diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index 9b7a2ec7..a0eedc8e 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -75,6 +75,19 @@
   - **CarrierInfo 構造修正**: DigitPosPromoter が carriers list に追加する形に変更（loop_var_name 置換ではなく）
   - **検証**: `phase2235_p2_digit_pos_min.hako` で alias 解決成功、エラーが次段階（substring init）に進展
   - **残課題**: substring method in body-local init（Phase 193 limitation） → Phase 225 で解決
+- **Phase 224-E 完了** ✅: DigitPos 条件正規化（`digit_pos < 0` → `!is_digit_pos` AST 変換）
+  - **問題**: Phase 228-8 までで `digit_pos: i32` → `is_digit_pos: bool` 昇格完了したが、条件 AST がまだ `digit_pos < 0` のまま
+  - **型エラー**: alias 後に `Bool(is_digit_pos) < Integer(0)` となり型不一致エラー
+  - **解決**: DigitPosConditionNormalizer Box で AST 変換（`digit_pos < 0` → `!is_digit_pos`）
+  - **実装箇所**: `src/mir/join_ir/lowering/digitpos_condition_normalizer.rs`（173 lines）
+  - **統合**: Pattern2 で promotion 成功後に自動適用（`pattern2_with_break.rs` line 332-344）
+  - **テスト**:
+    - 単体テスト 5/5 PASS（happy path, wrong operator/variable/constant, non-binary-op）
+    - digitpos 関連 11 tests PASS
+    - trim 関連 32 tests PASS（回帰なし）
+    - E2E: `phase2235_p2_digit_pos_min.hako` で型エラー完全解消確認
+  - **成果**: 型エラーの根本原因を解消（alias だけでは不十分、AST 構造変換が必要）
+  - **詳細**: [phase224-digitpos-condition-normalizer.md](docs/development/current/main/phase224-digitpos-condition-normalizer.md)
 - **Phase 225 完了** ✅: LoopBodyLocalInit MethodCall メタ駆動化（ハードコード完全削除）
   - **問題**: Phase 193 の `emit_method_call_init` にハードコードされた whitelist (`SUPPORTED_INIT_METHODS`) と Box 名 match 文
   - **解決**: MethodCallLowerer への委譲により単一責任原則達成
diff --git a/docs/development/current/main/joinir-architecture-overview.md b/docs/development/current/main/joinir-architecture-overview.md
index 729880ce..990317f9 100644
--- a/docs/development/current/main/joinir-architecture-overview.md
+++ b/docs/development/current/main/joinir-architecture-overview.md
@@ -374,13 +374,16 @@ Local Region (1000+):
   - 入出力:
     - 入力: `DigitPosPromotionRequest`（cond_scope, break_cond/continue_cond, loop_body）
     - 出力: `DigitPosPromotionResult::Promoted { carrier_info, promoted_var, carrier_name }` または `CannotPromote { reason, vars }`
-  - 現状の制約（Phase 224-continuation で対応予定）:
-    - **Promotion は成功**: LoopBodyCondPromoter → DigitPosPromoter → Promoted ✅
-    - **Lowerer integration gap**: lower_loop_with_break_minimal が昇格済み変数を認識せず、break condition AST に元の変数名が残っているため独立チェックでエラー。
-    - **Solution**: Option B（promoted variable tracking）で昇格済み変数リストを lowerer に渡す（1-2h 実装予定）。
+  - **Phase 224-E 完了（AST 条件正規化）**:
+    - **DigitPosConditionNormalizer Box**: `digit_pos < 0` → `!is_digit_pos` の AST 変換。
+    - **実装箇所**: `src/mir/join_ir/lowering/digitpos_condition_normalizer.rs`（173 lines）。
+    - **統合**: Pattern2 で promotion 成功後に自動適用（`pattern2_with_break.rs` line 332-344）。
+    - **単体テスト**: 5/5 PASS（happy path, wrong operator/variable/constant, non-binary-op）。
+    - **E2E テスト**: `phase2235_p2_digit_pos_min.hako` で型エラー解消確認。
+    - **回帰テスト**: digitpos (11 tests), trim (32 tests) 全て PASS。
   - 参考:
-    - 設計ドキュメント: `docs/development/current/main/phase224-digitpos-promoter-design.md`
-    - 完全サマリ: `docs/development/current/main/PHASE_224_SUMMARY.md`
+    - 設計ドキュメント: `docs/development/current/main/phase224-digitpos-condition-normalizer.md`
+    - 実装サマリ: `docs/development/current/main/PHASE_224_SUMMARY.md`
     - テストケース: `apps/tests/phase2235_p2_digit_pos_min.hako`
 
 - **ContinueBranchNormalizer / LoopUpdateAnalyzer**
diff --git a/docs/development/current/main/phase224-digitpos-condition-normalizer.md b/docs/development/current/main/phase224-digitpos-condition-normalizer.md
new file mode 100644
index 00000000..7d9d686c
--- /dev/null
+++ b/docs/development/current/main/phase224-digitpos-condition-normalizer.md
@@ -0,0 +1,188 @@
+# Phase 224-E: DigitPos Condition Normalizer
+
+## Problem Statement
+
+### Background
+Phase 228-8 successfully implemented the DigitPos pattern promotion:
+- `digit_pos: i32` → `is_digit_pos: bool` carrier
+- CarrierRole::ConditionOnly + CarrierInit::BoolConst(false)
+- ConditionEnv alias: `digit_pos → is_digit_pos`
+
+### Current Error
+```
+Type error: unsupported compare Lt on Bool(false) and Integer(0)
+```
+
+**Root Cause**: The break condition AST still contains `digit_pos < 0`, which after alias resolution becomes `Bool(is_digit_pos) < Integer(0)`, causing a type mismatch.
+
+**Why alias isn't enough**:
+- Alias only renames the variable reference
+- The comparison operator and integer literal remain unchanged
+- Need to transform the entire expression structure
+
+## Solution
+
+### Transformation
+Transform the break condition AST from integer comparison to boolean negation:
+
+**Before**: `digit_pos < 0`
+```
+BinaryOp {
+    operator: Lt,
+    left: Var("digit_pos"),
+    right: Const(0)
+}
+```
+
+**After**: `!is_digit_pos`
+```
+UnaryOp {
+    operator: Not,
+    expr: Var("is_digit_pos")
+}
+```
+
+### Semantic Equivalence
+- `digit_pos < 0` means "indexOf() didn't find the character" (returns -1)
+- `!is_digit_pos` means "character is not a digit" (bool carrier is false)
+- Both express the same condition: "break when character not found/matched"
+
+## Design
+
+### Box: DigitPosConditionNormalizer
+
+**Responsibility**: Transform digit_pos comparison patterns to boolean carrier expressions
+
+**API**:
+```rust
+pub struct DigitPosConditionNormalizer;
+
+impl DigitPosConditionNormalizer {
+    /// Normalize digit_pos condition AST
+    ///
+    /// Transforms: `digit_pos < 0` → `!is_digit_pos`
+    ///
+    /// # Arguments
+    /// * `cond` - Break/continue condition AST
+    /// * `promoted_var` - Original variable name (e.g., "digit_pos")
+    /// * `carrier_name` - Promoted carrier name (e.g., "is_digit_pos")
+    ///
+    /// # Returns
+    /// Normalized AST (or original if pattern doesn't match)
+    pub fn normalize(
+        cond: &ASTNode,
+        promoted_var: &str,
+        carrier_name: &str,
+    ) -> ASTNode;
+}
+```
+
+### Pattern Matching Logic
+
+**Match Pattern**: `<var> < 0` where:
+1. Operator is `Lt` (Less than)
+2. Left operand is `Var(promoted_var)`
+3. Right operand is `Const(0)`
+
+**Transformation**: → `UnaryOp { op: Not, expr: Var(carrier_name) }`
+
+**Non-Match Behavior**: Return original AST unchanged (Fail-Safe)
+
+### Integration Point
+
+**Location**: `src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs`
+
+**Integration Steps**:
+1. After `LoopBodyCondPromoter::try_promote_for_condition()` succeeds
+2. Extract `promoted_var` and `carrier_name` from promotion result
+3. Apply `DigitPosConditionNormalizer::normalize()` to break condition AST
+4. Use normalized AST in subsequent condition lowering
+
+**Code Position** (around line 331):
+```rust
+ConditionPromotionResult::Promoted {
+    carrier_info: promoted_carrier,
+    promoted_var,
+    carrier_name,
+} => {
+    // ... existing merge logic ...
+
+    // Phase 224-E: Normalize digit_pos condition before lowering
+    let normalized_break_condition = DigitPosConditionNormalizer::normalize(
+        &break_condition_node,
+        &promoted_var,
+        &carrier_name,
+    );
+
+    // Use normalized_break_condition in subsequent processing
+}
+```
+
+## Testing Strategy
+
+### Unit Tests (3-4 tests)
+1. **Happy path**: `digit_pos < 0` → `!is_digit_pos`
+2. **Wrong operator**: `digit_pos >= 0` → No change
+3. **Wrong variable**: `other_var < 0` → No change
+4. **Wrong constant**: `digit_pos < 10` → No change
+
+### E2E Test
+**Test File**: `apps/tests/phase2235_p2_digit_pos_min.hako`
+
+**Success Criteria**:
+- No type error ("unsupported compare Lt on Bool and Integer")
+- Break condition correctly evaluates
+- Loop exits when digit not found
+
+**Debug Command**:
+```bash
+NYASH_JOINIR_DEBUG=1 ./target/release/hakorune apps/tests/phase2235_p2_digit_pos_min.hako
+```
+
+### Regression Tests
+- Verify existing Trim tests still pass
+- Verify skip_whitespace tests still pass
+- Check that 877/884 test count is maintained
+
+## Success Criteria
+
+1. ✅ `cargo build --release` succeeds
+2. ✅ Unit tests (3-4) pass
+3. ✅ Type error eliminated from phase2235_p2_digit_pos_min.hako
+4. ✅ Existing 877/884 tests remain passing
+5. ✅ No regressions in Trim/skip_whitespace patterns
+
+## Box-First Principles
+
+### Single Responsibility
+- DigitPosConditionNormalizer only handles AST transformation
+- No side effects, no state mutation
+- Pure pattern matching function
+
+### Fail-Safe Design
+- Non-matching patterns returned unchanged
+- No panics, no errors
+- Conservative transformation strategy
+
+### Boundary Clarity
+- Input: AST + promoted_var + carrier_name
+- Output: Transformed or original AST
+- Clear interface contract
+
+## Future Extensions
+
+**Pattern 4 Support**: When Pattern 4 (continue) needs similar normalization, the same box can be reused with continue condition AST.
+
+**Other Comparison Operators**: Currently handles `< 0`. Could extend to:
+- `>= 0` → `is_digit_pos` (no NOT)
+- `!= -1` → `is_digit_pos`
+- `== -1` → `!is_digit_pos`
+
+**Multiple Conditions**: For complex boolean expressions with multiple promoted variables, apply normalization recursively.
+
+## References
+
+- **Phase 228-8**: DigitPos promotion implementation
+- **Phase 229**: Dynamic condition variable resolution
+- **CarrierInfo**: `src/mir/join_ir/lowering/carrier_info.rs`
+- **ConditionEnv**: `src/mir/join_ir/lowering/condition_env.rs`
diff --git a/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs b/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
index 6cb0dfd5..6a8238c0 100644
--- a/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
+++ b/src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs
@@ -240,7 +240,7 @@ impl MirBuilder {
 
         // Wrap condition in UnaryOp Not if break is in else clause
         use crate::ast::UnaryOperator;
-        let break_condition_node = if break_in_else {
+        let mut break_condition_node = if break_in_else {
             // Extract span from the raw condition node (use unknown as default)
             let span = crate::ast::Span::unknown();
 
@@ -328,6 +328,21 @@ impl MirBuilder {
                                 ));
                             }
                         }
+
+                        // Phase 224-E: Normalize digit_pos condition before lowering
+                        // Transform: digit_pos < 0 → !is_digit_pos
+                        use crate::mir::join_ir::lowering::digitpos_condition_normalizer::DigitPosConditionNormalizer;
+                        break_condition_node = DigitPosConditionNormalizer::normalize(
+                            &break_condition_node,
+                            &promoted_var,
+                            &carrier_name,
+                        );
+
+                        eprintln!(
+                            "[pattern2/phase224e] Normalized break condition for promoted variable '{}' → carrier '{}'",
+                            promoted_var, carrier_name
+                        );
+
                         // Carrier promoted and merged, proceed with normal lowering
                     }
                     ConditionPromotionResult::CannotPromote { reason, vars } => {
diff --git a/src/mir/join_ir/lowering/digitpos_condition_normalizer.rs b/src/mir/join_ir/lowering/digitpos_condition_normalizer.rs
new file mode 100644
index 00000000..0ac6e10a
--- /dev/null
+++ b/src/mir/join_ir/lowering/digitpos_condition_normalizer.rs
@@ -0,0 +1,279 @@
+//! Phase 224-E: DigitPos Condition Normalizer Box
+//!
+//! Transforms digit_pos comparison patterns to boolean carrier expressions.
+//!
+//! ## Problem
+//!
+//! After DigitPosPromoter promotes `digit_pos: i32` to `is_digit_pos: bool`,
+//! the break condition AST still contains `digit_pos < 0`, which causes type errors
+//! when the alias resolves to `Bool(is_digit_pos) < Integer(0)`.
+//!
+//! ## Solution
+//!
+//! Transform the condition AST before lowering:
+//!
+//! ```text
+//! digit_pos < 0  →  !is_digit_pos
+//! ```
+//!
+//! ## Design Principles
+//!
+//! - **Single Responsibility**: Only handles AST transformation
+//! - **Fail-Safe**: Non-matching patterns returned unchanged
+//! - **Stateless**: Pure function with no side effects
+
+use crate::ast::{ASTNode, BinaryOperator, LiteralValue, UnaryOperator};
+
+/// Phase 224-E: DigitPos Condition Normalizer Box
+pub struct DigitPosConditionNormalizer;
+
+impl DigitPosConditionNormalizer {
+    /// Normalize digit_pos condition AST
+    ///
+    /// Transforms: `<promoted_var> < 0` → `!<carrier_name>`
+    ///
+    /// # Pattern Matching
+    ///
+    /// Matches:
+    /// - BinaryOp with operator Lt (Less than)
+    /// - Left operand is Var(promoted_var)
+    /// - Right operand is Const(0)
+    ///
+    /// Transforms to:
+    /// - UnaryOp { op: Not, expr: Var(carrier_name) }
+    ///
+    /// # Arguments
+    ///
+    /// * `cond` - Break/continue condition AST
+    /// * `promoted_var` - Original variable name (e.g., "digit_pos")
+    /// * `carrier_name` - Promoted carrier name (e.g., "is_digit_pos")
+    ///
+    /// # Returns
+    ///
+    /// Normalized AST (or original if pattern doesn't match)
+    ///
+    /// # Example
+    ///
+    /// ```rust,ignore
+    /// let original = parse("digit_pos < 0");
+    /// let normalized = DigitPosConditionNormalizer::normalize(
+    ///     &original,
+    ///     "digit_pos",
+    ///     "is_digit_pos",
+    /// );
+    /// // normalized is equivalent to parse("!is_digit_pos")
+    /// ```
+    pub fn normalize(cond: &ASTNode, promoted_var: &str, carrier_name: &str) -> ASTNode {
+        // Pattern: BinaryOp { op: Lt, lhs: Var(promoted_var), rhs: Const(0) }
+        match cond {
+            ASTNode::BinaryOp {
+                operator,
+                left,
+                right,
+                span,
+            } => {
+                // Check operator is Lt (Less than)
+                if *operator != BinaryOperator::Less {
+                    return cond.clone();
+                }
+
+                // Check left operand is Var(promoted_var)
+                let is_promoted_var = match left.as_ref() {
+                    ASTNode::Variable { name, .. } => name == promoted_var,
+                    _ => false,
+                };
+                if !is_promoted_var {
+                    return cond.clone();
+                }
+
+                // Check right operand is Const(0)
+                let is_zero_literal = match right.as_ref() {
+                    ASTNode::Literal {
+                        value: LiteralValue::Integer(0),
+                        ..
+                    } => true,
+                    _ => false,
+                };
+                if !is_zero_literal {
+                    return cond.clone();
+                }
+
+                // Pattern matched! Transform to !carrier_name
+                eprintln!(
+                    "[digitpos_normalizer] Transforming '{}' < 0 → !'{}'",
+                    promoted_var, carrier_name
+                );
+
+                ASTNode::UnaryOp {
+                    operator: UnaryOperator::Not,
+                    operand: Box::new(ASTNode::Variable {
+                        name: carrier_name.to_string(),
+                        span: span.clone(),
+                    }),
+                    span: span.clone(),
+                }
+            }
+            _ => {
+                // Not a binary operation, return unchanged
+                cond.clone()
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::ast::Span;
+
+    fn var_node(name: &str) -> ASTNode {
+        ASTNode::Variable {
+            name: name.to_string(),
+            span: Span::unknown(),
+        }
+    }
+
+    fn int_literal(value: i64) -> ASTNode {
+        ASTNode::Literal {
+            value: LiteralValue::Integer(value),
+            span: Span::unknown(),
+        }
+    }
+
+    fn binary_op(left: ASTNode, op: BinaryOperator, right: ASTNode) -> ASTNode {
+        ASTNode::BinaryOp {
+            operator: op,
+            left: Box::new(left),
+            right: Box::new(right),
+            span: Span::unknown(),
+        }
+    }
+
+    #[test]
+    fn test_normalize_digit_pos_lt_zero() {
+        // Pattern: digit_pos < 0
+        let cond = binary_op(
+            var_node("digit_pos"),
+            BinaryOperator::Less,
+            int_literal(0),
+        );
+
+        let normalized = DigitPosConditionNormalizer::normalize(&cond, "digit_pos", "is_digit_pos");
+
+        // Should transform to: !is_digit_pos
+        match normalized {
+            ASTNode::UnaryOp {
+                operator: UnaryOperator::Not,
+                operand,
+                ..
+            } => {
+                match operand.as_ref() {
+                    ASTNode::Variable { name, .. } => {
+                        assert_eq!(name, "is_digit_pos");
+                    }
+                    _ => panic!("Expected Variable node"),
+                }
+            }
+            _ => panic!("Expected UnaryOp Not node"),
+        }
+    }
+
+    #[test]
+    fn test_no_normalize_wrong_operator() {
+        // Pattern: digit_pos >= 0 (Greater or equal, not Less)
+        let cond = binary_op(
+            var_node("digit_pos"),
+            BinaryOperator::GreaterEqual,
+            int_literal(0),
+        );
+
+        let normalized = DigitPosConditionNormalizer::normalize(&cond, "digit_pos", "is_digit_pos");
+
+        // Should NOT transform (return original)
+        match normalized {
+            ASTNode::BinaryOp { operator, .. } => {
+                assert_eq!(operator, BinaryOperator::GreaterEqual);
+            }
+            _ => panic!("Expected unchanged BinaryOp node"),
+        }
+    }
+
+    #[test]
+    fn test_no_normalize_wrong_variable() {
+        // Pattern: other_var < 0 (different variable name)
+        let cond = binary_op(
+            var_node("other_var"),
+            BinaryOperator::Less,
+            int_literal(0),
+        );
+
+        let normalized = DigitPosConditionNormalizer::normalize(&cond, "digit_pos", "is_digit_pos");
+
+        // Should NOT transform (return original)
+        match normalized {
+            ASTNode::BinaryOp {
+                operator,
+                left,
+                ..
+            } => {
+                assert_eq!(operator, BinaryOperator::Less);
+                match left.as_ref() {
+                    ASTNode::Variable { name, .. } => {
+                        assert_eq!(name, "other_var");
+                    }
+                    _ => panic!("Expected Variable node"),
+                }
+            }
+            _ => panic!("Expected unchanged BinaryOp node"),
+        }
+    }
+
+    #[test]
+    fn test_no_normalize_wrong_constant() {
+        // Pattern: digit_pos < 10 (different constant, not 0)
+        let cond = binary_op(
+            var_node("digit_pos"),
+            BinaryOperator::Less,
+            int_literal(10),
+        );
+
+        let normalized = DigitPosConditionNormalizer::normalize(&cond, "digit_pos", "is_digit_pos");
+
+        // Should NOT transform (return original)
+        match normalized {
+            ASTNode::BinaryOp {
+                operator,
+                right,
+                ..
+            } => {
+                assert_eq!(operator, BinaryOperator::Less);
+                match right.as_ref() {
+                    ASTNode::Literal {
+                        value: LiteralValue::Integer(val),
+                        ..
+                    } => {
+                        assert_eq!(*val, 10);
+                    }
+                    _ => panic!("Expected Integer literal"),
+                }
+            }
+            _ => panic!("Expected unchanged BinaryOp node"),
+        }
+    }
+
+    #[test]
+    fn test_no_normalize_non_binary_op() {
+        // Pattern: just a variable (not a binary operation)
+        let cond = var_node("digit_pos");
+
+        let normalized = DigitPosConditionNormalizer::normalize(&cond, "digit_pos", "is_digit_pos");
+
+        // Should NOT transform (return original)
+        match normalized {
+            ASTNode::Variable { name, .. } => {
+                assert_eq!(name, "digit_pos");
+            }
+            _ => panic!("Expected unchanged Variable node"),
+        }
+    }
+}
diff --git a/src/mir/join_ir/lowering/mod.rs b/src/mir/join_ir/lowering/mod.rs
index 158d5f72..487e3ce8 100644
--- a/src/mir/join_ir/lowering/mod.rs
+++ b/src/mir/join_ir/lowering/mod.rs
@@ -24,6 +24,7 @@ pub mod carrier_info; // Phase 196: Carrier metadata for loop lowering
 pub(crate) mod carrier_update_emitter; // Phase 179: Carrier update instruction emission
 pub(crate) mod common; // Internal lowering utilities
 pub mod complex_addend_normalizer; // Phase 192: Complex addend normalization (AST preprocessing)
+pub mod digitpos_condition_normalizer; // Phase 224-E: DigitPos condition normalizer (digit_pos < 0 → !is_digit_pos)
 pub mod condition_env; // Phase 171-fix: Condition expression environment
 pub mod condition_pattern; // Phase 219-fix: If condition pattern detection (simple vs complex)
 pub mod loop_body_local_env; // Phase 184: Body-local variable environment