docs: Phase 132 DONE - loop(true) + post-loop complete

Update documentation to mark Phase 132 as complete:

**10-Now.md**:
- Add Phase 132 completion entry (P0/P0.5/P1/R0)
- Document what was solved:
  - loop(true) + post VM/LLVM EXE parity (exit code 3)
  - Continuation contracts SSOT化
  - merge が by-name 推測禁止
- Entry link: docs/development/current/main/phases/phase-132/README.md

**phase-132/README.md**:
- Update Status: IN PROGRESS → DONE ✅
- Add Current Status section with P0/P0.5/P1/R0 completion details
- Document SSOT achievements:
  - JoinInlineBoundary::default_continuations()
  - src/mir/builder/control_flow/joinir/merge/README.md (merge contracts)
  - src/mir/builder/control_flow/joinir/legacy/README.md (removal conditions)
- Test placement: continuation_contract.rs
- Test results: All Phase 131/132/97 smokes PASS

Phase 132 Summary:
- P0: post_k generation (loop_true_break_once.rs extension)
- P0.5: Suffix router for StepTree (post statements visibility fix)
- P1: k_exit continuation classification fix (structural check)
- R0: Infrastructure refactoring (SSOT + legacy isolation + docs)

Key achievements:
- VM/LLVM EXE parity for loop(true) + post-loop
- Continuation contracts SSOT and documented
- Legacy code path isolated for future removal
- Code quality improved (warnings reduced)

Related: Phase 132 loop(true) + post-loop complete implementation

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

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

docs/development/current/main/10-Now.md

@@ -35,6 +35,29 @@
 - Unit tests: 1155/1155 PASS
 - 入口: `docs/development/current/main/phases/phase-129/README.md`
 
+## 2025-12-18：Phase 132 完了 ✅
+
+**Phase 132: loop(true) break-once + post-loop minimal（dev-only）**
+- 目的: Phase 131 を拡張し、ループ後の最小 post 計算まで Normalized shadow で固定（PHI-free 維持）
+- 仕様:
+  - `loop(true) { x = 1; break }; x = x + 2; return x` は exit code `3`（VM/LLVM EXE parity）
+  - post_k continuation で post-loop statements を処理
+- 実装:
+  - **P0**: post_k 生成（loop_true_break_once.rs 拡張）
+  - **P0.5**: StepTree が post-loop statements を保持（suffix router box 追加）
+  - **P1**: k_exit continuation 分類修正（構造ベースの判定）
+  - **R0**: Continuation SSOT 一本化 + legacy 隔離 + docs 整備
+- SSOT:
+  - `JoinInlineBoundary::default_continuations()` - continuation ID の集約
+  - `src/mir/builder/control_flow/joinir/merge/README.md` - merge 契約明文化
+  - `src/mir/builder/control_flow/joinir/legacy/README.md` - legacy 撤去条件
+- テスト配置: `src/mir/builder/control_flow/joinir/merge/tests/continuation_contract.rs`
+- 検証:
+  - `bash tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_vm.sh`
+  - `bash tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_llvm_exe.sh`
+- 回帰: Phase 131/97 維持確認（全 PASS）
+- 入口: `docs/development/current/main/phases/phase-132/README.md`
+
 ## 2025-12-18：Phase 131 P2 完了 ✅
 
 **Phase 131: loop(true) break-once Normalized（dev-only）**

docs/development/current/main/phases/phase-132/README.md

@@ -1,148 +1,348 @@
-# Phase 132: Exit Values Parity (VM == LLVM)
+# Phase 132: loop(true) break-once with Minimal Post Computation (dev-only)
 
-**Date**: 2025-12-15  
-**Status**: ✅ Done  
-**Scope**: ループ exit 値（exit PHI / boundary）が VM/LLVM で一致することを固定する（Pattern 1 と Case C を含む）
+**Date**: 2025-12-18
+**Status**: DONE ✅
+**Scope**: loop(true) break-once + post-loop minimal computation (Normalized shadow)
 
 ---
 
-## 背景
+## Previous Phase 132 Work (2025-12-15) ✅ Done
 
-最小ケース:
+### Phase 132-P1 to P3: Exit Values Parity and LLVM Python Fixes
+
+- **P1**: FunctionLowerContext Box for state isolation
+- **P2**: Exit PHI ValueId collision fix (Case C)
+- **P3**: Exit PHI collision early detection (debug-only)
+
+All previous Phase 132 work is complete and documented in commit history.
+
+---
+
+## Phase 132-P4: loop(true) break-once with Post Computation (NEW)
+
+**Goal**: Extend Phase 131 `loop(true){...; break}` to support minimal post-loop computation.
+
+Related:
+- Entry: `docs/development/current/main/10-Now.md`
+- Phase 131 (loop baseline): `docs/development/current/main/phases/phase-131/README.md`
+- Phase 130 (post_k pattern): `docs/development/current/main/phases/phase-130/README.md`
+- ControlTree SSOT: `docs/development/current/main/design/control-tree.md`
+
+### Goal
+
+Extend Phase 131 `loop(true){...; break}` to support minimal post-loop computation:
+
+- Enable `x = x + 2` after loop exit, then return
+- Keep **PHI禁止**: merge via env + continuations only
+- Keep **dev-only** and **既定挙動不変**: unmatched shapes fall back (strict can Fail-Fast)
+
+### Non-Goals
+
+- No general loop conditions (only `true` literal)
+- No continue support (only break at end of body)
+- No nested control flow inside loop body
+- No multiple breaks or conditional breaks
+- No complex post-loop computation (one assignment + return only)
+
+### Accepted Forms
+
+#### ✅ Supported
 
 ```nyash
-static box Main {
-  main() {
-    local i = 0
-    loop(i < 3) { i = i + 1 }
-    return i  // 期待: 3
-  }
+// Form: loop(true) with break + minimal post computation
+local x
+x = 0
+loop(true) {
+    x = 1
+    break
 }
+x = x + 2
+return x  // Expected: 3 (1 + 2)
 ```
 
-- VM: `RC: 3` ✅
-- LLVM: `Result: 0` ❌（修正前）
+#### ❌ Not Supported
 
----
+```nyash
+// Multiple post-loop statements
+loop(true) { x = 1; break }
+x = x + 2
+y = x + 3
+return y
 
-## 根本原因（2層）
+// Continue (not break)
+loop(true) { x = 1; continue }
 
-### 1) JoinIR/Boundary 層: exit 値が境界を通っていない
+// Nested control flow
+loop(true) { if (y == 1) { x = 2 }; break }
 
-- Pattern 1 の JoinIR で `k_exit` に渡す args が空のままだと、exit 側でホストの `variable_map["i"]` が更新されない。
-- その結果 `return i` が初期値（0）を返し得る。
+// General loop conditions
+loop(x < 10) { x = x + 1; break }
+```
 
-### 2) LLVM Python 層: PHI の SSOT が壊れている
+### SSOT Contracts
 
-- `phi.basic_block` が llvmlite で確定前は `None` になり得るため、PHI を落とす filter を信頼できない。
-- `builder.vmap` にある PHI placeholder を、Pass A の “sync created values” が上書きしてしまい、`ret` が PHI ではなく `0` を参照することがある。
+#### EnvLayout (Phase 126)
 
----
+Same as Phase 131:
+- `writes`: Variables assigned in the fragment
+- `inputs`: Variables read from outer scope
+- `env_fields()`: `writes ++ inputs` (SSOT for parameter order)
 
-## 修正内容
+#### Loop + Post Structure Contract
 
-### JoinIR/Boundary 層（exit 値を明示的に渡す）
+For `loop(true) { body ; break }; <post>; return`:
 
-- `src/mir/join_ir/lowering/simple_while_minimal.rs`
-  - `Jump(k_exit, [i_param])` として exit 値を渡す
-- `src/mir/builder/control_flow/joinir/patterns/pattern1_minimal.rs`
-  - `LoopExitBinding` を作成して `with_exit_bindings()` で境界に設定
+1. **Condition**: Must be Bool literal `true` (cond_ast check)
+2. **Body**: Must be a Block ending with Break statement
+3. **Post-loop**: One assignment statement (`x = x + <int literal>`) followed by one return statement
+4. **No exits**: No return/continue in body (only break at end)
+5. **Assignments**: Body contains only Assign(int literal/var/add) and LocalDecl
 
-### LLVM Python 層（PHI SSOT を保護する）
+#### Generated JoinModule Structure
 
-- `src/llvm_py/builders/block_lower.py`
-  - PHI filtering を `predeclared_ret_phis` ベースにし、`phi.basic_block` 依存を排除
-  - `builder.vmap` の既存 PHI（placeholder）を上書きしない（PHI を SSOT として保護）
+```
+main(env) → TailCall(loop_step, env)
 
----
+loop_step(env) →
+    TailCall(loop_body, env)  // condition is always true, no branch
 
-## 検証
+loop_body(env) →
+    <assign statements update env>
+    TailCall(k_exit, env)
 
-- `/tmp/p1_return_i.hako` が VM/LLVM で `3` を返す
-- `NYASH_LLVM_STRICT=1` でも “miss→0” に落ちない（Fail-Fast が維持される）
+k_exit(env) →
+    TailCall(post_k, env)  // Phase 132-P4: NEW (was Ret in Phase 131)
 
-詳細ログ:
-- `docs/development/current/main/investigations/phase132-llvm-exit-phi-wrong-result.md`
+post_k(env) →
+    <post assignment: x = env[x] + 2>
+    Ret(env[x])
+```
 
----
+**Key Differences from Phase 131**:
+- Phase 131: `k_exit(env) → Ret(env[x])`
+- Phase 132-P4: `k_exit(env) → TailCall(post_k, env)`, `post_k(env) → <assign>; Ret(env[x])`
 
-## 追加: Phase 132-P2（Case C）Exit PHI ValueId collision fix
+**Invariants**:
+- No PHI instructions (all merging via env parameters)
+- All continuations take full env as parameters
+- Post-loop assignment updates env before return
 
-Case C（`apps/tests/llvm_stage3_loop_only.hako`）の LLVM EXE 検証で、
-**exit PHI の ValueId 衝突**が原因で `Result: 0` になる問題が見つかった。
+#### Reconnection Mode
 
-### Root Cause
+Phase 132-P4 uses **DirectValue mode** (same as Phase 131):
+- No exit PHI generation
+- Final env values from `post_k` are reconnected directly to host `variable_map`
+- ExitMeta carries `exit_values: Vec<(String, ValueId)>` for reconnection
 
-- `src/mir/builder/control_flow/joinir/merge/exit_phi_builder.rs` が
-  PHI dst の割り当てに `builder.value_gen.next()`（module-level）を使っており、
-  同一関数内で ValueId が衝突し得た。
+### VM + LLVM Parity
 
-### Fix
+Both backends must produce identical results:
+- VM: Rust VM backend (`--backend vm`)
+- LLVM: LLVM EXE backend via llvm_exe_runner.sh
 
-- PHI dst の割り当てを `func.next_value_id()`（function-level）へ統一。
+Expected contract for fixture: exit code `3` (1 + 2)
 
-コミット:
-- `bd07b7f4 fix(joinir): Phase 132-P2 - Exit PHI ValueId collision fix`
+### Work Items
 
-### Verification
+#### Step 0: Documentation ✅
 
-- Pattern 1: VM/LLVM ともに `3`
-- Case C: VM/LLVM ともに `Result: 3`
+- ✅ Create Phase 132-P4 documentation in `README.md`
+- TODO: Update `docs/development/current/main/10-Now.md`
 
-調査ログ:
-- `docs/development/current/main/investigations/phase132-case-c-llvm-exe.md`
+#### Step 1: Fixtures + Smokes
 
----
+- New fixture: `apps/tests/phase132_loop_true_break_once_post_add_min.hako`
+  - Expected exit code: `3` (1 + 2)
+  - Form: x=0; loop(true) { x=1; break }; x=x+2; return x
+- VM smoke: `tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_vm.sh`
+- LLVM EXE smoke: `tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_llvm_exe.sh`
 
-## 追加: Phase 132-P3（debug-only）Exit PHI collision early detection
+#### Step 2: Implementation
 
-同種の ValueId 衝突が “LLVM 実行時” にしか露見しないと切り分けコストが高いので、
-JoinIR merge の契約検証（debug build）で **早期に Fail-Fast** する検証 Box を追加した。
+- Extend: `src/mir/control_tree/normalized_shadow/loop_true_break_once.rs`
+  - Box: `LoopTrueBreakOnceBuilderBox` (existing)
+  - Accept: `loop(true) { body ; break }; <post>; return` pattern
+  - Reject (Ok(None)): Non-matching patterns
+  - Generate: main → loop_step → loop_body → k_exit → post_k (no PHI)
+  - Reuse: Phase 130's `lower_assign_stmt` for post-loop assignment
 
-- 検証: `verify_exit_phi_no_collision()`
-- 実装: `src/mir/builder/control_flow/joinir/merge/contract_checks.rs`
-- 呼び出し元: `verify_exit_line(...)`（`#[cfg(debug_assertions)]`）
+#### Step 3: Verification
 
-検出例（概念）:
-- `bb0: %1 = const 0`
-- `exit block: %1 = phi ...`（衝突）
+```bash
+cargo test --lib
+cargo build --release -p nyash-rust --features llvm
 
-期待される振る舞い:
-- debug build では compile/run 中に panic で即停止（原因と修正案が出る）
-- release build の既定挙動は変えない（検証は `debug_assertions` のみ）
+# Phase 132-P4 smokes (NEW)
+bash tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_vm.sh
+bash tools/smokes/v2/profiles/integration/apps/phase132_loop_true_break_once_post_add_llvm_exe.sh
 
----
+# Regressions (Phase 131)
+bash tools/smokes/v2/profiles/integration/apps/phase131_loop_true_break_once_vm.sh
+bash tools/smokes/v2/profiles/integration/apps/phase131_loop_true_break_once_llvm_exe.sh
 
-## 追加: Phase 132-P1（LLVM Python）FunctionLowerContext Box
+# Regressions (Phase 97 - stable baseline)
+bash tools/smokes/v2/profiles/integration/apps/phase97_next_non_ws_llvm_exe.sh
+```
 
-Phase 131–132 で顕在化した「関数間の状態漏洩（block id / value id の衝突）」を、
-tuple-key の小手先ではなく **構造で根治**するために、関数ローカル状態を 1 箱に隔離した。
+#### Step 4: Commits
 
-- 実装: `src/llvm_py/context/function_lower_context.py`
-- 統合: `src/llvm_py/builders/function_lower.py`
+1. `docs: Phase 132-P4 structure documentation`
+2. `test(joinir): Phase 132-P4 loop(true) break-once + post fixture + VM/LLVM smokes`
+3. `feat(control_tree): Phase 132-P4 loop(true) break-once with minimal post computation (dev-only)`
+4. `docs: Phase 132-P4 DONE`
 
-箱の責務（SSOT）:
-- `block_end_values`（snapshot）
-- `def_blocks`
-- `jump_only_blocks`
-- `phi_manager`
-- resolver caches（i64/ptr/f64/end_i64 など）
+### Implementation Notes
 
-狙い:
-- 関数単位で state を自動破棄し、cross-function collision を "起こせない構造" にする
-- 追加の手動クリアや tuple-key を不要にする
+#### Design Principles
 
-### Phase 132-P2 Follow-up: Dict ctx Cleanup
+1. **Box-First**: Post-loop lowering is a separate concern from loop body lowering
+   - Consider extracting to `PostLoopLowererBox` if complexity grows
+2. **Reuse Infrastructure**: Leverage Phase 130's post_k pattern and `lower_assign_stmt`
+3. **Fail-Fast**: Contract violations in supported patterns → `freeze_with_hint`
+4. **Ok(None) Fallback**: Out of scope patterns → return `Ok(None)` for legacy fallback
 
-完成: SSOT 統一を完全化するため、`src/llvm_py/builders/function_lower.py` の
-`builder.ctx = dict(...)` を削除し、FunctionLowerContext への統一を完成させた。
+#### Reconnection Strategy
 
-- 削除: lines 313-330（dict ctx の作成と `builder.resolver.ctx` の割り当て）
-- 入口: `instruction_lower.py` の全ハンドラが既に `context=owner.context` で呼び出されているため、
-  manual ctx dict は不要
-- テスト追加: `phase132_multifunc_isolation_min.hako`（f(2) + f(3) = 5 を exit code で検証）
+Phase 132-P4 continues using **DirectValue mode**:
+- `ExitMeta.exit_values` must point to the **final** ValueIds after post_k execution
+- Not the k_exit parameters, not the loop_body values, but post_k's updated env values
+- This is the SSOT for variable_map reconnection
 
-**状態**:
-- ✅ Dict ctx 削除
-- ✅ Instruction handlers は `context=owner.context` で統一
-- ✅ Multi-function isolation test Case C 追加（smoke test phase132_exit_phi_parity.sh）
+#### Post-Loop Detection
+
+Check StepNode structure:
+```rust
+let (prefix_nodes, loop_node, post_nodes) = extract_loop_true_pattern(&step_tree.root);
+
+// Phase 131: post_nodes.is_empty() or post_nodes == [Return(Variable)]
+// Phase 132-P4: post_nodes == [Assign(Add), Return(Variable)]
+```
+
+#### Reusing Phase 130's lower_assign_stmt
+
+Phase 130 already supports:
+- `x = y` (Variable)
+- `x = x + <int literal>` (Add)
+
+Phase 132-P4 can directly reuse this for post-loop assignment lowering.
+
+### Acceptance Criteria
+
+- ✅ cargo test --lib PASS
+- ✅ cargo build --release -p nyash-rust --features llvm PASS
+- ✅ Phase 132-P4 new smokes: 2/2 PASS (VM + LLVM EXE)
+- ✅ Phase 131 regression smokes: 2/2 PASS
+- ✅ Phase 97 regression smoke: 1/1 PASS
+- ✅ Dev toggle OFF → no impact (Ok(None) fallback)
+
+### Box-First Feedback Points
+
+#### Modularization Opportunities
+
+1. **PostLoopLowererBox**: If post-loop logic grows beyond one assignment + return
+   - Separate from loop body lowering
+   - Single responsibility: lower post-loop statements into post_k
+2. **ContinuationBuilderBox**: Common pattern for building continuation functions
+   - Reusable across loop_true, if-only, etc.
+   - SSOT for env parameter allocation and env map building
+
+#### Legacy Cleanup
+
+1. **Direct env map updates**: No legacy "host side PHI merging" in Normalized path
+   - All updates via env parameters and continuations
+   - DirectValue reconnection is the clean modern approach
+2. **Fail-Fast discipline**: Phase 132-P4 should maintain Phase 131's strict error handling
+   - Use `freeze_with_hint` for contract violations
+   - Clear hints guide users to fix patterns
+
+#### SSOT Maintenance
+
+1. **ExitMeta.exit_values**: Must reference post_k's final env values
+   - Not loop_body values, not k_exit parameters
+   - This is critical for DirectValue reconnection correctness
+2. **EnvLayout.env_fields()**: SSOT for all env parameter lists
+   - Used consistently in main, loop_step, loop_body, k_exit, post_k
+   - Any deviation is a contract violation
+
+### Current Status
+
+Phase 132 - DONE ✅ (2025-12-18)
+
+#### P0: post_k Generation ✅
+
+- Extended `loop_true_break_once.rs` to generate post_k continuation
+- Reused Phase 130's `lower_assign_stmt` for post-loop statements
+- ExitMeta uses DirectValue mode (PHI-free)
+- Fixture: `apps/tests/phase132_loop_true_break_once_post_add_min.hako`
+- Expected exit code: 3
+
+#### P0.5: Suffix Router for StepTree ✅
+
+- **Root cause**: routing.rs created StepTree from Loop node only, losing post statements
+- **Solution**: New `normalized_shadow_suffix_router_box.rs`
+  - Detects block suffix: Loop + Assign* + Return
+  - Creates StepTree from entire suffix (Block([Loop, Assign, Return]))
+- Modified `build_block()` to call suffix router (dev-only)
+- StepTree unchanged: Block is SSOT for statement order
+- No data duplication: Loop doesn't hold post_nodes
+
+#### P1: k_exit Continuation Fix ✅
+
+- **Problem**: k_exit with TailCall(post_k) was classified as skippable continuation
+- **Root cause**: Classification was name-based, didn't examine function body
+- **Solution**: Check function body structure before classifying as skippable
+- Non-skippable pattern: continuation with TailCall to another function
+- VM/LLVM EXE parity achieved (exit code 3)
+
+#### R0: Refactoring Infrastructure ✅
+
+**Task 1: Continuation SSOT 一本化**
+- Added `JoinInlineBoundary::default_continuations()`
+- Replaced all `BTreeSet::from([JoinFuncId::new(2)])` hardcoding (7 locations)
+- Single source of truth for continuation function IDs
+
+**Task 2: merge 契約 docs SSOT 化**
+- New: `src/mir/builder/control_flow/joinir/merge/README.md`
+- Documented continuation contracts, skip conditions, forbidden behaviors
+- Prohibited by-name/by-id classification
+
+**Task 3: テスト配置正規化**
+- New: `src/mir/builder/control_flow/joinir/merge/tests/continuation_contract.rs`
+- Moved tests from instruction_rewriter.rs to dedicated test file
+- Added 4 test cases (Case A-D)
+
+**Task 4: legacy 導線隔離**
+- New: `src/mir/builder/control_flow/joinir/legacy/`
+- Moved `routing_legacy_binding.rs` to `legacy/routing_legacy_binding.rs`
+- Added `legacy/README.md` with removal conditions
+- No cfg(feature="legacy") (docs-only isolation for now)
+
+**Task 5: ノイズ除去**
+- Removed unused imports (ConstValue, MirInstruction)
+- Reduced warnings in touched files
+
+#### Test Results ✅
+
+```bash
+cargo test --lib: 1176 PASS
+Phase 132 VM: PASS (exit code 3)
+Phase 132 LLVM EXE: PASS (exit code 3)
+Phase 131 regression: PASS
+Phase 97 regression: PASS
+```
+
+#### Key Achievements
+
+- ✅ loop(true) + post-loop works in both VM and LLVM EXE
+- ✅ Continuation contracts SSOT化
+- ✅ merge が by-name 推測禁止
+- ✅ Legacy code path isolated for future removal
+- ✅ Code quality improved (warnings reduced)
+
+#### Documentation
+
+- Entry: `docs/development/current/main/10-Now.md`
+- SSOT: `JoinInlineBoundary::default_continuations()`
+- SSOT: `src/mir/builder/control_flow/joinir/merge/README.md` (merge contracts)
+- Tests: `src/mir/builder/control_flow/joinir/merge/tests/continuation_contract.rs`
+- Legacy: `src/mir/builder/control_flow/joinir/legacy/README.md` (removal conditions)