diff --git a/CLAUDE.md b/CLAUDE.md
index 145a3bc4..f98e29ec 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -66,8 +66,11 @@ NYASH_CLI_VERBOSE=1 ./tools/jit_smoke.sh
 # ラウンドトリップ (パーサーパイプ + JSON)
 ./tools/ny_roundtrip_smoke.sh
 
-# Nyコンパイラ MVP経路 (実験的)
+# Nyコンパイラ MVP経路 (Phase 15.3実装中!)
 NYASH_USE_NY_COMPILER=1 ./target/release/nyash program.nyash
+
+# JSON v0 Bridge経由実行（完成済み）
+python tools/ny_parser_mvp.py program.nyash | ./target/release/nyash --ny-parser-pipe
 ```
 
 ### 🐧 Linux/WSL版
@@ -193,6 +196,12 @@ NYASH_DISABLE_PLUGINS=1 ./target/release/nyash program.nyash
 # ラウンドトリップテスト
 ./tools/ny_roundtrip_smoke.sh
 
+# Stage-2 PHIスモーク（If/Loop PHI合流）
+./tools/ny_parser_stage2_phi_smoke.sh
+
+# Stage-2 Bridgeスモーク（算術/比較/短絡/if）
+./tools/ny_stage2_bridge_smoke.sh
+
 # プラグインスモーク（オプション）
 NYASH_SKIP_TOML_ENV=1 ./tools/smoke_plugins.sh
 
@@ -223,10 +232,13 @@ NYASH_LLVM_USE_HARNESS=1 ./target/release/nyash program.nyash
 
 ## 📝 Update (2025-09-14) 🎉 セルフホスティング大前進！
 - ✅ Python LLVM実装が実用レベル到達！（esc_dirname_smoke, min_str_cat_loop, dep_tree_min_string全てPASS）
-- 🚀 パーサーのNyash実装開始！ChatGPT5が`apps/selfhost/parser/`で実装中
+- 🚀 **Phase 15.3開始！** NyashコンパイラMVP実装が`apps/selfhost-compiler/`でスタート！
+- ✅ JSON v0 Bridge完成 - If/Loop PHI生成実装済み（ChatGPT実装）
+- 🔧 Python MVPパーサーStage-2完成 - local/if/loop/call/method/new対応
 - 📚 peek式の再発見 - when→peekに名前変更、ブロック/値/文すべて対応済み
 - 🧠 箱理論でSSA構築を簡略化（650行→100行）- 論文執筆完了
 - 🤝 AI協働の知見を論文化 - 実装駆動型学習の重要性を実証
+- 🎯 **LoopForm戦略決定**: PHIは逆Lowering時に自動生成（Codex推奨）
 - 📋 詳細: [Phase 15 README](docs/development/roadmap/phases/phase-15/README.md)
 
 ### 🚀 新発見：プラグイン全方向ビルド戦略
@@ -246,6 +258,12 @@ clang main.o filebox.o pathbox.o libnyrt.a -o nyash_static.exe
 ### 🏗️ Everything is Box
 - すべての値がBox（StringBox, IntegerBox, BoolBox等）
 - ユーザー定義Box: `box ClassName { field1: TypeBox field2: TypeBox }`
+- **MIR14命令**: たった14個の命令で全機能実現！
+  - 基本演算(5): Const, UnaryOp, BinOp, Compare, TypeOp
+  - メモリ(2): Load, Store  
+  - 制御(4): Branch, Jump, Return, Phi
+  - Box(2): NewBox, BoxCall
+  - 外部(1): ExternCall
 
 ### 🌟 完全明示デリゲーション
 ```nyash
diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index 679cacf0..0ba711b3 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -1,12 +1,39 @@
 # Current Task (2025-09-14 改定) — Phase 15 llvmlite（既定）+ PyVM（新規）
 
+Handoff — TL;DR（2025‑09‑15）
+- フェーズ: 15.3（Ny コンパイラMVP 入口を統合済み／Stage‑1 実装中）
+- ランナー統合: `NYASH_USE_NY_COMPILER=1` で selfhost compiler を子プロセス実行→stdout の JSON v0 を Bridge→MIR 実行（失敗時は自動フォールバック）
+- Selfhost compiler 配置: `apps/selfhost-compiler/`（`compiler.nyash` がエントリ。parser/emitter骨子あり）
+- 進捗:
+  - Stage‑1 パーサ骨子（number/string/term/expr/returnスキップ）実装済み（2パス gpos 方針）。
+  - セミコロン最小対応: selfhost 側で `;` を空白同等にスキップ（改行ベース＋必要時のみ;）。Rustパーサは未対応のまま。
+  - 仕様ドキュメント更新: `docs/reference/language/statements.md`（改行＋最小ASI）。
+  - imports/namespace/nyash.toml: Phase‑15 中は Runner(Rust) で解決継続。selfhost は `using` 受理（no‑op）を 15.3後半に導入予定（計画: `docs/development/roadmap/phases/phase-15/imports-namespace-plan.md`）。VM 変更は不要。
+- そのまま回せるスモーク（緑）:
+  - `tools/ny_stage2_bridge_smoke.sh`（算術/比較/短絡/ネストif）
+  - `tools/ny_parser_stage2_phi_smoke.sh`（If/Loop PHI）
+  - `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/esc_dirname_smoke.nyash`
+  - `tools/selfhost_compiler_smoke.sh`（selfhost 入口／MVPはResult:0）
+- 次にやること（短期）:
+  1) Stage‑1: `return 1+2*3` の JSON v0 正常化（左結合/優先度準拠）→ Bridge → MIR 実行 = 7 を確定。
+  2) 最小ASI導入（深さ0・直前が継続子でない改行のみ文終端）。代表ケースのスモーク追加（if/else連結、return継続、演算子継続、ドットチェイン）。
+  3) Stage‑2 着手（local/if/loop/call/method/new/var/論理/比較）— PHI は Bridge 側に委譲のまま。
+- 守ること:
+  - PHI: Bridge 側（If/Loop）で合流、LoopForm(Core‑14) 導入時に逆Loweringで自動化へ（現状維持）。
+  - imports/namespace: 15.3 は Runner で解決維持（selfhost は no‑op 受理のみ）。
+  - フォールバックは常時安全（selfhost 経路失敗→既存経路）。
+
+
 Quick Summary（反映内容）
 - 実装済み: peek CFG修正、llvmlite文字列ブリッジ、混在‘+’結合、追加テスト緑。
 - JSON v0 Bridge拡張: Stmt(Expr/Local/If/Loop)、Expr(Call/Method/New/Var) 降下を実装。
 - PHI合流: If/Loop の PHI 合流を Bridge 側で実装（If: then/else→merge、Loop: preheader/loop‑latch→header）。
 - PythonパーサMVP: Stage‑2 サブセット（local/if/loop/call/method/new/var ほか）を出力。
+- Ny コンパイラMVP（入口）: `NYASH_USE_NY_COMPILER=1` で Ny→JSON v0 パスを試行（失敗時は自動フォールバック）。初期実装は `apps/selfhost-compiler/compiler.nyash`（優先）/`apps/selfhost/parser/ny_parser_v0/main.nyash` を子プロセスで実行して JSON を収集。
+- 文分離ポリシー: 「改行ベース＋必要時のみセミコロン」。最小ASI（深さ0かつ直前が継続子でない改行のみ文終端）。ドキュメント反映済み。
 - Outstanding: then/else 片側のみで新規生成された変数のスコープ（現在は外へ未伝播）。
 - Next（handoff）: Stage‑2 E2E緑化→me の扱い検討（Method糖衣）。
+- 後続計画: MIR‑SSA（Sealed SSA）骨子を 15.2 終盤で投入（既定OFF）、15.3 で並走→15.3 終盤で既定化。
 - How to run: 下の手順に確認コマンドを追記。
 
 Hot Update — 2025‑09‑14（JSON v0 Bridge/Parser Stage‑2 + Parity hardening）
@@ -15,6 +42,7 @@ Hot Update — 2025‑09‑14（JSON v0 Bridge/Parser Stage‑2 + Parity hardeni
   - console.* の文字列引数を to_i8p_h ブリッジで正規化（from_i8_string 直呼び回避）。
   - “文字列＋数値” 混在 ‘+’ を concat_si/is＋from_i8_string による橋渡しで安定化、両辺文字列は concat_hh。
   - 代表追加テスト（緑）: string_ops_basic / me_method_call / loop_if_phi。
+  - 追加パリティ確認（緑）: string_ops_basic / peek_expr_block / peek_return_value / ternary_basic / ternary_nested / esc_dirname_smoke。
 
 - JSON v0 Bridge（Option A）の受け口を Stage‑2 方向に拡張（src/runner/json_v0_bridge.rs）
   - StmtV0: Expr / Local / If / Loop を追加。If/Loop は実ブロック生成（then/else/merge、cond/body/exit）まで実装、未終端 Jump 補完、最後に未終端ブロックへ ret 0 補完。
@@ -35,7 +63,10 @@ Outstanding（要対応）
 Next（handoff short plan）
 1) JSON Bridge: PHI 合流実装（If/Loop）と最小テスト追加（ループ後/if後の変数参照）。
 2) Parser MVP: Stage‑2 生成 JSON の if/loop ケースで Bridge→MIR→PyVM/llvmlite の parity 緑化。
-3) me の扱い検討（当面は Method 降下で十分。必要なら me→Main.method/N 直呼シンタックスを Bridge 側で糖衣対応）。
+3) me の扱い（MVP方針）
+   - JSON v0: `Method{ recv: Var{"me"} }` を許容（文脈があれば var_map に解決）。
+   - Bridge: 既定は未定義エラー。デバッグ用に `NYASH_BRIDGE_ME_DUMMY=1`（任意 `NYASH_BRIDGE_ME_CLASS`=Main 既定）で `NewBox{class}` を注入して `me` を仮解決。
+   - 将来: Ny Builder が box/method 文脈で `me` を提供（Bridge のダミーは撤去予定）。
 
 How to run（現状確認）
 - Build（release）: `cargo build --release`（必要に応じて `NYASH_CLI_VERBOSE=1`）。
@@ -44,6 +75,38 @@ How to run（現状確認）
 - Parser Stage‑2 → Bridge: `python3 tools/ny_parser_mvp.py tmp/sample.ny | target/release/nyash --ny-parser-pipe`。
 - Bridge smoke（一式）: `./tools/ny_parser_bridge_smoke.sh`（pipe/--json-file の両経路）。
 - Stage‑2 PHI smoke: `./tools/ny_parser_stage2_phi_smoke.sh`（If/Loop の PHI 合流検証）。
+- me dummy smoke（デバッグゲート）: `./tools/ny_me_dummy_smoke.sh`（`NYASH_BRIDGE_ME_DUMMY=1` で Var("me") をダミー注入）。
+- Stage‑2 Bridge smoke（サブセット一括）: `./tools/ny_stage2_bridge_smoke.sh`（算術/比較/短絡/ネストif）。
+- 自己ホスト準備（ブートストラップ）: `./tools/bootstrap_selfhost_smoke.sh`（c0→c1→c1'、MVPはフォールバック許容）。
+- Nyコンパイラ入口スモーク: `./tools/selfhost_compiler_smoke.sh`（json_v0 emit → Result:0）。
+
+Phase 15.3 — Ny compiler MVP 詳細計画（抜粋）
+- 入口: Runner に `NYASH_USE_NY_COMPILER=1` を追加し、selfhost compiler を子プロセス実行（stdout の JSON v0 を Bridge へ）。失敗は自動フォールバック。
+- Stage‑1（小さく積む）
+  1) return / 整数 / 文字列 / 四則 / 括弧（左結合）。
+  2) 文分離（最小ASI）: 改行=文区切り、継続子（+ - * / . ,）やグルーピング中は継続。
+  3) スモーク: `return 1+2*3` → JSON v0 → Bridge → MIR 実行 = 7。
+- Stage‑2（本命）
+  - local / if / loop / call / method / new / var / 比較 / 論理（短絡）。
+  - PHI: Bridge 側の合流（If/Loop）に依存（Phase‑15 中は現行維持）。
+  - スモーク: nested if / loop 累積 / 短絡 and/or × if/loop。
+- 受け入れ（15.3）
+  - Stage‑1: 代表サンプル緑（PyVM/llvmlite 一致）。
+  - Bootstrap: `tools/bootstrap_selfhost_smoke.sh` PASS（フォールバックは許容）。
+  - Docs: `docs/reference/language/statements.md` 公開（方針/例/実装ノート）。
+
+Parity memo（確認済み）
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/string_ops_basic.nyash` → 緑
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/peek_expr_block.nyash` → 緑
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/peek_return_value.nyash` → 緑
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/ternary_basic.nyash` → 緑
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/ternary_nested.nyash` → 緑
+- `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/esc_dirname_smoke.nyash` → 緑
+
+Notes — PHI 方針（Phase‑15→Core‑14）
+- Phase‑15: 現行の Bridge‑PHI（If/Loop 合流）を維持して完成まで駆け抜ける（変更しない）。
+- Core‑14: LoopForm を強化し、逆Loweringで PHI を自動生成（構造ブロック→合流点 PHI）。
+- JSON v0: Phase‑15 は従来通り PHI を含める／Core‑14 以降は非必須（将来は除外方向）。
 
 Context Snapshot — Open After Reset
 - Status: A6 受入（PyVM↔llvmlite parity + LLVM verify→.o→EXE）完了。
@@ -120,6 +183,7 @@ Hot Update — 2025‑09‑14（Language + Docs）
   - 言語索引: `docs/reference/language/README.md`
   - 安定パス（スタブ）: `docs/reference/language/LANGUAGE_REFERENCE_2025.md`（private実体へ誘導）
   - アーキ索引/受け皿: `docs/reference/architecture/{nyash_core_concepts.md, execution-backends.md, TECHNICAL_ARCHITECTURE_2025.md}`
+  - 文分離ポリシー: `docs/reference/language/statements.md`（改行ベース＋必要時のみセミコロン、最小ASI）
 - Parser MVP（Stage 1）:
   - Python 実装: `tools/ny_parser_mvp.py` を追加、Roundtrip スモーク `tools/ny_parser_mvp_roundtrip.sh` で緑。
   - Nyash 実装スケルトン: `apps/selfhost/parser/ny_parser_v0/main.nyash`（改修継続）。
diff --git a/app_parity_esc_dirname_smoke b/app_parity_esc_dirname_smoke
index 4838e9ad..6dd284d8 100644
Binary files a/app_parity_esc_dirname_smoke and b/app_parity_esc_dirname_smoke differ
diff --git a/app_parity_ternary_basic b/app_parity_ternary_basic
index a8ddf97f..bd11e67a 100644
Binary files a/app_parity_ternary_basic and b/app_parity_ternary_basic differ
diff --git a/app_parity_ternary_nested b/app_parity_ternary_nested
index ee7d8dca..40f13645 100644
Binary files a/app_parity_ternary_nested and b/app_parity_ternary_nested differ
diff --git a/apps/selfhost-compiler/README.md b/apps/selfhost-compiler/README.md
new file mode 100644
index 00000000..e6dd8569
--- /dev/null
+++ b/apps/selfhost-compiler/README.md
@@ -0,0 +1,18 @@
+# Nyash Selfhost Compiler (MVP scaffold)
+
+This is the Phase 15.3 work-in-progress Nyash compiler implemented in Ny.
+
+Layout
+- `compiler.nyash`: entry (CompilerBox). Reads `tmp/ny_parser_input.ny`, prints JSON v0.
+- `parser/`: lexer/parser/ast (scaffolds; to be filled as we extend Stage‑2)
+- `mir/`: builder/optimizer stubs (future; current target is JSON v0 emit)
+- `tests/`: Stage‑1/2 samples (TBD)
+
+Run (behind flag)
+- `NYASH_USE_NY_COMPILER=1 target/release/nyash --backend vm <program.nyash>`
+  - The runner writes the input to `tmp/ny_parser_input.ny` and invokes this program.
+  - It captures a JSON v0 line from stdout and executes it via the JSON bridge.
+
+Notes
+- Early MVP emits a minimal JSON v0 (currently a placeholder: return 0). We will gradually wire lexer/parser/emitter.
+- Keep JSON v0 spec in `docs/reference/ir/json_v0.md`.
diff --git a/apps/selfhost-compiler/compiler.nyash b/apps/selfhost-compiler/compiler.nyash
new file mode 100644
index 00000000..111e2650
--- /dev/null
+++ b/apps/selfhost-compiler/compiler.nyash
@@ -0,0 +1,309 @@
+// Selfhost Compiler MVP (Phase 15.3)
+// Reads tmp/ny_parser_input.ny and prints a minimal JSON v0 program.
+
+static box Main {
+  // ---- IO helper ----
+  read_all(path) {
+    local fb = new FileBox()
+    fb.open(path, "r")
+    local s = fb.read()
+    fb.close()
+    return s
+  }
+
+  // ---- JSON helpers ----
+  esc_json(s) {
+    local out = ""
+    local i = 0
+    local n = s.length()
+    loop(i < n) {
+      local ch = s.substring(i, i+1)
+      if ch == "\\" { out = out + "\\\\" } else {
+        if ch == "\"" { out = out + "\\\"" } else { out = out + ch }
+      }
+      i = i + 1
+    }
+    return out
+  }
+
+  // ---- Lexer helpers ----
+  is_digit(ch) {
+    return ch == "0" || ch == "1" || ch == "2" || ch == "3" || ch == "4" || ch == "5" || ch == "6" || ch == "7" || ch == "8" || ch == "9"
+  }
+  is_space(ch) { return ch == " " || ch == "\t" || ch == "\n" || ch == "\r" || ch == ";" }
+
+  // ---- Parser (Stage-1/mini Stage-2) ----
+  // Global cursor for second-pass parser (no pack strings)
+  gpos_set(i) {
+    me.gpos = i
+    return 0
+  }
+  gpos_get() { return me.gpos }
+
+  parse_number2(src, i) {
+    local n = src.length()
+    local j = i
+    loop(j < n && me.is_digit(src.substring(j, j+1))) { j = j + 1 }
+    local s = src.substring(i, j)
+    me.gpos_set(j)
+    return "{\"type\":\"Int\",\"value\":" + s + "}"
+  }
+
+  parse_string2(src, i) {
+    local n = src.length()
+    local j = i + 1
+    local out = ""
+    local done = 0
+    loop(j < n && done == 0) {
+      local ch = src.substring(j, j+1)
+      if ch == "\"" {
+        j = j + 1
+        done = 1
+      } else {
+      if ch == "\\" && j + 1 < n {
+        local nx = src.substring(j+1, j+2)
+        if nx == "\"" { out = out + "\"" } else { if nx == "\\" { out = out + "\\" } else { out = out + nx } }
+        j = j + 2
+      } else {
+        out = out + ch
+        j = j + 1
+      }
+      }
+    }
+    me.gpos_set(j)
+    return "{\"type\":\"Str\",\"value\":\"" + me.esc_json(out) + "\"}"
+  }
+
+  parse_factor2(src, i) {
+    local j = me.skip_ws(src, i)
+    local ch = src.substring(j, j+1)
+    if ch == "(" {
+      local inner = me.parse_expr2(src, j + 1)
+      local k = me.gpos_get()
+      k = me.skip_ws(src, k)
+      if src.substring(k, k+1) == ")" { k = k + 1 }
+      me.gpos_set(k)
+      return inner
+    }
+    if ch == "\"" { return me.parse_string2(src, j) }
+    return me.parse_number2(src, j)
+  }
+
+  parse_term2(src, i) {
+    local lhs = me.parse_factor2(src, i)
+    local j = me.gpos_get()
+    local cont = 1
+    loop(cont == 1) {
+      j = me.skip_ws(src, j)
+      if j >= src.length() { cont = 0 } else {
+        local op = src.substring(j, j+1)
+        if op != "*" && op != "/" { cont = 0 } else {
+          local rhs = me.parse_factor2(src, j+1)
+          j = me.gpos_get()
+          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
+        }
+      }
+    }
+    me.gpos_set(j)
+    return lhs
+  }
+
+  parse_expr2(src, i) {
+    local lhs = me.parse_term2(src, i)
+    local j = me.gpos_get()
+    local cont = 1
+    loop(cont == 1) {
+      j = me.skip_ws(src, j)
+      if j >= src.length() { cont = 0 } else {
+        local op = src.substring(j, j+1)
+        if op != "+" && op != "-" { cont = 0 } else {
+          local rhs = me.parse_term2(src, j+1)
+          j = me.gpos_get()
+          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
+        }
+      }
+    }
+    me.gpos_set(j)
+    return lhs
+  }
+
+  parse_program2(src) {
+    local i = me.skip_ws(src, 0)
+    local j = me.skip_return_kw(src, i)
+    if j == i { j = i } // optional 'return'
+    local expr = me.parse_expr2(src, j)
+    return "{\"version\":0,\"kind\":\"Program\",\"body\":[{\"type\":\"Return\",\"expr\":" + expr + "}]}"
+  }
+  i2s(n) {
+    // integer to decimal string (non-negative only for MVP)
+    if n == 0 { return "0" }
+    local x = n
+    if x < 0 { x = 0 } // MVP: clamp negatives to 0 to avoid surprises
+    local out = ""
+    loop(x > 0) {
+      local q = x / 10
+      local d = x - q * 10
+      local ch = "0"
+      if d == 1 { ch = "1" } else {
+        if d == 2 { ch = "2" } else {
+          if d == 3 { ch = "3" } else {
+            if d == 4 { ch = "4" } else {
+              if d == 5 { ch = "5" } else {
+                if d == 6 { ch = "6" } else {
+                  if d == 7 { ch = "7" } else {
+                    if d == 8 { ch = "8" } else {
+                      if d == 9 { ch = "9" }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+      out = ch + out
+      x = q
+    }
+    return out
+  }
+  to_int(s) {
+    local n = s.length()
+    if n == 0 { return 0 }
+    local i = 0
+    local acc = 0
+    loop(i < n) {
+      local d = s.substring(i, i+1)
+      local dv = 0
+      if d == "1" { dv = 1 } else { if d == "2" { dv = 2 } else { if d == "3" { dv = 3 } else { if d == "4" { dv = 4 } else { if d == "5" { dv = 5 } else { if d == "6" { dv = 6 } else { if d == "7" { dv = 7 } else { if d == "8" { dv = 8 } else { if d == "9" { dv = 9 } } } } } } } } }
+      acc = acc * 10 + dv
+      i = i + 1
+    }
+    return acc
+  }
+
+  parse_number(src, i) {
+    local n = src.length()
+    local j = i
+    loop(j < n && me.is_digit(src.substring(j, j+1))) { j = j + 1 }
+    local s = src.substring(i, j)
+    local json = "{\"type\":\"Int\",\"value\":" + s + "}"
+    return json + "@" + me.i2s(j)
+  }
+
+  parse_string(src, i) {
+    local n = src.length()
+    local j = i + 1
+    local out = ""
+    loop(j < n) {
+      local ch = src.substring(j, j+1)
+      if ch == "\"" {
+        j = j + 1
+        return "{\"type\":\"Str\",\"value\":\"" + me.esc_json(out) + "\"}@" + j
+      }
+      if ch == "\\" && j + 1 < n {
+        local nx = src.substring(j+1, j+2)
+        if nx == "\"" { out = out + "\"" } else { if nx == "\\" { out = out + "\\" } else { out = out + nx } }
+        j = j + 2
+      } else {
+        out = out + ch
+        j = j + 1
+      }
+    }
+    return "{\"type\":\"Str\",\"value\":\"" + me.esc_json(out) + "\"}@" + me.i2s(j)
+  }
+
+  skip_ws(src, i) {
+    local n = src.length()
+    loop(i < n && me.is_space(src.substring(i, i+1))) { i = i + 1 }
+    return i
+  }
+
+  skip_return_kw(src, i) {
+    // If source at i starts with "return", advance; otherwise return i unchanged
+    local n = src.length()
+    local j = i
+    if j < n && src.substring(j, j+1) == "r" { j = j + 1 } else { return i }
+    if j < n && src.substring(j, j+1) == "e" { j = j + 1 } else { return i }
+    if j < n && src.substring(j, j+1) == "t" { j = j + 1 } else { return i }
+    if j < n && src.substring(j, j+1) == "u" { j = j + 1 } else { return i }
+    if j < n && src.substring(j, j+1) == "r" { j = j + 1 } else { return i }
+    if j < n && src.substring(j, j+1) == "n" { j = j + 1 } else { return i }
+    return j
+  }
+
+  parse_factor(src, i) {
+    i = me.skip_ws(src, i)
+    local ch = src.substring(i, i+1)
+    if ch == "(" {
+      local p = me.parse_expr(src, i + 1)
+      local at = p.lastIndexOf("@")
+      local ej = p.substring(0, at)
+      local j = me.to_int(p.substring(at+1, p.length()))
+      j = me.skip_ws(src, j)
+      if src.substring(j, j+1) == ")" { j = j + 1 }
+      return ej + "@" + me.i2s(j)
+    }
+    if ch == "\"" { return me.parse_string(src, i) }
+    return me.parse_number(src, i)
+  }
+
+  parse_term(src, i) {
+    local p = me.parse_factor(src, i)
+    local at = p.lastIndexOf("@")
+    local lhs = p.substring(0, at)
+    local j = me.to_int(p.substring(at+1, p.length()))
+    local cont = 1
+    loop(cont == 1) {
+      j = me.skip_ws(src, j)
+      if j >= src.length() { cont = 0 } else {
+        local op = src.substring(j, j+1)
+        if op != "*" && op != "/" { cont = 0 } else {
+          local q = me.parse_factor(src, j+1)
+          local at2 = q.lastIndexOf("@")
+          local rhs = q.substring(0, at2)
+          j = me.to_int(q.substring(at2+1, q.length()))
+          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
+        }
+      }
+    }
+    return lhs + "@" + me.i2s(j)
+  }
+
+  parse_expr(src, i) {
+    local p = me.parse_term(src, i)
+    local at = p.lastIndexOf("@")
+    local lhs = p.substring(0, at)
+    local j = me.to_int(p.substring(at+1, p.length()))
+    local cont = 1
+    loop(cont == 1) {
+      j = me.skip_ws(src, j)
+      if j >= src.length() { cont = 0 } else {
+        local op = src.substring(j, j+1)
+        if op != "+" && op != "-" { cont = 0 } else {
+          local q = me.parse_term(src, j+1)
+          local at2 = q.lastIndexOf("@")
+          local rhs = q.substring(0, at2)
+          j = me.to_int(q.substring(at2+1, q.length()))
+          lhs = "{\"type\":\"Binary\",\"op\":\"" + op + "\",\"lhs\":" + lhs + ",\"rhs\":" + rhs + "}"
+        }
+      }
+    }
+    return lhs + "@" + me.i2s(j)
+  }
+
+  parse_program(src) {
+    // Legacy packed path (debug) removed; use parser2
+    return me.parse_program2(src)
+  }
+
+  main(args) {
+    // Parse the input and emit JSON v0
+    local src = me.read_all("tmp/ny_parser_input.ny")
+    if src == null { src = "return 1+2*3" }
+    local json = me.parse_program(src)
+    local console = new ConsoleBox()
+    // console.println(json) -- final output only
+    console.println(json)
+    return 0
+  }
+}
diff --git a/apps/selfhost-compiler/emitter/json_v0.nyash b/apps/selfhost-compiler/emitter/json_v0.nyash
new file mode 100644
index 00000000..4dab9a6a
--- /dev/null
+++ b/apps/selfhost-compiler/emitter/json_v0.nyash
@@ -0,0 +1,8 @@
+// JSON v0 emitter (MVP placeholder)
+static box JsonV0Emitter {
+  // Emit a minimal Program{return 0}
+  program_return0() {
+    return "{\"version\":0,\"kind\":\"Program\",\"body\":[{\"type\":\"Return\",\"expr\":{\"type\":\"Int\",\"value\":0}}]}"
+  }
+}
+
diff --git a/apps/selfhost-compiler/mir/builder.nyash b/apps/selfhost-compiler/mir/builder.nyash
new file mode 100644
index 00000000..16324230
--- /dev/null
+++ b/apps/selfhost-compiler/mir/builder.nyash
@@ -0,0 +1,5 @@
+static box MirBuilder {
+  // placeholder
+  main(args) { return 0 }
+}
+
diff --git a/apps/selfhost-compiler/mir/optimizer.nyash b/apps/selfhost-compiler/mir/optimizer.nyash
new file mode 100644
index 00000000..4df27d1f
--- /dev/null
+++ b/apps/selfhost-compiler/mir/optimizer.nyash
@@ -0,0 +1,5 @@
+static box Optimizer {
+  // placeholder
+  main(args) { return 0 }
+}
+
diff --git a/apps/selfhost-compiler/parser/ast.nyash b/apps/selfhost-compiler/parser/ast.nyash
new file mode 100644
index 00000000..912dd3af
--- /dev/null
+++ b/apps/selfhost-compiler/parser/ast.nyash
@@ -0,0 +1,5 @@
+static box AST {
+  // scaffold for future AST node constructors
+  main(args) { return 0 }
+}
+
diff --git a/apps/selfhost-compiler/parser/lexer.nyash b/apps/selfhost-compiler/parser/lexer.nyash
new file mode 100644
index 00000000..06051d74
--- /dev/null
+++ b/apps/selfhost-compiler/parser/lexer.nyash
@@ -0,0 +1,5 @@
+static box Lexer {
+  // scaffold for future implementation
+  main(args) { return 0 }
+}
+
diff --git a/apps/selfhost-compiler/parser/parser.nyash b/apps/selfhost-compiler/parser/parser.nyash
new file mode 100644
index 00000000..70193cf8
--- /dev/null
+++ b/apps/selfhost-compiler/parser/parser.nyash
@@ -0,0 +1,5 @@
+static box Parser {
+  // scaffold for future implementation
+  main(args) { return 0 }
+}
+
diff --git a/apps/selfhost-compiler/tests/stage1/README.md b/apps/selfhost-compiler/tests/stage1/README.md
new file mode 100644
index 00000000..85a037a6
--- /dev/null
+++ b/apps/selfhost-compiler/tests/stage1/README.md
@@ -0,0 +1,4 @@
+Stage‑1 tests (scaffold)
+
+Add minimal Ny source samples here. Harness TBD.
+
diff --git a/docs/development/roadmap/phases/phase-15/README.md b/docs/development/roadmap/phases/phase-15/README.md
index 682aa355..b6445d49 100644
--- a/docs/development/roadmap/phases/phase-15/README.md
+++ b/docs/development/roadmap/phases/phase-15/README.md
@@ -31,6 +31,14 @@ MIR 13命令の美しさを最大限に活かし、外部コンパイラ依存
 - dep_tree_min_string: PyVM↔llvmlite パリティ一致、llvmlite 経路で `.ll verify → .o → EXE` 完走。
 - 一時救済ゲート `NYASH_LLVM_ESC_JSON_FIX` は受入には未使用（OFF）。
 
+#### PHI 取り扱い方針（Phase‑15 中）
+- 現行: JSON v0 Bridge 側で If/Loop の PHI を生成（安定・緑）。
+- 方針: Phase‑15 ではこのまま完成させる（変更しない）。
+- 理由: LoopForm（Core‑14）導入時に、逆Loweringで PHI を自動生成する案（推薦）に寄せるため。
+  - PHI は「合流点での別名付け」であり、Boxの操作ではない。
+  - 抽象レイヤの純度維持（Everything is Box）。
+  - 実装責務の一極化（行数削減／保守性向上）。
+
 ### Phase 15.3: NyashコンパイラMVP（次フェーズ着手）
 - PyVM 安定後、Nyash製パーサ/レクサ（サブセット）と MIR ビルダを段階導入
 - フラグでRustフォールバックと併存（例: `NYASH_USE_NY_COMPILER=1`）
@@ -41,16 +49,76 @@ MIR 13命令の美しさを最大限に活かし、外部コンパイラ依存
 - ステージ2: 文/式サブセット拡張（local/if/loop/call/method/new/me/substring/length/lastIndexOf）。
 - ステージ3: Ny AST→MIR JSON 降下（直接 llvmlite/PyVM へ渡す）。
 
+#### Phase 15.3 — Detailed Plan（Ny compiler MVP）
+- Directory layout（selfhost compiler）
+  - `apps/selfhost-compiler/compiler.nyash`（CompilerBox entry; Ny→JSON v0 emit）
+  - `apps/selfhost-compiler/parser/{lexer.nyash,parser.nyash,ast.nyash}`（Stage‑2 へ段階拡張）
+  - `apps/selfhost-compiler/emitter/json_v0.nyash`（将来: emit 分離。MVPは inline でも可）
+  - `apps/selfhost-compiler/mir/{builder.nyash,optimizer.nyash}`（将来）
+  - `apps/selfhost-compiler/tests/{stage1,stage2}`（サンプルと期待JSON）
+
+- Runner integration（安全ゲート）
+  - フラグ: `NYASH_USE_NY_COMPILER=1`（既定OFF）
+  - 子プロセス: `--backend vm` で selfhost compiler を起動し、stdout から JSON v0 1行を収集
+  - 環境: `NYASH_JSON_ONLY=1` を子に渡して余計な出力を抑制。失敗時は静かにフォールバック
+
+- Stage‑1（小さく積む）
+  1) return / 整数 / 文字列 / 四則 / 括弧（左結合）
+  2) 文分離（最小ASI）: 改行=文区切り、継続子（+ - * / . ,）やグルーピング中は継続
+  3) 代表スモーク: `return 1+2*3` → JSON v0 → Bridge → MIR 実行 = 7
+
+- Stage‑2（本命へ）
+  - local / if / loop / call / method / new / var / 比較 / 論理（短絡）
+  - PHI: Bridge 側の合流（If/Loop）に依存（Phase‑15中は現行維持）
+  - 代表スモーク: nested if / loop 累積 / 短絡 and/or と if/loop の交錯
+
+- Acceptance（15.3）
+  - Stage‑1: 代表サンプルで JSON v0 emit → Bridge → PyVM/llvmlite で一致（差分なし）
+  - Bootstrap: `tools/bootstrap_selfhost_smoke.sh` で c0→c1→c1' が PASS（フォールバックは許容）
+  - Docs: 文分離ポリシー（改行＋最小ASI）を公開（link: reference/language/statements.md）
+
+- Smokes / Tools（更新）
+  - `tools/selfhost_compiler_smoke.sh`（入口）
+  - `tools/ny_stage2_bridge_smoke.sh`（算術/比較/短絡/ネストif）
+  - `tools/ny_parser_stage2_phi_smoke.sh`（If/Loop の PHI 合流）
+  - `tools/parity.sh --lhs pyvm --rhs llvmlite <test.nyash>`（常時）
+
+Imports/Namespace plan（15.3‑late）
+- See: imports-namespace-plan.md — keep `nyash.toml` resolution in runner; accept `using` in Ny compiler as no‑op (no resolution) gated by `NYASH_ENABLE_USING=1`.
+
+- Operational switches
+  - `NYASH_USE_NY_COMPILER=1`（selfhost compiler 経路ON）
+  - `NYASH_JSON_ONLY=1`（子プロセスの余計な出力抑止）
+  - `NYASH_DISABLE_PLUGINS=1`（必要に応じて子のみ最小化）
+  - 文分離: 最小ASIルール（深さ0・直前が継続子でない改行のみ終端）
+
+- Risks / Rollback
+  - 子プロセス出力がJSONでない→フォールバックで安全運用
+  - 代表ケースで parity 不一致→selfhost 経路のみ切替OFF
+  - 影響範囲: CLI/Runner 層の限定的変更（ゲートOFFなら既存経路と同値）
+
 【受入（MVP）】
 - `tools/ny_roundtrip_smoke.sh` 緑（Case A/B）。
 - `apps/tests/esc_dirname_smoke.nyash` / `apps/selfhost/tools/dep_tree_min_string.nyash` を Ny パーサ経路で実行し、PyVM/llvmlite とパリティ一致（stdout/exit）。
 
+#### 予告: LoopForm（Core‑14）での PHI 自動化（Phase‑15 後）
+- LoopForm を強化し、`loop.begin(loop_carried_values) / loop.iter / loop.branch / loop.end` の構造的情報から逆Loweringで PHI を合成。
+- If/短絡についても同様に、構造ブロックから合流点を決めて PHI を自動化。
+- スケジュール: Phase‑15 後（Core‑14）で検討・実装。Phase‑15 では変更しない。
+
 ### Phase 15.4: VM層のNyash化（PyVMからの置換）
 - PyVM を足場に、VMコアを Nyash 実装へ段階移植（命令サブセットから）
 - 動的ディスパッチで13命令処理を目標に拡張
 
 詳細：[セルフホスティング戦略 2025年9月版](implementation/self-hosting-strategy-2025-09.md)
 
+---
+
+補足: JSON v0 の扱い（互換）
+- Phase‑15: Bridge で PHI を生成（現行継続）。
+- Core‑14 以降: LoopForm で PHI 自動化後、JSON 側の PHI は非必須（将来は除外方向）。
+- 型メタ（“+”の文字列混在／文字列比較）は継続。
+
 ## 📊 主要成果物
 
 ### コンパイラコンポーネント
@@ -65,7 +133,7 @@ MIR 13命令の美しさを最大限に活かし、外部コンパイラ依存
 ### 自動生成基盤
 - [ ] boxes.yaml（Box型定義）
 - [ ] externs.yaml（C ABI境界）
-- [ ] semantics.yaml（MIR15定義）
+- [ ] semantics.yaml（MIR14定義）
 - [ ] build.rs（自動生成システム）
 
 ### ブートストラップ
@@ -75,13 +143,21 @@ MIR 13命令の美しさを最大限に活かし、外部コンパイラ依存
 
 ## 🔧 技術的アプローチ
 
-### MIR 13命令の革命
-- **基本演算(5)**: Const, UnaryOp, BinOp, Compare, TypeOp
-- **メモリ(2)**: Load, Store
-- **制御(4)**: Branch, Jump, Return, Phi
-- **Box(1)**: BoxCall（すべての箱操作を統合）
-- **外部(1)**: ExternCall
-
+### MIR 14命令の革命
+1. Const - 定数
+  2. BinOp - 二項演算
+  3. UnaryOp - 単項演算（復活！）
+  4. Compare - 比較
+  5. Jump - 無条件ジャンプ
+  6. Branch - 条件分岐
+  7. Return - 戻り値
+  8. Phi - SSA合流
+  9. Call - 関数呼び出し
+  10. BoxCall - Box操作（配列/フィールド/メソッド統一！）
+  11. ExternCall - 外部呼び出し
+  12. TypeOp - 型操作
+  13. Safepoint - GC安全点
+  14. Barrier - メモリバリア
 この究極のシンプルさにより、直接x86変換も現実的に！
 
 ### バックエンドの選択肢
@@ -238,6 +314,8 @@ ny_free_buf(buffer)
 ### ✅ クイックスモーク（現状）
 - PyVM↔llvmlite パリティ: `tools/parity.sh --lhs pyvm --rhs llvmlite apps/tests/esc_dirname_smoke.nyash`
 - dep_tree（ハーネスON）: `NYASH_LLVM_FEATURE=llvm ./tools/build_llvm.sh apps/selfhost/tools/dep_tree_min_string.nyash -o app_dep && ./app_dep`
+- JSON v0 bridge spec: `docs/reference/ir/json_v0.md`
+- Stage‑2 smokes: `tools/ny_stage2_bridge_smoke.sh`, `tools/ny_parser_stage2_phi_smoke.sh`, `tools/ny_me_dummy_smoke.sh`
 
 ### 📚 関連フェーズ
 - [Phase 10: Cranelift JIT](../phase-10/)
diff --git a/docs/development/roadmap/phases/phase-15/ROADMAP.md b/docs/development/roadmap/phases/phase-15/ROADMAP.md
index 0bc0768c..efd7e546 100644
--- a/docs/development/roadmap/phases/phase-15/ROADMAP.md
+++ b/docs/development/roadmap/phases/phase-15/ROADMAP.md
@@ -35,6 +35,17 @@ This roadmap is a living checklist to advance Phase 15 with small, safe boxes. U
    - No circular dependency: nyrt provides StringBox/ArrayBox via C ABI
    - Flag path: `NYASH_USE_NY_COMPILER=1` to switch rust→ny compiler; rust parser as fallback
    - Add apps/selfhost-compiler/ and minimal smokes
+   - Stage‑1 checklist:
+     - [ ] return/int/string/arithmetic/paren JSON v0 emit
+     - [ ] Minimal ASI（newline separator + continuation tokens）
+     - [ ] Smokes: `return 1+2*3` / grouping / string literal
+   - Stage‑2 checklist:
+     - [ ] local/if/loop/call/method/new/var/logical/compare
+     - [ ] PHI 合流は Bridge に委譲（If/Loop）
+     - [ ] Smokes: nested if / loop 累積 / and/or × if/loop
+4) PHI 自動化は Phase‑15 後（Core‑14 LoopForm）
+   - Phase‑15: 現行の Bridge‑PHI を維持し、E2E 緑とパリティを最優先
+   - Core‑14: LoopForm 強化＋逆Loweringで PHI を自動生成（合流点の定型化）
 4) Bootstrap loop (c0→c1→c1')
    - Use existing trace/hash harness to compare parity; add optional CI gate
    - **This achieves self-hosting!** Nyash compiles Nyash
@@ -63,6 +74,8 @@ This roadmap is a living checklist to advance Phase 15 with small, safe boxes. U
 
 - Parser path: `--parser {rust|ny}` or `NYASH_USE_NY_PARSER=1`
 - JSON dump: `NYASH_DUMP_JSON_IR=1`
+- （予告）LoopForm: Core‑14 で仕様化予定
+ - Selfhost compiler: `NYASH_USE_NY_COMPILER=1`, child quiet: `NYASH_JSON_ONLY=1`
 - Load Ny plugins: `NYASH_LOAD_NY_PLUGINS=1` / `--load-ny-plugins`
 - AOT smoke: `CLIF_SMOKE_RUN=1`
 
@@ -83,6 +96,8 @@ This roadmap is a living checklist to advance Phase 15 with small, safe boxes. U
 - v0 E2E green (parser pipe + direct bridge) including Ny compiler MVP switch
 - v1 minimal samples pass via JSON bridge
 - AOT P2: emit→link→run stable for constant/arith
+- Phase‑15 STOP には PHI 切替を含めない（PHI は LoopForm/Core‑14 で扱う）
+ - 15.3: Stage‑1 代表サンプル緑 + Bootstrap smoke（フォールバック許容）+ 文分離ポリシー公開
 - Docs/recipes usable on Windows/Unix
 
 ## Notes
diff --git a/docs/development/roadmap/phases/phase-15/imports-namespace-plan.md b/docs/development/roadmap/phases/phase-15/imports-namespace-plan.md
new file mode 100644
index 00000000..488ca0f1
--- /dev/null
+++ b/docs/development/roadmap/phases/phase-15/imports-namespace-plan.md
@@ -0,0 +1,38 @@
+# Phase 15.3 — Imports/Namespace/nyash.toml Plan
+
+Status: 15.3 planning; focus remains on Stage‑1/2 compiler MVP. This document scopes when and how to bring `nyash.toml`/include/import/namespace into the selfhost path without destabilizing parity.
+
+Goals
+- Keep runner‑level `nyash.toml` parsing/resolution as the source of truth during 15.3.
+- Accept `using/import` syntax in the Ny compiler as a no‑op (record only) until resolution is delegated.
+- Avoid VM changes; resolution happens before codegen.
+
+Scope & Sequence (Phase 15.3)
+1) Stage‑1/2 compiler stability (primary)
+   - Ny→JSON v0 → Bridge → PyVM/llvmlite parity maintained
+   - PHI merge remains on Bridge (If/Loop)
+2) Imports/Namespace minimal acceptance (15.3‑late)
+   - Parse `using ns` / `using "path" [as alias]` as statements in the Ny compiler
+   - Do not resolve; emit no JSON entries (or emit metadata) — runner continues to strip/handle
+   - Gate via `NYASH_ENABLE_USING=1`
+3) Runner remains in charge
+   - Keep existing Rust runner’s `using` stripping + modules registry population
+   - `nyash.toml` parsing stays in Rust (Phase 15)
+
+Out of scope (Phase 15)
+- Porting `nyash.toml` parsing to Ny
+- Cross‑module codegen/linking in Ny compiler
+- Advanced include resolution / package graph
+
+Acceptance (15.3)
+- Ny compiler can lex/parse `using` forms without breaking Stage‑1/2 programs
+- Runner path (Rust) continues to resolve `using` and `nyash.toml` as before (parity unchanged)
+
+Looking ahead (Core‑14 / Phase 16)
+- Evaluate moving `nyash.toml` parsing to Ny as a library box (ConfigBox)
+- Unify include/import/namespace into a single resolver pass in Ny with a small JSON side channel back to the runner
+- Keep VM unchanged; all resolution before MIR build
+
+Switches
+- `NYASH_ENABLE_USING=1` — enable `using` acceptance in Ny compiler (no resolution)
+- `NYASH_SKIP_TOML_ENV=1` — skip applying [env] in nyash.toml (existing)
diff --git a/docs/guides/language-guide.md b/docs/guides/language-guide.md
index 2f525d5c..5bb8a17c 100644
--- a/docs/guides/language-guide.md
+++ b/docs/guides/language-guide.md
@@ -52,3 +52,7 @@ When you need the implementation details
 - Tokenizer: src/tokenizer.rs
 - Parser: src/parser/expressions.rs, src/parser/statements.rs
 - Lowering to MIR: src/mir/builder/**
+Statement Separation (Semicolons)
+- Newline separates statements by default; semicolons are optional.
+- Use semicolons only when placing multiple statements on one line.
+- Minimal ASI rules: newline does not end a statement when the line ends with an operator/dot/comma, or while inside grouping.
diff --git a/docs/phase-15/cranelift/CRANELIFT_TASKS.md b/docs/phase-15/cranelift/CRANELIFT_TASKS.md
deleted file mode 100644
index f5f37cfe..00000000
--- a/docs/phase-15/cranelift/CRANELIFT_TASKS.md
+++ /dev/null
@@ -1,25 +0,0 @@
-# Cranelift / AOT/JIT‑AOT Tasks (Phase 15)
-
-このドキュメントは Cranelift backend（AOT/JIT‑AOT）関連の課題・進捗を集約します。
-selfhosting‑dev ブランチでは VM/JIT 中心で開発するため、詳細はこちらへ集約し、`CURRENT_TASK.md` は軽量化しました。
-
-最終更新: 2025‑09‑06（CURRENT_TASK から分離）
-
-参考リンク
-- 旧コンテンツ・完全版アーカイブ: `../../archives/CURRENT_TASK-2025-09-06.md`
-- フェーズ概要: `../README.md`
-
-現状サマリ（抜粋）
-- StringBox.length/len が 0 になるケースの是正（Lower 二段フォールバック: string.len_h → any.length_h）
-- Hostcall registry/extern thunks の追補（`SYM_STRING_LEN_H` 登録）
-- AOT でのまれな segfault（DT_TEXTREL 警告）の追跡（TLS/extern 紐付け順）
-
-優先課題（案）
-1) Return 材化の強化（JIT‑direct/JIT‑AOT 共通）
-2) Cranelift import シンボル解決の検証（`extern_thunks::nyash_string_len_h` の実呼出し保証）
-3) AOT ツールチェーン（リンク・フラグ）の最小安定セット定義
-
-運用メモ
-- selfhosting‑dev では本ファイルの参照のみ（直接の実装変更は Cranelift 専用ブランチで実施）。
-- 共有面（ランナー/IR など）に変更が必要な場合は feature gate と互換 API を優先し、両ブランチが同時に衝突しない形へ調整。
-
diff --git a/docs/reference/ir/json_v0.md b/docs/reference/ir/json_v0.md
new file mode 100644
index 00000000..18c39dae
--- /dev/null
+++ b/docs/reference/ir/json_v0.md
@@ -0,0 +1,81 @@
+# Ny JSON IR v0 — Minimal Spec (Stage‑2)
+
+Status: experimental but stable for Phase‑15 Stage‑2. Input to `--ny-parser-pipe`.
+
+Version and root
+- `version`: 0
+- `kind`: "Program"
+- `body`: array of statements
+
+Statements (`StmtV0`)
+- `Return { expr }`
+- `Extern { iface, method, args[] }` (optional; passes through to `ExternCall`)
+- `Expr { expr }` (expression statement; side effects only)
+- `Local { name, expr }` (Stage‑2)
+- `If { cond, then: Stmt[], else?: Stmt[] }` (Stage‑2)
+- `Loop { cond, body: Stmt[] }` (Stage‑2; while(cond) body)
+
+Expressions (`ExprV0`)
+- `Int { value }` where `value` is JSON number or digit string
+- `Str { value: string }`
+- `Bool { value: bool }`
+- `Binary { op: "+"|"-"|"*"|"/", lhs, rhs }`
+- `Compare { op: "=="|"!="|"<"|"<="|">"|">=", lhs, rhs }`
+- `Logical { op: "&&"|"||", lhs, rhs }` (short‑circuit)
+- `Call { name: string, args[] }` (function by name)
+- `Method { recv: Expr, method: string, args[] }` (box method)
+- `New { class: string, args[] }` (construct Box)
+- `Var { name: string }`
+
+CFG conventions (lowered by the bridge)
+- If: create `then_bb`, `else_bb`, `merge_bb`. Both branches jump to merge if unterminated.
+- Loop: `preheader -> cond_bb -> (body_bb or exit_bb)`, body jumps back to cond.
+- Short‑circuit Logical: create `rhs_bb`, `fall_bb`, `merge_bb` with constants on fall path.
+- All blocks end with a terminator (branch/jump/return).
+
+PHI merging (current behavior)
+- If: locals updated in `then`/`else` merge at `merge_bb` via `phi`.
+  - Else欠落時は else 側に分岐前(base)を採用。
+  - 片側にしか存在しない新規変数はスコープ外として外へ未伝播。
+- Loop: `cond_bb` にヘッダ PHI を先置き（preheader/base と latch/body end を合流）。
+- 目的: Stage‑2 を早期に安定化させるための橋渡し。将来（Core‑14）は LoopForm からの逆LoweringでPHI自動化予定。
+
+Type meta (emitter/LLVM harness cooperation)
+- `+` with any string operand → string concat path（handle固定）。
+- `==/!=` with both strings → string compare path。
+
+Special notes
+- `Var("me")`: Bridge 既定では未定義エラー。デバッグ用に `NYASH_BRIDGE_ME_DUMMY=1` でダミー `NewBox{class}` を注入可（`NYASH_BRIDGE_ME_CLASS` 省略時は `Main`）。
+- `--ny-parser-pipe` は stdin の JSON v0 を受け取り、MIR→MIR‑Interp 経由で実行する。
+
+CLI/Env cheatsheet
+- Pipe: `echo '{...}' | target/release/nyash --ny-parser-pipe`
+- File: `target/release/nyash --json-file sample.json`
+- Verbose MIR dump: `NYASH_CLI_VERBOSE=1`
+- me dummy: `NYASH_BRIDGE_ME_DUMMY=1 NYASH_BRIDGE_ME_CLASS=ConsoleBox`
+
+Examples
+
+Arithmetic
+```json
+{"version":0,"kind":"Program","body":[
+  {"type":"Return","expr":{
+    "type":"Binary","op":"+",
+    "lhs":{"type":"Int","value":1},
+    "rhs":{"type":"Binary","op":"*","lhs":{"type":"Int","value":2},"rhs":{"type":"Int","value":3}}
+  }}
+]}
+```
+
+If with local + PHI merge
+```json
+{"version":0,"kind":"Program","body":[
+  {"type":"Local","name":"x","expr":{"type":"Int","value":1}},
+  {"type":"If","cond":{"type":"Compare","op":"<","lhs":{"type":"Int","value":1},"rhs":{"type":"Int","value":2}},
+    "then":[{"type":"Local","name":"x","expr":{"type":"Int","value":10}}],
+    "else":[{"type":"Local","name":"x","expr":{"type":"Int","value":20}}]
+  },
+  {"type":"Return","expr":{"type":"Var","name":"x"}}
+]}
+```
+
diff --git a/docs/reference/language/README.md b/docs/reference/language/README.md
index 2f584bc8..cc07d7f4 100644
--- a/docs/reference/language/README.md
+++ b/docs/reference/language/README.md
@@ -10,6 +10,9 @@ This is the entry point for Nyash language documentation.
 - Sugar Transformations (?., ??, |> and friends): parser/sugar.rs (source) and tools/nyfmt/NYFMT_POC_ROADMAP.md
 - Peek Expression Design/Usage: covered in the Language Reference and Phase 12.7 specs above
 
+Statement separation and semicolons
+- See: reference/language/statements.md — newline as primary separator; semicolons optional for multiple statements on one line; minimal ASI rules.
+
 Related implementation notes
 - Tokenizer: src/tokenizer.rs
 - Parser (expressions/statements): src/parser/expressions.rs, src/parser/statements.rs
diff --git a/docs/reference/language/statements.md b/docs/reference/language/statements.md
new file mode 100644
index 00000000..50ff878a
--- /dev/null
+++ b/docs/reference/language/statements.md
@@ -0,0 +1,70 @@
+# Statement Separation and Semicolons
+
+Status: Adopted for Phase 15.3+; parser implementation is staged.
+
+Policy
+- Newline as primary statement separator.
+- Semicolons are optional and only needed when multiple statements appear on one physical line.
+- Minimal ASI (auto semicolon insertion) rules to avoid surprises.
+
+Rules (minimal and predictable)
+- Newline ends a statement when:
+  - Parenthesis/brace/bracket depth is 0, and
+  - The line does not end with a continuation token (`+ - * / . ,` etc.).
+- Newline does NOT end a statement when:
+  - Inside any open grouping `(...)`, `[...]`, `{...}`; or
+  - The previous token is a continuation token.
+- `return/break/continue` end the statement at newline unless the value is on the same line or grouped via parentheses.
+- `if/else` (and similar paired constructs): do not insert a semicolon between a block and a following `else`.
+- One‑line multi‑statements are allowed with semicolons: `x = 1; y = 2; print(y)`.
+- Method chains can break across lines after a dot: `obj\n  .method()` (newline treated as whitespace).
+
+Style guidance
+- Prefer newline separation (no semicolons) for readability.
+- Use semicolons only when placing multiple statements on a single line.
+
+Examples
+```nyash
+// Preferred (no semicolons)
+local x = 5
+x = x + 1
+print(x)
+
+// One line with multiple statements (use semicolons)
+local x = 5; x = x + 1; print(x)
+
+// Line continuation by operator
+local n = 1 +
+          2 +
+          3
+
+// Grouping across lines
+return (
+  1 + 2 + 3
+)
+
+// if / else on separate lines without inserting a semicolon
+if cond {
+  x = x - 1
+}
+else {
+  print(x)
+}
+
+// Dot chain across lines
+local v = obj
+  .methodA()
+  .methodB(42)
+```
+
+Implementation notes (parser)
+- Tokenizer keeps track of grouping depth.
+- At newline, attempt ASI only when depth==0 and previous token is not a continuation.
+- Error messages should suggest adding a continuation token or grouping when a newline unexpectedly ends a statement.
+
+Parser dev notes (Stage‑1/2)
+- return + newline: treat bare `return` as statement end. To return an expression on the next line, require grouping with parentheses.
+- if/else: never insert a semicolon between a closed block and `else` (ASI禁止箇所)。
+- Dot chains: treat `.` followed by newline as whitespace (line continuation)。
+- One‑line multi‑statements: accept `;` as statement separator, but formatter should prefer newlines.
+- Unary minus: disambiguate from binary minus; implement after Stage‑1（当面は括弧で回避）。
diff --git a/src/runner/json_v0_bridge.rs b/src/runner/json_v0_bridge.rs
index 0fea754e..2cd46dfc 100644
--- a/src/runner/json_v0_bridge.rs
+++ b/src/runner/json_v0_bridge.rs
@@ -242,10 +242,23 @@ fn lower_expr_with_vars(
     match e {
         ExprV0::Var { name } => {
             if let Some(&vid) = vars.get(name) {
-                Ok((vid, cur_bb))
-            } else {
-                Err(format!("undefined variable: {}", name))
+                return Ok((vid, cur_bb));
             }
+            if name == "me" {
+                // Optional gate: allow a dummy 'me' instance for Stage-2 JSON smoke
+                if std::env::var("NYASH_BRIDGE_ME_DUMMY").ok().as_deref() == Some("1") {
+                    let class = std::env::var("NYASH_BRIDGE_ME_CLASS").unwrap_or_else(|_| "Main".to_string());
+                    let dst = f.next_value_id();
+                    if let Some(bb) = f.get_block_mut(cur_bb) {
+                        bb.add_instruction(MirInstruction::NewBox { dst, box_type: class, args: vec![] });
+                    }
+                    vars.insert("me".to_string(), dst);
+                    return Ok((dst, cur_bb));
+                } else {
+                    return Err("undefined 'me' outside box context (set NYASH_BRIDGE_ME_DUMMY=1 to inject placeholder)".into());
+                }
+            }
+            Err(format!("undefined variable: {}", name))
         }
         ExprV0::Call { name, args } => {
             // Lower args
diff --git a/src/runner/modes/common.rs b/src/runner/modes/common.rs
index 61d83be3..53720485 100644
--- a/src/runner/modes/common.rs
+++ b/src/runner/modes/common.rs
@@ -36,6 +36,14 @@ fn suggest_in_base(base: &str, leaf: &str, out: &mut Vec<String>) {
 impl NyashRunner {
     /// File-mode dispatcher (thin wrapper around backend/mode selection)
     pub(crate) fn run_file(&self, filename: &str) {
+        // Phase-15.3: Ny compiler MVP (Ny -> JSON v0) behind env gate
+        if std::env::var("NYASH_USE_NY_COMPILER").ok().as_deref() == Some("1") {
+            if self.try_run_ny_compiler_pipeline(filename) {
+                return;
+            } else if std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+                eprintln!("[ny-compiler] fallback to default path (MVP unavailable for this input)");
+            }
+        }
         // Direct v0 bridge when requested via CLI/env
         let use_ny_parser = self.config.parser_ny || std::env::var("NYASH_USE_NY_PARSER").ok().as_deref() == Some("1");
         if use_ny_parser {
@@ -141,6 +149,84 @@ impl NyashRunner {
         }
     }
 
+    /// Phase-15.3: Attempt Ny compiler pipeline (Ny -> JSON v0 via Ny program), then execute MIR
+    fn try_run_ny_compiler_pipeline(&self, filename: &str) -> bool {
+        use std::io::Write;
+        // Read input source
+        let code = match fs::read_to_string(filename) {
+            Ok(c) => c,
+            Err(e) => { eprintln!("[ny-compiler] read error: {}", e); return false; }
+        };
+        // Write to tmp/ny_parser_input.ny (as expected by Ny parser v0)
+        let tmp_dir = std::path::Path::new("tmp");
+        if let Err(e) = std::fs::create_dir_all(tmp_dir) {
+            eprintln!("[ny-compiler] mkdir tmp failed: {}", e);
+            return false;
+        }
+        let tmp_path = tmp_dir.join("ny_parser_input.ny");
+        match std::fs::File::create(&tmp_path) {
+            Ok(mut f) => {
+                if let Err(e) = f.write_all(code.as_bytes()) {
+                    eprintln!("[ny-compiler] write tmp failed: {}", e);
+                    return false;
+                }
+            }
+            Err(e) => { eprintln!("[ny-compiler] open tmp failed: {}", e); return false; }
+        }
+        // Locate current exe to invoke Ny VM for the Ny parser program
+        let exe = match std::env::current_exe() {
+            Ok(p) => p,
+            Err(e) => { eprintln!("[ny-compiler] current_exe failed: {}", e); return false; }
+        };
+        // Prefer new selfhost-compiler entry; fallback to legacy ny_parser_v0
+        let cand_new = std::path::Path::new("apps/selfhost-compiler/compiler.nyash");
+        let cand_old = std::path::Path::new("apps/selfhost/parser/ny_parser_v0/main.nyash");
+        let parser_prog = if cand_new.exists() { cand_new } else { cand_old };
+        if !parser_prog.exists() { eprintln!("[ny-compiler] compiler program not found: {}", parser_prog.display()); return false; }
+        let mut cmd = std::process::Command::new(exe);
+        cmd.arg("--backend").arg("vm").arg(parser_prog);
+        // Propagate minimal env; disable plugins to reduce noise
+        cmd.env_remove("NYASH_USE_NY_COMPILER");
+        // Suppress parent runner's result printing in child
+        cmd.env("NYASH_JSON_ONLY", "1");
+        let out = match cmd.output() {
+            Ok(o) => o,
+            Err(e) => { eprintln!("[ny-compiler] spawn failed: {}", e); return false; }
+        };
+        if !out.status.success() {
+            if let Ok(s) = String::from_utf8(out.stderr) { eprintln!("[ny-compiler] parser stderr:\n{}", s); }
+            return false;
+        }
+        let stdout = match String::from_utf8(out.stdout) { Ok(s) => s, Err(_) => String::new() };
+        let mut json_line = String::new();
+        for line in stdout.lines() {
+            let t = line.trim();
+            if t.starts_with('{') && t.contains("\"version\":0") { json_line = t.to_string(); break; }
+        }
+        if json_line.is_empty() {
+            if std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+                let head: String = stdout.chars().take(200).collect();
+                eprintln!("[ny-compiler] JSON not found in child stdout (head): {}", head.replace('\n', "\\n"));
+            }
+            return false;
+        }
+        // Parse JSON v0 → MIR module
+        match json_v0_bridge::parse_json_v0_to_module(&json_line) {
+            Ok(module) => {
+                if std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+                    println!("🚀 Ny compiler MVP (ny→json_v0) path ON");
+                }
+                json_v0_bridge::maybe_dump_mir(&module);
+                self.execute_mir_module(&module);
+                true
+            }
+            Err(e) => {
+                eprintln!("[ny-compiler] JSON parse failed: {}", e);
+                false
+            }
+        }
+    }
+
     /// Execute Nyash file with interpreter (common helper)
     pub(crate) fn execute_nyash_file(&self, filename: &str) {
         let quiet_pipe = std::env::var("NYASH_JSON_ONLY").ok().as_deref() == Some("1");
diff --git a/tools/ny_me_dummy_smoke.sh b/tools/ny_me_dummy_smoke.sh
new file mode 100644
index 00000000..425d6947
--- /dev/null
+++ b/tools/ny_me_dummy_smoke.sh
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+ROOT_DIR=$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd)
+BIN="$ROOT_DIR/target/release/nyash"
+
+if [[ ! -x "$BIN" ]]; then
+  echo "[build] nyash (release) ..." >&2
+  cargo build --release >/dev/null
+fi
+
+TMP_DIR="$ROOT_DIR/tmp"
+mkdir -p "$TMP_DIR"
+
+# Enable me dummy injection for entire run
+export NYASH_BRIDGE_ME_DUMMY=1
+export NYASH_BRIDGE_ME_CLASS=ConsoleBox
+
+# Case 1: me bound to a var and unused (ensures Var("me") resolves)
+cat >"$TMP_DIR/me_dummy_bind_only.ny" <<'NY'
+local x = me
+return 0
+NY
+
+OUT1=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/me_dummy_bind_only.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT1" | rg -q '^Result:\s*0\b' && echo "✅ me dummy (bind only) OK" || { echo "❌ me dummy (bind only) FAILED"; echo "$OUT1"; exit 1; }
+
+# Case 2: me used inside an if branch
+cat >"$TMP_DIR/me_dummy_in_if.ny" <<'NY'
+if 1 < 2 {
+  local y = me
+}
+return 0
+NY
+
+OUT2=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/me_dummy_in_if.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT2" | rg -q '^Result:\s*0\b' && echo "✅ me dummy (in if) OK" || { echo "❌ me dummy (in if) FAILED"; echo "$OUT2"; exit 1; }
+
+echo "All me-dummy smokes PASS" >&2
diff --git a/tools/ny_parser_stage2_phi_smoke.sh b/tools/ny_parser_stage2_phi_smoke.sh
index 38c93ad2..717624b7 100644
--- a/tools/ny_parser_stage2_phi_smoke.sh
+++ b/tools/ny_parser_stage2_phi_smoke.sh
@@ -41,5 +41,34 @@ NY
 OUT2=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/phi_loop_sample.ny" | "$BIN" --ny-parser-pipe || true)
 echo "$OUT2" | rg -q '^Result:\s*3\b' && echo "✅ Loop PHI merge OK" || { echo "❌ Loop PHI merge FAILED"; echo "$OUT2"; exit 1; }
 
-echo "All Stage-2 PHI smokes PASS" >&2
+# If (no-else) PHI merge with base
+cat >"$TMP_DIR/phi_if_noelse_sample.ny" <<'NY'
+local x = 1
+if 1 > 2 {
+  local x = 10
+}
+return x
+NY
 
+OUT3=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/phi_if_noelse_sample.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT3" | rg -q '^Result:\s*1\b' && echo "✅ If(no-else) PHI merge OK" || { echo "❌ If(no-else) PHI merge FAILED"; echo "$OUT3"; exit 1; }
+
+# Nested If PHI merge
+cat >"$TMP_DIR/phi_if_nested_sample.ny" <<'NY'
+local x = 1
+if 1 < 2 {
+  if 2 < 1 {
+    local x = 100
+  } else {
+    local x = 200
+  }
+} else {
+  local x = 300
+}
+return x
+NY
+
+OUT4=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/phi_if_nested_sample.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT4" | rg -q '^Result:\s*200\b' && echo "✅ Nested If PHI merge OK" || { echo "❌ Nested If PHI merge FAILED"; echo "$OUT4"; exit 1; }
+
+echo "All Stage-2 PHI smokes PASS" >&2
diff --git a/tools/ny_stage2_bridge_smoke.sh b/tools/ny_stage2_bridge_smoke.sh
new file mode 100644
index 00000000..c0e6fa8b
--- /dev/null
+++ b/tools/ny_stage2_bridge_smoke.sh
@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+ROOT_DIR=$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd)
+BIN="$ROOT_DIR/target/release/nyash"
+
+if [[ ! -x "$BIN" ]]; then
+  echo "[build] nyash (release) ..." >&2
+  (cd "$ROOT_DIR" && cargo build --release >/dev/null)
+fi
+
+TMP_DIR="$ROOT_DIR/tmp"
+mkdir -p "$TMP_DIR"
+
+pass_case() { echo "✅ $1" >&2; }
+fail_case() { echo "❌ $1" >&2; echo "$2" >&2; exit 1; }
+
+# Case A: arithmetic
+printf 'return 1+2*3\n' > "$TMP_DIR/s2_a_arith.ny"
+OUT=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/s2_a_arith.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT" | rg -q '^Result:\s*7\b' && pass_case "Stage2 arithmetic" || fail_case "Stage2 arithmetic" "$OUT"
+
+# Case B: logical and (short-circuit)
+cat > "$TMP_DIR/s2_b_and.ny" <<'NY'
+return (1 < 2) && (2 < 3)
+NY
+OUT=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/s2_b_and.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT" | rg -q '^Result:\s*true\b' && pass_case "Stage2 logical AND" || fail_case "Stage2 logical AND" "$OUT"
+
+# Case C: logical or (short-circuit)
+cat > "$TMP_DIR/s2_c_or.ny" <<'NY'
+return (1 > 2) || (2 < 3)
+NY
+OUT=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/s2_c_or.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT" | rg -q '^Result:\s*true\b' && pass_case "Stage2 logical OR" || fail_case "Stage2 logical OR" "$OUT"
+
+# Case D: compare eq
+cat > "$TMP_DIR/s2_d_eq.ny" <<'NY'
+return (1 + 1) == 2
+NY
+OUT=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/s2_d_eq.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT" | rg -q '^Result:\s*true\b' && pass_case "Stage2 compare ==" || fail_case "Stage2 compare ==" "$OUT"
+
+# Case E: nested if with locals -> 200
+cat > "$TMP_DIR/s2_e_nested_if.ny" <<'NY'
+local x = 1
+if 1 < 2 {
+  if 2 < 1 {
+    local x = 100
+  } else {
+    local x = 200
+  }
+} else {
+  local x = 300
+}
+return x
+NY
+OUT=$(python3 "$ROOT_DIR/tools/ny_parser_mvp.py" "$TMP_DIR/s2_e_nested_if.ny" | "$BIN" --ny-parser-pipe || true)
+echo "$OUT" | rg -q '^Result:\s*200\b' && pass_case "Stage2 nested if" || fail_case "Stage2 nested if" "$OUT"
+
+echo "All Stage-2 bridge smokes PASS" >&2
+
diff --git a/tools/selfhost_compiler_smoke.sh b/tools/selfhost_compiler_smoke.sh
new file mode 100644
index 00000000..6c0aef83
--- /dev/null
+++ b/tools/selfhost_compiler_smoke.sh
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+ROOT_DIR=$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd)
+BIN="$ROOT_DIR/target/release/nyash"
+
+if [[ ! -x "$BIN" ]]; then
+  echo "[build] nyash (release) ..." >&2
+  (cd "$ROOT_DIR" && cargo build --release >/dev/null)
+fi
+
+TMP_DIR="$ROOT_DIR/tmp"
+mkdir -p "$TMP_DIR"
+
+printf 'return 1+2*3\n' > "$TMP_DIR/ny_parser_input.ny"
+
+OUT=$(NYASH_USE_NY_COMPILER=1 NYASH_CLI_VERBOSE=1 "$BIN" --backend vm "$ROOT_DIR/apps/examples/string_p0.nyash" || true)
+if echo "$OUT" | rg -q 'ny compiler MVP \(ny→json_v0\) path ON' && echo "$OUT" | rg -q '^Result:\s*0\b'; then
+  echo "✅ ny compiler MVP path OK (json_v0 emit + result 0)"
+else
+  echo "WARN: ny compiler path not used; fallback executed (acceptable during MVP)"
+  echo "$OUT" | sed -n '1,120p'
+fi
+
+echo "All selfhost compiler smokes PASS" >&2