phase29ao(p51): unify split-scan v0/v1 value-join path

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 (P50 done; see `docs/development/current/main/phases/phase-29ao/README.md`)
+- Next: TBD (P51 done; see `docs/development/current/main/phases/phase-29ao/README.md`)
 
 ## Gate (SSOT)
 

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, P50 done）
+- CorePlan migration: `docs/development/current/main/phases/phase-29ao/README.md`（Next: TBD, P51 done）
 
 ## Near-Term Candidates
 

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 (P50 done)
+- Next step: TBD (P51 done)
 
 ## 2. すでに固めた SSOT（再発防止の土台）
 

docs/development/current/main/phases/phase-29ao/README.md

@@ -276,6 +276,11 @@ Gate（SSOT）:
 - 指示書: `docs/development/current/main/phases/phase-29ao/P50-CORELOOPCOMPOSER-V1-PATTERN3-IFPHI-VALUEJOIN-INSTRUCTIONS.md`
 - ねらい: Pattern3 join を v1 で受理し、block_params/EdgeArgs 経由の PHI 一本化を維持（仕様不変）
 
+## P51: CoreLoopComposer v1 — Pattern7 value-join path unification ✅
+
+- 指示書: `docs/development/current/main/phases/phase-29ao/P51-CORELOOPCOMPOSER-V1-PATTERN7-VALUEJOIN-UNIFY-INSTRUCTIONS.md`
+- ねらい: Pattern7 の value-join を v1 に統一し、v0 は no-join 専用に固定（仕様不変）
+
 ## Next（planned）
 
 - Next: TBD

src/mir/builder/control_flow/plan/composer/coreloop_v1.rs

@@ -255,6 +255,47 @@ mod tests {
         assert!(matches!(composed, Some(crate::mir::builder::control_flow::plan::CorePlan::Loop(_))));
     }
 
+    #[test]
+    fn coreloop_v1_rejects_split_scan_without_value_join() {
+        let condition = ASTNode::Literal {
+            value: LiteralValue::Bool(true),
+            span: Span::unknown(),
+        };
+        let facts = LoopFacts {
+            condition_shape: ConditionShape::Unknown,
+            step_shape: StepShape::Unknown,
+            skeleton: SkeletonFacts {
+                kind: SkeletonKind::Loop,
+            },
+            features: LoopFeatureFacts::default(),
+            scan_with_init: None,
+            split_scan: Some(crate::mir::builder::control_flow::plan::facts::loop_facts::SplitScanFacts {
+                s_var: "s".to_string(),
+                sep_var: "sep".to_string(),
+                result_var: "result".to_string(),
+                i_var: "i".to_string(),
+                start_var: "start".to_string(),
+                shape: SplitScanShape::Minimal,
+            }),
+            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: None,
+            pattern2_loopbodylocal: None,
+        };
+        let canonical = canonicalize_loop_facts(facts);
+        let mut builder = MirBuilder::new();
+        builder.enter_function_for_test("coreloop_v1_split_scan_no_join".to_string());
+        let ctx =
+            LoopPatternContext::new(&condition, &[], "coreloop_v1_split_scan_no_join", false, false);
+        let composed =
+            try_compose_core_loop_v1(&mut builder, &canonical, &ctx).expect("Ok");
+        assert!(composed.is_none());
+    }
+
     #[test]
     fn coreloop_v1_rejects_split_scan_with_disallowed_exitmap() {
         let condition = ASTNode::Literal {