phase29an(p6): gate planner by skeleton kind

src/mir/builder/control_flow/plan/planner/build.rs

@@ -45,6 +45,11 @@ pub(in crate::mir::builder) fn build_plan_from_facts_ctx(
     // unreachable in normal execution today. We still implement the SSOT
     // boundary here so that future Facts work cannot drift.
 
+    match facts.facts.skeleton.kind {
+        SkeletonKind::Loop => {}
+        _ => return Ok(None),
+    }
+
     let allow_pattern1 = match ctx.pattern_kind {
         Some(LoopPatternKind::Pattern1SimpleWhile) | None => true,
         Some(_) => false,
@@ -451,6 +456,37 @@ mod tests {
         }
     }
 
+    #[test]
+    fn planner_gates_non_loop_skeletons() {
+        let facts = LoopFacts {
+            condition_shape: ConditionShape::Unknown,
+            step_shape: StepShape::Unknown,
+            skeleton: SkeletonFacts {
+                kind: SkeletonKind::If2,
+            },
+            features: LoopFeatureFacts::default(),
+            scan_with_init: Some(ScanWithInitFacts {
+                loop_var: "i".to_string(),
+                haystack: "s".to_string(),
+                needle: "ch".to_string(),
+                step_lit: 1,
+            }),
+            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: None,
+            pattern2_loopbodylocal: None,
+        };
+        let canonical = canonicalize_loop_facts(facts);
+        let plan = build_plan_from_facts_ctx(&PlannerContext::default_for_legacy(), canonical)
+            .expect("Ok");
+        assert!(plan.is_none());
+    }
+
     #[test]
     fn planner_builds_pattern1_simplewhile_plan_from_facts() {
         let loop_condition = ASTNode::BinaryOp {