feat(llvm): Phase 132 - Pattern 1 exit value parity fix + Box-First refactoring

## Phase 132: Exit PHI Value Parity Fix

### Problem
Pattern 1 (Simple While) returned 0 instead of final loop variable value (3)
- VM: RC: 3 ✅ (correct)
- LLVM: Result: 0 ❌ (wrong)

### Root Cause (Two Layers)
1. **JoinIR/Boundary**: Missing exit_bindings → ExitLineReconnector not firing
2. **LLVM Python**: block_end_values snapshot dropping PHI values

### Fix
**JoinIR** (simple_while_minimal.rs):
- Jump(k_exit, [i_param]) passes exit value

**Boundary** (pattern1_minimal.rs):
- Added LoopExitBinding with carrier_name="i", role=LoopState
- Enables ExitLineReconnector to update variable_map

**LLVM** (block_lower.py):
- Use predeclared_ret_phis for reliable PHI filtering
- Protect builder.vmap PHIs from overwrites (SSOT principle)

### Result
- ✅ VM: RC: 3
- ✅ LLVM: Result: 3
- ✅ VM/LLVM parity achieved

## Phase 132-Post: Box-First Refactoring

### Rust Side
**JoinModule::require_function()** (mod.rs):
- Encapsulate function search logic
- 10 lines → 1 line (90% reduction)
- Reusable for Pattern 2-5

### Python Side
**PhiManager Box** (phi_manager.py - new):
- Centralized PHI lifecycle management
- 47 lines → 8 lines (83% reduction)
- SSOT: builder.vmap owns PHIs
- Fail-Fast: No silent overwrites

**Integration**:
- LLVMBuilder: Added phi_manager
- block_lower.py: Delegated to PhiManager
- tagging.py: Register PHIs with manager

### Documentation
**New Files**:
- docs/development/architecture/exit-phi-design.md
- docs/development/current/main/investigations/phase132-llvm-exit-phi-wrong-result.md
- docs/development/current/main/phases/phase-132/

**Updated**:
- docs/development/current/main/10-Now.md
- docs/development/current/main/phase131-3-llvm-lowering-inventory.md

### Design Principles
- Box-First: Logic encapsulated in classes/methods
- SSOT: Single Source of Truth (builder.vmap for PHIs)
- Fail-Fast: Early explicit failures, no fallbacks
- Separation of Concerns: 3-layer architecture

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CURRENT_TASK.md

@@ -4,7 +4,7 @@
 詳細は `docs/development/current/main/` 以下の各 Phase 文書と、JoinIR の SSOT である  
 `docs/development/current/main/joinir-architecture-overview.md` を参照してね。
 
-最終更新: 2025-12-14
+最終更新: 2025-12-15
 
 過去ログ（肥大化した旧 CURRENT_TASK）はここに退避したよ:
 - `docs/development/current/main/CURRENT_TASK_ARCHIVE_2025-12-13.md`
@@ -18,7 +18,10 @@
 - debug flag SSOT / DebugOutputBox 移行 / error tags 集約 / carrier init builder まで整備済み。
 - **LLVM exe line SSOT 確立**: `tools/build_llvm.sh` を使用した .hako → executable パイプライン標準化完了。
 - **LLVM AOT（Python llvmlite）ループ復旧**: `apps/tests/loop_min_while.hako` が EMIT/LINK/RUN まで到達（Phase 131-3..10）。
-  - 残り: `loop(true)` + `break/continue` の JoinIR パターン穴（Case C）
+  - Case C（`loop(true)` + break/continue）は Phase 131-11 で Pattern/shape guard の基盤まで到達。残りは Case C の parity/仕上げ（SSOT を見ながら詰める）。
+- **Phase 132 完了**: Pattern 1（Simple While）の `return i` が VM/LLVM で一致（3 を返す）まで根治。
+  - JoinIR/Boundary: exit 値を境界に明示的に渡す
+  - LLVM Python: PHI を落とす/上書きする経路を除去（PHI SSOT を保護）
 - **Phase 88 完了**: continue + 可変ステップ（i=i+const 差分）を dev-only fixture で固定、StepCalculator Box 抽出。
 - **Phase 89 完了**: P0（ContinueReturn detector）+ P1（lowering 実装）完了。
 - **Phase 90 完了**: ParseStringComposite + `Null` literal + ContinueReturn（同一値の複数 return-if）を dev-only fixture で固定。
@@ -35,6 +38,8 @@
 - `docs/development/current/main/phase131-2-box-resolution-map.md`
 - `docs/development/current/main/phase131-3-llvm-lowering-inventory.md`
 - `docs/development/current/main/phase131-5-taglink-fix-summary.md`
+- `docs/development/current/main/phases/phase-132/README.md`
+- `docs/development/current/main/investigations/phase132-llvm-exit-phi-wrong-result.md`
 
 ---