diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index 9309b559..1a83dbd3 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -17,12 +17,14 @@
   - 制御構造と PHI の意味論は **JoinIR（＋LoopScopeShape/IfPhiContext 等の薄い箱）** に一本化する。
   - 実行の SSOT は VM / LLVM ラインとし、JoinIR→MIR→VM/LLVM は「構造 SSOT → 実行 SSOT」への変換として扱う。
   - 既存の PHI 箱（if_phi.rs / PhiBuilderBox / conservative.rs / Trio 等）は、JoinIR 側のカバレッジが十分になったところから順に削っていく。
-  - Stage-3 parser デフォルトON化（Phase 30.1 完了）: `config::env::parser_stage3_enabled()` で NYASH_FEATURES=stage3 をSSOT化し、legacy env は明示OFF専用の互換に縮退。
+- Stage-3 parser デフォルトON化（Phase 30.1 完了）: `config::env::parser_stage3_enabled()` で NYASH_FEATURES=stage3 をSSOT化し、legacy env は明示OFF専用の互換に縮退。
+- JoinIR Strict 着手（Phase 81）: `NYASH_JOINIR_STRICT=1` で代表パスのフォールバックを禁止（JoinIR失敗は即エラー）。dev/trace は観測のみ継続。
 
 - **これから（Phase 69+）**
   - wasm/Web デモライン: JoinIR ベースの軽量デモ実装。
   - 最適化ライン: JoinIR の最適化パスと LLVM/ny-llvmc 統合。
   - Trio 削除ライン: 完了（Phase 70、LoopScopeShape SSOT）
+  - JoinIR Strict ライン（Phase 81）: 代表 If/Loop/VM ブリッジについては `NYASH_JOINIR_STRICT=1` で常に JoinIR 経路のみを通すようにし、レガシー if_phi / LoopBuilder / 旧 MIR Builder は「未対応関数専用」に縮退。
 
 ---
 
@@ -97,7 +99,7 @@
 - 未了:
   - 69-5: conservative.rs の docs/ 移設も今後の小フェーズとして残しておく。
 - 追加完了 (Phase 70):
-  - 69-4: Trio 3 箱（LoopVarClassBox / LoopExitLivenessBox / LocalScopeInspectorBox）を削除し、LoopScopeShape を SSOT とする構成に移行。
+  - 69-4: Trio 3 箱（LoopVarClassBox / LoopExitLivenessBox / LocalScopeInspectorBox）を削除し、LoopScopeShape を SSOT とする構成に移行。2025-12-01 時点でコードベース再スキャン済みで、Trio 本体ファイルおよび Trio Box 直接参照は **src/mir/** から完全に除去されていることを確認（名称としての「Trio」は docs の歴史メモ内にのみ残存）。
 
 ## 2. 次の一手（Phase 69+）
 
@@ -107,6 +109,15 @@
   - GenericTypeResolver 経由で全 P3-C ケースをカバー
   - `infer_type_from_phi` 本体削除と if_phi.rs 大掃除
 
+- **Phase 71: Self‑Hosting 再ブートストラップ（docs 起点 / SSA デバッグモードで一時停止中）**
+  - `docs/private/roadmap2/phases/phase-71-selfhost-reboot/README.md` で代表パス 1 本（Stage‑3 + JoinIR 前提）と ENV 方針を整理済み。
+  - 代表パス（仮固定）: `NYASH_FEATURES=stage3 NYASH_USE_NY_COMPILER=1 NYASH_NY_COMPILER_EMIT_ONLY=1 ./tools/selfhost/selfhost_build.sh --in apps/tests/stage1_run_min.hako --run`
+  - プラグイン初期化（nyash.toml 経由）は NYASH_DEBUG_PLUGIN=1 で成功確認済みだが、Stage‑B/SSA/JoinIR/dev verify の複合経路で Program(JSON v0) emit 前に失敗し、`Stage‑B emit failed` で selfhost_minimal が落ちている。
+  - RAW 観測フラグ追加済み: `NYASH_SELFHOST_KEEP_RAW` / `NYASH_EMIT_MIR_KEEP_RAW` で Stage‑B rc/stdout/stderr/抽出状況を `logs/selfhost` / `logs/emit_mir` に保存可能。`stageb_min_emit.sh` でも dev verify ON/OFF いずれも Program 行 0 件（ssa-undef-debug は trim/parse_params 系に集中）。
+  - SSA 修正進捗: `FuncScannerBox.parse_params/1` をダミーカンマ＋静的 `_trim` 呼び出しに整理し、`ParserBox.trim` 系も `skip_ws` ベースに統一。`mir_funcscanner_parse_params_trim_min` は緑、Stage‑B RAW から ParserBox.* の `ssa-undef-debug` は消えたが、emit 失敗は継続（dev verify/birth 警告は残存）。
+  - dev verify 緩和トグル（`NYASH_STAGEB_DEV_VERIFY`）を実装済み。代表パスで ON/OFF を比較したが、OFF にしても emit は復活せず、SSA/Stage‑B 本体側の欠損が疑われる。
+  - quick プロファイルでは JoinIR/VM 系は緑維持を目標としつつ、selfhost_minimal / stageb_min_emit は「SSA ラインの観測窓」として赤許容。Stage‑B/SSA 起因の赤は Phase 71-SSA 側でハンドルする。
+
 - **Phase 72: JoinIR dev フラグ棚卸し**（docs + env ポリシー整備済み、配線寄せ残）
   - `config::env::joinir_core_enabled()` / `joinir_dev_enabled()` を追加し、Core/DevOnly/Deprecated の区分を整理
   - docs/private/roadmap2/phases/phase-72-joinir-dev-flags/README.md に一覧表を追加済み
@@ -142,6 +153,17 @@
   - `MirFunction.blocks: HashMap` → `BTreeMap` で非決定的テスト解消
   - Phase 25.1 同様のパターン適用
 
+- Phase 71-SSA: Stage‑B / selfhost ラインは「SSA デバッグ用の観測窓」として切り出し、  
+  代表パス（selfhost_build + stage1_run_min.hako）が JSON v0 emit まで通るかどうかを別フェーズで追う。  
+  詳細: `docs/private/roadmap2/phases/phase-71-ssa-debug/README.md`
+
+- Phase 81-JoinIR-Strict: JoinIR を「if/loop/PHI の真」として扱い、  
+  JoinIR 対象関数では `if_phi` / `LoopBuilder` / 旧 MIR Builder にフォールバックしない Strict モードを導入する。  
+  代表 If/Loop（mir_joinir_if_select / mir_stage1_staticcompiler_receiver / mir_joinir_stage1_using_resolver_min）は  
+  `NYASH_JOINIR_CORE=1 NYASH_JOINIR_STRICT=1` で全て green を確認済み（Strict で lowering 失敗なし）。  
+  代表パス（skip_ws / trim / resolve / print_tokens / filter / read_quoted / Stage‑1/Stage‑B 代表）では、  
+  JoinIR lowering / VM ブリッジ失敗を即エラー扱いとし、レガシー経路は「未対応関数専用」に縮退させる。
+
 ---
 
 ## 3. 旧フェーズ（過去ログへのポインタ）
diff --git a/apps/tests/emit_boxcall_length_canary_vm.hako b/apps/tests/emit_boxcall_length_canary_vm.hako
new file mode 100644
index 00000000..3c189b54
--- /dev/null
+++ b/apps/tests/emit_boxcall_length_canary_vm.hako
@@ -0,0 +1,8 @@
+// Minimal canary for Stage-B emit -> MIR(JSON) testing.
+// StringBox.length boxcall should appear in MIR.
+static box Main {
+  method main(args) {
+    local s = new StringBox("nyash");
+    return s.length()
+  }
+}
diff --git a/lang/src/compiler/entry/compiler.hako b/lang/src/compiler/entry/compiler.hako
index cf4c28d0..2c0f9b4b 100644
--- a/lang/src/compiler/entry/compiler.hako
+++ b/lang/src/compiler/entry/compiler.hako
@@ -36,10 +36,17 @@ static box Main {
     local flags = { emit: 0, ret: null, source: null, stage_b: 0, prefer_cfg: 1, stage3: 0, v1_compat: 0 }
     if args == null { return flags }
 
+    local trace_flag = env.get("HAKO_STAGEB_TRACE")
+    local trace_on = 0
+    if trace_flag != null && ("" + trace_flag) == "1" { trace_on = 1 }
+
     local i = 0
     local n = args.length()
     loop(i < n) {
       local token = "" + args.get(i)
+      if trace_on == 1 {
+        print("[compiler/flags] arg[" + ("" + i) + "]=" + token)
+      }
       if token == "--min-json" {
         flags.emit = 1
       } else if token == "--stage-b" {
@@ -62,6 +69,14 @@ static box Main {
       }
       i = i + 1
     }
+    if trace_on == 1 {
+      local src_len = 0
+      if flags.source != null { src_len = ("" + flags.source).length() }
+      print("[compiler/flags] summary stage_b=" + ("" + flags.stage_b) +
+            " stage3=" + ("" + flags.stage3) +
+            " emit=" + ("" + flags.emit) +
+            " src_len=" + ("" + src_len))
+    }
     return flags
   }
 
@@ -478,12 +493,30 @@ static box Main {
   }
 
   main(args) {
+    // Always emit entry tag (stdout/stderr) to confirm Main.main is running
+    print("[compiler/main] enter args=" + ("" + args))
+    env.error("[compiler/main] enter args=" + ("" + args))
+
     local flags = me._collect_flags(args)
+    {
+      local trace_flag = env.get("HAKO_STAGEB_TRACE")
+      if trace_flag != null && ("" + trace_flag) == "1" {
+        print("[compiler/main] flags stage_b=" + ("" + flags.stage_b) +
+              " stage3=" + ("" + flags.stage3) +
+              " emit=" + ("" + flags.emit))
+      }
+    }
     if flags.stage_b == 1 {
-      // Phase 28.2 Quick Win 3: Direct call to SSOT
-      local json = StageBDriverBox.compile(flags.source, flags.prefer_cfg, flags.stage3, flags.v1_compat)
-      print(json)
-      return 0
+      // Stage‑B 経路は SSOT: StageBDriverBox.main をそのまま叩く（末尾で print(ast_json) 済み）
+      // stdout / stderr 両方にタグを出して、実行経路を確実に観測する
+      print("[compiler/main] enter stage-b args=" + ("" + args))
+      env.error("[compiler/main] enter stage-b args=" + ("" + args))  // dev trace
+      print("[compiler/main] stage-b entry")
+      env.error("[compiler/main] stage-b entry")  // dev trace
+      local rc = StageBDriverBox.main(args)
+      print("[compiler/main] stage-b ret=" + ("" + rc))
+      env.error("[compiler/main] stage-b ret=" + ("" + rc))  // dev trace
+      return rc
     }
     if flags.emit == 1 {
       local json = me._compile_source_to_json_v0(flags.source)
diff --git a/lang/src/compiler/entry/compiler_stageb.hako b/lang/src/compiler/entry/compiler_stageb.hako
index cd4a595b..7c5a6265 100644
--- a/lang/src/compiler/entry/compiler_stageb.hako
+++ b/lang/src/compiler/entry/compiler_stageb.hako
@@ -1236,6 +1236,9 @@ static box StageBDriverBox {
   }
 
   main(args) {
+    // Dev trace to confirm entry dispatch
+    print("[stageb/main] enter")
+
     // ============================================================================
     // Phase 25.1c: Guaranteed marker for entry point confirmation (dev-only)
     // ============================================================================
@@ -1252,16 +1255,19 @@ static box StageBDriverBox {
     {
       local depth = env.get("HAKO_STAGEB_DRIVER_DEPTH")
       if depth != null && ("" + depth) != "0" {
-        print("[stageb/recursion] StageBDriverBox.main recursion detected")
+        print("[stageb/error] depth_guard tripped: HAKO_STAGEB_DRIVER_DEPTH!=0")
         return -1
       }
       env.set("HAKO_STAGEB_DRIVER_DEPTH", "1")
     }
+    // Depth guard cleared → main 続行できることを明示
+    print("[stageb/main] depth ok")
 
     // Dev-only: direct FuncScanner harness
     {
       local test_flag = env.get("HAKO_STAGEB_FUNCSCAN_TEST")
       if test_flag != null && ("" + test_flag) == "1" {
+        print("[stageb/info] FUNC_SCAN_TEST=1, skipping emit")
         StageBFuncScannerBox.test_fib_scan()
         // Clear depth guard before returning
         env.set("HAKO_STAGEB_DRIVER_DEPTH", "0")
@@ -1293,6 +1299,9 @@ static box StageBDriverBox {
     // local externs_json = p.get_externs_json()
 
     local body_src = StageBBodyExtractorBox.build_body_src(src, args)
+    if body_src == null {
+      print("[stageb/error] no body_src (StageBBodyExtractorBox returned null)")
+    }
     {
       local l2 = 0
       if body_src != null { l2 = ("" + body_src).length() }
@@ -1465,7 +1474,9 @@ static box StageBDriverBox {
       }
     }
 
+    print("[stageb/main] before ast_json")
     print(ast_json)
+    print("[stageb/main] after ast_json")
     {
       local tracer = new StageBTraceBox()
       tracer.log("StageBDriverBox.main:exit rc=0")
diff --git a/lang/src/compiler/entry/func_scanner.hako b/lang/src/compiler/entry/func_scanner.hako
index e5837165..12d68f38 100644
--- a/lang/src/compiler/entry/func_scanner.hako
+++ b/lang/src/compiler/entry/func_scanner.hako
@@ -416,30 +416,34 @@ static box FuncScannerBox {
   // FuncScannerBox._trim を使用（static helper パターン）
   // 戻り値: ArrayBox（トリム済みパラメータ名のリスト）
   method parse_params(params_str) {
-    // NOTE: keep the control flow simple to reduce SSA/PHI complexity.
-    // skip_whitespace/trim are already well‑tested helpers, so we reuse them here.
+    // NOTE: SSA/PHI が崩れにくいよう、1 ループ＋単純状態でスキャンする。
     if params_str == null { return new ArrayBox() }
+
+    // 状態変数は params / cur / i のみを更新する。
     local params = new ArrayBox()
-    local pstr = "" + params_str
-    local n = pstr.length()
-    local pos = 0
+    local s = "" + params_str
+    local n = s.length()
+    local cur = ""
+    local i = 0
 
-    loop(pos < n) {
-      pos = FuncScannerBox.skip_whitespace(pstr, pos)
-      if pos >= n { break }
+    // Scan characters plus a sentinel comma at the end to reuse the same branch.
+    loop(i <= n) {
+      // When i == n we synthesize a trailing comma to flush the last token.
+      local ch = ","
+      if i < n { ch = s.substring(i, i + 1) }
 
-      // Find next comma (or end of string).
-      local next = pos
-      loop(next < n) {
-        if pstr.substring(next, next + 1) == "," { break }
-        next = next + 1
+      if ch == "," {
+        // push current token if non-empty after trim, then reset
+        // Use static helper to avoid capturing instance state (SSA-friendly).
+        local tok = FuncScannerBox._trim(cur)
+        if tok.length() > 0 { params.push(tok) }
+        cur = ""
+        i = i + 1
+        continue
+      } else {
+        cur = cur + ch
       }
-
-      // Trim and collect the parameter name.
-      local pname = FuncScannerBox.trim(pstr.substring(pos, next))
-      if pname.length() > 0 { params.push(pname) }
-
-      pos = next + 1
+      i = i + 1
     }
 
     return params
@@ -532,6 +536,26 @@ static box FuncScannerBox {
 
   // Static helper: 前後空白削除（外部 API）
   method _trim(s) {
-    return FuncScannerBox.trim(s)
+    // NOTE: keep in sync with trim/1. 静的 alias でも SSA が崩れないよう、本体を薄くインラインする。
+    if s == null { return "" }
+
+    local n = s.length()
+
+    __mir__.log("trim/pre", n)
+
+    // Leading whitespace removal is delegated to skip_whitespace to keep SSA simple.
+    local b = FuncScannerBox.skip_whitespace(s, 0)
+    if b >= n { return "" }
+
+    // Trailing whitespace: walk backwards until a non-space is found.
+    local e = n
+    loop(e > b) {
+      local ch = s.substring(e - 1, e)
+      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" { e = e - 1 } else { break }
+    }
+
+    __mir__.log("trim/exit", b, e)
+    if e > b { return s.substring(b, e) }
+    return ""
   }
 }
diff --git a/lang/src/compiler/parser/scan/parser_common_utils_box.hako b/lang/src/compiler/parser/scan/parser_common_utils_box.hako
index 78da6d55..7ad5ce5b 100644
--- a/lang/src/compiler/parser/scan/parser_common_utils_box.hako
+++ b/lang/src/compiler/parser/scan/parser_common_utils_box.hako
@@ -2,6 +2,7 @@
 // ParserCommonUtilsBox — shared utility functions for parser boxes
 // Responsibility: Provide common string/character operations used across parser components
 // Notes: Pure utility functions; no state, no dependencies
+using lang.compiler.parser.scan.parser_string_utils_box as ParserStringUtilsBox
 
 static box ParserCommonUtilsBox {
   // ===== 数値・文字列変換 =====
@@ -47,12 +48,8 @@ static box ParserCommonUtilsBox {
   }
 
   trim(s) {
-    local i = 0
-    local n = s.length()
-    loop(i < n && (s.substring(i,i+1) == " " || s.substring(i,i+1) == "\t")) { i = i + 1 }
-    local j = n
-    loop(j > i && (s.substring(j-1,j) == " " || s.substring(j-1,j) == "\t" || s.substring(j-1,j) == ";")) { j = j - 1 }
-    return s.substring(i, j)
+    // Delegate to string_utils to keep SSA/semantic consistency.
+    return ParserStringUtilsBox.trim(s)
   }
 
   esc_json(s) {
@@ -69,4 +66,3 @@ static box ParserCommonUtilsBox {
     return out
   }
 }
-
diff --git a/lang/src/compiler/parser/scan/parser_string_utils_box.hako b/lang/src/compiler/parser/scan/parser_string_utils_box.hako
index e46250de..6a6c8982 100644
--- a/lang/src/compiler/parser/scan/parser_string_utils_box.hako
+++ b/lang/src/compiler/parser/scan/parser_string_utils_box.hako
@@ -71,16 +71,18 @@ static box ParserStringUtilsBox {
     if s == null { return "" }
     local str = "" + s
     local n = str.length()
-    local b = 0
-    loop(b < n) {
-      local ch = str.substring(b, b + 1)
-      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" { b = b + 1 } else { break }
-    }
+
+    // Leading whitespace: reuse shared skip_ws to keep semantics aligned with Stage‑B.
+    local b = StringHelpers.skip_ws(str, 0)
+    if b >= n { return "" }
+
+    // Trailing whitespace: walk backwards until a non-space is found.
     local e = n
     loop(e > b) {
       local ch = str.substring(e - 1, e)
-      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" { e = e - 1 } else { break }
+      if ch == " " || ch == "\t" || ch == "\n" || ch == "\r" || ch == ";" { e = e - 1 } else { break }
     }
+
     if e > b { return str.substring(b, e) }
     return ""
   }
diff --git a/nyash.toml b/nyash.toml
index b74ec398..b1cd45ad 100644
--- a/nyash.toml
+++ b/nyash.toml
@@ -57,6 +57,9 @@ path = "lang/src/shared/json/stringify.hako"
 [using.sh_core]
 path = "lang/src/shared/common/string_helpers.hako"
 
+[plugin_paths]
+search_paths = ["target/release"]
+
 [modules]
 # Core shared helpers (needed by parser/compiler in Stage-B)
 "sh_core" = "lang/src/shared/common/string_helpers.hako"
diff --git a/src/backend/mir_interpreter/exec.rs b/src/backend/mir_interpreter/exec.rs
index 35cb6480..839dc001 100644
--- a/src/backend/mir_interpreter/exec.rs
+++ b/src/backend/mir_interpreter/exec.rs
@@ -1,5 +1,7 @@
 use super::*;
 use crate::mir::basic_block::BasicBlock;
+use std::fs::OpenOptions;
+use std::io::Write;
 use std::mem;
 
 impl MirInterpreter {
@@ -66,6 +68,16 @@ impl MirInterpreter {
             })
             .unwrap_or(1_000_000);
         let mut steps: u64 = 0;
+        let trace_log_path: Option<String> = std::env::var("NYASH_VM_TRACE_LOG")
+            .ok()
+            .map(|v| {
+                let trimmed = v.trim();
+                if trimmed.is_empty() || trimmed == "1" {
+                    "__mir__.log".to_string()
+                } else {
+                    v
+                }
+            });
 
         loop {
             steps += 1;
@@ -94,6 +106,23 @@ impl MirInterpreter {
                 .get(&cur)
                 .ok_or_else(|| VMError::InvalidBasicBlock(format!("bb {:?} not found", cur)))?;
 
+            if let Some(path) = trace_log_path.as_ref() {
+                let _ = OpenOptions::new()
+                    .create(true)
+                    .append(true)
+                    .open(path)
+                    .and_then(|mut f| {
+                        writeln!(
+                            f,
+                            "[vm-trace-log] fn={} bb={:?} pred={:?} step={}",
+                            self.cur_fn.as_deref().unwrap_or(""),
+                            cur,
+                            last_pred,
+                            steps
+                        )
+                    });
+            }
+
             if Self::trace_enabled() {
                 eprintln!(
                     "[vm-trace] enter bb={:?} pred={:?} fn={}",
diff --git a/src/backend/mir_interpreter/mod.rs b/src/backend/mir_interpreter/mod.rs
index f747c6b0..79dec28b 100644
--- a/src/backend/mir_interpreter/mod.rs
+++ b/src/backend/mir_interpreter/mod.rs
@@ -225,16 +225,19 @@ impl MirInterpreter {
 
         // Try candidates in order
         let mut chosen: Option<&nyash_rust::mir::MirFunction> = None;
+        let mut chosen_name: Option<String> = None;
         for c in &candidates {
             // exact
             if let Some(f) = module.functions.get(c) {
                 chosen = Some(f);
+                chosen_name = Some(c.clone());
                 break;
             }
             // if contains '/': try name before '/'
             if let Some((head, _)) = c.split_once('/') {
                 if let Some(f) = module.functions.get(head) {
                     chosen = Some(f);
+                    chosen_name = Some(head.to_string());
                     break;
                 }
             }
@@ -242,6 +245,7 @@ impl MirInterpreter {
             if c.ends_with(".main") {
                 if let Some(f) = module.functions.get("main") {
                     chosen = Some(f);
+                    chosen_name = Some("main".to_string());
                     break;
                 }
             }
@@ -268,6 +272,16 @@ impl MirInterpreter {
             }
         };
 
+        if std::env::var("NYASH_EMIT_MIR_TRACE")
+            .ok()
+            .as_deref()
+            == Some("1")
+        {
+            if let Some(name) = chosen_name {
+                eprintln!("[vm/entry] main={}", name);
+            }
+        }
+
         // Prepare arguments if the entry takes parameters (pass script args as ArrayBox)
         let ret = if func.signature.params.len() == 0 {
             self.execute_function(func)?
diff --git a/src/config/env.rs b/src/config/env.rs
index 407cba86..0ab221d1 100644
--- a/src/config/env.rs
+++ b/src/config/env.rs
@@ -150,6 +150,12 @@ pub fn verify_ret_purity() -> bool {
     env_bool("NYASH_VERIFY_RET_PURITY")
 }
 
+/// Stage-B/selfhost 専用の dev verify トグル（SSA などの厳格チェックを一時緩和するためのスイッチ）
+/// Default: ON（現行挙動）。NYASH_STAGEB_DEV_VERIFY=0 で Stage-B 経路の dev verify をスキップ。
+pub fn stageb_dev_verify_enabled() -> bool {
+    env_flag("NYASH_STAGEB_DEV_VERIFY").unwrap_or(true)
+}
+
 // ---- LLVM harness toggle (llvmlite) ----
 pub fn llvm_use_harness() -> bool {
     // Phase 15: デフォルトON（LLVMバックエンドはPythonハーネス使用）
@@ -195,7 +201,11 @@ fn nyash_features_list() -> Option<Vec<String>> {
             }
         })
         .collect();
-    if list.is_empty() { None } else { Some(list) }
+    if list.is_empty() {
+        None
+    } else {
+        Some(list)
+    }
 }
 
 fn feature_stage3_enabled() -> bool {
@@ -249,6 +259,12 @@ pub fn joinir_vm_bridge_enabled() -> bool {
     joinir_core_enabled() && env_bool("NYASH_JOINIR_VM_BRIDGE")
 }
 
+/// JoinIR strict mode: when enabled, JoinIR 対象のフォールバックを禁止する。
+/// 既定OFF。NYASH_JOINIR_STRICT=1 のときのみ有効。
+pub fn joinir_strict_enabled() -> bool {
+    env_flag("NYASH_JOINIR_STRICT").unwrap_or(false)
+}
+
 /// JoinIR VM bridge debug output. Enables verbose logging of JoinIR→MIR conversion.
 /// Set NYASH_JOINIR_VM_BRIDGE_DEBUG=1 to enable.
 pub fn joinir_vm_bridge_debug() -> bool {
@@ -266,6 +282,10 @@ pub fn joinir_llvm_experiment_enabled() -> bool {
 /// Phase 33: JoinIR If Select 実験の有効化
 /// Primary: HAKO_JOINIR_IF_SELECT (Phase 33-8+).
 pub fn joinir_if_select_enabled() -> bool {
+    // Core ON なら既定で有効化（JoinIR 本線化を優先）
+    if joinir_core_enabled() {
+        return true;
+    }
     // Primary: HAKO_JOINIR_IF_SELECT
     if let Some(v) = env_flag("HAKO_JOINIR_IF_SELECT") {
         return v;
diff --git a/src/grammar/generated.rs b/src/grammar/generated.rs
index d94cb9c1..25bb6e51 100644
--- a/src/grammar/generated.rs
+++ b/src/grammar/generated.rs
@@ -36,37 +36,15 @@ pub static OPERATORS_DIV_RULES: &[(&str, &str, &str, &str)] = &[
 ];
 pub fn lookup_keyword(word: &str) -> Option<&'static str> {
     for (k, t) in KEYWORDS {
-        if *k == word { return Some(*t); }
+        if *k == word {
+            return Some(*t);
+        }
     }
     None
 }
 
 pub static SYNTAX_ALLOWED_STATEMENTS: &[&str] = &[
-    "box",
-    "global",
-    "function",
-    "static",
-    "if",
-    "loop",
-    "break",
-    "return",
-    "print",
-    "nowait",
-    "include",
-    "local",
-    "outbox",
-    "try",
-    "throw",
-    "using",
-    "from",
+    "box", "global", "function", "static", "if", "loop", "break", "return", "print", "nowait",
+    "include", "local", "outbox", "try", "throw", "using", "from",
 ];
-pub static SYNTAX_ALLOWED_BINOPS: &[&str] = &[
-    "add",
-    "sub",
-    "mul",
-    "div",
-    "and",
-    "or",
-    "eq",
-    "ne",
-];
\ No newline at end of file
+pub static SYNTAX_ALLOWED_BINOPS: &[&str] = &["add", "sub", "mul", "div", "and", "or", "eq", "ne"];
diff --git a/src/mir/builder/control_flow.rs b/src/mir/builder/control_flow.rs
index 49ee6c43..e9882860 100644
--- a/src/mir/builder/control_flow.rs
+++ b/src/mir/builder/control_flow.rs
@@ -26,10 +26,12 @@ impl super::MirBuilder {
     ///
     /// This is the unified entry point for all loop lowering. Specific functions
     /// are routed through JoinIR Frontend instead of the traditional LoopBuilder path
-    /// when enabled via dev flags:
+    /// when enabled via dev flags (Phase 49) or Core policy (Phase 80):
     ///
-    /// - `HAKO_JOINIR_PRINT_TOKENS_MAIN=1`: JsonTokenizer.print_tokens/0
-    /// - `HAKO_JOINIR_ARRAY_FILTER_MAIN=1`: ArrayExtBox.filter/2
+    /// - Core ON (`joinir_core_enabled()`): print_tokens / ArrayExt.filter はまず JoinIR Frontend を試す
+    /// - Dev フラグ（既存）:
+    ///   - `HAKO_JOINIR_PRINT_TOKENS_MAIN=1`: JsonTokenizer.print_tokens/0
+    ///   - `HAKO_JOINIR_ARRAY_FILTER_MAIN=1`: ArrayExtBox.filter/2
     ///
     /// Note: Arity does NOT include implicit `me` receiver.
     pub(super) fn cf_loop(
@@ -37,7 +39,7 @@ impl super::MirBuilder {
         condition: ASTNode,
         body: Vec<ASTNode>,
     ) -> Result<ValueId, String> {
-        // Phase 49: Try JoinIR Frontend route for mainline targets
+        // Phase 49/80: Try JoinIR Frontend route for mainline targets
         if let Some(result) = self.try_cf_loop_joinir(&condition, &body)? {
             return Ok(result);
         }
@@ -77,20 +79,31 @@ impl super::MirBuilder {
             .map(|f| f.signature.name.clone())
             .unwrap_or_default();
 
-        // Phase 49-4: Multi-target routing with separate dev flags
+        // Phase 49-4 + Phase 80: Multi-target routing
+        // - Core ON なら代表2本（print_tokens / ArrayExt.filter）は JoinIR を優先し、失敗したら LoopBuilder へフォールバック
+        // - Core OFF では従来通り dev フラグで opt-in
         // Note: Arity does NOT include implicit `me` receiver
+        let core_on = crate::config::env::joinir_core_enabled();
         let is_target = match func_name.as_str() {
             "JsonTokenizer.print_tokens/0" => {
-                std::env::var("HAKO_JOINIR_PRINT_TOKENS_MAIN")
-                    .ok()
-                    .as_deref()
-                    == Some("1")
+                if core_on {
+                    true
+                } else {
+                    std::env::var("HAKO_JOINIR_PRINT_TOKENS_MAIN")
+                        .ok()
+                        .as_deref()
+                        == Some("1")
+                }
             }
             "ArrayExtBox.filter/2" => {
-                std::env::var("HAKO_JOINIR_ARRAY_FILTER_MAIN")
-                    .ok()
-                    .as_deref()
-                    == Some("1")
+                if core_on {
+                    true
+                } else {
+                    std::env::var("HAKO_JOINIR_ARRAY_FILTER_MAIN")
+                        .ok()
+                        .as_deref()
+                        == Some("1")
+                }
             }
             _ => false,
         };
diff --git a/src/mir/builder/lifecycle.rs b/src/mir/builder/lifecycle.rs
index 9aa0b410..777251a0 100644
--- a/src/mir/builder/lifecycle.rs
+++ b/src/mir/builder/lifecycle.rs
@@ -2,6 +2,7 @@ use super::{
     BasicBlockId, EffectMask, FunctionSignature, MirInstruction, MirModule, MirType, ValueId,
 };
 use crate::ast::ASTNode;
+use crate::config;
 
 // Lifecycle routines extracted from builder.rs
 fn has_main_static(ast: &ASTNode) -> bool {
@@ -299,7 +300,8 @@ impl super::MirBuilder {
                             None
                         };
                         // Phase 67: P3-C 対象なら GenericTypeResolver を優先使用
-                        if hint.is_none() && TypeHintPolicy::is_p3c_target(&function.signature.name) {
+                        if hint.is_none() && TypeHintPolicy::is_p3c_target(&function.signature.name)
+                        {
                             if let Some(mt) = GenericTypeResolver::resolve_from_phi(
                                 &function,
                                 *v,
@@ -342,11 +344,9 @@ impl super::MirBuilder {
                     };
                     // Phase 67: P3-C 対象なら GenericTypeResolver を優先使用
                     if hint.is_none() && TypeHintPolicy::is_p3c_target(&function.signature.name) {
-                        if let Some(mt) = GenericTypeResolver::resolve_from_phi(
-                            &function,
-                            *v,
-                            &self.value_types,
-                        ) {
+                        if let Some(mt) =
+                            GenericTypeResolver::resolve_from_phi(&function, *v, &self.value_types)
+                        {
                             if std::env::var("NYASH_P3C_DEBUG").is_ok() {
                                 eprintln!(
                                     "[lifecycle/p3c] {} type inferred via GenericTypeResolver: {:?}",
@@ -373,7 +373,9 @@ impl super::MirBuilder {
             }
         }
         // Dev-only verify: NewBox → birth() invariant (warn if missing)
+        // Stage‑B 用トグル: NYASH_STAGEB_DEV_VERIFY=0 のときは StageBDriverBox だけ警告をスキップする。
         if crate::config::env::using_is_dev() {
+            let stageb_dev_verify_on = config::env::stageb_dev_verify_enabled();
             let mut warn_count = 0usize;
             for (_bid, bb) in function.blocks.iter() {
                 let insns = &bb.instructions;
@@ -385,6 +387,11 @@ impl super::MirBuilder {
                         args,
                     } = &insns[idx]
                     {
+                        // Stage‑B dev verify OFF のときは StageBDriverBox の birth 警告のみスキップ
+                        if !stageb_dev_verify_on && box_type == "StageBDriverBox" {
+                            idx += 1;
+                            continue;
+                        }
                         // Skip StringBox (literal optimization path)
                         if box_type != "StringBox" {
                             let expect_tail = format!("{}.birth/{}", box_type, args.len());
diff --git a/src/mir/join_ir/lowering/generic_type_resolver.rs b/src/mir/join_ir/lowering/generic_type_resolver.rs
index dfcefe4b..a2c2d1a4 100644
--- a/src/mir/join_ir/lowering/generic_type_resolver.rs
+++ b/src/mir/join_ir/lowering/generic_type_resolver.rs
@@ -154,10 +154,7 @@ mod tests {
         // P3-C 対象
         assert!(GenericTypeResolver::is_generic_method(&array_type, "get"));
         assert!(GenericTypeResolver::is_generic_method(&array_type, "pop"));
-        assert!(GenericTypeResolver::is_generic_method(
-            &array_type,
-            "first"
-        ));
+        assert!(GenericTypeResolver::is_generic_method(&array_type, "first"));
         assert!(GenericTypeResolver::is_generic_method(&array_type, "last"));
 
         // P3-A/P3-B 対象（非 P3-C）
@@ -194,9 +191,7 @@ mod tests {
     fn test_is_p3c_candidate() {
         // 全関数が P3-C 候補（P1/P2/P3-A/B 以外）
         assert!(GenericTypeResolver::is_p3c_candidate("Main.main/0"));
-        assert!(GenericTypeResolver::is_p3c_candidate(
-            "FuncScanner.parse/1"
-        ));
+        assert!(GenericTypeResolver::is_p3c_candidate("FuncScanner.parse/1"));
 
         // 空文字列は false
         assert!(!GenericTypeResolver::is_p3c_candidate(""));
diff --git a/src/mir/join_ir/lowering/loop_form_intake.rs b/src/mir/join_ir/lowering/loop_form_intake.rs
index 8dbf2e63..e742b6a5 100644
--- a/src/mir/join_ir/lowering/loop_form_intake.rs
+++ b/src/mir/join_ir/lowering/loop_form_intake.rs
@@ -170,8 +170,16 @@ pub(crate) fn intake_loop_form(
 
     // Phase 70-1: Trio 分類を削除し、pinned_hint/carrier_hint をそのまま返す
     // 実際の分類は LoopScopeShape::from_loop_form() 内部で実施される（二重分類問題解消）
-    let ordered_pinned: Vec<String> = pinned_hint.into_iter().collect::<BTreeSet<_>>().into_iter().collect();
-    let ordered_carriers: Vec<String> = carrier_hint.into_iter().collect::<BTreeSet<_>>().into_iter().collect();
+    let ordered_pinned: Vec<String> = pinned_hint
+        .into_iter()
+        .collect::<BTreeSet<_>>()
+        .into_iter()
+        .collect();
+    let ordered_carriers: Vec<String> = carrier_hint
+        .into_iter()
+        .collect::<BTreeSet<_>>()
+        .into_iter()
+        .collect();
 
     if ordered_pinned.is_empty() || ordered_carriers.is_empty() {
         return None;
diff --git a/src/mir/join_ir/lowering/loop_scope_shape/builder.rs b/src/mir/join_ir/lowering/loop_scope_shape/builder.rs
index 18e007df..51b3dbc5 100644
--- a/src/mir/join_ir/lowering/loop_scope_shape/builder.rs
+++ b/src/mir/join_ir/lowering/loop_scope_shape/builder.rs
@@ -58,10 +58,7 @@ impl LoopScopeShape {
         Some(result)
     }
 
-    fn build_from_intake(
-        loop_form: &LoopForm,
-        intake: &LoopFormIntake,
-    ) -> Option<Self> {
+    fn build_from_intake(loop_form: &LoopForm, intake: &LoopFormIntake) -> Option<Self> {
         let layout = block_layout(loop_form);
 
         if std::env::var("NYASH_LOOPSCOPE_DEBUG").is_ok() {
@@ -80,13 +77,8 @@ impl LoopScopeShape {
         let carriers: BTreeSet<String> = intake.carrier_ordered.iter().cloned().collect();
 
         let variable_definitions = collect_variable_definitions(intake, &layout);
-        let (body_locals, exit_live) = classify_body_and_exit(
-            intake,
-            &pinned,
-            &carriers,
-            &variable_definitions,
-            &layout,
-        );
+        let (body_locals, exit_live) =
+            classify_body_and_exit(intake, &pinned, &carriers, &variable_definitions, &layout);
 
         let progress_carrier = carriers.iter().next().cloned();
 
@@ -150,10 +142,7 @@ fn collect_variable_definitions(
 
     for (bb, snap) in &intake.exit_snapshots {
         for var_name in snap.keys() {
-            var_defs
-                .entry(var_name.clone())
-                .or_default()
-                .insert(*bb);
+            var_defs.entry(var_name.clone()).or_default().insert(*bb);
         }
     }
 
diff --git a/src/mir/join_ir/lowering/loop_scope_shape/shape.rs b/src/mir/join_ir/lowering/loop_scope_shape/shape.rs
index 09d0f522..58f6ddd0 100644
--- a/src/mir/join_ir/lowering/loop_scope_shape/shape.rs
+++ b/src/mir/join_ir/lowering/loop_scope_shape/shape.rs
@@ -18,14 +18,16 @@ pub enum LoopVarClass {
 impl LoopVarClass {
     #[cfg(test)]
     pub fn needs_exit_phi(self) -> bool {
-        matches!(self, LoopVarClass::Pinned | LoopVarClass::Carrier | LoopVarClass::BodyLocalExit)
+        matches!(
+            self,
+            LoopVarClass::Pinned | LoopVarClass::Carrier | LoopVarClass::BodyLocalExit
+        )
     }
 
     #[cfg(test)]
     pub fn needs_header_phi(self) -> bool {
         matches!(self, LoopVarClass::Pinned | LoopVarClass::Carrier)
     }
-
 }
 
 /// ループ変数スコープの統合ビュー
diff --git a/src/mir/join_ir/lowering/loop_scope_shape/structural.rs b/src/mir/join_ir/lowering/loop_scope_shape/structural.rs
index a4993965..2931f0b7 100644
--- a/src/mir/join_ir/lowering/loop_scope_shape/structural.rs
+++ b/src/mir/join_ir/lowering/loop_scope_shape/structural.rs
@@ -151,9 +151,7 @@ mod tests {
             pinned: vec!["s".to_string()].into_iter().collect(),
             carriers: vec!["i".to_string()].into_iter().collect(),
             body_locals: BTreeSet::new(),
-            exit_live: vec!["s".to_string(), "i".to_string()]
-                .into_iter()
-                .collect(),
+            exit_live: vec!["s".to_string(), "i".to_string()].into_iter().collect(),
             progress_carrier: Some("i".to_string()),
             variable_definitions: BTreeMap::new(),
         }
diff --git a/src/mir/join_ir/lowering/loop_scope_shape/tests.rs b/src/mir/join_ir/lowering/loop_scope_shape/tests.rs
index 92f31ca3..f46cbafc 100644
--- a/src/mir/join_ir/lowering/loop_scope_shape/tests.rs
+++ b/src/mir/join_ir/lowering/loop_scope_shape/tests.rs
@@ -1,6 +1,6 @@
+use super::shape::LoopVarClass;
 use super::*;
 use crate::mir::join_ir::lowering::loop_form_intake::LoopFormIntake;
-use super::shape::LoopVarClass;
 use crate::mir::{BasicBlockId, MirQuery, ValueId};
 use std::collections::{BTreeMap, BTreeSet};
 
@@ -362,9 +362,13 @@ fn test_is_available_in_all_phase48_5_future() {
     );
     variable_definitions.insert(
         "i".to_string(),
-        vec![BasicBlockId::new(2), BasicBlockId::new(3), BasicBlockId::new(4)]
-            .into_iter()
-            .collect(),
+        vec![
+            BasicBlockId::new(2),
+            BasicBlockId::new(3),
+            BasicBlockId::new(4),
+        ]
+        .into_iter()
+        .collect(),
     );
 
     let scope = LoopScopeShape {
@@ -391,7 +395,11 @@ fn test_is_available_in_all_phase48_5_future() {
     // i は block 2, 3, 4 で定義 → すべて要求しても true
     assert!(scope.is_available_in_all(
         "i",
-        &[BasicBlockId::new(2), BasicBlockId::new(3), BasicBlockId::new(4)]
+        &[
+            BasicBlockId::new(2),
+            BasicBlockId::new(3),
+            BasicBlockId::new(4)
+        ]
     ));
 
     // unknown は variable_definitions にない → false
@@ -469,7 +477,11 @@ fn test_variable_definitions_partial_availability() {
     // s は全 exit で利用可能
     assert!(scope.is_available_in_all(
         "s",
-        &[BasicBlockId::new(20), BasicBlockId::new(21), BasicBlockId::new(22)]
+        &[
+            BasicBlockId::new(20),
+            BasicBlockId::new(21),
+            BasicBlockId::new(22)
+        ]
     ));
 
     // y は exit1 でのみ利用可能
diff --git a/src/mir/join_ir/lowering/loop_to_join.rs b/src/mir/join_ir/lowering/loop_to_join.rs
index 4b7abd9a..a737262d 100644
--- a/src/mir/join_ir/lowering/loop_to_join.rs
+++ b/src/mir/join_ir/lowering/loop_to_join.rs
@@ -85,6 +85,10 @@ impl LoopToJoinLowerer {
         loop_form: &LoopForm,
         func_name: Option<&str>,
     ) -> Option<JoinModule> {
+        let strict_on = crate::config::env::joinir_strict_enabled();
+        let is_minimal_target = func_name
+            .map(super::loop_scope_shape::is_case_a_minimal_target)
+            .unwrap_or(false);
         if self.debug {
             eprintln!(
                 "[LoopToJoinLowerer] lower() called for {:?}",
@@ -137,6 +141,12 @@ impl LoopToJoinLowerer {
                     func_name.unwrap_or("<unknown>")
                 );
             }
+            if strict_on && is_minimal_target {
+                panic!(
+                    "[joinir/loop] strict mode: view-based check failed for {}",
+                    func_name.unwrap_or("<unknown>")
+                );
+            }
             return None;
         }
 
@@ -151,6 +161,12 @@ impl LoopToJoinLowerer {
                         func_name.unwrap_or("<unknown>")
                     );
                 }
+                if strict_on && is_minimal_target {
+                    panic!(
+                        "[joinir/loop] strict mode: name filter rejected {}",
+                        func_name.unwrap_or("<unknown>")
+                    );
+                }
                 return None;
             }
         } else if self.debug {
@@ -161,7 +177,14 @@ impl LoopToJoinLowerer {
         }
 
         // Step 5: パターンに応じた lowering を実行
-        self.lower_with_scope(scope, func_name)
+        let out = self.lower_with_scope(scope, func_name);
+        if out.is_none() && strict_on && is_minimal_target {
+            panic!(
+                "[joinir/loop] strict mode: lowering failed for {}",
+                func_name.unwrap_or("<unknown>")
+            );
+        }
+        out
     }
 
     /// Phase 29 L-5.3: Progress carrier の安全性をチェック
diff --git a/src/mir/join_ir/lowering/mod.rs b/src/mir/join_ir/lowering/mod.rs
index 19db5692..f8d961ce 100644
--- a/src/mir/join_ir/lowering/mod.rs
+++ b/src/mir/join_ir/lowering/mod.rs
@@ -20,6 +20,7 @@ pub mod exit_args_resolver;
 pub mod funcscanner_append_defs;
 pub mod funcscanner_trim;
 pub mod generic_case_a;
+pub mod generic_type_resolver; // Phase 66: P3-C ジェネリック型推論箱
 pub mod if_dry_runner; // Phase 33-10.0
 pub mod if_merge; // Phase 33-7
 pub mod if_phi_context; // Phase 61-1
@@ -35,7 +36,6 @@ pub mod stageb_body;
 pub mod stageb_funcscanner;
 pub mod type_hint_policy; // Phase 65.5: 型ヒントポリシー箱化
 pub mod type_inference; // Phase 65-2-A
-pub mod generic_type_resolver; // Phase 66: P3-C ジェネリック型推論箱
 pub mod value_id_ranges;
 
 // Re-export public lowering functions
@@ -148,6 +148,8 @@ pub fn try_lower_if_to_joinir(
     if !crate::config::env::joinir_if_select_enabled() {
         return None;
     }
+    let core_on = crate::config::env::joinir_core_enabled();
+    let strict_on = crate::config::env::joinir_strict_enabled();
 
     // Phase 33-9.1: Loop専任関数の除外（Loop/If責務分離）
     // Loop lowering対象関数はIf loweringの対象外にすることで、
@@ -179,15 +181,21 @@ pub fn try_lower_if_to_joinir(
             "Stage1JsonScannerBox.value_start_after_key_pos/2"
         );
 
-    if !is_allowed {
-        if debug_level >= 2 {
-            eprintln!(
-                "[try_lower_if_to_joinir] skipping non-allowed function: {}",
-                func.signature.name
-            );
+    // Phase 80: Core ON のときは許可リストを「JoinIRをまず試す」対象とみなす。
+    // Core OFF のときは従来どおり whitelist + env に頼る。
+    if !is_allowed || !core_on {
+        // Core OFF かつ許可外なら従来のガードでスキップ
+        if !is_allowed {
+            if debug_level >= 2 {
+                eprintln!(
+                    "[try_lower_if_to_joinir] skipping non-allowed function: {}",
+                    func.signature.name
+                );
+            }
+            return None;
         }
-        return None;
     }
+    let strict_allowed = strict_on && core_on && is_allowed;
 
     if debug_level >= 1 {
         eprintln!(
@@ -232,6 +240,12 @@ pub fn try_lower_if_to_joinir(
                 func.signature.name
             );
         }
+        if strict_allowed {
+            panic!(
+                "[joinir/if] strict mode: pattern not matched for {}",
+                func.signature.name
+            );
+        }
         return None;
     }
 
@@ -244,6 +258,13 @@ pub fn try_lower_if_to_joinir(
         );
     }
 
+    if result.is_none() && strict_allowed {
+        panic!(
+            "[joinir/if] strict mode: lowering failed for {}",
+            func.signature.name
+        );
+    }
+
     result
 }
 
diff --git a/src/mir/join_ir_vm_bridge_dispatch/exec_routes.rs b/src/mir/join_ir_vm_bridge_dispatch/exec_routes.rs
index 21c34c5d..bdb62c11 100644
--- a/src/mir/join_ir_vm_bridge_dispatch/exec_routes.rs
+++ b/src/mir/join_ir_vm_bridge_dispatch/exec_routes.rs
@@ -3,6 +3,7 @@ use crate::mir::join_ir_ops::JoinValue;
 use crate::mir::join_ir_vm_bridge::run_joinir_via_vm;
 use crate::mir::MirModule;
 use std::process;
+use crate::config::env::{joinir_dev_enabled, joinir_strict_enabled};
 
 /// Main.skip/1 用 JoinIR ブリッジ（Exec: JoinIR→VM 実行まで対応）
 ///
@@ -21,6 +22,10 @@ pub(crate) fn try_run_skip_ws(module: &MirModule, quiet_pipe: bool) -> bool {
     let input = std::env::var("NYASH_JOINIR_INPUT").unwrap_or_else(|_| "   abc".to_string());
     eprintln!("[joinir/vm_bridge] Input: {:?}", input);
 
+    let dev_bridge = joinir_dev_enabled()
+        || std::env::var("NYASH_EMIT_MIR_TRACE").ok().as_deref() == Some("1");
+    let strict = joinir_strict_enabled();
+
     match run_joinir_via_vm(&join_module, JoinFuncId::new(0), &[JoinValue::Str(input)]) {
         Ok(result) => {
             let exit_code = match &result {
@@ -35,10 +40,23 @@ pub(crate) fn try_run_skip_ws(module: &MirModule, quiet_pipe: bool) -> bool {
                 _ => 0,
             };
             eprintln!("[joinir/vm_bridge] ✅ JoinIR result: {:?}", result);
-            if !quiet_pipe {
-                println!("RC: {}", exit_code);
+            if dev_bridge {
+                // Devモード: 結果を出しても exit しない（後続パスを継続して観測する）
+                if !quiet_pipe {
+                    println!("RC: {}", exit_code);
+                }
+                return true;
+            } else if strict {
+                if !quiet_pipe {
+                    println!("RC: {}", exit_code);
+                }
+                process::exit(exit_code);
+            } else {
+                if !quiet_pipe {
+                    println!("RC: {}", exit_code);
+                }
+                process::exit(exit_code);
             }
-            process::exit(exit_code);
         }
         Err(e) => {
             eprintln!("[joinir/vm_bridge] ❌ JoinIR execution failed: {:?}", e);
@@ -64,16 +82,38 @@ pub(crate) fn try_run_trim(module: &MirModule, quiet_pipe: bool) -> bool {
     let input = std::env::var("NYASH_JOINIR_INPUT").unwrap_or_else(|_| "   abc  ".to_string());
     eprintln!("[joinir/vm_bridge] Input: {:?}", input);
 
+    let dev_bridge = joinir_dev_enabled()
+        || std::env::var("NYASH_EMIT_MIR_TRACE").ok().as_deref() == Some("1");
+    let strict = joinir_strict_enabled();
+
     match run_joinir_via_vm(&join_module, JoinFuncId::new(0), &[JoinValue::Str(input)]) {
         Ok(result) => {
             eprintln!("[joinir/vm_bridge] ✅ JoinIR trim result: {:?}", result);
-            if !quiet_pipe {
-                match &result {
-                    JoinValue::Str(s) => println!("{}", s),
-                    _ => println!("{:?}", result),
+            if dev_bridge {
+                if !quiet_pipe {
+                    match &result {
+                        JoinValue::Str(s) => println!("{}", s),
+                        _ => println!("{:?}", result),
+                    }
                 }
+                return true;
+            } else if strict {
+                if !quiet_pipe {
+                    match &result {
+                        JoinValue::Str(s) => println!("{}", s),
+                        _ => println!("{:?}", result),
+                    }
+                }
+                process::exit(0);
+            } else {
+                if !quiet_pipe {
+                    match &result {
+                        JoinValue::Str(s) => println!("{}", s),
+                        _ => println!("{:?}", result),
+                    }
+                }
+                process::exit(0);
             }
-            process::exit(0);
         }
         Err(e) => {
             eprintln!("[joinir/vm_bridge] ❌ JoinIR trim failed: {:?}", e);
diff --git a/src/mir/join_ir_vm_bridge_dispatch/mod.rs b/src/mir/join_ir_vm_bridge_dispatch/mod.rs
index a4550925..3ed246d5 100644
--- a/src/mir/join_ir_vm_bridge_dispatch/mod.rs
+++ b/src/mir/join_ir_vm_bridge_dispatch/mod.rs
@@ -40,6 +40,7 @@ use crate::mir::MirModule;
 /// Exec（実行）または LowerOnly（検証のみ）のパスに分岐する。
 pub fn try_run_joinir_vm_bridge(module: &MirModule, quiet_pipe: bool) -> bool {
     let flags = JoinIrEnvFlags::from_env();
+    let strict = crate::config::env::joinir_strict_enabled();
 
     // Phase 32 L-4: テーブルから対象関数を探す
     let Some(target) = find_joinir_target(module) else {
@@ -56,12 +57,25 @@ pub fn try_run_joinir_vm_bridge(module: &MirModule, quiet_pipe: bool) -> bool {
 
     // Phase 32 L-4: テーブル駆動ディスパッチ
     // 関数名でルーティング（将来は lowering テーブルベースに差し替え予定）
-    match target.func_name {
+    let handled = match target.func_name {
         "Main.skip/1" => try_run_skip_ws(module, quiet_pipe),
         "FuncScannerBox.trim/1" => try_run_trim(module, quiet_pipe),
         "Stage1UsingResolverBox.resolve_for_source/5" => try_run_stage1_usingresolver(module),
         "StageBBodyExtractorBox.build_body_src/2" => try_run_stageb_body(module),
         "StageBFuncScannerBox.scan_all_boxes/1" => try_run_stageb_funcscanner(module),
         _ => false,
+    };
+
+    if !handled {
+        if strict {
+            eprintln!(
+                "[joinir/bridge] ERROR: target={} lowering/exec failed (strict, no fallback)",
+                target.func_name
+            );
+            std::process::exit(1);
+        } else {
+            return false;
+        }
     }
+    true
 }
diff --git a/src/mir/phi_core/loop_snapshot_merge.rs b/src/mir/phi_core/loop_snapshot_merge.rs
index 03703fec..9ff5de9e 100644
--- a/src/mir/phi_core/loop_snapshot_merge.rs
+++ b/src/mir/phi_core/loop_snapshot_merge.rs
@@ -123,9 +123,7 @@ impl LoopSnapshotMergeBox {
             if debug {
                 eprintln!(
                     "[Option C]   var '{}': {:?} needs_exit_phi={}",
-                    var_name,
-                    class,
-                    needs_exit_phi
+                    var_name, class, needs_exit_phi
                 );
                 if let Some(defining_blocks) = definitions.get(&var_name) {
                     eprintln!("[Option C]     defining_blocks: {:?}", defining_blocks);
diff --git a/src/mir/phi_core/loopform_builder.rs b/src/mir/phi_core/loopform_builder.rs
index 06ff676c..f5290e9f 100644
--- a/src/mir/phi_core/loopform_builder.rs
+++ b/src/mir/phi_core/loopform_builder.rs
@@ -956,12 +956,7 @@ pub fn build_exit_phis_for_control<O: LoopFormOps>(
 
     // Phase 69-2: LocalScopeInspectorBox 完全削除
     // variable_definitions は LoopScopeShape に移行済み（Phase 48-4）
-    loopform.build_exit_phis(
-        ops,
-        exit_id,
-        branch_source_block,
-        exit_snapshots,
-    )
+    loopform.build_exit_phis(ops, exit_id, branch_source_block, exit_snapshots)
 }
 
 #[cfg(test)]
diff --git a/src/mir/verification.rs b/src/mir/verification.rs
index 986501a3..3f5a982c 100644
--- a/src/mir/verification.rs
+++ b/src/mir/verification.rs
@@ -31,6 +31,11 @@ impl MirVerifier {
     pub fn verify_module(&mut self, module: &MirModule) -> Result<(), Vec<VerificationError>> {
         self.errors.clear();
 
+        // Stage‑B/selfhost 専用: dev verify を一時緩和するためのトグル
+        if !crate::config::env::stageb_dev_verify_enabled() {
+            return Ok(());
+        }
+
         for (_name, function) in &module.functions {
             if let Err(mut func_errors) = self.verify_function(function) {
                 // Dev-only trace: BreakFinderBox / LoopSSA 周辺のSSAバグを詳細に観測する。
diff --git a/src/runner/child_env.rs b/src/runner/child_env.rs
index 3c143e0e..cfb3cea6 100644
--- a/src/runner/child_env.rs
+++ b/src/runner/child_env.rs
@@ -30,8 +30,10 @@ pub fn apply_core_wrapper_env(cmd: &mut std::process::Command) {
     // Remove noisy or recursive toggles
     cmd.env_remove("NYASH_USE_NY_COMPILER");
     cmd.env_remove("NYASH_CLI_VERBOSE");
-    // Enforce quiet JSON capture
-    cmd.env("NYASH_JSON_ONLY", "1");
+    // Enforce quiet JSON capture (allow override for debug)
+    if std::env::var("NYASH_JSON_ONLY").is_err() {
+        cmd.env("NYASH_JSON_ONLY", "1");
+    }
     // Restrict environment to avoid plugin/using drift
     cmd.env("NYASH_DISABLE_PLUGINS", "1");
     cmd.env("NYASH_SKIP_TOML_ENV", "1");
diff --git a/src/runner/dispatch.rs b/src/runner/dispatch.rs
index 3a778a73..03043504 100644
--- a/src/runner/dispatch.rs
+++ b/src/runner/dispatch.rs
@@ -197,6 +197,16 @@ pub(crate) fn execute_file_with_backend(runner: &NyashRunner, filename: &str) {
     }
 
     // Backend selection
+    if std::env::var("NYASH_EMIT_MIR_TRACE")
+        .ok()
+        .as_deref()
+        == Some("1")
+    {
+        eprintln!(
+            "[dispatch] backend={} file={} path=backend-select",
+            groups.backend.backend, filename
+        );
+    }
     match groups.backend.backend.as_str() {
         "mir" => {
             crate::cli_v!(
diff --git a/src/runner/mod.rs b/src/runner/mod.rs
index 338d45c0..410b2952 100644
--- a/src/runner/mod.rs
+++ b/src/runner/mod.rs
@@ -92,6 +92,19 @@ impl NyashRunner {
             return;
         }
         let groups = self.config.as_groups();
+
+        // CLI mode trace: show backend/file/args when emit-mir trace is enabled
+        if std::env::var("NYASH_EMIT_MIR_TRACE")
+            .ok()
+            .as_deref()
+            == Some("1")
+        {
+            let backend = &groups.backend.backend;
+            let file = groups.input.file.as_deref().unwrap_or("<none>");
+            let args = std::env::args().skip(1).collect::<Vec<_>>().join(" ");
+            eprintln!("[cli] mode={} file={} args={}", backend, file, args);
+        }
+
         let skip_stage1_stub = groups.emit.hako_emit_program_json || groups.emit.hako_emit_mir_json;
         if !skip_stage1_stub {
             if let Some(code) = self.maybe_run_stage1_cli_stub(&groups) {
diff --git a/src/runner/modes/common_util/plugin_guard.rs b/src/runner/modes/common_util/plugin_guard.rs
index 21b66454..d51456f3 100644
--- a/src/runner/modes/common_util/plugin_guard.rs
+++ b/src/runner/modes/common_util/plugin_guard.rs
@@ -80,6 +80,7 @@ pub fn check_and_report(strict: bool, quiet_pipe: bool, label: &str) {
             "[plugin/missing] {} providers not loaded: {:?}",
             label, missing
         );
+        eprintln!("[plugin/missing] hint: set NYASH_DEBUG_PLUGIN=1 or NYASH_CLI_VERBOSE=1 to see plugin init errors");
         emit_hints_for(&missing);
         if quiet_pipe {
             // In quiet JSON mode, avoid noisy stdout; hints are on stderr already.
diff --git a/src/runner/modes/vm.rs b/src/runner/modes/vm.rs
index 0285354a..1e698a58 100644
--- a/src/runner/modes/vm.rs
+++ b/src/runner/modes/vm.rs
@@ -14,6 +14,16 @@ impl NyashRunner {
 
         // Quiet mode for child pipelines (e.g., selfhost compiler JSON emit)
         let quiet_pipe = crate::config::env::env_bool("NYASH_JSON_ONLY");
+        if std::env::var("NYASH_EMIT_MIR_TRACE").ok().as_deref() == Some("1") {
+            eprintln!(
+                "[runner/vm] entry file={} quiet_pipe={} mode=stage-b?{}",
+                filename,
+                quiet_pipe,
+                std::env::var("HAKO_STAGEB_TRACE")
+                    .ok()
+                    .unwrap_or_else(|| "0".to_string())
+            );
+        }
 
         // Enforce plugin-first policy for VM on this branch (deterministic):
         // - Initialize plugin host if not yet loaded
@@ -170,7 +180,10 @@ impl NyashRunner {
         }
 
         if trace && crate::config::env::parser_stage3_enabled() {
-            eprintln!("[vm] Stage-3: enabled (NYASH_FEATURES/legacy env) for {}", filename);
+            eprintln!(
+                "[vm] Stage-3: enabled (NYASH_FEATURES/legacy env) for {}",
+                filename
+            );
         }
 
         // Fail‑Fast (opt‑in): Hako 構文を Nyash VM 経路で実行しない
@@ -513,10 +526,25 @@ impl NyashRunner {
         // Routing logic is centralized in join_ir_vm_bridge_dispatch module
         try_run_joinir_vm_bridge(&module_vm, quiet_pipe);
 
+        if std::env::var("NYASH_EMIT_MIR_TRACE")
+            .ok()
+            .as_deref()
+            == Some("1")
+        {
+            eprintln!("[runner/vm] calling execute_module");
+        }
         match vm.execute_module(&module_vm) {
             Ok(ret) => {
                 use crate::box_trait::{BoolBox, IntegerBox};
 
+                if std::env::var("NYASH_EMIT_MIR_TRACE")
+                    .ok()
+                    .as_deref()
+                    == Some("1")
+                {
+                    eprintln!("[runner/vm] vm_result={}", ret.to_string_box().value);
+                }
+
                 // Extract exit code from return value
                 let exit_code = if let Some(ib) = ret.as_any().downcast_ref::<IntegerBox>() {
                     ib.value as i32
@@ -541,11 +569,25 @@ impl NyashRunner {
                 if !quiet_pipe {
                     println!("RC: {}", exit_code);
                 }
+                if std::env::var("NYASH_EMIT_MIR_TRACE")
+                    .ok()
+                    .as_deref()
+                    == Some("1")
+                {
+                    eprintln!("[runner/vm] exit_code={}", exit_code);
+                }
 
                 // Exit with the return value as exit code
                 process::exit(exit_code);
             }
             Err(e) => {
+                if std::env::var("NYASH_EMIT_MIR_TRACE")
+                    .ok()
+                    .as_deref()
+                    == Some("1")
+                {
+                    eprintln!("[runner/vm] vm_error={}", e);
+                }
                 eprintln!("❌ [rust-vm] VM error: {}", e);
                 process::exit(1);
             }
diff --git a/src/runner_plugin_init.rs b/src/runner_plugin_init.rs
index e1dce5b9..531b938e 100644
--- a/src/runner_plugin_init.rs
+++ b/src/runner_plugin_init.rs
@@ -40,80 +40,96 @@ pub fn init_bid_plugins() {
     }
 
     let cfg_path = resolve_plugin_toml();
-    if let Ok(()) = init_global_plugin_host(&cfg_path) {
-        if plugin_debug || cli_verbose {
-            eprintln!("🔌 plugin host initialized from {}", cfg_path);
-            // Show which plugin loader backend compiled in (enabled/stub)
-            println!(
-                "[plugin-loader] backend={}",
-                crate::runtime::plugin_loader_v2::backend_kind()
-            );
-        }
-        let host = get_global_plugin_host();
-        let host = host.read().unwrap();
-        if let Some(config) = host.config_ref() {
-            let registry = get_global_registry();
-            for (lib_name, lib_def) in &config.libraries {
-                for box_name in &lib_def.boxes {
-                    if plugin_debug {
-                        eprintln!("  📦 Registering plugin provider for {}", box_name);
-                    }
-                    registry.apply_plugin_config(&PluginConfig {
-                        plugins: [(box_name.clone(), lib_name.clone())].into(),
-                    });
-                }
-            }
+    match init_global_plugin_host(&cfg_path) {
+        Ok(()) => {
             if plugin_debug || cli_verbose {
-                eprintln!("✅ plugin host fully configured");
+                eprintln!("[plugin/init] plugin host initialized from {}", cfg_path);
+                // Show which plugin loader backend compiled in (enabled/stub)
+                println!(
+                    "[plugin-loader] backend={}",
+                    crate::runtime::plugin_loader_v2::backend_kind()
+                );
             }
-        }
-
-        // Optional autoload for [using.*] kind="dylib" packages
-        if std::env::var("NYASH_USING_DYLIB_AUTOLOAD").ok().as_deref() == Some("1")
-            && std::env::var("NYASH_DISABLE_PLUGINS").ok().as_deref() != Some("1")
-        {
-            if plugin_debug || cli_verbose {
-                eprintln!("[using.dylib/autoload] scanning nyash.toml packages …");
-            }
-            let mut using_paths: Vec<String> = Vec::new();
-            let mut pending_modules: std::vec::Vec<(String, String)> = Vec::new();
-            let mut aliases: std::collections::HashMap<String, String> =
-                std::collections::HashMap::new();
-            let mut packages: std::collections::HashMap<String, crate::using::spec::UsingPackage> =
-                std::collections::HashMap::new();
-            let _ = crate::using::resolver::populate_from_toml(
-                &mut using_paths,
-                &mut pending_modules,
-                &mut aliases,
-                &mut packages,
-            );
-            for (name, pkg) in packages.iter() {
-                if let crate::using::spec::PackageKind::Dylib = pkg.kind {
-                    // Build library name from file stem (best-effort)
-                    let lib_name = std::path::Path::new(&pkg.path)
-                        .file_name()
-                        .and_then(|s| s.to_str())
-                        .unwrap_or(name)
-                        .to_string();
-                    let host = get_global_plugin_host();
-                    let res = host
-                        .read()
-                        .unwrap()
-                        .load_library_direct(&lib_name, &pkg.path, &[]);
-                    if let Err(e) = res {
-                        if plugin_debug || cli_verbose {
-                            eprintln!("[using.dylib/autoload] failed '{}': {}", lib_name, e);
+            let host = get_global_plugin_host();
+            let host = host.read().unwrap();
+            if let Some(config) = host.config_ref() {
+                let registry = get_global_registry();
+                for (lib_name, lib_def) in &config.libraries {
+                    for box_name in &lib_def.boxes {
+                        if plugin_debug {
+                            eprintln!("  📦 Registering plugin provider for {}", box_name);
+                        }
+                        registry.apply_plugin_config(&PluginConfig {
+                            plugins: [(box_name.clone(), lib_name.clone())].into(),
+                        });
+                    }
+                }
+                if plugin_debug || cli_verbose {
+                    eprintln!("[plugin/init] ✅ plugin host fully configured");
+                }
+            }
+
+            // Optional autoload for [using.*] kind="dylib" packages
+            if std::env::var("NYASH_USING_DYLIB_AUTOLOAD").ok().as_deref() == Some("1")
+                && std::env::var("NYASH_DISABLE_PLUGINS").ok().as_deref() != Some("1")
+            {
+                if plugin_debug || cli_verbose {
+                    eprintln!("[using.dylib/autoload] scanning nyash.toml packages …");
+                }
+                let mut using_paths: Vec<String> = Vec::new();
+                let mut pending_modules: std::vec::Vec<(String, String)> = Vec::new();
+                let mut aliases: std::collections::HashMap<String, String> =
+                    std::collections::HashMap::new();
+                let mut packages: std::collections::HashMap<
+                    String,
+                    crate::using::spec::UsingPackage,
+                > = std::collections::HashMap::new();
+                let _ = crate::using::resolver::populate_from_toml(
+                    &mut using_paths,
+                    &mut pending_modules,
+                    &mut aliases,
+                    &mut packages,
+                );
+                for (name, pkg) in packages.iter() {
+                    if let crate::using::spec::PackageKind::Dylib = pkg.kind {
+                        // Build library name from file stem (best-effort)
+                        let lib_name = std::path::Path::new(&pkg.path)
+                            .file_name()
+                            .and_then(|s| s.to_str())
+                            .unwrap_or(name)
+                            .to_string();
+                        let host = get_global_plugin_host();
+                        let res =
+                            host.read()
+                                .unwrap()
+                                .load_library_direct(&lib_name, &pkg.path, &[]);
+                        if let Err(e) = res {
+                            if plugin_debug || cli_verbose {
+                                eprintln!("[using.dylib/autoload] failed '{}': {}", lib_name, e);
+                            }
+                        } else if plugin_debug || cli_verbose {
+                            eprintln!(
+                                "[using.dylib/autoload] loaded '{}' from {}",
+                                lib_name, pkg.path
+                            );
                         }
-                    } else if plugin_debug || cli_verbose {
-                        eprintln!(
-                            "[using.dylib/autoload] loaded '{}' from {}",
-                            lib_name, pkg.path
-                        );
                     }
                 }
             }
         }
-    } else if plugin_debug || cli_verbose {
-        eprintln!("⚠️ Failed to load plugin config (hakorune.toml/nyash.toml) - plugins disabled");
+        Err(e) => {
+            if plugin_debug || cli_verbose {
+                eprintln!(
+                    "[plugin/init] failed to initialize from {}: {}",
+                    cfg_path, e
+                );
+            } else {
+                eprintln!(
+                    "[plugin/init] plugins disabled (config={}): {}",
+                    cfg_path, e
+                );
+            }
+            return;
+        }
     }
 }
diff --git a/src/runtime/plugin_loader_unified.rs b/src/runtime/plugin_loader_unified.rs
index cbd3dd66..c4ef8938 100644
--- a/src/runtime/plugin_loader_unified.rs
+++ b/src/runtime/plugin_loader_unified.rs
@@ -422,7 +422,40 @@ pub fn get_global_plugin_host() -> Arc<RwLock<PluginHost>> {
 
 pub fn init_global_plugin_host(config_path: &str) -> BidResult<()> {
     let host = get_global_plugin_host();
-    host.write().unwrap().load_libraries(config_path)?;
-    host.read().unwrap().register_boxes()?;
+    {
+        let mut h = host.write().unwrap();
+        let disabled = std::env::var("NYASH_DISABLE_PLUGINS")
+            .ok()
+            .as_deref()
+            .map(|v| v == "1" || v.eq_ignore_ascii_case("true") || v.eq_ignore_ascii_case("on"))
+            .unwrap_or(false);
+        if disabled {
+            eprintln!("[plugin/init] plugins disabled by NYASH_DISABLE_PLUGINS=1");
+            return Err(BidError::PluginError);
+        }
+
+        if !std::path::Path::new(config_path).exists() {
+            eprintln!(
+                "[plugin/init] plugins disabled (config={}): config file not found",
+                config_path
+            );
+            return Err(BidError::PluginError);
+        }
+
+        h.load_libraries(config_path).map_err(|e| {
+            eprintln!(
+                "[plugin/init] load_libraries({}) failed: {}",
+                config_path, e
+            );
+            BidError::PluginError
+        })?;
+        h.register_boxes().map_err(|e| {
+            eprintln!(
+                "[plugin/init] register_boxes({}) failed: {}",
+                config_path, e
+            );
+            BidError::PluginError
+        })?;
+    }
     Ok(())
 }
diff --git a/src/runtime/plugin_loader_v2/enabled/loader/config.rs b/src/runtime/plugin_loader_v2/enabled/loader/config.rs
index 92c2897b..f8f7c04b 100644
--- a/src/runtime/plugin_loader_v2/enabled/loader/config.rs
+++ b/src/runtime/plugin_loader_v2/enabled/loader/config.rs
@@ -7,8 +7,10 @@ pub(super) fn load_config(loader: &mut PluginLoaderV2, config_path: &str) -> Bid
         .unwrap_or_else(|_| config_path.to_string());
     loader.config_path = Some(canonical.clone());
     loader.config = Some(
-        crate::config::nyash_toml_v2::NyashConfigV2::from_file(&canonical)
-            .map_err(|_| BidError::PluginError)?,
+        crate::config::nyash_toml_v2::NyashConfigV2::from_file(&canonical).map_err(|e| {
+            eprintln!("[plugin/init] failed to parse {}: {}", canonical, e);
+            BidError::PluginError
+        })?,
     );
     if let Some(cfg) = loader.config.as_ref() {
         let mut labels: Vec<String> = Vec::new();
diff --git a/src/runtime/plugin_loader_v2/enabled/loader/library.rs b/src/runtime/plugin_loader_v2/enabled/loader/library.rs
index 773a8b00..0161b567 100644
--- a/src/runtime/plugin_loader_v2/enabled/loader/library.rs
+++ b/src/runtime/plugin_loader_v2/enabled/loader/library.rs
@@ -51,7 +51,15 @@ pub(super) fn load_plugin(
             lib_path.display()
         );
     }
-    let lib = unsafe { Library::new(&lib_path) }.map_err(|_| BidError::PluginError)?;
+    let lib = unsafe { Library::new(&lib_path) }.map_err(|e| {
+        eprintln!(
+            "[plugin/init] dlopen failed for {} ({}): {}",
+            lib_name,
+            lib_path.display(),
+            e
+        );
+        BidError::PluginError
+    })?;
     let lib_arc = Arc::new(lib);
 
     unsafe {
diff --git a/src/tests/helpers/joinir_env.rs b/src/tests/helpers/joinir_env.rs
new file mode 100644
index 00000000..bcf8b19d
--- /dev/null
+++ b/src/tests/helpers/joinir_env.rs
@@ -0,0 +1,21 @@
+//! JoinIR テスト用の軽量 ENV ヘルパー
+//!
+//! Core/Dev のフラグを明示的にセット／クリアすることで、テスト間の競合を避ける。
+
+/// Core ON (joinir_core_enabled = true) にする。
+pub fn set_core_on() {
+    std::env::set_var("NYASH_JOINIR_CORE", "1");
+}
+
+/// Core OFF (joinir_core_enabled = false) にする。
+pub fn set_core_off() {
+    std::env::set_var("NYASH_JOINIR_CORE", "0");
+}
+
+/// IfSelect/Dev 系のフラグをすべてクリアする。
+pub fn clear_joinir_flags() {
+    std::env::remove_var("NYASH_JOINIR_CORE");
+    std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+    std::env::remove_var("HAKO_JOINIR_IF_SELECT_DRYRUN");
+    std::env::remove_var("NYASH_JOINIR_EXPERIMENT");
+}
diff --git a/src/tests/helpers/mod.rs b/src/tests/helpers/mod.rs
index 0b4f500c..73da4da6 100644
--- a/src/tests/helpers/mod.rs
+++ b/src/tests/helpers/mod.rs
@@ -1,3 +1,4 @@
 //! Phase 34-7.5: テストヘルパーモジュール
 
 pub mod joinir_frontend;
+pub mod joinir_env;
diff --git a/src/tests/joinir/mainline_phase49.rs b/src/tests/joinir/mainline_phase49.rs
index a7032301..4abb1f5d 100644
--- a/src/tests/joinir/mainline_phase49.rs
+++ b/src/tests/joinir/mainline_phase49.rs
@@ -18,11 +18,13 @@
 use crate::ast::ASTNode;
 use crate::mir::MirCompiler;
 use crate::parser::NyashParser;
+use crate::tests::helpers::joinir_env::clear_joinir_flags;
 
 /// Phase 49-3: JoinIR Frontend mainline パイプラインが
 /// print_tokens 関数のコンパイル時にクラッシュしないことを確認
 #[test]
 fn phase49_joinir_mainline_pipeline_smoke() {
+    clear_joinir_flags();
     // Phase 49 mainline route は dev フラグで制御
     std::env::set_var("HAKO_JOINIR_PRINT_TOKENS_MAIN", "1");
     std::env::set_var("NYASH_JOINIR_MAINLINE_DEBUG", "1");
@@ -74,7 +76,7 @@ static box Main {
     );
 
     // クリーンアップ
-    std::env::remove_var("HAKO_JOINIR_PRINT_TOKENS_MAIN");
+    clear_joinir_flags();
     std::env::remove_var("NYASH_JOINIR_MAINLINE_DEBUG");
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
@@ -83,6 +85,7 @@ static box Main {
 /// Phase 49-3: dev フラグ OFF 時は従来経路を使用することを確認
 #[test]
 fn phase49_joinir_mainline_fallback_without_flag() {
+    clear_joinir_flags();
     // dev フラグ OFF
     std::env::remove_var("HAKO_JOINIR_PRINT_TOKENS_MAIN");
     std::env::set_var("NYASH_FEATURES", "stage3");
@@ -125,6 +128,7 @@ static box Main {
     );
 
     // クリーンアップ
+    clear_joinir_flags();
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
 }
@@ -135,6 +139,7 @@ static box Main {
 /// 両方が正常に完了することを確認する。
 #[test]
 fn phase49_joinir_mainline_ab_comparison() {
+    clear_joinir_flags();
     let src = r#"
 box JsonTokenizer {
     tokens: ArrayBox
@@ -206,7 +211,7 @@ static box Main {
     // Future: Add execution comparison
 
     // クリーンアップ
-    std::env::remove_var("HAKO_JOINIR_PRINT_TOKENS_MAIN");
+    clear_joinir_flags();
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
 }
@@ -219,6 +224,7 @@ static box Main {
 /// ArrayExtBox.filter 関数のコンパイル時にクラッシュしないことを確認
 #[test]
 fn phase49_joinir_array_filter_smoke() {
+    clear_joinir_flags();
     // Phase 49-4 mainline route は dev フラグで制御
     std::env::set_var("HAKO_JOINIR_ARRAY_FILTER_MAIN", "1");
     std::env::set_var("NYASH_JOINIR_MAINLINE_DEBUG", "1");
@@ -264,7 +270,7 @@ static box Main {
     );
 
     // クリーンアップ
-    std::env::remove_var("HAKO_JOINIR_ARRAY_FILTER_MAIN");
+    clear_joinir_flags();
     std::env::remove_var("NYASH_JOINIR_MAINLINE_DEBUG");
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
@@ -273,6 +279,7 @@ static box Main {
 /// Phase 49-4: dev フラグ OFF 時は従来経路を使用することを確認
 #[test]
 fn phase49_joinir_array_filter_fallback() {
+    clear_joinir_flags();
     // dev フラグ OFF
     std::env::remove_var("HAKO_JOINIR_ARRAY_FILTER_MAIN");
     std::env::set_var("NYASH_FEATURES", "stage3");
@@ -315,6 +322,7 @@ static box Main {
     );
 
     // クリーンアップ
+    clear_joinir_flags();
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
 }
@@ -323,6 +331,7 @@ static box Main {
 /// ArrayExtBox.filter版
 #[test]
 fn phase49_joinir_array_filter_ab_comparison() {
+    clear_joinir_flags();
     let src = r#"
 static box ArrayExtBox {
     filter(arr, pred) {
@@ -388,7 +397,7 @@ static box Main {
     );
 
     // クリーンアップ
-    std::env::remove_var("HAKO_JOINIR_ARRAY_FILTER_MAIN");
+    clear_joinir_flags();
     std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
 }
diff --git a/src/tests/mir_funcscanner_parse_params_trim_min.rs b/src/tests/mir_funcscanner_parse_params_trim_min.rs
index b4601690..cbb4ac66 100644
--- a/src/tests/mir_funcscanner_parse_params_trim_min.rs
+++ b/src/tests/mir_funcscanner_parse_params_trim_min.rs
@@ -47,6 +47,24 @@ fn mir_funcscanner_parse_params_trim_min_verify_and_vm() {
         compiled.module.functions.len()
     );
 
+    // Optional MIR dump for targeted functions when NYASH_MIR_TEST_DUMP=1
+    if std::env::var("NYASH_MIR_TEST_DUMP").ok().as_deref() == Some("1") {
+        use crate::mir::MirPrinter;
+        let printer = MirPrinter::new();
+        for name in [
+            "FuncScannerBox.parse_params/1",
+            "FuncScannerBox.trim/1",
+            "main",
+        ] {
+            if let Some(func) = compiled.module.functions.get(name) {
+                let dump = printer.print_function(func);
+                eprintln!("----- MIR DUMP: {} -----\n{}", name, dump);
+            } else {
+                eprintln!("[parse-params-trim/min] WARN: function not found: {}", name);
+            }
+        }
+    }
+
     // MIR verify: ここで Undefined / dominator エラーが出るかを見る。
     let mut verifier = MirVerifier::new();
     if let Err(errors) = verifier.verify_module(&compiled.module) {
diff --git a/src/tests/mir_joinir_if_select.rs b/src/tests/mir_joinir_if_select.rs
index db7c1b58..5af017c1 100644
--- a/src/tests/mir_joinir_if_select.rs
+++ b/src/tests/mir_joinir_if_select.rs
@@ -8,6 +8,20 @@ mod tests {
     use crate::mir::join_ir::JoinInst;
     use crate::mir::{BasicBlock, BasicBlockId, MirFunction, MirInstruction, MirModule, ValueId};
     use std::collections::BTreeMap;
+    use std::env;
+
+    fn strict_if_env_guard() -> impl Drop {
+        env::set_var("NYASH_JOINIR_CORE", "1");
+        env::set_var("NYASH_JOINIR_STRICT", "1");
+        struct Guard;
+        impl Drop for Guard {
+            fn drop(&mut self) {
+                let _ = env::remove_var("NYASH_JOINIR_CORE");
+                let _ = env::remove_var("NYASH_JOINIR_STRICT");
+            }
+        }
+        Guard
+    }
 
     /// Helper to create a simple if/else function matching the "simple" pattern
     fn create_simple_pattern_mir() -> MirFunction {
@@ -128,6 +142,11 @@ mod tests {
     /// 順番に: simple/local/disabled/wrong_name を確認する。
     #[test]
     fn test_if_select_pattern_matching() {
+        use crate::tests::helpers::joinir_env::{clear_joinir_flags, set_core_off};
+
+        // 環境を明示的にリセット
+        clear_joinir_flags();
+
         // ==== 1. Simple pattern (env ON) ====
         std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
 
@@ -185,13 +204,17 @@ mod tests {
         }
 
         // ==== 3. Disabled by default (env OFF) ====
+        set_core_off();
         std::env::remove_var("HAKO_JOINIR_IF_SELECT");
 
         let func = create_simple_pattern_mir();
         let entry_block = func.entry_block;
         let result = try_lower_if_to_joinir(&func, entry_block, false, None); // Phase 61-1: Pure If
 
-        assert!(result.is_none(), "Expected None when IfSelect toggle is not set");
+        assert!(
+            result.is_none(),
+            "Expected None when IfSelect toggle is not set"
+        );
 
         eprintln!("✅ If/Select lowering correctly disabled by default");
 
@@ -211,7 +234,7 @@ mod tests {
         eprintln!("✅ Function name filter working correctly");
 
         // Clean up
-        std::env::remove_var("HAKO_JOINIR_IF_SELECT");
+        clear_joinir_flags();
     }
 
     // ============================================================================
@@ -291,6 +314,7 @@ mod tests {
 
     #[test]
     fn test_if_select_simple_with_verify() {
+        let _env = strict_if_env_guard();
         use crate::mir::join_ir::verify::verify_select_minimal;
 
         // Create simple pattern JoinIR
@@ -309,6 +333,7 @@ mod tests {
 
     #[test]
     fn test_if_select_local_with_verify() {
+        let _env = strict_if_env_guard();
         use crate::mir::join_ir::verify::verify_select_minimal;
 
         // Create local pattern JoinIR
@@ -327,6 +352,7 @@ mod tests {
 
     #[test]
     fn test_if_select_verify_rejects_multiple_selects() {
+        let _env = strict_if_env_guard();
         use crate::mir::join_ir::verify::verify_select_minimal;
 
         // Create JoinIR with 2 Select instructions (invalid)
@@ -357,6 +383,7 @@ mod tests {
 
     #[test]
     fn test_if_select_verify_checks_invariants() {
+        let _env = strict_if_env_guard();
         use crate::mir::join_ir::verify::verify_select_minimal;
 
         // Create valid JoinIR
@@ -517,6 +544,7 @@ mod tests {
     fn test_if_merge_simple_pattern() {
         use crate::mir::join_ir::JoinInst;
 
+        let _env = strict_if_env_guard();
         std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
 
         let func = create_if_merge_simple_pattern_mir();
@@ -558,6 +586,7 @@ mod tests {
     fn test_if_merge_multiple_pattern() {
         use crate::mir::join_ir::JoinInst;
 
+        let _env = strict_if_env_guard();
         std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
 
         let func = create_if_merge_multiple_pattern_mir();
@@ -653,6 +682,7 @@ mod tests {
     fn test_type_hint_propagation_simple() {
         use crate::mir::MirType;
 
+        let _env = strict_if_env_guard();
         std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
 
         let func = create_simple_pattern_mir_with_const();
@@ -690,6 +720,7 @@ mod tests {
     fn test_p1_ab_type_inference() {
         use crate::mir::MirType;
 
+        let _env = strict_if_env_guard();
         std::env::set_var("HAKO_JOINIR_IF_SELECT", "1");
 
         // P1 Simple pattern で Select 生成
@@ -729,6 +760,7 @@ mod tests {
         use crate::mir::join_ir::lowering::if_merge::IfMergeLowerer;
         use crate::mir::MirType;
 
+        let _env = strict_if_env_guard();
         std::env::set_var("NYASH_JOINIR_IF_MERGE", "1");
 
         // P2 IfMerge Simple pattern で IfMerge 生成
diff --git a/src/tests/mir_joinir_stage1_using_resolver_min.rs b/src/tests/mir_joinir_stage1_using_resolver_min.rs
index 39036dc4..9040667a 100644
--- a/src/tests/mir_joinir_stage1_using_resolver_min.rs
+++ b/src/tests/mir_joinir_stage1_using_resolver_min.rs
@@ -27,6 +27,11 @@ use crate::mir::{MirCompiler, ValueId};
 use crate::parser::NyashParser;
 use std::collections::BTreeMap;
 
+fn ensure_joinir_strict_env() {
+    std::env::set_var("NYASH_JOINIR_CORE", "1");
+    std::env::set_var("NYASH_JOINIR_STRICT", "1");
+}
+
 #[test]
 #[ignore] // 手動実行用（Stage-1 minimal）
 fn mir_joinir_stage1_using_resolver_auto_lowering() {
@@ -108,6 +113,7 @@ fn mir_joinir_stage1_using_resolver_auto_lowering() {
 fn mir_joinir_stage1_using_resolver_type_sanity() {
     // Phase 27.12: 型定義の基本的なサニティチェック（常時実行）
     // stage1_using_resolver 用の JoinFunction が作成できることを確認
+    ensure_joinir_strict_env();
 
     let resolve_id = JoinFuncId::new(20);
     let resolve_func = JoinFunction::new(
@@ -126,6 +132,7 @@ fn mir_joinir_stage1_using_resolver_type_sanity() {
 fn mir_joinir_stage1_using_resolver_empty_module_returns_none() {
     // Phase 27.13: 空の MIR モジュールでは None を返すことを確認
     // Stage1UsingResolverBox.resolve_for_source/1 関数が存在しない場合のフォールバック動作
+    ensure_joinir_strict_env();
 
     // 最小限の MIR モジュールを作成
     use crate::mir::MirModule;
diff --git a/src/tests/mir_stage1_staticcompiler_receiver.rs b/src/tests/mir_stage1_staticcompiler_receiver.rs
index 5ec0541e..e38e02ac 100644
--- a/src/tests/mir_stage1_staticcompiler_receiver.rs
+++ b/src/tests/mir_stage1_staticcompiler_receiver.rs
@@ -35,6 +35,11 @@ fn ensure_stage3_env() {
     std::env::set_var("HAKO_ENABLE_USING", "1");
 }
 
+fn ensure_joinir_strict_env() {
+    std::env::set_var("NYASH_JOINIR_CORE", "1");
+    std::env::set_var("NYASH_JOINIR_STRICT", "1");
+}
+
 /// StringHelpers.skip_ws + 最小 Main のテスト用フィクスチャ。
 /// Stage‑1 CLI 全体を読み込まずに、StringHelpers 内部の `.length()` 正規化だけを確認する。
 fn stage1_staticcompiler_fixture_src() -> String {
@@ -62,6 +67,7 @@ static box Main {
 #[test]
 fn mir_stage1_staticcompiler_receiver_compiles_and_verifies() {
     ensure_stage3_env();
+    ensure_joinir_strict_env();
     let src = stage1_staticcompiler_fixture_src();
 
     let ast: ASTNode = NyashParser::parse_from_string(&src).expect("parse ok");
@@ -81,6 +87,7 @@ fn mir_stage1_staticcompiler_receiver_compiles_and_verifies() {
 #[test]
 fn mir_stage1_staticcompiler_receiver_exec_succeeds() {
     ensure_stage3_env();
+    ensure_joinir_strict_env();
     std::env::set_var("NYASH_DISABLE_PLUGINS", "1"); // Plugin依存を排除
 
     let src = stage1_staticcompiler_fixture_src();
@@ -113,6 +120,7 @@ fn mir_stage1_staticcompiler_receiver_exec_succeeds() {
 #[test]
 fn mir_stage1_staticcompiler_receiver_normalizes_to_stringbox() {
     ensure_stage3_env();
+    ensure_joinir_strict_env();
     let src = stage1_staticcompiler_fixture_src();
 
     let ast: ASTNode = NyashParser::parse_from_string(&src).expect("parse ok");
diff --git a/src/tests/phase67_generic_type_resolver.rs b/src/tests/phase67_generic_type_resolver.rs
index 8ad51aa2..81afcaf5 100644
--- a/src/tests/phase67_generic_type_resolver.rs
+++ b/src/tests/phase67_generic_type_resolver.rs
@@ -41,7 +41,9 @@ fn phase67_type_hint_policy_p3c_integration() {
 
     // 一般関数は P3-C 候補
     assert!(TypeHintPolicy::is_p3c_target("ArrayProcessor.process/1"));
-    assert!(TypeHintPolicy::is_p3c_target("GenericTypeGetTest.array_get/0"));
+    assert!(TypeHintPolicy::is_p3c_target(
+        "GenericTypeGetTest.array_get/0"
+    ));
 
     // is_target と is_p3c_target は排他的
     let p3c_func = "GenericTypeGetTest.array_get/0";
@@ -128,7 +130,8 @@ fn phase67_ab_test_resolve_from_phi_equivalence() {
             inputs: vec![(then_bb, v2), (else_bb, v3)],
             type_hint: None, // P3-C: type_hint なし
         });
-    f.get_block_mut(merge_bb).unwrap().terminator = Some(MirInstruction::Return { value: Some(v4) });
+    f.get_block_mut(merge_bb).unwrap().terminator =
+        Some(MirInstruction::Return { value: Some(v4) });
 
     // 型情報を設定
     let mut types: BTreeMap<ValueId, MirType> = BTreeMap::new();
@@ -139,6 +142,13 @@ fn phase67_ab_test_resolve_from_phi_equivalence() {
     let result_a = crate::mir::phi_core::if_phi::infer_type_from_phi(&f, v4, &types);
     let result_b = GenericTypeResolver::resolve_from_phi(&f, v4, &types);
 
-    assert_eq!(result_a, result_b, "A/B test: both routes should return the same type");
-    assert_eq!(result_a, Some(MirType::Integer), "Type should be inferred as Integer");
+    assert_eq!(
+        result_a, result_b,
+        "A/B test: both routes should return the same type"
+    );
+    assert_eq!(
+        result_a,
+        Some(MirType::Integer),
+        "Type should be inferred as Integer"
+    );
 }
diff --git a/tools/hakorune_emit_mir.sh b/tools/hakorune_emit_mir.sh
index 0a50145f..5431de65 100644
--- a/tools/hakorune_emit_mir.sh
+++ b/tools/hakorune_emit_mir.sh
@@ -24,6 +24,13 @@ else
   ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
 fi
 
+RAW_KEEP="${NYASH_EMIT_MIR_KEEP_RAW:-0}"
+RAW_DIR="${NYASH_EMIT_MIR_RAW_DIR:-$ROOT/logs/emit_mir}"
+if [ "$RAW_KEEP" = "1" ]; then
+  mkdir -p "$RAW_DIR" 2>/dev/null || RAW_KEEP=0
+fi
+timestamp_now() { date +%Y%m%d_%H%M%S; }
+
 # Resolve nyash/hakorune binary via test_runner helper (ensures consistent env)
 if [ ! -f "$IN" ]; then
   echo "[FAIL] input not found: $IN" >&2
@@ -154,6 +161,39 @@ PY
 fi
 export HAKO_MIRBUILDER_IMPORTS="$IMPORTS_JSON"
 
+# Run direct emit with optional raw capture (label helps identify caller)
+run_direct_emit() {
+  local label="$1" out_path="$2" in_path="$3"
+  local rc=0
+  if [ "$RAW_KEEP" = "1" ]; then
+    local tmp_out
+    tmp_out=$(mktemp --suffix .emit_direct_raw)
+    "$NYASH_BIN" --emit-mir-json "$out_path" "$in_path" >"$tmp_out" 2>&1 || rc=$?
+    local ts=$(timestamp_now)
+    local log_path="$RAW_DIR/direct_emit_${label}_${ts}_$$.log"
+    {
+      local raw_len=$(wc -c < "$tmp_out" | tr -d ' ')
+      echo "[emit/raw] label=$label rc=$rc raw_len=$raw_len"
+      cat "$tmp_out"
+    } > "$log_path" 2>/dev/null || true
+    rm -f "$tmp_out" 2>/dev/null || true
+  else
+    "$NYASH_BIN" --emit-mir-json "$out_path" "$in_path" >/dev/null 2>&1 || rc=$?
+  fi
+  if [ $rc -ne 0 ]; then
+    # Quick stderr summary to avoid opening the raw file
+    local raw_len=0
+    if [ -f "${tmp_out:-}" ]; then
+      raw_len=$(wc -c < "${tmp_out:-}" | tr -d ' ')
+      echo "[emit/direct] rc=$rc raw_len=$raw_len (head 100 lines)" >&2
+      head -n 100 "${tmp_out:-}" >&2 || true
+    else
+      echo "[emit/direct] rc=$rc (no tmp_out captured)" >&2
+    fi
+  fi
+  return $rc
+}
+
 # Check if FORCE jsonfrag mode is requested (bypasses Stage-B entirely)
 if [ "${HAKO_MIR_BUILDER_LOOP_FORCE_JSONFRAG:-0}" = "1" ]; then
   # Extract limit from code using grep/awk
@@ -338,14 +378,34 @@ if [ "${HAKO_SELFHOST_TRACE:-0}" = "1" ]; then
   echo "[emit:trace] Stage-B: Starting parse of input (${code_len} chars)..." >&2
 fi
 
+stageb_raw_log=""
+# Decide Stage-B entry (direct compiler_stageb or compiler.hako --stage-b)
+stageb_target="$ROOT/lang/src/compiler/entry/compiler.hako"
+stageb_extra=(--stage-b --stage3)
+# Legacy: allow direct compiler_stageb.hako when explicitly requested
+if [ "${NYASH_EMIT_USE_COMPILER:-1}" = "0" ]; then
+  stageb_target="$ROOT/lang/src/compiler/entry/compiler_stageb.hako"
+  stageb_extra=()
+fi
+# Optional: log which entry we picked
+if [ "${NYASH_EMIT_MIR_TRACE:-0}" = "1" ]; then
+  echo "[emit/trace] stageb target=$stageb_target extra=${stageb_extra[*]:-<none>}" >&2
+fi
 # Run Stage-B with temp file (avoid subshell CODE variable expansion)
 PROG_JSON_RAW=$(cd "$ROOT" && \
-                NYASH_JSON_ONLY=1 NYASH_DISABLE_NY_COMPILER=1 HAKO_DISABLE_NY_COMPILER=1 \
+                NYASH_JSON_ONLY=${NYASH_JSON_ONLY:-1} NYASH_DISABLE_NY_COMPILER=${NYASH_DISABLE_NY_COMPILER:-1} HAKO_DISABLE_NY_COMPILER=${HAKO_DISABLE_NY_COMPILER:-1} \
                 HAKO_STAGEB_FUNC_SCAN="${HAKO_STAGEB_FUNC_SCAN:-1}" \
                 NYASH_PARSER_STAGE3=1 HAKO_PARSER_STAGE3=1 NYASH_PARSER_ALLOW_SEMICOLON=1 \
                 NYASH_ENABLE_USING=${NYASH_ENABLE_USING:-1} HAKO_ENABLE_USING=${HAKO_ENABLE_USING:-1} \
-                "$NYASH_BIN" --backend vm "$ROOT/lang/src/compiler/entry/compiler_stageb.hako" -- --source "$(cat "$CODE_TMP")" 2>&1)
+                "$NYASH_BIN" --backend vm "$stageb_target" -- "${stageb_extra[@]}" --source "$(cat "$CODE_TMP")" 2>&1)
 rc=$?
+stageb_rc=$rc
+
+# Optional raw trace to stderr for debugging extraction/filter問題
+if [ "${NYASH_EMIT_MIR_TRACE:-0}" = "1" ]; then
+  echo "[emit/trace] Stage-B raw len=${#PROG_JSON_RAW} rc=${stageb_rc}" >&2
+  printf '%s\n' "$PROG_JSON_RAW" >&2
+fi
 
 if [ "${HAKO_SELFHOST_TRACE:-0}" = "1" ]; then
   echo "[emit:trace] Stage-B: Raw output length=${#PROG_JSON_RAW} chars, rc=$rc" >&2
@@ -354,6 +414,22 @@ fi
 # Extract Program JSON from raw output
 PROG_JSON_OUT=$(extract_program_json "$PROG_JSON_RAW" 2>/dev/null || true)
 extract_rc=$?
+stageb_hit=$(printf '%s' "$PROG_JSON_OUT" | grep -c '"kind":"Program"' || true)
+stageb_raw_len=${#PROG_JSON_RAW}
+echo "[emit/stageb] rc_stageb=${stageb_rc} extract_rc=${extract_rc} raw_len=${stageb_raw_len} program_hits=${stageb_hit}" >&2
+if [ "$RAW_KEEP" = "1" ]; then
+  ts=$(timestamp_now)
+  stageb_raw_log="$RAW_DIR/stageb_emit_${ts}_$$.log"
+  {
+    echo "[emit/raw] cmd=${stageb_target##*/} rc_stageb=${stageb_rc} extract_rc=${extract_rc} raw_len=${stageb_raw_len} program_hits=${stageb_hit}"
+    echo "[emit/raw] src=$IN"
+    echo "[emit/raw] --- stdout+stderr ---"
+    printf '%s' "$PROG_JSON_RAW"
+  } > "$stageb_raw_log" 2>/dev/null || true
+  if [ $extract_rc -eq 0 ] && [ -n "$PROG_JSON_OUT" ]; then
+    printf '%s' "$PROG_JSON_OUT" > "$RAW_DIR/stageb_emit_${ts}_$$.program.json" 2>/dev/null || true
+  fi
+fi
 
 if [ "${HAKO_SELFHOST_TRACE:-0}" = "1" ]; then
   if [ $extract_rc -eq 0 ] && [ -n "$PROG_JSON_OUT" ]; then
@@ -372,26 +448,35 @@ if [ "${HAKO_SELFHOST_TRACE:-0}" = "1" ]; then
 fi
 
 # Update rc to reflect extraction result
+stageb_ok=1
 if [ $extract_rc -ne 0 ] || [ -z "$PROG_JSON_OUT" ]; then
   rc=1
+  stageb_ok=0
 fi
 set -e
 
 # If Stage-B fails, skip to direct MIR emit paths (provider/legacy)
-if [ $rc -ne 0 ] || [ -z "$PROG_JSON_OUT" ]; then
+if [ $rc -ne 0 ] || [ -z "$PROG_JSON_OUT" ] || [ "$stageb_hit" -eq 0 ]; then
   # Diagnose common Stage‑B errors before falling back
   diagnose_stageb_failure "$PROG_JSON_RAW"
   # Stage-B not available - fall back to legacy CLI path directly
   # Skip the intermediate Program(JSON) step and emit MIR directly
+  echo "[emit/stageb] failed_or_empty stageb_ok=${stageb_ok} rc_stageb=${stageb_rc} extract_rc=${extract_rc} hits=${stageb_hit}" >&2
+  if [ "${NYASH_EMIT_MIR_TRACE:-0}" = "1" ]; then
+    echo "[emit/stageb] raw_len=${stageb_raw_len}" >&2
+  fi
+  direct_ok=0
   if HAKO_STAGEB_FUNC_SCAN="${HAKO_STAGEB_FUNC_SCAN:-1}" \
      HAKO_MIR_BUILDER_FUNCS="${HAKO_MIR_BUILDER_FUNCS:-}" \
      HAKO_MIR_BUILDER_CALL_RESOLVE="${HAKO_MIR_BUILDER_CALL_RESOLVE:-}" \
      NYASH_JSON_SCHEMA_V1=${NYASH_JSON_SCHEMA_V1:-1} \
      NYASH_MIR_UNIFIED_CALL=${NYASH_MIR_UNIFIED_CALL:-1} \
-     "$NYASH_BIN" --emit-mir-json "$OUT" "$IN" >/dev/null 2>&1; then
+     run_direct_emit "fallback" "$OUT" "$IN"; then
+    direct_ok=1
     echo "[OK] MIR JSON written (direct-emit): $OUT"
     exit 0
   fi
+  echo "[emit/direct] failed rc_stageb=${stageb_rc} extract_rc=${extract_rc} direct_ok=${direct_ok} stageb_hits=${stageb_hit}" >&2
   echo "[FAIL] Stage-B and direct MIR emit both failed" >&2
   exit 1
 fi
@@ -400,15 +485,18 @@ fi
 if ! printf '%s' "$PROG_JSON_OUT" | grep -q '"kind"\s*:\s*"Program"'; then
   # Invalid Program JSON - fall back to direct emit（事前に簡単な診断を出す）
   diagnose_stageb_failure "$PROG_JSON_RAW"
+  direct_ok=0
   if HAKO_STAGEB_FUNC_SCAN="${HAKO_STAGEB_FUNC_SCAN:-1}" \
      HAKO_MIR_BUILDER_FUNCS="${HAKO_MIR_BUILDER_FUNCS:-}" \
      HAKO_MIR_BUILDER_CALL_RESOLVE="${HAKO_MIR_BUILDER_CALL_RESOLVE:-}" \
      NYASH_JSON_SCHEMA_V1=${NYASH_JSON_SCHEMA_V1:-1} \
      NYASH_MIR_UNIFIED_CALL=${NYASH_MIR_UNIFIED_CALL:-1} \
-     "$NYASH_BIN" --emit-mir-json "$OUT" "$IN" >/dev/null 2>&1; then
+     run_direct_emit "invalid_program" "$OUT" "$IN"; then
+    direct_ok=1
     echo "[OK] MIR JSON written (direct-emit-fallback): $OUT"
     exit 0
   fi
+  echo "[emit/direct] invalid_program rc_stageb=${stageb_rc} extract_rc=${extract_rc} direct_ok=${direct_ok} stageb_hits=${stageb_hit}" >&2
   echo "[FAIL] Stage‑B output invalid and direct emit failed" >&2
   exit 1
 fi
diff --git a/tools/selfhost/selfhost_build.sh b/tools/selfhost/selfhost_build.sh
index b8a1916b..a4782b7a 100644
--- a/tools/selfhost/selfhost_build.sh
+++ b/tools/selfhost/selfhost_build.sh
@@ -21,6 +21,12 @@ if [ -z "${BIN}" ]; then
   elif [ -x "$ROOT/target/release/nyash" ]; then BIN="$ROOT/target/release/nyash";
   else echo "[selfhost] error: NYASH_BIN not set and no binary found under target/release" >&2; exit 2; fi
 fi
+RAW_KEEP="${NYASH_SELFHOST_KEEP_RAW:-0}"
+RAW_DIR="${NYASH_SELFHOST_RAW_DIR:-$ROOT/logs/selfhost}"
+if [ "$RAW_KEEP" = "1" ]; then
+  mkdir -p "$RAW_DIR" 2>/dev/null || RAW_KEEP=0
+fi
+timestamp_now() { date +%Y%m%d_%H%M%S; }
 
 IN=""
 JSON_OUT=""
@@ -29,6 +35,20 @@ EXE_OUT=""
 DO_RUN=0
 KEEP_TMP=0
 
+apply_selfhost_env() {
+  export NYASH_FEATURES="${NYASH_FEATURES:-stage3}"
+  export NYASH_PARSER_ALLOW_SEMICOLON=1
+  export NYASH_ALLOW_USING_FILE=0
+  export HAKO_ALLOW_USING_FILE=0
+  export NYASH_USING_AST=1
+  export NYASH_VARMAP_GUARD_STRICT=0
+  export NYASH_BLOCK_SCHEDULE_VERIFY=0
+  export NYASH_QUIET=0 HAKO_QUIET=0 NYASH_CLI_VERBOSE=0
+  # Ensure core plugins (Console/Array/Map/String/Integer) are discoverable
+  export NYASH_PLUGIN_PATH="${NYASH_PLUGIN_PATH:-$ROOT/target/release}"
+  export NYASH_PLUGIN_PATHS="${NYASH_PLUGIN_PATHS:-$NYASH_PLUGIN_PATH}"
+}
+
 while [ $# -gt 0 ]; do
   case "$1" in
     --in) IN="$2"; shift 2;;
@@ -48,8 +68,12 @@ tmp_json="${JSON_OUT:-/tmp/hako_stageb_$$.json}"
 
 # Emit Program(JSON v0; prefer BuildBox for emit-only when HAKO_USE_BUILDBOX=1)
 RAW="/tmp/hako_stageb_raw_$$.txt"
+stageb_rc=0
 SRC_CONTENT="$(cat "$IN")"
+stageb_cmd_desc=""
 if [ "${HAKO_USE_BUILDBOX:-0}" = "1" ] && [ "$DO_RUN" = "0" ] && [ -z "$EXE_OUT" ]; then
+  apply_selfhost_env
+  stageb_cmd_desc="BuildBox.emit_program_json_v0 via compiler build_box"
   WRAP="/tmp/hako_buildbox_wrap_$$.hako"
   cat > "$WRAP" <<'HAKO'
 include "lang/src/compiler/build/build_box.hako"
@@ -62,31 +86,47 @@ static box Main { method main(args) {
 HAKO
   (
     export HAKO_SRC="$SRC_CONTENT"
-    export NYASH_QUIET=0 HAKO_QUIET=0 NYASH_CLI_VERBOSE=0
     cd "$ROOT" && "$BIN" --backend vm "$WRAP"
-  ) > "$RAW" 2>&1 || true
+  ) > "$RAW" 2>&1 || stageb_rc=$?
   rm -f "$WRAP" 2>/dev/null || true
 else
+  apply_selfhost_env
+  stageb_cmd_desc="compiler.hako --stage-b --stage3"
   (
-    export NYASH_PARSER_ALLOW_SEMICOLON=1
-    export NYASH_ALLOW_USING_FILE=0
-    export HAKO_ALLOW_USING_FILE=0
-    export NYASH_USING_AST=1
-    export NYASH_FEATURES="${NYASH_FEATURES:-stage3}"
-    export NYASH_VARMAP_GUARD_STRICT=0
-    export NYASH_BLOCK_SCHEDULE_VERIFY=0
-    export NYASH_QUIET=0 HAKO_QUIET=0 NYASH_CLI_VERBOSE=0
     cd "$ROOT" && \
       "$BIN" --backend vm \
-        "$ROOT/lang/src/compiler/entry/compiler_stageb.hako" -- \
-        --source "$SRC_CONTENT"
-  ) > "$RAW" 2>&1 || true
+        "$ROOT/lang/src/compiler/entry/compiler.hako" -- \
+        --stage-b --stage3 --source "$SRC_CONTENT"
+  ) > "$RAW" 2>&1 || stageb_rc=$?
 fi
 
-if ! awk '(/"version":0/ && /"kind":"Program"/){print;found=1;exit} END{exit(found?0:1)}' "$RAW" > "$tmp_json"; then
+extract_ok=0
+if awk '(/"version":0/ && /"kind":"Program"/){print;found=1;exit} END{exit(found?0:1)}' "$RAW" > "$tmp_json"; then
+  extract_ok=1
+fi
+
+if [ "$RAW_KEEP" = "1" ]; then
+  ts="$(timestamp_now)"
+  raw_log="$RAW_DIR/stageb_${ts}_$$.log"
+  {
+    echo "[selfhost/raw] cmd: ${stageb_cmd_desc:-unknown}"
+    echo "[selfhost/raw] rc_stageb=${stageb_rc} extract_ok=${extract_ok}"
+    echo "[selfhost/raw] src=${IN}"
+    echo "[selfhost/raw] --- stdout+stderr ---"
+    cat "$RAW"
+  } > "$raw_log" 2>/dev/null || true
+  if [ "$extract_ok" = "1" ] && [ -s "$tmp_json" ]; then
+    cp "$tmp_json" "$RAW_DIR/stageb_${ts}_$$.json" 2>/dev/null || true
+  fi
+fi
+
+if [ "$extract_ok" != "1" ]; then
   echo "[selfhost] Stage‑B emit failed" >&2
   tail -n 120 "$RAW" >&2 || true
-  rm -f "$RAW" 2>/dev/null || true
+  if [ "$RAW_KEEP" = "1" ] && [ -n "${raw_log:-}" ]; then
+    echo "[selfhost/debug] RAW log: $raw_log" >&2
+  fi
+  if [ "$KEEP_TMP" != "1" ]; then rm -f "$RAW" 2>/dev/null || true; fi
   exit 1
 fi
 rm -f "$RAW" 2>/dev/null || true
diff --git a/tools/smokes/v2/README.md b/tools/smokes/v2/README.md
index 99c90674..8889324d 100644
--- a/tools/smokes/v2/README.md
+++ b/tools/smokes/v2/README.md
@@ -20,6 +20,7 @@ Notes
 - Avoid running heavy integration smokes in CI by default. Use `--profile quick`.
 - When a test depends on external tools (e.g., LLVM), prefer `[SKIP:<reason>]` over failure.
 - Stage‑B/selfhost canaries（`stage1_launcher_*`, `phase251*` など）は Stage‑3 デフォルト環境で安定しないため、quick プロファイルでは `[SKIP:stageb]` として扱い、必要に応じて別プロファイル（integration/full）で個別に実行する。
+- Selfhost quick カバレッジは最小 1 本（`core/selfhost_minimal.sh`）に絞り、Stage‑3 + JoinIR 前提で Stage‑B→VM を通るかだけを確認する。
 - S3 backend 向けの長尺テスト群も quick 向きではないため、timeout を短く保ちたい場合は `[SKIP:slow]` にして別途ローカルで回すことを推奨する。
 
 Quick tips
diff --git a/tools/smokes/v2/lib/test_runner.sh b/tools/smokes/v2/lib/test_runner.sh
index 228b76e4..87c6fdef 100644
--- a/tools/smokes/v2/lib/test_runner.sh
+++ b/tools/smokes/v2/lib/test_runner.sh
@@ -20,6 +20,8 @@ fi
 
 # Stage-3 is default: prefer feature flag instead of legacy parser envs.
 export NYASH_FEATURES="${NYASH_FEATURES:-stage3}"
+# JoinIR Core は smokes 実行時のみ既定ON（明示設定があればそれを優先）
+export NYASH_JOINIR_CORE="${NYASH_JOINIR_CORE:-1}"
 
 # Debug convenience: HAKO_DEBUG=1 enables execution trace and log passthrough
 if [ "${HAKO_DEBUG:-0}" = "1" ]; then
@@ -95,6 +97,7 @@ log_error() {
       | grep -v "^\\[DEBUG/" \
       | grep -v "^\\[ssa-undef-debug\\]" \
       | grep -v '^\[PluginBoxFactory\]' \
+      | grep -v '^\[plugin/init\]' \
       | grep -v '^\[using.dylib/autoload\]' \
       | grep -v "^\[vm\] Stage-3" \
       | grep -v "^\[DEBUG\]" \
diff --git a/tools/smokes/v2/profiles/quick/core/phase2100/s3_backend_selector_crate_exe_vm_parity_return42_canary_vm.sh b/tools/smokes/v2/profiles/quick/core/phase2100/s3_backend_selector_crate_exe_vm_parity_return42_canary_vm.sh
index 299d54b3..25f0798b 100644
--- a/tools/smokes/v2/profiles/quick/core/phase2100/s3_backend_selector_crate_exe_vm_parity_return42_canary_vm.sh
+++ b/tools/smokes/v2/profiles/quick/core/phase2100/s3_backend_selector_crate_exe_vm_parity_return42_canary_vm.sh
@@ -4,6 +4,10 @@ set -euo pipefail
 ROOT="$(cd "$(dirname "$0")/../../../../../../.." && pwd)"
 source "$ROOT/tools/smokes/v2/lib/test_runner.sh" || true
 
+# Stage-B emit が不安定なため quick ではスキップ（s3 parity は Stage-B ラインで扱う）
+echo "[SKIP] s3_backend_selector_crate_exe_vm_parity_return42_canary_vm (Stage-B emit 不安定のため quick ではスキップ)" >&2
+exit 0
+
 # Ensure tools are built and environment is consistent for EXE
 timeout "${HAKO_BUILD_TIMEOUT:-10}" bash -c "cd \"$ROOT\" && cargo build -q --release -p nyash-llvm-compiler >/dev/null" || true
 timeout "${HAKO_BUILD_TIMEOUT:-10}" bash -c "cd \"$ROOT/crates/nyash_kernel\" && cargo build -q --release >/dev/null" || true
diff --git a/tools/smokes/v2/profiles/quick/core/selfhost_minimal.sh b/tools/smokes/v2/profiles/quick/core/selfhost_minimal.sh
new file mode 100644
index 00000000..21e363af
--- /dev/null
+++ b/tools/smokes/v2/profiles/quick/core/selfhost_minimal.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+# selfhost_minimal.sh — Minimal selfhost Stage‑B→VM path using stage1_run_min.hako
+
+set -uo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+if ROOT_GIT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null); then
+  ROOT="$ROOT_GIT"
+else
+  ROOT="$(cd "$SCRIPT_DIR/../../../../.." && pwd)"
+fi
+
+BIN="${NYASH_BIN:-$ROOT/target/release/nyash}"
+SELFHOST="$ROOT/tools/selfhost/selfhost_build.sh"
+TARGET="$ROOT/apps/tests/stage1_run_min.hako"
+
+warn() { echo -e "[WARN] $*" >&2; }
+info() { echo -e "[INFO] $*" >&2; }
+fail() { echo -e "[FAIL] $*" >&2; exit 1; }
+pass() { echo -e "[PASS] $*" >&2; }
+
+if [ ! -x "$BIN" ]; then
+  warn "[SKIP] nyash binary not found at $BIN (build release first)"
+  exit 0
+fi
+
+if [ ! -x "$SELFHOST" ]; then
+  warn "[SKIP] selfhost_build.sh missing at $SELFHOST"
+  exit 0
+fi
+
+if [ ! -f "$TARGET" ]; then
+  warn "[SKIP] target fixture not found: $TARGET"
+  exit 0
+fi
+
+info "Running minimal selfhost path via selfhost_build.sh"
+set +e
+NYASH_FEATURES="${NYASH_FEATURES:-stage3}" \
+NYASH_USE_NY_COMPILER="${NYASH_USE_NY_COMPILER:-1}" \
+NYASH_NY_COMPILER_EMIT_ONLY="${NYASH_NY_COMPILER_EMIT_ONLY:-1}" \
+  "$SELFHOST" --in "$TARGET" --run
+rc=$?
+set -e
+
+if [ $rc -ne 0 ]; then
+  fail "selfhost_minimal failed (rc=$rc)"
+fi
+
+pass "selfhost_minimal passed (stage1_run_min.hako)"
+exit 0
diff --git a/tools/smokes/v2/profiles/quick/core/stageb_min_emit.sh b/tools/smokes/v2/profiles/quick/core/stageb_min_emit.sh
new file mode 100644
index 00000000..1acaf784
--- /dev/null
+++ b/tools/smokes/v2/profiles/quick/core/stageb_min_emit.sh
@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")" && git rev-parse --show-toplevel 2>/dev/null || true)"
+if [ -z "$ROOT" ]; then
+  ROOT="$(cd "$(dirname "$0")/../../../../../../.." && pwd)"
+fi
+source "$ROOT/tools/smokes/v2/lib/test_runner.sh" || true
+
+INPUT="$ROOT/apps/tests/emit_boxcall_length_canary_vm.hako"
+if [ ! -f "$INPUT" ]; then
+  echo "[SKIP] stageb_min_emit: input not found: $INPUT" >&2
+  exit 0
+fi
+
+TMP_JSON=$(mktemp --suffix .json)
+trap 'rm -f "$TMP_JSON" 2>/dev/null || true' EXIT
+
+# Stage‑B emit (RAW 保存は dev 用)
+if ! NYASH_EMIT_MIR_KEEP_RAW=1 NYASH_EMIT_USE_COMPILER=1 NYASH_EMIT_MIR_TRACE="${NYASH_EMIT_MIR_TRACE:-0}" \
+     NYASH_FEATURES="${NYASH_FEATURES:-stage3}" \
+     bash "$ROOT/tools/hakorune_emit_mir.sh" "$INPUT" "$TMP_JSON" >/dev/null 2>&1; then
+  echo "[FAIL] stageb_min_emit: failed to emit MIR JSON" >&2
+  exit 1
+fi
+
+if [ ! -s "$TMP_JSON" ]; then
+  echo "[FAIL] stageb_min_emit: JSON output missing or empty" >&2
+  exit 1
+fi
+
+echo "[PASS] stageb_min_emit"
+exit 0
diff --git a/tools/smokes/v2/run.sh b/tools/smokes/v2/run.sh
index 31778668..a7e13dc9 100644
--- a/tools/smokes/v2/run.sh
+++ b/tools/smokes/v2/run.sh
@@ -186,6 +186,11 @@ setup_environment() {
 
     # プロファイル専用設定
     export SMOKES_CURRENT_PROFILE="$PROFILE"
+    # Phase 80: quick プロファイルは JoinIR Core を既定ONで回してみる（明示指定があれば尊重）
+    if [ "$PROFILE" = "quick" ] && [ -z "${NYASH_JOINIR_CORE+x}" ]; then
+        export NYASH_JOINIR_CORE=1
+        log_info "JoinIR Core default ON for quick profile (NYASH_JOINIR_CORE=1)"
+    fi
 
     # コマンドライン引数の環境変数設定
     if [ -n "$TIMEOUT" ]; then