diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index e0fa1f52..f9f93d57 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -230,7 +230,7 @@
 14. **Phase 57-OWNERSHIP-ANALYZER-DEV（完了✅ 2025-12-12）**: OwnershipPlan を生成する解析箱の実装
    - `OwnershipAnalyzer` を追加し、ネスト含む reads/writes/owned を集計→ carriers/relay/captures を plan 化。
    - 既存 fixtures（pattern2/3, jsonparser, selfhost）で plan の回帰テストを追加。
-   - 設計詳細: [phase57-ownership-analyzer.md](docs/development/current/main/phase57-ownership-analyzer.md)
+   - 設計詳細: [PHASE_57_SUMMARY.md](docs/development/current/main/PHASE_57_SUMMARY.md)
 15. **Phase 58-OWNERSHIP-PLUMB-P2-DEV（完了✅ 2025-12-12）**: P2 conversion helper (dev-only)
    - `plan_to_p2_inputs()` でOwnershipPlan→P2LoweringInputs変換
    - Fail-Fast: relay_writes 未対応（Phase 60で対応予定）
@@ -242,10 +242,19 @@
    - Fail-Fast: relay_writes 未対応（Phase 60で対応予定）
    - 4つのユニットテスト + 2つのintegrationテスト
    - 設計詳細: [PHASE_59_SUMMARY.md](docs/development/current/main/PHASE_59_SUMMARY.md)
-17. **Phase 60-OWNERSHIP-RELAY-IMPL（次のフォーカス候補）**: Relay support for P2/P3
-   - relay_writes対応実装
-   - P2/P3両方の変換器に統合
-18. JoinIR Verify / 最適化まわり
+17. **Phase 60-OWNERSHIP-RELAY-IMPL（完了✅ 2025-12-12）**: Relay support for P2/P3 (dev-only)
+   - `plan_to_p2_inputs_with_relay()` / `plan_to_p3_inputs_with_relay()` を追加（単一hopのみ許可、multi-hopはFail-Fast）
+   - P2 Break lowering を dev-only で ownership-with-relay に接続し、legacy 経路との VM 出力一致を比較テストで固定。
+   - shape_guard の selfhost family 分離を最小更新（selfhost shapes 優先時の混線を遮断）。
+18. **Phase 61-IFSUM-BREAK-STRUCTURAL（完了✅ 2025-12-12）**: if-sum + break を別箱で構造的に導入（dev-only）
+   - Break(P2) から P3 固有ロジック（by-name）を撤去し、責務混線を解消。
+   - 新箱 `if_sum_break_pattern` を追加し、`return Var+Var` を含む if-sum+break を構造判定→Fail-Fast で lowering。
+   - OwnershipPlan を param order/carriers の SSOT に使い、carriers!=return vars の混線を遮断。
+   - 詳細: [PHASE_61_SUMMARY.md](docs/development/current/main/PHASE_61_SUMMARY.md)
+19. **Phase 62-OWNERSHIP-P3-ROUTE-DESIGN（次のフォーカス候補）**: P3 本番ルートへ OwnershipPlan を渡す設計
+   - MIR→JoinIR の `pattern3_with_if_phi.rs` は OwnershipPlan を受け取らないため、AST-based ownership 解析の接続点を設計する。
+   - dev-only で段階接続し、legacy と stdout/exit 一致の比較で回帰を固定（既定挙動は不変）。
+20. JoinIR Verify / 最適化まわり
    - すでに PHI/ValueId 契約は debug ビルドで検証しているので、
      必要なら SSA‑DFA や軽い最適化（Loop invariant / Strength reduction）を検討。
 
diff --git a/docs/development/current/main/PHASE_61_SUMMARY.md b/docs/development/current/main/PHASE_61_SUMMARY.md
new file mode 100644
index 00000000..f787eff9
--- /dev/null
+++ b/docs/development/current/main/PHASE_61_SUMMARY.md
@@ -0,0 +1,56 @@
+# Phase 61 Summary: IF-SUM + BREAK (dev-only, structural)
+
+## Goal
+
+Phase 61 は「Break(P2) に P3 固有ロジックを混ぜない」を達成しつつ、selfhost の `if-sum + break` 形状を **by-name なし**で JoinIR Frontend に載せる。
+
+## Problem (Phase 61 前)
+
+- `break_pattern.rs`（Break/P2 箱）の param-order 決定で、`selfhost_if_sum_p3*` を名指しして P3 helper を優先する案は、
+  - 責務混線（Break 箱が P3(if-sum) の意味論まで背負う）
+  - dev-only でも撤去困難な by-name 分岐になりやすい
+  という理由で採用しない。
+
+## Solution (Phase 61)
+
+### 1) Break(P2) を構造ベースに戻す
+
+- `src/mir/join_ir/frontend/ast_lowerer/loop_patterns/break_pattern.rs`
+  - Break(P2) の ownership 経路は `plan_to_p2_inputs_with_relay` のみを使用し、P3 専用分岐を排除する。
+
+### 2) 新箱 `if_sum_break_pattern` を追加（dev-only）
+
+- `src/mir/join_ir/frontend/ast_lowerer/loop_patterns/if_sum_break_pattern.rs`
+  - 対象: `break-if + update-if + counter-update + return Var+Var`
+  - 検出は構造のみ（by-name なし）。
+  - lowering は Select ベースで `sum`/`count` を更新し、exit では `sum + count` を 1 値にして `k_exit` に渡す。
+
+### 3) Ownership を SSOT に使う（param order / carriers）
+
+- `OwnershipAnalyzer` → `plan_to_p3_inputs_with_relay` で carriers/captures を得る。
+- Fail-Fast: carriers が Return の 2 変数と一致しない場合は拒否（canonical P3 群との混線防止）。
+- relay は単一hopのみ許可（multi-hop は Fail-Fast 維持）。
+
+## Fail-Fast Contract
+
+- Return が `Var + Var` 以外なら対象外。
+- loop body が `[break-if, update-if, counter-update]` の最小形状から外れるなら対象外。
+- counter update が `i = i + 1` 形で検出できないなら Err。
+- relay_path.len() > 1 は Err。
+- carriers != return vars は Err。
+
+## Tests
+
+- `tests/normalized_joinir_min.rs`
+  - selfhost P3 fixture を Program(JSON v0) として解析し、relay_writes→carriers 変換が成立することを固定。
+  - selfhost P3（NormalizedDev 経路）については stdout/exit + 期待値（意味論）で固定し、比較テスト依存を避ける。
+
+## Notes (Reproducibility)
+
+- `docs/private` は submodule のため、fixture JSON を参照する場合は **submodule 側で追跡されていること**を前提とする。
+  - 未追跡のままローカルだけで存在すると、clean checkout で `include_str!` が壊れる。
+
+## Next Candidates
+
+- Phase 62: P3(if-sum) の「本番 MIR→JoinIR ルート」へ OwnershipPlan を渡す設計（AST-based ownership 解析の接続点を設計 → dev-only で段階接続）。
+- Phase 63+: multi-hop / merge relay の意味論設計（Fail-Fast を解除する前に SSOT と不変条件を明文化）。
diff --git a/docs/development/current/main/phase56-ownership-relay-design.md b/docs/development/current/main/phase56-ownership-relay-design.md
index 80006f30..7cbee573 100644
--- a/docs/development/current/main/phase56-ownership-relay-design.md
+++ b/docs/development/current/main/phase56-ownership-relay-design.md
@@ -138,8 +138,11 @@ pub struct OwnershipPlan {
 - **Phase 57**: OwnershipAnalyzer implementation (dev-only)
 - **Phase 58**: P2 plumbing (dev-only)
 - **Phase 59**: P3 plumbing (dev-only)
-- **Phase 60**: Cleanup dev heuristics
-- **Phase 61**: Canonical promotion decision
+- **Phase 60**: Single-hop relay threading for fixtures (dev-only)
+- **Phase 61**: P3 側の接続点を決めて段階接続（dev-only）
+  - まずは fixtures ルート（Program(JSON v0)）で、if-sum+break を別箱として構造的に接続する
+  - 詳細: `docs/development/current/main/PHASE_61_SUMMARY.md`
+  - MIR→JoinIR の本番ルート（`pattern3_with_if_phi.rs`）へ寄せるのは別フェーズで設計→接続
 
 ## Module Boundary
 
@@ -244,6 +247,13 @@ loop {
 
 ### Implementation Details
 
+**Input JSON Compatibility**:
+- テスト用の簡易スキーマ: top-level `functions` + stmt/expr の `kind` を解釈
+- Program(JSON v0): top-level `defs` + stmt/expr の `type` を解釈
+- `Local` は JSON v0 で「新規束縛」と「rebind/update」が混在し得るため、
+  解析では「scope chain で既に定義済みなら write / 未定義なら define」として扱う（dev-only 前提）。
+  - Note: `docs/private` は submodule のため、fixture JSON を参照する場合は submodule 側で追跡されていることを前提とする。
+
 **Body-Local Ownership Rule**:
 ```rust
 // Example: local in if/block → enclosing loop owns it
@@ -267,5 +277,9 @@ loop {
 ## Status
 
 - ✅ Phase 56: Design + interface skeleton completed
-- ✅ Phase 57: Analyzer implemented (dev-only, not connected to lowering yet)
-- ⏳ Phase 58+: Plumbing integration pending
+- ✅ Phase 57: Analyzer implemented (dev-only)
+- ✅ Phase 58-59: plan_to_lowering helpers (P2/P3) with Fail-Fast relay
+- ✅ Phase 60 (dev-only): single-hop relay threading for P2 fixtures
+  - `plan_to_p2_inputs_with_relay` promotes relay_writes to carriers (relay_path.len()<=1 only)
+  - Frontend Break(P2) lowering uses ownership-with-relay; legacy path preserved for comparison
+  - P3 stays analysis-only; real threading is Phase 61+
diff --git a/docs/private b/docs/private
index 1e76c99f..00e3e637 160000
--- a/docs/private
+++ b/docs/private
@@ -1 +1 @@
-Subproject commit 1e76c99f441fca6fab7ec6cda97773f5f3aa9361
+Subproject commit 00e3e63780ecccd5e8c9a4773f07c54629431eb8
diff --git a/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/break_pattern.rs b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/break_pattern.rs
index a36793ea..f89a2cbe 100644
--- a/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/break_pattern.rs
+++ b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/break_pattern.rs
@@ -25,10 +25,17 @@ use super::common::{
     process_local_inits,
 };
 use super::param_guess::{build_param_order, compute_param_guess};
+#[cfg(feature = "normalized_dev")]
+use super::if_sum_break_pattern;
 use super::{AstToJoinIrLowerer, JoinModule, LoweringError};
 use crate::mir::join_ir::{JoinFunction, JoinInst};
 use crate::mir::ValueId;
 
+#[cfg(feature = "normalized_dev")]
+use crate::mir::join_ir::ownership::{
+    plan_to_p2_inputs_with_relay, OwnershipAnalyzer,
+};
+
 /// Break パターンを JoinModule に変換
 ///
 /// # Arguments
@@ -37,6 +44,26 @@ use crate::mir::ValueId;
 pub fn lower(
     lowerer: &mut AstToJoinIrLowerer,
     program_json: &serde_json::Value,
+) -> Result<JoinModule, LoweringError> {
+    #[cfg(feature = "normalized_dev")]
+    {
+        if let Some(module) = if_sum_break_pattern::try_lower_if_sum_break(lowerer, program_json)? {
+            return Ok(module);
+        }
+        if let Ok(module) = lower_with_ownership_relay(lowerer, program_json) {
+            return Ok(module);
+        }
+    }
+
+    lower_legacy_param_guess(lowerer, program_json)
+}
+
+/// Legacy Break lowering (Phase P4) using param_guess heuristics.
+///
+/// This remains as a fallback and is also used for Phase 60 comparison tests.
+fn lower_legacy_param_guess(
+    lowerer: &mut AstToJoinIrLowerer,
+    program_json: &serde_json::Value,
 ) -> Result<JoinModule, LoweringError> {
     // 1. Program(JSON) をパース
     let parsed = parse_program_json(program_json);
@@ -101,6 +128,136 @@ pub fn lower(
     Ok(build_join_module(entry_func, loop_step_func, k_exit_func))
 }
 
+/// Phase 60 dev-only Break lowering using OwnershipAnalyzer + relay threading.
+///
+/// This function is only compiled with `normalized_dev` and is fail-fast on
+/// multi-hop relay (relay_path.len()>1).
+#[cfg(feature = "normalized_dev")]
+fn lower_with_ownership_relay(
+    lowerer: &mut AstToJoinIrLowerer,
+    program_json: &serde_json::Value,
+) -> Result<JoinModule, LoweringError> {
+    // Parse and build contexts similarly to legacy path.
+    let parsed = parse_program_json(program_json);
+    let (ctx, mut entry_ctx) = create_loop_context(lowerer, &parsed);
+    let init_insts = process_local_inits(lowerer, &parsed, &mut entry_ctx);
+
+    let loop_node = &parsed.stmts[parsed.loop_node_idx];
+    let loop_body = loop_node["body"]
+        .as_array()
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "Loop must have 'body' array".to_string(),
+        })?;
+
+    let (break_if_idx, break_if_stmt) = loop_body
+        .iter()
+        .enumerate()
+        .find(|(_, stmt)| {
+            stmt["type"].as_str() == Some("If")
+                && stmt["then"].as_array().map_or(false, |then| {
+                    then.iter().any(|s| s["type"].as_str() == Some("Break"))
+                })
+        })
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "Break pattern must have If + Break".to_string(),
+        })?;
+
+    let break_cond_expr = &break_if_stmt["cond"];
+    let loop_cond_expr = &loop_node["cond"];
+
+    // Use legacy guess only to stabilize loop_var/acc names.
+    let legacy_guess = compute_param_guess(&entry_ctx);
+    let loop_var_name = legacy_guess.loop_var.0.clone();
+    let acc_name = legacy_guess.acc.0.clone();
+
+    let param_order = compute_param_order_from_ownership(program_json, &entry_ctx, &loop_var_name)
+        .unwrap_or_else(|| build_param_order(&legacy_guess, &entry_ctx));
+
+    // Ensure accumulator is present in param list (avoid missing carrier ordering).
+    let mut param_order = param_order;
+    if !param_order.iter().any(|(n, _)| n == &acc_name) {
+        if let Some(id) = entry_ctx.get_var(&acc_name) {
+            param_order.push((acc_name.clone(), id));
+        }
+    }
+
+    let entry_func =
+        create_entry_function_break(&ctx, &parsed, init_insts, &mut entry_ctx, &param_order);
+
+    let loop_step_func = create_loop_step_function_break(
+        lowerer,
+        &ctx,
+        &parsed.func_name,
+        loop_cond_expr,
+        break_cond_expr,
+        loop_body,
+        &param_order,
+        &loop_var_name,
+        &acc_name,
+        break_if_idx,
+    )?;
+
+    let k_exit_func = create_k_exit_function(&ctx, &parsed.func_name);
+    Ok(build_join_module(entry_func, loop_step_func, k_exit_func))
+}
+
+#[cfg(feature = "normalized_dev")]
+fn compute_param_order_from_ownership(
+    program_json: &serde_json::Value,
+    entry_ctx: &super::super::context::ExtractCtx,
+    loop_var_name: &str,
+) -> Option<Vec<(String, ValueId)>> {
+    let mut analyzer = OwnershipAnalyzer::new();
+    let plans = analyzer.analyze_json(program_json).ok()?;
+
+    let loop_plan = plans
+        .iter()
+        // Prefer the actual loop scope (loop var is re-bound inside loop => relay_writes)
+        .find(|p| p.relay_writes.iter().any(|r| r.name == loop_var_name))
+        // Fallback: any loop plan with relay_writes
+        .or_else(|| plans.iter().find(|p| !p.relay_writes.is_empty()))
+        // Last resort: any plan that owns loop_var_name (loop-local case)
+        .or_else(|| plans.iter().find(|p| p.owned_vars.iter().any(|v| v.name == loop_var_name)))?;
+
+    let inputs = plan_to_p2_inputs_with_relay(loop_plan, loop_var_name).ok()?;
+
+    let mut order: Vec<(String, ValueId)> = Vec::new();
+    let mut seen = std::collections::BTreeSet::<String>::new();
+
+    if let Some(id) = entry_ctx.get_var(loop_var_name) {
+        order.push((loop_var_name.to_string(), id));
+        seen.insert(loop_var_name.to_string());
+    }
+
+    for carrier in inputs.carriers {
+        if seen.contains(&carrier.name) {
+            continue;
+        }
+        if let Some(id) = entry_ctx.get_var(&carrier.name) {
+            order.push((carrier.name.clone(), id));
+            seen.insert(carrier.name);
+        }
+    }
+
+    for (name, var_id) in &entry_ctx.var_map {
+        if !seen.contains(name) {
+            order.push((name.clone(), *var_id));
+            seen.insert(name.clone());
+        }
+    }
+
+    Some(order)
+}
+
+/// Expose legacy Break lowering for Phase 60 comparison tests (dev-only).
+#[cfg(feature = "normalized_dev")]
+pub fn lower_break_legacy_for_comparison(
+    lowerer: &mut AstToJoinIrLowerer,
+    program_json: &serde_json::Value,
+) -> Result<JoinModule, LoweringError> {
+    lower_legacy_param_guess(lowerer, program_json)
+}
+
 /// Break パターン用 entry 関数を生成
 fn create_entry_function_break(
     ctx: &super::common::LoopContext,
diff --git a/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/if_sum_break_pattern.rs b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/if_sum_break_pattern.rs
new file mode 100644
index 00000000..9f9f4663
--- /dev/null
+++ b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/if_sum_break_pattern.rs
@@ -0,0 +1,503 @@
+//! Phase 61: If-Sum + Break pattern (dev-only)
+//!
+//! ## Responsibility
+//! Break 付き if-sum ループを、sum/count の複数キャリアで k_exit に渡し、
+//! k_exit で `sum + count` を返す。
+//!
+//! ## Fail-Fast Boundary
+//! - Return が `Var + Var` 以外 → not matched
+//! - ループ末尾の counter update が `i = i + 1` 形で検出できない → Err
+//! - Ownership relay が single-hop 以外 → Err
+//! - loop-carried carriers が Return の 2 変数と一致しない → Err
+
+#![cfg(feature = "normalized_dev")]
+
+use super::common::{
+    build_join_module, create_k_exit_function, create_loop_context, parse_program_json,
+    process_local_inits,
+};
+use super::{AstToJoinIrLowerer, JoinModule, LoweringError};
+use crate::mir::join_ir::{BinOpKind, JoinFunction, JoinInst, MirLikeInst};
+use crate::mir::ValueId;
+use crate::mir::join_ir::ownership::{plan_to_p3_inputs_with_relay, OwnershipAnalyzer};
+
+pub fn try_lower_if_sum_break(
+    lowerer: &mut AstToJoinIrLowerer,
+    program_json: &serde_json::Value,
+) -> Result<Option<JoinModule>, LoweringError> {
+    let parsed = parse_program_json(program_json);
+
+    let return_expr = parsed.stmts.last().and_then(|s| {
+        if s["type"].as_str() == Some("Return") {
+            s.get("expr")
+        } else {
+            None
+        }
+    });
+
+    let Some((ret_lhs, ret_rhs)) = parse_return_var_plus_var(return_expr) else {
+        return Ok(None);
+    };
+
+    let loop_node = &parsed.stmts[parsed.loop_node_idx];
+    let loop_body = loop_node["body"]
+        .as_array()
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "Loop must have 'body' array".to_string(),
+        })?;
+
+    let (break_if_idx, break_if_stmt) = match find_break_if(loop_body) {
+        Some(v) => v,
+        None => return Ok(None),
+    };
+    if break_if_idx != 0 {
+        return Ok(None);
+    }
+    let break_cond_expr = &break_if_stmt["cond"];
+
+    // Limit scope (Phase 61 dev-only): [break-if, update-if, counter-update] only.
+    if loop_body.len() != 3 {
+        return Ok(None);
+    }
+
+    let update_if_stmt = match find_single_update_if(loop_body, break_if_idx) {
+        Some(v) => v,
+        None => return Ok(None),
+    };
+
+    let counter_update_stmt = loop_body
+        .last()
+        .expect("loop_body len checked")
+        .clone();
+
+    let loop_var_name = detect_counter_update_loop_var(loop_body).ok_or_else(|| {
+        LoweringError::InvalidLoopBody {
+            message: "if-sum-break requires trailing counter update like i = i + 1".to_string(),
+        }
+    })?;
+
+    if ret_lhs == loop_var_name || ret_rhs == loop_var_name || ret_lhs == ret_rhs {
+        return Ok(None);
+    }
+
+    // === Ownership SSOT: param order = [loop_var] + carriers + captures ===
+    let (ctx, mut entry_ctx) = create_loop_context(lowerer, &parsed);
+    let init_insts = process_local_inits(lowerer, &parsed, &mut entry_ctx);
+
+    let mut analyzer = OwnershipAnalyzer::new();
+    let plans = analyzer
+        .analyze_json(program_json)
+        .map_err(|e| LoweringError::JsonParseError { message: e })?;
+
+    let loop_plan = plans
+        .iter()
+        .find(|p| p.relay_writes.iter().any(|r| r.name == loop_var_name))
+        .or_else(|| plans.iter().find(|p| p.owned_vars.iter().any(|v| v.name == loop_var_name)))
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "if-sum-break: failed to find loop ownership plan".to_string(),
+        })?;
+
+    let inputs = plan_to_p3_inputs_with_relay(loop_plan, &loop_var_name).map_err(|e| {
+        LoweringError::JsonParseError { message: e }
+    })?;
+
+    // Ensure carriers are exactly the return vars (fail-fast mixing protection).
+    let carrier_names: std::collections::BTreeSet<String> =
+        inputs.carriers.iter().map(|c| c.name.clone()).collect();
+    let expected: std::collections::BTreeSet<String> =
+        [ret_lhs.clone(), ret_rhs.clone()].into_iter().collect();
+
+    if carrier_names != expected {
+        return Err(LoweringError::InvalidLoopBody {
+            message: format!(
+                "if-sum-break: carriers {:?} must equal return vars {:?}",
+                carrier_names, expected
+            ),
+        });
+    }
+
+    let mut param_order: Vec<(String, ValueId)> = Vec::new();
+    let mut seen = std::collections::BTreeSet::<String>::new();
+
+    let loop_var_id = entry_ctx
+        .get_var(&loop_var_name)
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: format!("loop var '{}' must be initialized before loop", loop_var_name),
+        })?;
+    param_order.push((loop_var_name.clone(), loop_var_id));
+    seen.insert(loop_var_name.clone());
+
+    for carrier in &inputs.carriers {
+        let id = entry_ctx
+            .get_var(&carrier.name)
+            .ok_or_else(|| LoweringError::InvalidLoopBody {
+                message: format!("carrier '{}' must be initialized before loop", carrier.name),
+            })?;
+        param_order.push((carrier.name.clone(), id));
+        seen.insert(carrier.name.clone());
+    }
+
+    for cap_name in &inputs.captures {
+        if seen.contains(cap_name) {
+            continue;
+        }
+        if let Some(id) = entry_ctx.get_var(cap_name) {
+            param_order.push((cap_name.clone(), id));
+            seen.insert(cap_name.clone());
+        }
+    }
+
+    // Include remaining params/vars deterministically
+    for (name, var_id) in &entry_ctx.var_map {
+        if !seen.contains(name) {
+            param_order.push((name.clone(), *var_id));
+            seen.insert(name.clone());
+        }
+    }
+
+    let entry_func = create_entry_function_if_sum_break(
+        &ctx,
+        &parsed,
+        init_insts,
+        &mut entry_ctx,
+        &param_order,
+    );
+
+    let loop_step_func = create_loop_step_function_if_sum_break(
+        lowerer,
+        &ctx,
+        &parsed.func_name,
+        &loop_node["cond"],
+        break_cond_expr,
+        update_if_stmt,
+        &counter_update_stmt,
+        &param_order,
+        &loop_var_name,
+        &ret_lhs,
+        &ret_rhs,
+    )?;
+
+    let k_exit_func = create_k_exit_function(&ctx, &parsed.func_name);
+
+    Ok(Some(build_join_module(entry_func, loop_step_func, k_exit_func)))
+}
+
+fn parse_return_var_plus_var(
+    expr: Option<&serde_json::Value>,
+) -> Option<(String, String)> {
+    let expr = expr?;
+    if expr["type"].as_str()? != "Binary" {
+        return None;
+    }
+    if expr["op"].as_str()? != "+" {
+        return None;
+    }
+    let lhs = expr["lhs"].as_object()?;
+    let rhs = expr["rhs"].as_object()?;
+    if lhs.get("type")?.as_str()? != "Var" || rhs.get("type")?.as_str()? != "Var" {
+        return None;
+    }
+    Some((
+        lhs.get("name")?.as_str()?.to_string(),
+        rhs.get("name")?.as_str()?.to_string(),
+    ))
+}
+
+fn find_break_if(loop_body: &[serde_json::Value]) -> Option<(usize, &serde_json::Value)> {
+    loop_body.iter().enumerate().find(|(_, stmt)| {
+        stmt["type"].as_str() == Some("If")
+            && stmt["then"].as_array().map_or(false, |then| {
+                then.iter().any(|s| s["type"].as_str() == Some("Break"))
+            })
+    })
+}
+
+fn detect_counter_update_loop_var(loop_body: &[serde_json::Value]) -> Option<String> {
+    let last = loop_body.last()?;
+    if last["type"].as_str()? != "Local" {
+        return None;
+    }
+    let name = last["name"].as_str()?.to_string();
+    let expr = last.get("expr")?;
+    if expr["type"].as_str()? != "Binary" || expr["op"].as_str()? != "+" {
+        return None;
+    }
+    let lhs = &expr["lhs"];
+    let rhs = &expr["rhs"];
+    if lhs["type"].as_str()? != "Var" || lhs["name"].as_str()? != name {
+        return None;
+    }
+    if rhs["type"].as_str()? != "Int" || rhs["value"].as_i64()? != 1 {
+        return None;
+    }
+    Some(name)
+}
+
+fn create_entry_function_if_sum_break(
+    ctx: &super::common::LoopContext,
+    parsed: &super::common::ParsedProgram,
+    init_insts: Vec<JoinInst>,
+    entry_ctx: &mut super::super::context::ExtractCtx,
+    param_order: &[(String, ValueId)],
+) -> JoinFunction {
+    let loop_args: Vec<ValueId> = param_order.iter().map(|(_, id)| *id).collect();
+    let loop_result = entry_ctx.alloc_var();
+    let mut body = init_insts;
+    body.push(JoinInst::Call {
+        func: ctx.loop_step_id,
+        args: loop_args,
+        k_next: None,
+        dst: Some(loop_result),
+    });
+    body.push(JoinInst::Ret {
+        value: Some(loop_result),
+    });
+    JoinFunction {
+        id: ctx.entry_id,
+        name: parsed.func_name.clone(),
+        params: (0..parsed.param_names.len())
+            .map(|i| ValueId(i as u32))
+            .collect(),
+        body,
+        exit_cont: None,
+    }
+}
+
+fn create_loop_step_function_if_sum_break(
+    lowerer: &mut AstToJoinIrLowerer,
+    ctx: &super::common::LoopContext,
+    func_name: &str,
+    loop_cond_expr: &serde_json::Value,
+    break_cond_expr: &serde_json::Value,
+    update_if_stmt: &serde_json::Value,
+    counter_update_stmt: &serde_json::Value,
+    param_order: &[(String, ValueId)],
+    loop_var_name: &str,
+    sum_name: &str,
+    count_name: &str,
+) -> Result<JoinFunction, LoweringError> {
+    use super::super::context::ExtractCtx;
+
+    let param_names: Vec<String> = param_order.iter().map(|(name, _)| name.clone()).collect();
+    let mut step_ctx = ExtractCtx::new(param_names.len() as u32);
+    for (idx, name) in param_names.iter().enumerate() {
+        step_ctx.register_param(name.clone(), ValueId(idx as u32));
+    }
+
+    let mut body = Vec::new();
+
+    // Header condition: if !loop_cond -> exit with (sum, count)
+    let (loop_cond_var, loop_cond_insts) = lowerer.extract_value(loop_cond_expr, &mut step_ctx);
+    body.extend(loop_cond_insts);
+    let header_exit_flag = step_ctx.alloc_var();
+    body.push(JoinInst::Compute(MirLikeInst::UnaryOp {
+        dst: header_exit_flag,
+        op: crate::mir::join_ir::UnaryOp::Not,
+        operand: loop_cond_var,
+    }));
+    let sum_before = step_ctx
+        .get_var(sum_name)
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: format!("{} must exist", sum_name),
+        })?;
+    let count_before = step_ctx
+        .get_var(count_name)
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: format!("{} must exist", count_name),
+        })?;
+    let acc_before = step_ctx.alloc_var();
+    body.push(JoinInst::Compute(MirLikeInst::BinOp {
+        dst: acc_before,
+        op: BinOpKind::Add,
+        lhs: sum_before,
+        rhs: count_before,
+    }));
+    body.push(JoinInst::Jump {
+        cont: ctx.k_exit_id.as_cont(),
+        args: vec![acc_before],
+        cond: Some(header_exit_flag),
+    });
+
+    // Break condition: if break_cond -> exit with (sum, count)
+    let (break_cond_var, break_cond_insts) = lowerer.extract_value(break_cond_expr, &mut step_ctx);
+    body.extend(break_cond_insts);
+    body.push(JoinInst::Jump {
+        cont: ctx.k_exit_id.as_cont(),
+        args: vec![acc_before],
+        cond: Some(break_cond_var),
+    });
+
+    // Update-if: cond ? then_update : else_update (Select-based, no if-in-loop lowering)
+    let update_cond_expr = &update_if_stmt["cond"];
+    let (update_cond_var, update_cond_insts) =
+        lowerer.extract_value(update_cond_expr, &mut step_ctx);
+    body.extend(update_cond_insts);
+
+    let (sum_then_expr, sum_else_expr) =
+        extract_if_branch_assignment(update_if_stmt, sum_name)?;
+    let (count_then_expr, count_else_expr) =
+        extract_if_branch_assignment(update_if_stmt, count_name)?;
+
+    let (sum_then_val, sum_then_insts) =
+        lowerer.extract_value(&sum_then_expr, &mut step_ctx);
+    let (sum_else_val, sum_else_insts) =
+        lowerer.extract_value(&sum_else_expr, &mut step_ctx);
+    let (count_then_val, count_then_insts) =
+        lowerer.extract_value(&count_then_expr, &mut step_ctx);
+    let (count_else_val, count_else_insts) =
+        lowerer.extract_value(&count_else_expr, &mut step_ctx);
+    body.extend(sum_then_insts);
+    body.extend(sum_else_insts);
+    body.extend(count_then_insts);
+    body.extend(count_else_insts);
+
+    let sum_next = step_ctx.alloc_var();
+    body.push(JoinInst::Compute(MirLikeInst::Select {
+        dst: sum_next,
+        cond: update_cond_var,
+        then_val: sum_then_val,
+        else_val: sum_else_val,
+    }));
+    step_ctx.register_param(sum_name.to_string(), sum_next);
+
+    let count_next = step_ctx.alloc_var();
+    body.push(JoinInst::Compute(MirLikeInst::Select {
+        dst: count_next,
+        cond: update_cond_var,
+        then_val: count_then_val,
+        else_val: count_else_val,
+    }));
+    step_ctx.register_param(count_name.to_string(), count_next);
+
+    // Counter update (must update loop var)
+    let counter_expr = counter_update_stmt.get("expr").ok_or_else(|| {
+        LoweringError::InvalidLoopBody {
+            message: "counter update must have 'expr'".to_string(),
+        }
+    })?;
+    let (i_next, i_insts) = lowerer.extract_value(counter_expr, &mut step_ctx);
+    body.extend(i_insts);
+    step_ctx.register_param(loop_var_name.to_string(), i_next);
+
+    // Recurse with updated params.
+    let recurse_result = step_ctx.alloc_var();
+    let mut recurse_args = Vec::new();
+    for name in &param_names {
+        let arg = step_ctx
+            .get_var(name)
+            .unwrap_or_else(|| panic!("param {} must exist", name));
+        recurse_args.push(arg);
+    }
+    body.push(JoinInst::Call {
+        func: ctx.loop_step_id,
+        args: recurse_args,
+        k_next: None,
+        dst: Some(recurse_result),
+    });
+    body.push(JoinInst::Ret {
+        value: Some(recurse_result),
+    });
+
+    Ok(JoinFunction {
+        id: ctx.loop_step_id,
+        name: format!("{}_loop_step", func_name),
+        params: (0..param_names.len())
+            .map(|i| ValueId(i as u32))
+            .collect(),
+        body,
+        exit_cont: None,
+    })
+}
+
+fn find_single_update_if<'a>(
+    loop_body: &'a [serde_json::Value],
+    break_if_idx: usize,
+) -> Option<&'a serde_json::Value> {
+    let mut found: Option<&serde_json::Value> = None;
+    for (idx, stmt) in loop_body.iter().enumerate() {
+        if idx == break_if_idx {
+            continue;
+        }
+        if stmt["type"].as_str() == Some("If") {
+            if found.is_some() {
+                return None;
+            }
+            found = Some(stmt);
+        }
+    }
+    found
+}
+
+fn extract_if_branch_assignment(
+    if_stmt: &serde_json::Value,
+    target: &str,
+) -> Result<(serde_json::Value, serde_json::Value), LoweringError> {
+    fn find_assignment_expr(branch: &[serde_json::Value], target: &str) -> Result<Option<serde_json::Value>, LoweringError> {
+        let mut found: Option<serde_json::Value> = None;
+        for stmt in branch {
+            match stmt["type"].as_str() {
+                Some("Local") => {
+                    let name = stmt["name"].as_str().ok_or_else(|| LoweringError::InvalidLoopBody {
+                        message: "Local must have 'name'".to_string(),
+                    })?;
+                    if name != target {
+                        continue;
+                    }
+                    if found.is_some() {
+                        return Err(LoweringError::InvalidLoopBody {
+                            message: format!("if-sum-break: multiple assignments to '{}'", target),
+                        });
+                    }
+                    let expr = stmt.get("expr").ok_or_else(|| LoweringError::InvalidLoopBody {
+                        message: "Local must have 'expr'".to_string(),
+                    })?;
+                    found = Some(expr.clone());
+                }
+                Some("Assignment") | Some("Assign") => {
+                    let name = stmt["target"].as_str().ok_or_else(|| LoweringError::InvalidLoopBody {
+                        message: "Assignment must have 'target'".to_string(),
+                    })?;
+                    if name != target {
+                        continue;
+                    }
+                    if found.is_some() {
+                        return Err(LoweringError::InvalidLoopBody {
+                            message: format!("if-sum-break: multiple assignments to '{}'", target),
+                        });
+                    }
+                    let expr = stmt.get("expr").or_else(|| stmt.get("value")).ok_or_else(|| {
+                        LoweringError::InvalidLoopBody {
+                            message: "Assignment must have 'expr' or 'value'".to_string(),
+                        }
+                    })?;
+                    found = Some(expr.clone());
+                }
+                _ => {
+                    return Err(LoweringError::InvalidLoopBody {
+                        message: "if-sum-break: unsupported statement in update if".to_string(),
+                    });
+                }
+            }
+        }
+        Ok(found)
+    }
+
+    let then_branch = if_stmt["then"]
+        .as_array()
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "If must have 'then' array".to_string(),
+        })?;
+    let else_branch = if_stmt["else"]
+        .as_array()
+        .ok_or_else(|| LoweringError::InvalidLoopBody {
+            message: "If must have 'else' array".to_string(),
+        })?;
+
+    let then_expr = find_assignment_expr(then_branch, target)?.unwrap_or_else(|| {
+        serde_json::json!({"type":"Var","name":target})
+    });
+    let else_expr = find_assignment_expr(else_branch, target)?.unwrap_or_else(|| {
+        serde_json::json!({"type":"Var","name":target})
+    });
+    Ok((then_expr, else_expr))
+}
diff --git a/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/mod.rs b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/mod.rs
index 0ba80901..5ef2b79a 100644
--- a/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/mod.rs
+++ b/src/mir/join_ir/frontend/ast_lowerer/loop_patterns/mod.rs
@@ -19,6 +19,8 @@ pub mod break_pattern;
 pub mod common;
 pub mod continue_pattern;
 pub mod filter;
+#[cfg(feature = "normalized_dev")]
+pub mod if_sum_break_pattern;
 pub mod param_guess;
 pub mod print_tokens;
 pub mod simple;
diff --git a/src/mir/join_ir/frontend/ast_lowerer/mod.rs b/src/mir/join_ir/frontend/ast_lowerer/mod.rs
index 578b2eef..284b6a94 100644
--- a/src/mir/join_ir/frontend/ast_lowerer/mod.rs
+++ b/src/mir/join_ir/frontend/ast_lowerer/mod.rs
@@ -189,6 +189,18 @@ impl AstToJoinIrLowerer {
     }
 }
 
+/// Phase 60 dev-only helper: legacy Break(P2) lowering for comparison tests.
+///
+/// `loop_patterns` is private, so this wrapper is exposed at the ast_lowerer boundary.
+#[cfg(feature = "normalized_dev")]
+pub fn lower_break_legacy_for_comparison(
+    lowerer: &mut AstToJoinIrLowerer,
+    program_json: &serde_json::Value,
+) -> JoinModule {
+    loop_patterns::break_pattern::lower_break_legacy_for_comparison(lowerer, program_json)
+        .unwrap_or_else(|e| panic!("legacy break lowering failed: {:?}", e))
+}
+
 impl Default for AstToJoinIrLowerer {
     fn default() -> Self {
         Self::new()
diff --git a/src/mir/join_ir/normalized.rs b/src/mir/join_ir/normalized.rs
index 6aa272f0..c12197e4 100644
--- a/src/mir/join_ir/normalized.rs
+++ b/src/mir/join_ir/normalized.rs
@@ -351,6 +351,10 @@ pub fn normalize_pattern2_minimal(structured: &JoinModule) -> NormalizedModule {
                     NormalizedDevShape::Pattern3IfSumMinimal
                         | NormalizedDevShape::Pattern3IfSumMulti
                         | NormalizedDevShape::Pattern3IfSumJson
+                        | NormalizedDevShape::SelfhostIfSumP3
+                        | NormalizedDevShape::SelfhostIfSumP3Ext
+                        | NormalizedDevShape::SelfhostStmtCountP3
+                        | NormalizedDevShape::SelfhostDetectFormatP3
                 )
             }) {
                 max = max.max(6);
diff --git a/src/mir/join_ir/normalized/shape_guard.rs b/src/mir/join_ir/normalized/shape_guard.rs
index 1563c0ee..2f7c3ba4 100644
--- a/src/mir/join_ir/normalized/shape_guard.rs
+++ b/src/mir/join_ir/normalized/shape_guard.rs
@@ -312,7 +312,10 @@ pub fn detect_shapes(module: &JoinModule) -> Vec<NormalizedDevShape> {
         || shapes.contains(&NormalizedDevShape::SelfhostArgsParseP2)
         || shapes.contains(&NormalizedDevShape::SelfhostVerifySchemaP2)
     {
-        shapes.retain(|s| *s != NormalizedDevShape::Pattern2Mini);
+        shapes.retain(|s| {
+            *s != NormalizedDevShape::Pattern2Mini
+                && *s != NormalizedDevShape::Pattern4ContinueMinimal
+        });
     }
     if shapes.contains(&NormalizedDevShape::SelfhostIfSumP3)
         || shapes.contains(&NormalizedDevShape::SelfhostIfSumP3Ext)
@@ -325,6 +328,7 @@ pub fn detect_shapes(module: &JoinModule) -> Vec<NormalizedDevShape> {
                 NormalizedDevShape::Pattern3IfSumMinimal
                     | NormalizedDevShape::Pattern3IfSumMulti
                     | NormalizedDevShape::Pattern3IfSumJson
+                    | NormalizedDevShape::Pattern4ContinueMinimal
             )
         });
     }
diff --git a/src/mir/join_ir/ownership/analyzer.rs b/src/mir/join_ir/ownership/analyzer.rs
index 67ac3741..24dacde4 100644
--- a/src/mir/join_ir/ownership/analyzer.rs
+++ b/src/mir/join_ir/ownership/analyzer.rs
@@ -51,11 +51,33 @@ impl OwnershipAnalyzer {
         self.scopes.clear();
         self.next_scope_id = 0;
 
-        // Find functions and analyze each
+        // Find functions and analyze each.
+        //
+        // Supported inputs:
+        // - "functions": [...], with statement nodes using "kind" (test schema)
+        // - "defs": [...], where FunctionDef nodes contain "params"/"body" (Program(JSON v0))
         if let Some(functions) = json.get("functions").and_then(|f| f.as_array()) {
             for func in functions {
                 self.analyze_function(func, None)?;
             }
+        } else if let Some(defs) = json.get("defs").and_then(|d| d.as_array()) {
+            let mut found = false;
+            for def in defs {
+                let def_kind = def
+                    .get("type")
+                    .or_else(|| def.get("kind"))
+                    .and_then(|k| k.as_str())
+                    .unwrap_or("");
+                if def_kind == "FunctionDef" {
+                    found = true;
+                    self.analyze_function(def, None)?;
+                }
+            }
+            if !found {
+                return Err("OwnershipAnalyzer: no FunctionDef found in 'defs'".to_string());
+            }
+        } else {
+            return Err("OwnershipAnalyzer: expected top-level 'functions' or 'defs' array".to_string());
         }
 
         // Convert ScopeInfo to OwnershipPlan
@@ -98,26 +120,45 @@ impl OwnershipAnalyzer {
     }
 
     fn analyze_statement(&mut self, stmt: &Value, current_scope: ScopeId) -> Result<(), String> {
-        let kind = stmt.get("kind").and_then(|k| k.as_str()).unwrap_or("");
+        let kind = stmt
+            .get("kind")
+            .or_else(|| stmt.get("type"))
+            .and_then(|k| k.as_str())
+            .unwrap_or("");
 
         match kind {
             "Local" => {
-                // Variable definition
+                // NOTE: Program(JSON v0) historically uses Local for both "new binding"
+                // and "rebind/update". This analyzer treats Local as:
+                // - definition when the name is not yet defined in scope chain
+                // - write when the name is already defined (rebind)
                 if let Some(name) = stmt.get("name").and_then(|n| n.as_str()) {
-                    // Find enclosing loop (or function) for ownership
-                    let owner_scope = self.find_enclosing_loop_or_function(current_scope);
-                    self.scopes.get_mut(&owner_scope).unwrap().defined.insert(name.to_string());
+                    if self.is_defined_in_scope_chain(current_scope, name) {
+                        self.scopes
+                            .get_mut(&current_scope)
+                            .unwrap()
+                            .writes
+                            .insert(name.to_string());
+                    } else {
+                        // Find enclosing loop (or function) for ownership
+                        let owner_scope = self.find_enclosing_loop_or_function(current_scope);
+                        self.scopes
+                            .get_mut(&owner_scope)
+                            .unwrap()
+                            .defined
+                            .insert(name.to_string());
+                    }
                 }
                 // Analyze initializer if present
-                if let Some(init) = stmt.get("init") {
+                if let Some(init) = stmt.get("init").or_else(|| stmt.get("expr")) {
                     self.analyze_expression(init, current_scope, false)?;
                 }
             }
-            "Assign" => {
+            "Assign" | "Assignment" => {
                 if let Some(target) = stmt.get("target").and_then(|t| t.as_str()) {
                     self.scopes.get_mut(&current_scope).unwrap().writes.insert(target.to_string());
                 }
-                if let Some(value) = stmt.get("value") {
+                if let Some(value) = stmt.get("value").or_else(|| stmt.get("expr")) {
                     self.analyze_expression(value, current_scope, false)?;
                 }
             }
@@ -125,7 +166,7 @@ impl OwnershipAnalyzer {
                 let loop_scope = self.alloc_scope(ScopeKind::Loop, Some(current_scope));
 
                 // Analyze condition (mark as condition_reads)
-                if let Some(cond) = stmt.get("condition") {
+                if let Some(cond) = stmt.get("condition").or_else(|| stmt.get("cond")) {
                     self.analyze_expression(cond, loop_scope, true)?;
                 }
 
@@ -141,7 +182,7 @@ impl OwnershipAnalyzer {
                 let if_scope = self.alloc_scope(ScopeKind::If, Some(current_scope));
 
                 // Analyze condition
-                if let Some(cond) = stmt.get("condition") {
+                if let Some(cond) = stmt.get("condition").or_else(|| stmt.get("cond")) {
                     self.analyze_expression(cond, if_scope, true)?;
                 }
 
@@ -158,7 +199,11 @@ impl OwnershipAnalyzer {
             "Block" => {
                 let block_scope = self.alloc_scope(ScopeKind::Block, Some(current_scope));
 
-                if let Some(stmts) = stmt.get("statements").and_then(|s| s.as_array()) {
+                let stmts = stmt
+                    .get("statements")
+                    .or_else(|| stmt.get("body"))
+                    .and_then(|s| s.as_array());
+                if let Some(stmts) = stmts {
                     for s in stmts {
                         self.analyze_statement(s, block_scope)?;
                     }
@@ -167,7 +212,7 @@ impl OwnershipAnalyzer {
                 self.propagate_to_parent(block_scope);
             }
             "Return" | "Break" | "Continue" => {
-                if let Some(value) = stmt.get("value") {
+                if let Some(value) = stmt.get("value").or_else(|| stmt.get("expr")) {
                     self.analyze_expression(value, current_scope, false)?;
                 }
             }
@@ -190,7 +235,11 @@ impl OwnershipAnalyzer {
     }
 
     fn analyze_expression(&mut self, expr: &Value, current_scope: ScopeId, is_condition: bool) -> Result<(), String> {
-        let kind = expr.get("kind").and_then(|k| k.as_str()).unwrap_or("");
+        let kind = expr
+            .get("kind")
+            .or_else(|| expr.get("type"))
+            .and_then(|k| k.as_str())
+            .unwrap_or("");
 
         match kind {
             "Var" | "Variable" | "Identifier" => {
@@ -248,6 +297,21 @@ impl OwnershipAnalyzer {
         Ok(())
     }
 
+    fn is_defined_in_scope_chain(&self, from_scope: ScopeId, name: &str) -> bool {
+        let mut current = Some(from_scope);
+        while let Some(id) = current {
+            let scope = match self.scopes.get(&id) {
+                Some(scope) => scope,
+                None => break,
+            };
+            if scope.defined.contains(name) {
+                return true;
+            }
+            current = scope.parent;
+        }
+        false
+    }
+
     /// Find enclosing Loop or Function scope (body-local ownership rule)
     fn find_enclosing_loop_or_function(&self, scope_id: ScopeId) -> ScopeId {
         let scope = &self.scopes[&scope_id];
@@ -629,4 +693,30 @@ mod tests {
 
         assert!(any_relay, "Some loop should relay 'total' to function");
     }
+
+    #[test]
+    fn test_program_json_v0_break_fixture_relay_and_capture() {
+        let program_json: serde_json::Value = serde_json::from_str(include_str!(
+            "../../../../docs/private/roadmap2/phases/phase-34-joinir-frontend/fixtures/loop_frontend_break.program.json"
+        ))
+        .expect("fixture json");
+
+        let mut analyzer = OwnershipAnalyzer::new();
+        let plans = analyzer
+            .analyze_json(&program_json)
+            .expect("Program(JSON v0) analysis should succeed");
+
+        let loop_plan = plans
+            .iter()
+            .find(|p| !p.relay_writes.is_empty())
+            .expect("expected a loop plan with relay_writes");
+
+        // i/acc are defined outside the loop but rebound inside loop body -> relay_writes
+        assert!(loop_plan.relay_writes.iter().any(|r| r.name == "i"));
+        assert!(loop_plan.relay_writes.iter().any(|r| r.name == "acc"));
+
+        // n is read-only in loop condition -> capture + condition_capture
+        assert!(loop_plan.captures.iter().any(|c| c.name == "n"));
+        assert!(loop_plan.condition_captures.iter().any(|c| c.name == "n"));
+    }
 }
diff --git a/src/mir/join_ir/ownership/plan_to_lowering.rs b/src/mir/join_ir/ownership/plan_to_lowering.rs
index db669dca..7e8ac3a8 100644
--- a/src/mir/join_ir/ownership/plan_to_lowering.rs
+++ b/src/mir/join_ir/ownership/plan_to_lowering.rs
@@ -89,6 +89,74 @@ pub fn plan_to_p2_inputs(
     })
 }
 
+/// Convert OwnershipPlan to P2 lowering inputs, allowing relay_writes (dev-only Phase 60).
+///
+/// Rules:
+/// - carriers = owned_vars where is_written && name != loop_var
+///            + relay_writes where name != loop_var
+/// - relay_path.len() > 1 is rejected (single-hop only)
+#[cfg(feature = "normalized_dev")]
+pub fn plan_to_p2_inputs_with_relay(
+    plan: &OwnershipPlan,
+    loop_var: &str,
+) -> Result<P2LoweringInputs, String> {
+    let mut carriers = Vec::new();
+
+    for var in &plan.owned_vars {
+        if var.name == loop_var || !var.is_written {
+            continue;
+        }
+
+        let role = if var.is_condition_only {
+            CarrierRole::ConditionOnly
+        } else {
+            CarrierRole::LoopState
+        };
+
+        carriers.push(CarrierVar {
+            name: var.name.clone(),
+            role,
+            init: CarrierInit::FromHost,
+            host_id: crate::mir::ValueId(0),
+            join_id: None,
+        });
+    }
+
+    for relay in &plan.relay_writes {
+        if relay.name == loop_var {
+            continue;
+        }
+        if relay.relay_path.len() > 1 {
+            return Err(format!(
+                "Phase 60 limitation: only single-hop relay supported for P2. Var='{}' relay_path_len={}",
+                relay.name,
+                relay.relay_path.len()
+            ));
+        }
+
+        carriers.push(CarrierVar {
+            name: relay.name.clone(),
+            role: CarrierRole::LoopState,
+            init: CarrierInit::FromHost,
+            host_id: crate::mir::ValueId(0),
+            join_id: None,
+        });
+    }
+
+    let captures: Vec<String> = plan.captures.iter().map(|c| c.name.clone()).collect();
+    let condition_captures: Vec<String> = plan
+        .condition_captures
+        .iter()
+        .map(|c| c.name.clone())
+        .collect();
+
+    Ok(P2LoweringInputs {
+        carriers,
+        captures,
+        condition_captures,
+    })
+}
+
 /// Convert OwnershipPlan to P3 (if-sum) lowering inputs.
 ///
 /// P3 patterns have multiple carriers (sum, count, etc.) updated conditionally.
@@ -152,6 +220,22 @@ pub fn plan_to_p3_inputs(
     })
 }
 
+/// Convert OwnershipPlan to P3 lowering inputs, allowing relay_writes (dev-only Phase 60).
+///
+/// Rules are identical to `plan_to_p2_inputs_with_relay`, but output type is P3LoweringInputs.
+#[cfg(feature = "normalized_dev")]
+pub fn plan_to_p3_inputs_with_relay(
+    plan: &OwnershipPlan,
+    loop_var: &str,
+) -> Result<P3LoweringInputs, String> {
+    let p2 = plan_to_p2_inputs_with_relay(plan, loop_var)?;
+    Ok(P3LoweringInputs {
+        carriers: p2.carriers,
+        captures: p2.captures,
+        condition_captures: p2.condition_captures,
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -220,6 +304,44 @@ mod tests {
             .contains("relay_writes not yet supported"));
     }
 
+    #[test]
+    #[cfg(feature = "normalized_dev")]
+    fn test_relay_single_hop_accepted_in_with_relay() {
+        let mut plan = OwnershipPlan::new(ScopeId(1));
+        plan.owned_vars.push(ScopeOwnedVar {
+            name: "i".to_string(),
+            is_written: true,
+            is_condition_only: false,
+        });
+        plan.relay_writes.push(RelayVar {
+            name: "sum".to_string(),
+            owner_scope: ScopeId(0),
+            relay_path: vec![ScopeId(42)],
+        });
+
+        let inputs = plan_to_p2_inputs_with_relay(&plan, "i").expect("with_relay should accept");
+        assert_eq!(inputs.carriers.len(), 1);
+        assert_eq!(inputs.carriers[0].name, "sum");
+        assert_eq!(inputs.carriers[0].role, CarrierRole::LoopState);
+    }
+
+    #[test]
+    #[cfg(feature = "normalized_dev")]
+    fn test_relay_multi_hop_rejected_in_with_relay() {
+        let mut plan = OwnershipPlan::new(ScopeId(1));
+        plan.relay_writes.push(RelayVar {
+            name: "outer_var".to_string(),
+            owner_scope: ScopeId(0),
+            relay_path: vec![ScopeId(1), ScopeId(2)],
+        });
+
+        let result = plan_to_p2_inputs_with_relay(&plan, "i");
+        assert!(result.is_err());
+        assert!(result
+            .unwrap_err()
+            .contains("only single-hop relay supported"));
+    }
+
     #[test]
     #[cfg(feature = "normalized_dev")]
     fn test_read_only_vars_not_carriers() {
@@ -402,4 +524,24 @@ mod tests {
             .unwrap_err()
             .contains("relay_writes not yet supported for P3"));
     }
+
+    #[test]
+    #[cfg(feature = "normalized_dev")]
+    fn test_p3_with_relay_accepts_single_hop() {
+        let mut plan = OwnershipPlan::new(ScopeId(1));
+        plan.owned_vars.push(ScopeOwnedVar {
+            name: "i".to_string(),
+            is_written: true,
+            is_condition_only: false,
+        });
+        plan.relay_writes.push(RelayVar {
+            name: "sum".to_string(),
+            owner_scope: ScopeId(0),
+            relay_path: vec![],
+        });
+
+        let inputs = plan_to_p3_inputs_with_relay(&plan, "i").expect("P3 with_relay should accept");
+        assert_eq!(inputs.carriers.len(), 1);
+        assert_eq!(inputs.carriers[0].name, "sum");
+    }
 }
diff --git a/tests/normalized_joinir_min.rs b/tests/normalized_joinir_min.rs
index 5624b0a4..fa9b1400 100644
--- a/tests/normalized_joinir_min.rs
+++ b/tests/normalized_joinir_min.rs
@@ -638,7 +638,7 @@ fn normalized_selfhost_if_sum_p3_vm_bridge_direct_matches_structured() {
     let _ctx = normalized_dev_test_ctx();
     let structured = build_selfhost_if_sum_p3_structured_for_normalized_dev();
     let entry = structured.entry.expect("structured entry required");
-    let cases = [0, 1, 3, 4];
+    let cases = [0, 1, 3, 4, 5];
 
     for n in cases {
         let input = [JoinValue::Int(n)];
@@ -646,6 +646,7 @@ fn normalized_selfhost_if_sum_p3_vm_bridge_direct_matches_structured() {
         let dev = run_joinir_vm_bridge(&structured, entry, &input, true);
 
         assert_eq!(base, dev, "vm bridge mismatch for selfhost_if_sum_p3 n={}", n);
+        assert_eq!(dev, JoinValue::Int(expected_selfhost_if_sum_p3(n)));
     }
 }
 
@@ -654,7 +655,7 @@ fn normalized_selfhost_if_sum_p3_ext_vm_bridge_direct_matches_structured() {
     let _ctx = normalized_dev_test_ctx();
     let structured = build_selfhost_if_sum_p3_ext_structured_for_normalized_dev();
     let entry = structured.entry.expect("structured entry required");
-    let cases = [0, 1, 3, 4];
+    let cases = [0, 1, 3, 4, 5];
 
     for n in cases {
         let input = [JoinValue::Int(n)];
@@ -662,9 +663,30 @@ fn normalized_selfhost_if_sum_p3_ext_vm_bridge_direct_matches_structured() {
         let dev = run_joinir_vm_bridge(&structured, entry, &input, true);
 
         assert_eq!(base, dev, "vm bridge mismatch for selfhost_if_sum_p3_ext n={}", n);
+        assert_eq!(dev, JoinValue::Int(expected_selfhost_if_sum_p3_ext(n)));
     }
 }
 
+fn expected_selfhost_if_sum_p3(n: i64) -> i64 {
+    if n <= 1 {
+        return 0;
+    }
+    let sum = (n - 1) * n / 2;
+    let count = n - 1;
+    sum + count
+}
+
+fn expected_selfhost_if_sum_p3_ext(n: i64) -> i64 {
+    if n <= 0 {
+        return 0;
+    }
+    // i=0: sum += 1
+    // i=1..n-1: sum += i, count += 1
+    let sum = 1 + (n - 1) * n / 2;
+    let count = n - 1;
+    sum + count
+}
+
 /// Phase 53: selfhost args-parse P2 (practical variation with string carrier)
 #[test]
 fn normalized_selfhost_args_parse_p2_vm_bridge_direct_matches_structured() {
@@ -1067,17 +1089,17 @@ fn test_phase54_structural_axis_discrimination_p3() {
     }
 }
 
-/// Phase 58: Compare ownership-based P2 lowering with existing path
+/// Phase 60: Ownership relay threading helpers for P2 (analysis + contract)
 ///
-/// This test demonstrates that OwnershipAnalyzer can analyze P2 fixtures
-/// and plan_to_p2_inputs can convert the result to reasonable CarrierVar structures.
-///
-/// Note: This is analysis-only testing. We're NOT modifying the actual lowering path yet.
-/// Full integration will come in Phase 60+ after validating the analysis is correct.
+/// plan_to_p2_inputs remains Fail-Fast on relay_writes (legacy contract),
+/// while plan_to_p2_inputs_with_relay accepts single-hop relay and promotes them
+/// to carriers (dev-only).
 #[test]
 #[cfg(feature = "normalized_dev")]
-fn test_phase58_ownership_p2_comparison() {
-    use nyash_rust::mir::join_ir::ownership::{plan_to_p2_inputs, OwnershipAnalyzer};
+fn test_phase60_ownership_p2_with_relay_conversion() {
+    use nyash_rust::mir::join_ir::ownership::{
+        plan_to_p2_inputs, plan_to_p2_inputs_with_relay, OwnershipAnalyzer,
+    };
     use serde_json::json;
 
     // Create a simple P2 fixture JSON (loop with i and sum)
@@ -1154,11 +1176,11 @@ fn test_phase58_ownership_p2_comparison() {
         loop_plan.relay_writes
     );
 
-    // Phase 58 Fail-Fast: relay_writes should be rejected
+    // Legacy Fail-Fast: relay_writes should be rejected
     let result = plan_to_p2_inputs(loop_plan, "i");
     assert!(
         result.is_err(),
-        "Phase 58: relay_writes should be rejected (not supported yet)"
+        "Legacy contract: relay_writes should be rejected"
     );
     let err = result.unwrap_err();
     assert!(
@@ -1167,7 +1189,22 @@ fn test_phase58_ownership_p2_comparison() {
         err
     );
 
-    eprintln!("[phase58/test] Phase 58 Fail-Fast verified: relay_writes correctly rejected");
+    // Phase 60 dev-only: with_relay should accept and include relay vars as carriers
+    let inputs_with_relay =
+        plan_to_p2_inputs_with_relay(loop_plan, "i").expect("with_relay should accept");
+    assert!(
+        inputs_with_relay.carriers.iter().any(|c| c.name == "sum"),
+        "relay carrier sum should be promoted"
+    );
+
+    eprintln!(
+        "[phase60/test] with_relay carriers={:?}",
+        inputs_with_relay
+            .carriers
+            .iter()
+            .map(|c| &c.name)
+            .collect::<Vec<_>>()
+    );
 
     // Also test the case where variables ARE owned by loop (future scenario)
     // This would work once we support loop-local carriers
@@ -1239,7 +1276,41 @@ fn test_phase58_ownership_p2_comparison() {
     assert_eq!(inputs.carriers.len(), 1, "Should have 1 carrier (sum)");
     assert_eq!(inputs.carriers[0].name, "sum");
 
-    eprintln!("[phase58/test] Phase 58 conversion verified: sum correctly extracted as carrier");
+    eprintln!("[phase60/test] Loop-local conversion verified");
+}
+
+/// Phase 60: P2 dev-only ownership relay route matches legacy Break lowering.
+#[test]
+#[cfg(feature = "normalized_dev")]
+fn test_phase60_break_lowering_ownership_matches_legacy() {
+    use nyash_rust::mir::join_ir::frontend::ast_lowerer::lower_break_legacy_for_comparison;
+    use nyash_rust::mir::join_ir::frontend::ast_lowerer::AstToJoinIrLowerer;
+
+    let _ctx = normalized_dev_test_ctx();
+
+    let program_json: serde_json::Value = serde_json::from_str(include_str!(
+        "../docs/private/roadmap2/phases/phase-34-joinir-frontend/fixtures/loop_frontend_break.program.json"
+    ))
+    .expect("fixture json");
+
+    let mut lowerer_new = AstToJoinIrLowerer::new();
+    let structured_new = lowerer_new.lower_program_json(&program_json);
+
+    let mut lowerer_old = AstToJoinIrLowerer::new();
+    let structured_old =
+        lower_break_legacy_for_comparison(&mut lowerer_old, &program_json);
+
+    let entry_new = structured_new.entry.expect("new entry");
+    let entry_old = structured_old.entry.expect("old entry");
+    let input = vec![JoinValue::Int(5)];
+
+    let out_old = run_joinir_vm_bridge(&structured_old, entry_old, &input, false);
+    let out_new = run_joinir_vm_bridge(&structured_new, entry_new, &input, false);
+
+    assert_eq!(
+        out_old, out_new,
+        "ownership relay dev route must match legacy output"
+    );
 }
 
 /// Phase 59: P3 with outer-owned carriers (relay case) should fail-fast
@@ -1412,3 +1483,40 @@ fn test_phase59_ownership_p3_loop_local_success() {
 
     eprintln!("[phase59/test] P3 loop-local conversion verified: sum and count correctly extracted as carriers");
 }
+
+/// Phase 60: Program(JSON v0) fixture (selfhost_if_sum_p3) should produce relay_writes and convert with single-hop relay.
+#[test]
+#[cfg(feature = "normalized_dev")]
+fn test_phase60_ownership_p3_program_json_fixture_with_relay() {
+    use nyash_rust::mir::join_ir::ownership::{plan_to_p3_inputs_with_relay, OwnershipAnalyzer};
+
+    let program_json: serde_json::Value = serde_json::from_str(include_str!(
+        "../docs/private/roadmap2/phases/normalized_dev/fixtures/selfhost_if_sum_p3.program.json"
+    ))
+    .expect("fixture json");
+
+    let mut analyzer = OwnershipAnalyzer::new();
+    let plans = analyzer
+        .analyze_json(&program_json)
+        .expect("Program(JSON v0) analysis should succeed");
+
+    let loop_plan = plans
+        .iter()
+        .find(|p| !p.relay_writes.is_empty())
+        .expect("expected a loop plan with relay_writes");
+
+    // i/sum/count are defined outside the loop but updated in the loop body -> relay_writes
+    assert!(loop_plan.relay_writes.iter().any(|r| r.name == "i"));
+    assert!(loop_plan.relay_writes.iter().any(|r| r.name == "sum"));
+    assert!(loop_plan.relay_writes.iter().any(|r| r.name == "count"));
+
+    let inputs = plan_to_p3_inputs_with_relay(loop_plan, "i").expect("with_relay should succeed");
+
+    let mut carriers: Vec<&str> = inputs.carriers.iter().map(|c| c.name.as_str()).collect();
+    carriers.sort();
+    assert_eq!(carriers, vec!["count", "sum"]);
+
+    // n is read-only in loop condition -> capture + condition_capture
+    assert!(inputs.captures.iter().any(|n| n == "n"));
+    assert!(inputs.condition_captures.iter().any(|n| n == "n"));
+}