diff --git a/docs/development/current/main/10-Now.md b/docs/development/current/main/10-Now.md
index 178986e0..05998f20 100644
--- a/docs/development/current/main/10-Now.md
+++ b/docs/development/current/main/10-Now.md
@@ -3,7 +3,7 @@
 ## Current Focus
 
 - Phase: `docs/development/current/main/phases/phase-29ao/README.md`
-- Next: TBD (P47 done; see `docs/development/current/main/phases/phase-29ao/README.md`)
+- Next: TBD (P48 done; see `docs/development/current/main/phases/phase-29ao/README.md`)
 
 ## Gate (SSOT)
 
diff --git a/docs/development/current/main/30-Backlog.md b/docs/development/current/main/30-Backlog.md
index c5b39a8b..7cd5c086 100644
--- a/docs/development/current/main/30-Backlog.md
+++ b/docs/development/current/main/30-Backlog.md
@@ -5,7 +5,7 @@ Scope: 「次にやる候補」を短く列挙するメモ。入口は `docs/dev
 
 ## Active
 
-- CorePlan migration: `docs/development/current/main/phases/phase-29ao/README.md`（Next: TBD, P47 done）
+- CorePlan migration: `docs/development/current/main/phases/phase-29ao/README.md`（Next: TBD, P48 done）
 
 ## Near-Term Candidates
 
diff --git a/docs/development/current/main/design/coreplan-migration-roadmap-ssot.md b/docs/development/current/main/design/coreplan-migration-roadmap-ssot.md
index c0f2598c..8fd57ee8 100644
--- a/docs/development/current/main/design/coreplan-migration-roadmap-ssot.md
+++ b/docs/development/current/main/design/coreplan-migration-roadmap-ssot.md
@@ -34,7 +34,7 @@ Related:
 ## 1.1 Current (active)
 
 - Active phase: `docs/development/current/main/phases/phase-29ao/README.md`
-- Next step: TBD (P47 done)
+- Next step: TBD (P48 done)
 
 ## 2. すでに固めた SSOT（再発防止の土台）
 
diff --git a/docs/development/current/main/phases/phase-29ao/README.md b/docs/development/current/main/phases/phase-29ao/README.md
index 19ee8bb9..49e0ea14 100644
--- a/docs/development/current/main/phases/phase-29ao/README.md
+++ b/docs/development/current/main/phases/phase-29ao/README.md
@@ -261,6 +261,11 @@ Gate（SSOT）:
 - 指示書: `docs/development/current/main/phases/phase-29ao/P47-CORELOOPCOMPOSER-V1-SPLITSCAN-VALUEJOIN-INSTRUCTIONS.md`
 - ねらい: Pattern7 value-join を v1 で受理し、block_params/EdgeArgs 経由の PHI 一本化を維持（仕様不変）
 
+## P48: CoreLoopComposer v1 — Pattern2 (Break) value-join minimal composition ✅
+
+- 指示書: `docs/development/current/main/phases/phase-29ao/P48-CORELOOPCOMPOSER-V1-PATTERN2-BREAK-VALUEJOIN-INSTRUCTIONS.md`
+- ねらい: Pattern2 after-join を v1 で受理し、block_params/EdgeArgs 経由の PHI 一本化を維持（仕様不変）
+
 ## Next（planned）
 
 - Next: TBD
diff --git a/src/mir/builder/control_flow/plan/composer/coreloop_gates.rs b/src/mir/builder/control_flow/plan/composer/coreloop_gates.rs
index 726d958b..fe9c69dd 100644
--- a/src/mir/builder/control_flow/plan/composer/coreloop_gates.rs
+++ b/src/mir/builder/control_flow/plan/composer/coreloop_gates.rs
@@ -7,6 +7,10 @@ pub(super) fn coreloop_base_gate(facts: &CanonicalLoopFacts) -> bool {
         && facts.cleanup_kinds_present.is_empty()
 }
 
+pub(super) fn coreloop_value_join_gate(facts: &CanonicalLoopFacts) -> bool {
+    coreloop_base_gate(facts) && facts.value_join_needed
+}
+
 pub(super) fn exit_kinds_allow_return_only(facts: &CanonicalLoopFacts) -> bool {
     facts.exit_kinds_present.is_empty()
         || (facts.exit_kinds_present.len() == 1
@@ -16,3 +20,7 @@ pub(super) fn exit_kinds_allow_return_only(facts: &CanonicalLoopFacts) -> bool {
 pub(super) fn exit_kinds_empty(facts: &CanonicalLoopFacts) -> bool {
     facts.exit_kinds_present.is_empty()
 }
+
+pub(super) fn pattern2_value_join_gate(facts: &CanonicalLoopFacts) -> bool {
+    coreloop_value_join_gate(facts) && exit_kinds_allow_return_only(facts)
+}
diff --git a/src/mir/builder/control_flow/plan/composer/coreloop_v1.rs b/src/mir/builder/control_flow/plan/composer/coreloop_v1.rs
index 154b1380..e7fee178 100644
--- a/src/mir/builder/control_flow/plan/composer/coreloop_v1.rs
+++ b/src/mir/builder/control_flow/plan/composer/coreloop_v1.rs
@@ -1,23 +1,32 @@
 use crate::mir::builder::control_flow::joinir::patterns::router::LoopPatternContext;
 use crate::mir::builder::control_flow::plan::composer::coreloop_gates::{
-    coreloop_base_gate, exit_kinds_allow_return_only,
+    coreloop_value_join_gate, exit_kinds_allow_return_only, pattern2_value_join_gate,
 };
 use crate::mir::builder::control_flow::plan::facts::scan_shapes::SplitScanShape;
 use crate::mir::builder::control_flow::plan::normalize::CanonicalLoopFacts;
 use crate::mir::builder::control_flow::plan::normalizer::PlanNormalizer;
-use crate::mir::builder::control_flow::plan::{CorePlan, SplitScanPlan};
+use crate::mir::builder::control_flow::plan::{
+    CorePlan, Pattern2BreakPlan, Pattern2PromotionHint, SplitScanPlan,
+};
 use crate::mir::builder::MirBuilder;
 
-#[allow(dead_code)]
 pub(in crate::mir::builder) fn try_compose_core_loop_v1(
     builder: &mut MirBuilder,
     facts: &CanonicalLoopFacts,
     ctx: &LoopPatternContext,
 ) -> Result<Option<CorePlan>, String> {
-    if !coreloop_base_gate(facts) {
-        return Ok(None);
+    if let Some(core) = try_compose_core_loop_v1_pattern2_break(builder, facts, ctx)? {
+        return Ok(Some(core));
     }
-    if !facts.value_join_needed {
+    try_compose_core_loop_v1_split_scan(builder, facts, ctx)
+}
+
+fn try_compose_core_loop_v1_split_scan(
+    builder: &mut MirBuilder,
+    facts: &CanonicalLoopFacts,
+    ctx: &LoopPatternContext,
+) -> Result<Option<CorePlan>, String> {
+    if !coreloop_value_join_gate(facts) {
         return Ok(None);
     }
 
@@ -43,14 +52,48 @@ pub(in crate::mir::builder) fn try_compose_core_loop_v1(
     Ok(Some(core))
 }
 
+pub(in crate::mir::builder) fn try_compose_core_loop_v1_pattern2_break(
+    builder: &mut MirBuilder,
+    facts: &CanonicalLoopFacts,
+    ctx: &LoopPatternContext,
+) -> Result<Option<CorePlan>, String> {
+    if !pattern2_value_join_gate(facts) {
+        return Ok(None);
+    }
+
+    let Some(pattern2) = facts.facts.pattern2_break.as_ref() else {
+        return Ok(None);
+    };
+    let promotion = facts
+        .facts
+        .pattern2_loopbodylocal
+        .as_ref()
+        .map(|facts| Pattern2PromotionHint::LoopBodyLocal(facts.clone()));
+
+    let plan = Pattern2BreakPlan {
+        loop_var: pattern2.loop_var.clone(),
+        carrier_var: pattern2.carrier_var.clone(),
+        loop_condition: pattern2.loop_condition.clone(),
+        break_condition: pattern2.break_condition.clone(),
+        carrier_update_in_break: pattern2.carrier_update_in_break.clone(),
+        carrier_update_in_body: pattern2.carrier_update_in_body.clone(),
+        loop_increment: pattern2.loop_increment.clone(),
+        promotion,
+    };
+    let core = PlanNormalizer::normalize_pattern2_break(builder, plan, ctx)?;
+    Ok(Some(core))
+}
+
 #[cfg(test)]
 mod tests {
     use super::try_compose_core_loop_v1;
-    use crate::ast::{ASTNode, LiteralValue, Span};
+    use crate::ast::{ASTNode, BinaryOperator, LiteralValue, Span};
     use crate::mir::builder::control_flow::plan::facts::feature_facts::{
-        ExitKindFacts, ExitMapFacts, LoopFeatureFacts, ValueJoinFacts,
+        CleanupFacts, CleanupKindFacts, ExitKindFacts, ExitMapFacts, LoopFeatureFacts,
+        ValueJoinFacts,
     };
     use crate::mir::builder::control_flow::plan::facts::loop_facts::LoopFacts;
+    use crate::mir::builder::control_flow::plan::facts::pattern2_break_facts::Pattern2BreakFacts;
     use crate::mir::builder::control_flow::plan::facts::scan_shapes::{
         ConditionShape, SplitScanShape, StepShape,
     };
@@ -63,6 +106,20 @@ mod tests {
     use crate::mir::MirType;
     use std::collections::BTreeSet;
 
+    fn v(name: &str) -> ASTNode {
+        ASTNode::Variable {
+            name: name.to_string(),
+            span: Span::unknown(),
+        }
+    }
+
+    fn lit_int(value: i64) -> ASTNode {
+        ASTNode::Literal {
+            value: LiteralValue::Integer(value),
+            span: Span::unknown(),
+        }
+    }
+
     #[test]
     fn coreloop_v1_composes_split_scan_with_value_join() {
         let condition = ASTNode::Literal {
@@ -185,4 +242,135 @@ mod tests {
             try_compose_core_loop_v1(&mut builder, &canonical, &ctx).expect("Ok");
         assert!(composed.is_none());
     }
+
+    #[test]
+    fn coreloop_v1_composes_pattern2_with_value_join() {
+        let loop_condition = ASTNode::BinaryOp {
+            operator: BinaryOperator::Less,
+            left: Box::new(v("i")),
+            right: Box::new(lit_int(3)),
+            span: Span::unknown(),
+        };
+        let break_condition = ASTNode::BinaryOp {
+            operator: BinaryOperator::Equal,
+            left: Box::new(v("i")),
+            right: Box::new(lit_int(1)),
+            span: Span::unknown(),
+        };
+        let carrier_update_in_body = ASTNode::BinaryOp {
+            operator: BinaryOperator::Add,
+            left: Box::new(v("sum")),
+            right: Box::new(lit_int(1)),
+            span: Span::unknown(),
+        };
+        let loop_increment = ASTNode::BinaryOp {
+            operator: BinaryOperator::Add,
+            left: Box::new(v("i")),
+            right: Box::new(lit_int(1)),
+            span: Span::unknown(),
+        };
+
+        let features = LoopFeatureFacts {
+            value_join: Some(ValueJoinFacts { needed: true }),
+            ..LoopFeatureFacts::default()
+        };
+        let facts = LoopFacts {
+            condition_shape: ConditionShape::Unknown,
+            step_shape: StepShape::Unknown,
+            skeleton: SkeletonFacts {
+                kind: SkeletonKind::Loop,
+            },
+            features,
+            scan_with_init: None,
+            split_scan: None,
+            pattern1_simplewhile: None,
+            pattern3_ifphi: None,
+            pattern4_continue: None,
+            pattern5_infinite_early_exit: None,
+            pattern8_bool_predicate_scan: None,
+            pattern9_accum_const_loop: None,
+            pattern2_break: Some(Pattern2BreakFacts {
+                loop_var: "i".to_string(),
+                carrier_var: "sum".to_string(),
+                loop_condition: loop_condition.clone(),
+                break_condition,
+                carrier_update_in_break: None,
+                carrier_update_in_body,
+                loop_increment,
+            }),
+            pattern2_loopbodylocal: None,
+        };
+        let canonical = canonicalize_loop_facts(facts);
+        let mut builder = MirBuilder::new();
+        builder.enter_function_for_test("coreloop_v1_pattern2".to_string());
+        let i_val = builder.alloc_typed(MirType::Integer);
+        let sum_val = builder.alloc_typed(MirType::Integer);
+        builder
+            .variable_ctx
+            .variable_map
+            .insert("i".to_string(), i_val);
+        builder
+            .variable_ctx
+            .variable_map
+            .insert("sum".to_string(), sum_val);
+        let ctx =
+            LoopPatternContext::new(&loop_condition, &[], "coreloop_v1_pattern2", false, false);
+        let composed =
+            try_compose_core_loop_v1(&mut builder, &canonical, &ctx).expect("Ok");
+        assert!(matches!(composed, Some(crate::mir::builder::control_flow::plan::CorePlan::Loop(_))));
+    }
+
+    #[test]
+    fn coreloop_v1_rejects_pattern2_with_cleanup() {
+        let condition = ASTNode::Literal {
+            value: LiteralValue::Bool(true),
+            span: Span::unknown(),
+        };
+        let mut kinds_present = BTreeSet::new();
+        kinds_present.insert(CleanupKindFacts::Return);
+        let features = LoopFeatureFacts {
+            cleanup: Some(CleanupFacts { kinds_present }),
+            value_join: Some(ValueJoinFacts { needed: true }),
+            ..LoopFeatureFacts::default()
+        };
+        let facts = LoopFacts {
+            condition_shape: ConditionShape::Unknown,
+            step_shape: StepShape::Unknown,
+            skeleton: SkeletonFacts {
+                kind: SkeletonKind::Loop,
+            },
+            features,
+            scan_with_init: None,
+            split_scan: None,
+            pattern1_simplewhile: None,
+            pattern3_ifphi: None,
+            pattern4_continue: None,
+            pattern5_infinite_early_exit: None,
+            pattern8_bool_predicate_scan: None,
+            pattern9_accum_const_loop: None,
+            pattern2_break: Some(Pattern2BreakFacts {
+                loop_var: "i".to_string(),
+                carrier_var: "sum".to_string(),
+                loop_condition: condition.clone(),
+                break_condition: condition.clone(),
+                carrier_update_in_break: None,
+                carrier_update_in_body: lit_int(0),
+                loop_increment: lit_int(0),
+            }),
+            pattern2_loopbodylocal: None,
+        };
+        let canonical = canonicalize_loop_facts(facts);
+        let mut builder = MirBuilder::new();
+        builder.enter_function_for_test("coreloop_v1_pattern2_cleanup".to_string());
+        let ctx = LoopPatternContext::new(
+            &condition,
+            &[],
+            "coreloop_v1_pattern2_cleanup",
+            false,
+            false,
+        );
+        let composed =
+            try_compose_core_loop_v1(&mut builder, &canonical, &ctx).expect("Ok");
+        assert!(composed.is_none());
+    }
 }
diff --git a/src/mir/builder/control_flow/plan/composer/shadow_adopt.rs b/src/mir/builder/control_flow/plan/composer/shadow_adopt.rs
index 211be4c3..88979243 100644
--- a/src/mir/builder/control_flow/plan/composer/shadow_adopt.rs
+++ b/src/mir/builder/control_flow/plan/composer/shadow_adopt.rs
@@ -4,6 +4,7 @@ use super::coreloop_v0::{
     try_compose_core_loop_v0_scan_with_init, try_compose_core_loop_v0_split_scan,
 };
 use super::coreloop_v1::try_compose_core_loop_v1;
+use super::coreloop_v1::try_compose_core_loop_v1_pattern2_break;
 use super::PlanNormalizer;
 use crate::mir::builder::control_flow::joinir::patterns::router::LoopPatternContext;
 use crate::mir::builder::control_flow::plan::normalize::CanonicalLoopFacts;
@@ -131,7 +132,12 @@ pub(in crate::mir::builder) fn try_release_adopt_core_plan_for_pattern2_break_su
         return Ok(None);
     }
 
-    match compose_coreplan_for_pattern2_break_subset(builder, facts, ctx) {
+    let composed = if facts.value_join_needed {
+        try_compose_core_loop_v1_pattern2_break(builder, facts, ctx)
+    } else {
+        compose_coreplan_for_pattern2_break_subset(builder, facts, ctx)
+    };
+    match composed {
         Ok(Some(core)) => Ok(Some(core)),
         Ok(None) | Err(_) => Ok(None),
     }
@@ -410,7 +416,11 @@ pub(in crate::mir::builder) fn try_shadow_adopt_core_plan(
             if facts.facts.pattern2_break.is_none() {
                 return Err("pattern2 strict/dev adopt failed: facts mismatch".to_string());
             }
-            let core_plan = compose_coreplan_for_pattern2_break_subset(builder, facts, ctx)?
+            let core_plan = if facts.value_join_needed {
+                try_compose_core_loop_v1_pattern2_break(builder, facts, ctx)?
+            } else {
+                compose_coreplan_for_pattern2_break_subset(builder, facts, ctx)?
+            }
                 .ok_or_else(|| "pattern2 strict/dev adopt failed: compose rejected".to_string())?;
             Ok(Some(ShadowAdoptOutcome {
                 core_plan,
diff --git a/src/mir/builder/control_flow/plan/normalizer/pattern2_break.rs b/src/mir/builder/control_flow/plan/normalizer/pattern2_break.rs
index 1f1d7f11..0e1e18be 100644
--- a/src/mir/builder/control_flow/plan/normalizer/pattern2_break.rs
+++ b/src/mir/builder/control_flow/plan/normalizer/pattern2_break.rs
@@ -30,7 +30,7 @@ impl super::PlanNormalizer {
     /// ```
     ///
     /// Key: after_bb PHI merges break path and natural exit path carrier values.
-    pub(super) fn normalize_pattern2_break(
+    pub(in crate::mir::builder) fn normalize_pattern2_break(
         builder: &mut MirBuilder,
         parts: Pattern2BreakPlan,
         ctx: &LoopPatternContext,