diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index e738637e..83001214 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -32,6 +32,18 @@ P0/P1 Safety Fixes (2025-09-19)
   - Updated to_http_string and Display/to_string to read via locks; manual Clone implemented.
   - Removes RefCell TODOs at http_message_box.rs:292–330 without violating BoxCore Send+Sync.
 
+LLVM Harness Gate (2025-09-19)
+- Added env gate `NYASH_LLVM_SANITIZE_EMPTY_PHI=1` to optionally drop malformed empty PHI lines before llvmlite parse.
+  - Default OFF; dev-only safety valve while finalizing PHI wiring.
+  - Code: src/llvm_py/llvm_builder.py (compile_to_object).
+
+Clone() Reduction — Phase 1 (Arc/str)
+- TypeBox internals
+  - `TypeBox.name: String` → `Arc<str>`.
+  - `TypeBox.type_parameters: Vec<String>` → `Vec<Arc<str>>`.
+  - Adjusted builder/registry and `full_name()` accordingly; public behavior unchanged.
+  - Rationale: share-on-clone for frequently copied identifiers, reduce String allocations.
+
 Refactor Plan (next 1–2 weeks)
 1) Split parse_box_declaration (667 lines) in src/parser/declarations/box_definition.rs
    - Targets (line ranges are indicative):
diff --git a/tools/test/smoke/llvm/ir_phi_empty_check.sh b/tools/test/smoke/llvm/ir_phi_empty_check.sh
new file mode 100644
index 00000000..b8bd8af7
--- /dev/null
+++ b/tools/test/smoke/llvm/ir_phi_empty_check.sh
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Small smoke: ensure no empty PHI appears in IR
+# Usage: tools/test/smoke/llvm/ir_phi_empty_check.sh [nyash_script]
+
+SCRIPT=${1:-apps/tests/loop_if_phi.nyash}
+
+echo "[phi-empty-check] building nyash (llvm features)" >&2
+LLVM_PREFIX=${LLVM_SYS_180_PREFIX:-$(command -v llvm-config-18 >/dev/null 2>&1 && llvm-config-18 --prefix || true)}
+if [[ -n "${LLVM_PREFIX}" ]]; then
+  LLVM_SYS_180_PREFIX="${LLVM_PREFIX}" cargo build --release --features llvm >/dev/null
+else
+  cargo build --release --features llvm >/dev/null
+fi
+
+IR_OUT=tmp/nyash_harness.ll
+mkdir -p tmp
+
+echo "[phi-empty-check] running harness on ${SCRIPT}" >&2
+NYASH_LLVM_USE_HARNESS=1 \
+NYASH_LLVM_DUMP_IR="${IR_OUT}" \
+./target/release/nyash --backend llvm "${SCRIPT}" >/dev/null || true
+
+if [[ ! -s "${IR_OUT}" ]]; then
+  echo "[phi-empty-check] WARN: IR dump not found; harness may have short-circuited" >&2
+  exit 0
+fi
+
+# Check: any phi i64 line must include '[' (incoming pairs)
+if rg -n "= phi i64( |$)" "${IR_OUT}" | rg -v "\\[" -n >/dev/null; then
+  echo "[phi-empty-check] FAIL: empty PHI found (no incoming list)" >&2
+  rg -n "\\= phi i64( |$)" "${IR_OUT}" | rg -v "\\[" -n || true
+  exit 1
+fi
+
+echo "[phi-empty-check] OK: no empty PHI detected in ${IR_OUT}" >&2
+exit 0