# Phase 4 Status - Executive Summary

**Date**: 2025-12-14
**Status**: E1 GO（opt-in）, E2 FROZEN, E3-4 GO（opt-in）
**Baseline**: Mixed 20M/ws=400（E1/E3-4 の ON/OFF に依存。結果は各 A/B セクション参照）

---

## Quick Status

### E2 Decision: FREEZE ✅ (NEUTRAL)

**Result**: -0.21% mean, -0.62% median (NEUTRAL)

**Why Freeze?**
- Alloc route optimization saturated by Phase 3 C3 (static routing)
- Free DUALHOT worked (+13%) because it skipped expensive ops
- Alloc DUALHOT doesn't work (-0.21%) because route already cached
- **Lesson**: Per-class specialization only helps when bypassing uncached overhead

**Action**: Keep as research box (default OFF), no further investigation

---

## E1/E3-4 Results (Mixed A/B)

### E1: ENV Snapshot Consolidation ✅ GO (opt-in)

**Result**: +3.92% avg, +4.01% median  
**ENV**: `HAKMEM_ENV_SNAPSHOT=1`（default OFF）

### E3-4: ENV Constructor Init ✅ GO (opt-in)

**Result**: +4.75% mean, +4.35% median（E1=1 前提）  
**ENV**: `HAKMEM_ENV_SNAPSHOT=1 HAKMEM_ENV_SNAPSHOT_CTOR=1`（default OFF）

**Note**: “constructor での pre-main init” を効かせたい場合はプロセス起動前に ENV を設定（bench_profile putenv だけでは遅い）

---

## Phase 4 Cumulative Status

**Active**:
- E1 (ENV Snapshot): +3.92% ✅ GO（opt-in）
- E3-4 (ENV CTOR): +4.75% ✅ GO（opt-in, requires E1）

**Frozen**:
- D3 (Alloc Gate Shape): +0.56% ⚪
- E2 (Alloc Per-Class FastPath): -0.21% ⚪

## Next Actions

1. E3-4 の “hint/refresh” 調整後に 10-run 再確認（昇格前の最終ゲート）
2. GO 維持なら `ENV_PROFILE_PRESETS.md` と `CURRENT_TASK.md` に “E1+E3-4 の推奨セット” を明記
3. E1/E3-4 ON の状態で perf を取り直して次の芯を選ぶ（alloc gate / free_tiny_fast_cold など）

---

## Key Lessons

1. **Route optimization saturated**: C3 already cached routes, E2 no benefit
2. **Shape optimization plateaued**: D3 +0.56% neutral, branch prediction saturated
3. **ENV consolidation successful**: E1 +3.92%, constructor init is next step
4. **Different optimization vectors needed**: Move beyond route/shape to init/dispatch overhead

---

**Full Analysis**: `/mnt/workdisk/public_share/hakmem/docs/analysis/PHASE4_COMPREHENSIVE_STATUS_ANALYSIS.md`