_min.hako b/apps/tests/phase129_if_only_join_k_as_last_min.hako
new file mode 100644
index 00000000..2b4546b0
--- /dev/null
+++ b/apps/tests/phase129_if_only_join_k_as_last_min.hako
@@ -0,0 +1,26 @@
+// Phase 129-B: if-only join_k as-last (Normalized shadow, dev-only)
+//
+// Pattern (function g): local x; if flag==1 { x=2; return x } else { return x }
+// - The `if` is the last statement (no post-if).
+// - Both branches return the same variable `x` (PHI forbidden; merge via join_k).
+//
+// Expected: prints "2" (flag=1 fixed)
+
+static box Main {
+    g(flag) {
+        local x
+        x = 1
+        if flag == 1 {
+            x = 2
+            return x
+        } else {
+            return x
+        }
+    }
+
+    main() {
+        print(Main.g(1))
+        return "OK"
+    }
+}
+
diff --git a/tools/smokes/v2/profiles/integration/apps/phase129_join_k_as_last_vm.sh b/tools/smokes/v2/profiles/integration/apps/phase129_join_k_as_last_vm.sh
new file mode 100644
index 00000000..58ff64c9
--- /dev/null
+++ b/tools/smokes/v2/profiles/integration/apps/phase129_join_k_as_last_vm.sh
@@ -0,0 +1,60 @@
+#!/bin/bash
+# Phase 129-B: If-only join_k as-last (Normalized shadow, VM)
+#
+# Dev-only gate:
+# - NYASH_JOINIR_DEV=1 enables shadow lowering + verification
+# - HAKO_JOINIR_STRICT=1 makes verification fail-fast
+
+source "$(dirname "$0")/../../../lib/test_runner.sh"
+source "$(dirname "$0")/../../../lib/output_validator.sh"
+export SMOKES_USE_PYVM=0
+require_env || exit 2
+
+PASS_COUNT=0
+FAIL_COUNT=0
+RUN_TIMEOUT_SECS=${RUN_TIMEOUT_SECS:-10}
+
+echo "[INFO] Phase 129-B: If-only join_k as-last (Normalized shadow, VM)"
+
+echo "[INFO] Test 1: phase129_if_only_join_k_as_last_min.hako"
+INPUT="$NYASH_ROOT/apps/tests/phase129_if_only_join_k_as_last_min.hako"
+
+set +e
+OUTPUT=$(timeout "$RUN_TIMEOUT_SECS" env \
+  NYASH_DISABLE_PLUGINS=1 \
+  HAKO_JOINIR_STRICT=1 \
+  NYASH_JOINIR_DEV=1 \
+  "$NYASH_BIN" --backend vm "$INPUT" 2>&1)
+EXIT_CODE=$?
+set -e
+
+if [ "$EXIT_CODE" -eq 124 ]; then
+  echo "[FAIL] hakorune timed out (>${RUN_TIMEOUT_SECS}s)"
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+elif [ "$EXIT_CODE" -eq 0 ]; then
+  EXPECTED="2"
+  if validate_numeric_output 1 "$EXPECTED" "$OUTPUT"; then
+    echo "[PASS] Output verified: 2 (exit code: $EXIT_CODE)"
+    PASS_COUNT=$((PASS_COUNT + 1))
+  else
+    echo "[INFO] output (tail):"
+    echo "$OUTPUT" | tail -n 50 || true
+    FAIL_COUNT=$((FAIL_COUNT + 1))
+  fi
+else
+  echo "[FAIL] hakorune failed with exit code $EXIT_CODE"
+  echo "[INFO] output (tail):"
+  echo "$OUTPUT" | tail -n 50 || true
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+fi
+
+echo "[INFO] PASS: $PASS_COUNT, FAIL: $FAIL_COUNT"
+
+if [ "$FAIL_COUNT" -eq 0 ]; then
+  test_pass "phase129_join_k_as_last_vm: All tests passed"
+  exit 0
+else
+  test_fail "phase129_join_k_as_last_vm: $FAIL_COUNT test(s) failed"
+  exit 1
+fi
+