Repair red main: admit the add-arrow fixture through the door instead of casting past it

src/v2/test/claim/body_lowering/arrow_body_form_witness_test.dag

@@ -1,5 +1,6 @@
 module v2.test.claim.body_lowering.arrow_body_form_witness
 
+import v2.compiler.normalized_tree { NormalizedTree, admit_normalized_tree }
 import v2.compiler.resolve { resolve }
 import v2.extdeps.languages.dag {
   dag_add_arrow_with_body_node,
@@ -10,7 +11,7 @@ import v2.extdeps.languages.dag {
   dag_match_arrow_with_body_node,
   dag_type_atom_node
 }
-import v2.std.diagnostic { Accepted, Rejected }
+import v2.std.diagnostic { Accepted, None, Outcome, Rejected }
 import v2.std.node {
   Arrow,
   Atom,
@@ -115,26 +116,40 @@ fn arrow_body_form_zero_arrow_fixture() -> Optional<Node> {
   }
 }
 
+// The add-arrow fixture reaches `resolve` through the admission door, never as a raw
+// `Node`. `resolve` declares `tree: NormalizedTree`, and BL-1 sealed that carrier so the
+// only way in is `admit_normalized_tree`; a fixture that reached past it would plant the
+// wrapper-payload conflation this witness population exists to keep out. The `Rejected`
+// arm FAILS the witness rather than skipping it — an unadmittable fixture is a defect in
+// the fixture, not a reason to report green.
+fn abf_admitted_add_arrow_tree() -> Outcome<NormalizedTree> {
+  admit_normalized_tree(root: dag_add_arrow_with_body_node(), diagnostics: None)
+}
+
 test fn arrow_body_form_eval_value_vertical_holds() -> Bool {
   let lm = dag_language_model()
   match arrow_body_form_zero_arrow_fixture() {
     Absent => false
     Present { value: zero_arrow } =>
-      match resolve(tree: dag_add_arrow_with_body_node(), lm: lm) {
-        Accepted { value: add_arrow, diagnostics: _ } =>
-          arrow_body_form_eval_unary_int_holds(
-            callee: arrow_body_form_id_arrow_fixture(),
-            arg_lex: "7",
-            expected: 7
-          )
-            && arrow_body_form_eval_nullary_int_holds(callee: zero_arrow, expected: 0)
-            && arrow_body_form_eval_binary_int_holds(
-              callee: add_arrow,
-              left_lex: "2",
-              right_lex: "3",
-              expected: 5
-            )
+      match abf_admitted_add_arrow_tree() {
         Rejected { diagnostics: _ } => false
+        Accepted { value: admitted_tree, diagnostics: _ } =>
+          match resolve(tree: admitted_tree, lm: lm) {
+            Accepted { value: add_arrow, diagnostics: _ } =>
+              arrow_body_form_eval_unary_int_holds(
+                callee: arrow_body_form_id_arrow_fixture(),
+                arg_lex: "7",
+                expected: 7
+              )
+                && arrow_body_form_eval_nullary_int_holds(callee: zero_arrow, expected: 0)
+                && arrow_body_form_eval_binary_int_holds(
+                  callee: add_arrow,
+                  left_lex: "2",
+                  right_lex: "3",
+                  expected: 5
+                )
+            Rejected { diagnostics: _ } => false
+          }
       }
   }
 }