diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index b7bb7e78..271cc660 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -235,11 +235,16 @@
           - AST 構造解析（名前依存禁止）、LHS 出現回数チェック
           - Implementation phases 定義（Phase 190-impl-A/B/C/D）
         - **次ステップ**: Phase 190-impl で実装（コード変更は別フェーズ）
-  - [ ] Phase 190-impl: NumberAccumulation 実装
-        - Phase 190-impl-A: Core Detection (LoopUpdateAnalyzer 拡張)
-        - Phase 190-impl-B: CarrierUpdateLowerer Extension (JoinIR emission)
-        - Phase 190-impl-C: Pattern2/4 Integration (can_lower 更新)
-        - Phase 190-impl-D: E2E Validation (JsonParserBox._atoi 動作確認)
+  - [x] **Phase 190-impl: NumberAccumulation 実装** ✅ (2025-12-09)
+        - Phase 190-impl-A: Core Detection (LoopUpdateAnalyzer 拡張) ✅
+        - Phase 190-impl-B: CarrierUpdateLowerer Extension (JoinIR emission) ✅
+        - Phase 190-impl-C: Pattern2/4 Integration (can_lower 更新) ✅
+        - Phase 190-impl-D: E2E Validation + PHI 配線デバッグ ✅
+          - **バグ発見**: body-local と carrier の ValueId 衝突問題
+          - **修正**: `body_local_start_offset = env.len() + carrier_info.carriers.len()`
+          - **E2E 結果**: `phase190_atoi_impl.hako` → 12 ✅、`phase190_parse_number_impl.hako` → 123 ✅
+          - ExitLine contract Verifier 追加（`#[cfg(debug_assertions)]`）
+        - **残課題**: body-local 変数 assignment は JoinIR 未対応（Phase 186 line に残タスク）
   - [ ] Phase 191: 複雑 NumberAccumulation 対応
         - Complex addend 対応 (`v = v * 10 + f(x)`)
         - Phase 189 キャリア検出ブロッカー解決
diff --git a/apps/tests/phase190_atoi_impl.hako b/apps/tests/phase190_atoi_impl.hako
index 853493fa..198c1609 100644
--- a/apps/tests/phase190_atoi_impl.hako
+++ b/apps/tests/phase190_atoi_impl.hako
@@ -4,9 +4,16 @@
 //
 // Note: Phase 190-impl-D found that body-local variable support is incomplete.
 // Using loop variable directly for now.
+//
+// Expected calculation:
+//   i=0: result = 0*10 + 0 = 0
+//   i=1: result = 0*10 + 1 = 1
+//   i=2: result = 1*10 + 2 = 12
+//   i=3: break (condition i >= 3)
+// Expected result: 12
 
-static box AtoiImpl {
-    method main() {
+static box Main {
+    main() {
         local result
         result = 0
         local i
@@ -19,6 +26,7 @@ static box AtoiImpl {
             result = result * 10 + i
             i = i + 1
         }
-        return result
+        print(result)
+        return 0
     }
 }
diff --git a/apps/tests/phase190_parse_number_impl.hako b/apps/tests/phase190_parse_number_impl.hako
index 279882ba..1b95c1d0 100644
--- a/apps/tests/phase190_parse_number_impl.hako
+++ b/apps/tests/phase190_parse_number_impl.hako
@@ -5,8 +5,8 @@
 // Expected: i=1,2,3 → num = 0*10+1 = 1 → 1*10+2 = 12 → 12*10+3 = 123
 // Result should be 123
 
-static box ParseNumberImpl {
-    method main() {
+static box Main {
+    main() {
         local num
         num = 0
         local i
@@ -19,6 +19,6 @@ static box ParseNumberImpl {
             i = i + 1
         }
         print(num)
-        return num
+        return 0
     }
 }
diff --git a/docs/development/current/main/phase190-number-update-design.md b/docs/development/current/main/phase190-number-update-design.md
index e5a379bd..afc721e0 100644
--- a/docs/development/current/main/phase190-number-update-design.md
+++ b/docs/development/current/main/phase190-number-update-design.md
@@ -970,4 +970,13 @@ Assignment {
 ## Revision History
 
 - **2025-12-09**: Initial design (Section 1-12)
-- **TBD**: Implementation review updates
+- **2025-12-09**: Phase 190-impl 完了
+  - Phase 190-impl-A: LoopUpdateAnalyzer に NumberAccumulation 検出実装
+  - Phase 190-impl-B: CarrierUpdateLowerer で 2-instruction emission 実装
+  - Phase 190-impl-C: Pattern2 can_lower ホワイトリスト更新
+  - Phase 190-impl-D: E2E 検証成功 + PHI 配線修正
+    - **バグ発見**: body-local と carrier の ValueId 衝突問題
+    - **修正**: `body_local_start_offset = env.len() + carrier_info.carriers.len()` で安全な ValueId 空間分割
+    - **E2E 結果**: `phase190_atoi_impl.hako` → 12 ✅、`phase190_parse_number_impl.hako` → 123 ✅
+    - **制約**: body-local 変数 assignment は JoinIR 未対応（Phase 186 残タスク）
+  - ExitLine contract Verifier 追加（`#[cfg(debug_assertions)]`）
diff --git a/src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs b/src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs
index 6297b0cf..4bda76af 100644
--- a/src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs
+++ b/src/mir/builder/control_flow/joinir/merge/exit_line/reconnector.rs
@@ -145,8 +145,68 @@ impl ExitLineReconnector {
             );
         }
 
+        // Phase 190-impl-D-3: Contract verification (debug build only)
+        // Ensures all exit_bindings have corresponding entries in carrier_phis and variable_map
+        #[cfg(debug_assertions)]
+        Self::verify_exit_line_contract(boundary, carrier_phis, &builder.variable_map);
+
         Ok(())
     }
+
+    /// Phase 190-impl-D-3: Verify exit line contract (debug build only)
+    ///
+    /// # Contract Requirements
+    ///
+    /// 1. Every exit_binding must have a corresponding entry in carrier_phis
+    /// 2. Every exit_binding's carrier must exist in variable_map after reconnect
+    /// 3. The variable_map entry must point to the PHI dst (not the original host value)
+    ///
+    /// # Panics
+    ///
+    /// Panics if any contract violation is detected. This helps catch bugs where:
+    /// - PHI is missing for a carrier (Phase 190-impl-D root cause)
+    /// - variable_map update was skipped
+    /// - ValueId collision occurred
+    #[cfg(debug_assertions)]
+    fn verify_exit_line_contract(
+        boundary: &JoinInlineBoundary,
+        carrier_phis: &BTreeMap<String, ValueId>,
+        variable_map: &std::collections::HashMap<String, ValueId>,
+    ) {
+        for binding in &boundary.exit_bindings {
+            // Contract 1: carrier_phis must contain this carrier
+            let phi_dst = carrier_phis.get(&binding.carrier_name);
+            if phi_dst.is_none() {
+                // Skip loop variable (it's handled separately in loop_header_phi)
+                // Only check carriers that have exit_bindings
+                eprintln!(
+                    "[JoinIR/ExitLine/Contract] WARNING: Carrier '{}' has exit_binding but no PHI in carrier_phis",
+                    binding.carrier_name
+                );
+                // Don't panic for now - loop variable might not be in carrier_phis
+                // Future: Distinguish loop_var from carriers in exit_bindings
+            }
+
+            // Contract 2: variable_map must contain this carrier after reconnect
+            let var_value = variable_map.get(&binding.carrier_name);
+            if var_value.is_none() {
+                panic!(
+                    "[JoinIR/ExitLine/Contract] VIOLATION: Carrier '{}' missing from variable_map after reconnect",
+                    binding.carrier_name
+                );
+            }
+
+            // Contract 3: variable_map entry should point to PHI dst (if PHI exists)
+            if let (Some(&phi), Some(&var)) = (phi_dst, var_value) {
+                if phi != var {
+                    panic!(
+                        "[JoinIR/ExitLine/Contract] VIOLATION: Carrier '{}' variable_map={:?} but PHI dst={:?} (mismatch!)",
+                        binding.carrier_name, var, phi
+                    );
+                }
+            }
+        }
+    }
 }
 
 #[cfg(test)]