diff --git a/lang/src/compiler/parser/parser_box.hako b/lang/src/compiler/parser/parser_box.hako
index 3637869b..d27cb3e0 100644
--- a/lang/src/compiler/parser/parser_box.hako
+++ b/lang/src/compiler/parser/parser_box.hako
@@ -351,17 +351,20 @@ box ParserBox {
     }
 
     loop(cont_prog == 1) {
-      // ✅ TRACE: main_prog loop progress (Task先生推奨トレースポイント)
-      local _loop_info = ""
-      if trace == 1 && (guard_prog < 5 || (guard_prog % 10) == 0) {
-        _loop_info = "[parse_program2:main] count=" + ("" + guard_prog) +
-                     " i=" + ("" + i) + " n=" + ("" + n)
-        if i < n {
-          local _end = i + 40
-          if _end > n { _end = n }
-          _loop_info = _loop_info + " ctx=\"" + src.substring(i, _end) + "\""
+      // ===== 1) WS SKIP (inline, simple structure) =====
+      loop(i < n) {
+        local ch_ws = src.substring(i, i + 1)
+        if ch_ws == " " || ch_ws == "\n" || ch_ws == "\r" || ch_ws == "\t" {
+          i = i + 1
+          continue
         }
-        print(_loop_info)
+        break
+      }
+
+      // ===== 2) EOF/GUARD CHECK (early exit) =====
+      if i >= n {
+        cont_prog = 0
+        break
       }
 
       if max_prog > 0 {
@@ -371,117 +374,78 @@ box ParserBox {
             print("[parser/program2:guard] max iteration reached at pos=" + ("" + i))
           }
           cont_prog = 0
+          break
         }
       }
-      // Fail-fast: EOF まで進んでいれば即座にループを抜ける（無限走行防止）。
-      if i >= n {
-        cont_prog = 0
-        break
+
+      // ===== 3) PARSE_STMT2 + GPOS_GET (unconditional execution) =====
+      local start_i = i
+      local s = me.parse_stmt2(src, i)
+      i = me.gpos_get()
+
+      // ===== 4) PROGRESS GUARD (ensure i always advances) =====
+      if i <= start_i {
+        if trace == 1 {
+          print("[parser/trace:program2] progress-guard bump i from " + ("" + start_i) + " to " + ("" + (start_i + 1)))
+        }
+        i = start_i + 1
+        if i > n { i = n }
+        me.gpos_set(i)
       }
+
+      // ===== 5) TRACE (simplified, at end) =====
       if trace == 1 {
-        local kind = "Stmt"
-        if i >= n {
-          kind = "EOF"
+        print("[parser/trace:program2] i=" + ("" + i) + " stmt_len=" + ("" + s.length()) + " guard=" + ("" + guard_prog))
+      }
+
+      // ===== 6) CONSUME OPTIONAL SEMICOLONS =====
+      local done_semi = 0
+      local guard_semi = 0
+      local max_semi = 100000
+
+      loop(done_semi == 0) {
+        if guard_semi > max_semi {
+          done_semi = 1
         } else {
-          if me.starts_with(src, i, "static box") == 1 { kind = "StaticBox" }
-          else {
-            if me.starts_with(src, i, "box ") == 1 { kind = "BoxDecl" }
-            else {
-              if me.starts_with(src, i, "method ") == 1 { kind = "Method" }
-            }
-          }
-        }
-        print("[parser/trace:program2] pos=" + ("" + i) + " kind=" + kind + " stage3=" + ("" + me.stage3))
-        // Dev-only: small preview of remaining source to debug top-level progress
-        {
-          local head = ""
-          if i < n {
-            local end = i + 40
-            if end > n { end = n }
-            head = src.substring(i, end)
-          }
-          print("[parser/trace:program2] head=\"" + head + "\"")
-        }
-      }
-      // Inline skip_ws instead of calling me.skip_ws(src, i)
-      if i < n {
-        local ws_cont_1 = 1
-        loop(ws_cont_1 == 1) {
-          if i < n {
-            local ch1 = src.substring(i, i + 1)
-            if ch1 == " " || ch1 == "\n" || ch1 == "\r" || ch1 == "\t" { i = i + 1 }
-            else { ws_cont_1 = 0 }
-          } else { ws_cont_1 = 0 }
-        }
-      }
-
-      if i >= src.length() {
-        cont_prog = 0
-      } else {
-        local start_i = i
-        if trace == 1 {
-          print("[parser/trace:program2] before_stmt i=" + ("" + i))
-        }
-        local s = me.parse_stmt2(src, i)
-        i = me.gpos_get()
-        if trace == 1 {
-          print("[parser/trace:program2] after_stmt i=" + ("" + i) + " stmt_len=" + ("" + s.length()))
+          guard_semi = guard_semi + 1
         }
 
-        // Progress guard
-        if i <= start_i {
-          if trace == 1 {
-            print("[parser/trace:program2] progress-guard bump i from " + ("" + start_i) + " to " + ("" + (start_i + 1)))
-          }
-          if i < src.length() { i = i + 1 }
-          else { i = src.length() }
-          me.gpos_set(i)
-        }
+        local before_semi = i
 
-        // consume optional semicolons
-        local done2 = 0
-        local guard2 = 0
-        local max2 = 100000
-
-        loop(done2 == 0) {
-          if guard2 > max2 { done2 = 1 }
-          else { guard2 = guard2 + 1 }
-
-          local before2 = i
-          // Inline skip_ws instead of calling me.skip_ws(src, i)
-          if i < n {
-            local ws_cont_2 = 1
-            loop(ws_cont_2 == 1) {
-              if i < n {
-                local ch2 = src.substring(i, i + 1)
-                if ch2 == " " || ch2 == "\n" || ch2 == "\r" || ch2 == "\t" { i = i + 1 }
-                else { ws_cont_2 = 0 }
-              } else { ws_cont_2 = 0 }
-            }
-          }
-
-          if i < src.length() && src.substring(i, i+1) == ";" {
+        // Inline ws skip
+        loop(i < n) {
+          local ch_semi = src.substring(i, i + 1)
+          if ch_semi == " " || ch_semi == "\n" || ch_semi == "\r" || ch_semi == "\t" {
             i = i + 1
-          } else {
-            done2 = 1
+            continue
           }
-
-          if i == before2 { done2 = 1 }
+          break
         }
 
-        if s.length() > 0 {
-          if first == 1 {
-            if trace == 1 {
-              print("[parser/trace:program2] emit-first stmt_len=" + ("" + s.length()))
-            }
-            body = body + s
-            first = 0
-          } else {
-            if trace == 1 {
-              print("[parser/trace:program2] emit stmt_len=" + ("" + s.length()))
-            }
-            body = body + "," + s
+        if i < n && src.substring(i, i+1) == ";" {
+          i = i + 1
+        } else {
+          done_semi = 1
+        }
+
+        if i == before_semi {
+          done_semi = 1
+        }
+      }
+
+      // ===== 7) EMIT STATEMENT =====
+      if s.length() > 0 {
+        if first == 1 {
+          if trace == 1 {
+            print("[parser/trace:program2] emit-first stmt_len=" + ("" + s.length()))
           }
+          body = body + s
+          first = 0
+        } else {
+          if trace == 1 {
+            print("[parser/trace:program2] emit stmt_len=" + ("" + s.length()))
+          }
+          body = body + "," + s
         }
       }
     }
diff --git a/lang/src/shared/common/string_helpers.hako b/lang/src/shared/common/string_helpers.hako
index 29b3ce9a..7137618a 100644
--- a/lang/src/shared/common/string_helpers.hako
+++ b/lang/src/shared/common/string_helpers.hako
@@ -172,14 +172,13 @@ static box StringHelpers {
     local s = "" + src
     local n = s.length()
     local j = i
-    local cont = 1
-    local guard = 0
-    local max = 100000
-    loop(cont == 1) {
-      if guard > max { return j } else { guard = guard + 1 }
-      if j < n {
-        if me.is_space(s.substring(j, j+1)) { j = j + 1 } else { cont = 0 }
-      } else { cont = 0 }
+    // Simplified loop structure for MirBuilder compatibility
+    loop(j < n) {
+      if me.is_space(s.substring(j, j+1)) {
+        j = j + 1
+        continue
+      }
+      break
     }
     return j
   }
diff --git a/src/runner/modes/vm.rs b/src/runner/modes/vm.rs
index 203d0a58..25229839 100644
--- a/src/runner/modes/vm.rs
+++ b/src/runner/modes/vm.rs
@@ -431,6 +431,15 @@ impl NyashRunner {
         }
 
         // Optional: dump MIR for diagnostics
+        // Phase 25.1: File dump for offline analysis (ParserBox等)
+        if let Ok(path) = std::env::var("RUST_MIR_DUMP_PATH") {
+            if let Ok(mut f) = std::fs::File::create(&path) {
+                let p = crate::mir::MirPrinter::new();
+                let _ = std::io::Write::write_all(&mut f, p.print_module(&module_vm).as_bytes());
+                eprintln!("[vm] MIR dumped to: {}", path);
+            }
+        }
+        // Existing: NYASH_VM_DUMP_MIR dumps to stderr
         if crate::config::env::env_bool("NYASH_VM_DUMP_MIR") {
             let p = crate::mir::MirPrinter::new();
             eprintln!("{}", p.print_module(&module_vm));
diff --git a/src/runner/modes/vm_fallback.rs b/src/runner/modes/vm_fallback.rs
index 527be1dd..c933c82c 100644
--- a/src/runner/modes/vm_fallback.rs
+++ b/src/runner/modes/vm_fallback.rs
@@ -294,6 +294,15 @@ impl NyashRunner {
         }
 
         // Optional: dump MIR for diagnostics (parity with vm path)
+        // Phase 25.1: File dump for offline analysis (ParserBox等)
+        if let Ok(path) = std::env::var("RUST_MIR_DUMP_PATH") {
+            if let Ok(mut f) = std::fs::File::create(&path) {
+                let p = crate::mir::MirPrinter::new();
+                let _ = std::io::Write::write_all(&mut f, p.print_module(&module_vm).as_bytes());
+                eprintln!("[vm-fallback] MIR dumped to: {}", path);
+            }
+        }
+        // Existing: NYASH_VM_DUMP_MIR dumps to stderr
         if crate::config::env::env_bool("NYASH_VM_DUMP_MIR") {
             let p = crate::mir::MirPrinter::new();
             eprintln!("{}", p.print_module(&module_vm));