diff --git a/src/v4/compiler/00_compile.dag b/src/v4/compiler/00_compile.dag
index 1cbb673f0f6..b4c7f10c681 100644
--- a/src/v4/compiler/00_compile.dag
+++ b/src/v4/compiler/00_compile.dag
@@ -27,7 +27,7 @@ import v4.std.diagnostic {
   ExternalContractUnknown,
   Locus,
   Outcome,
-  PortLocus,
+  port_locus,
   Rejected,
   Unavailable,
   bind_outcome,
@@ -217,7 +217,7 @@ fn compile_inferred(
     Eval { runtime: _ } =>
       outcome_rejected(
         compile_eval_not_realized_diagnostic(
-          at: PortLocus { port: compile_stage_locus_port }
+          at: port_locus(port: compile_stage_locus_port)
         )
       )
   }
@@ -290,7 +290,7 @@ fn compile_ingest_staging(source: Source, target: TargetModel) -> Outcome<Target
   Rejected {
     diagnostics: diagnostics_singleton(
       d: compile_pipeline_not_realized_diagnostic(
-        at: PortLocus { port: compile_stage_locus_port }
+        at: port_locus(port: compile_stage_locus_port)
       )
     )
   }
diff --git a/src/v4/compiler/02_parse.dag b/src/v4/compiler/02_parse.dag
index e8b9388e98b..7627517c26e 100644
--- a/src/v4/compiler/02_parse.dag
+++ b/src/v4/compiler/02_parse.dag
@@ -10,7 +10,7 @@ module v4.compiler.parse
 
 
 import v4.compiler.tokenize { TokenStream }
-import v4.std.diagnostic {Correction, Diagnostic, ExternalContractUnknown, Locus, Outcome, PortLocus, UserInputBoundary, Accepted, None, diagnostics_singleton}
+import v4.std.diagnostic {Correction, Diagnostic, ExternalContractUnknown, Locus, Outcome, port_locus, UserInputBoundary, Accepted, None, diagnostics_singleton}
 import v4.std.node { Atom, Conj, Edge, Named, Node, Symbol, TypeNode, well_formed }
 
 
@@ -210,9 +210,7 @@ fn grammar_to_node(grammar: Grammar) -> Node {
 
 
 fn parse(tokens: TokenStream, grammar: Grammar) -> Outcome<ParseTree> {
-  let at = PortLocus {
-    port: parse_stage_locus_port
-  }
+  let at = port_locus(port: parse_stage_locus_port)
   let ntok = count(tokens.tokens)
   let grammar_node = grammar_to_node(grammar: grammar)
   if !well_formed(n: grammar_node) {
diff --git a/src/v4/compiler/03_normalize.dag b/src/v4/compiler/03_normalize.dag
index 51b2f67af9b..82fb3bd5dbd 100644
--- a/src/v4/compiler/03_normalize.dag
+++ b/src/v4/compiler/03_normalize.dag
@@ -18,7 +18,7 @@ import v4.extdeps.languages.dag {
 }
 import v4.std.diagnostic {
   Diagnostic,
-  NodeLocus,
+  node_locus,
   Outcome,
   UserInputBoundary,
   Accepted,
@@ -93,7 +93,7 @@ fn classify_sugar(n: Node) -> SurfaceSugarKind? {
 fn malformed_sugar_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: normalize_reason_malformed_sugar,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: UserInputBoundary }
   }
 }
@@ -102,7 +102,7 @@ fn malformed_sugar_diagnostic(n: Node) -> Diagnostic {
 fn post_normalize_not_well_formed_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: normalize_reason_post_normalize_not_well_formed,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: UserInputBoundary }
   }
 }
diff --git a/src/v4/compiler/03_resolve.dag b/src/v4/compiler/03_resolve.dag
index a1d8e3aeae7..866312a3626 100644
--- a/src/v4/compiler/03_resolve.dag
+++ b/src/v4/compiler/03_resolve.dag
@@ -17,7 +17,7 @@ import v4.extdeps.languages.dag {
 import v4.std.collection { Set }
 import v4.std.diagnostic {
   Diagnostic,
-  NodeLocus,
+  node_locus,
   Outcome,
   UserInputBoundary,
   Accepted,
@@ -217,7 +217,7 @@ fn lookup_chain(s: Scope, name: Symbol) -> Symbol? {
 fn malformed_tree_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: resolve_reason_malformed_tree,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: UserInputBoundary }
   }
 }
@@ -226,7 +226,7 @@ fn malformed_tree_diagnostic(n: Node) -> Diagnostic {
 fn unbound_symbol_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: resolve_reason_unbound_symbol,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: UserInputBoundary }
   }
 }
diff --git a/src/v4/compiler/04_infer.dag b/src/v4/compiler/04_infer.dag
index 7957b5ad0e8..4795efa9e12 100644
--- a/src/v4/compiler/04_infer.dag
+++ b/src/v4/compiler/04_infer.dag
@@ -24,7 +24,7 @@ import v4.std.constraints {
 import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
   Unavailable,
   Accepted,
@@ -106,14 +106,14 @@ data infer_canonical_grounding_incoherent: Symbol = infer_canonical_grounding_in
 fn infer_facts_lookup_miss_diagnostic(key: Node) -> Diagnostic {
   Diagnostic {
     reason: infer_facts_lookup_miss,
-    at: NodeLocus { node: key },
+    at: node_locus(node: key),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn infer_canonical_grounding_incoherent_diagnostic(node: Node) -> Diagnostic {
   Diagnostic {
     reason: infer_canonical_grounding_incoherent,
-    at: NodeLocus { node: node },
+    at: node_locus(node: node),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
@@ -122,7 +122,7 @@ fn infer_canonical_grounding_incoherent_diagnostic(node: Node) -> Diagnostic {
 fn infer_descent_not_derived_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: infer_descent_not_derived,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/compiler/05_emit.dag b/src/v4/compiler/05_emit.dag
index 84ec6d6dd45..f6853d7ea5c 100644
--- a/src/v4/compiler/05_emit.dag
+++ b/src/v4/compiler/05_emit.dag
@@ -32,7 +32,7 @@ import v4.std.diagnostic {
   Accepted,
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
   Rejected,
   Unavailable,
@@ -46,7 +46,7 @@ data emit_serialize_emitted_mismatch: Symbol = emit_serialize_emitted_mismatch
 fn emit_serialize_emitted_mismatch_diagnostic(emitted: Node, target: TargetModel) -> Diagnostic {
   Diagnostic {
     reason: emit_serialize_emitted_mismatch,
-    at: NodeLocus { node: emitted },
+    at: node_locus(node: emitted),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/compiler/05_eval.dag b/src/v4/compiler/05_eval.dag
index 23343db47aa..f5912b6ee62 100644
--- a/src/v4/compiler/05_eval.dag
+++ b/src/v4/compiler/05_eval.dag
@@ -52,7 +52,7 @@ import v4.std.diagnostic {
   Correction,
   Diagnostic,
   NoCorrectionReason,
-  NodeLocus,
+  node_locus,
   Outcome,
   Unavailable,
   Accepted,
@@ -182,7 +182,7 @@ data eval_rejected_canonical_mismatch: Symbol = eval_rejected_canonical_mismatch
 fn eval_diagnostic(reason: Symbol, node: Node) -> Diagnostic {
   Diagnostic {
     reason: reason,
-    at: NodeLocus { node: node },
+    at: node_locus(node: node),
     correction: Unavailable { reason: AmbiguousIntent }
   }
 }
diff --git a/src/v4/compiler/06_translate.dag b/src/v4/compiler/06_translate.dag
index c75a9f6df68..6372689209d 100644
--- a/src/v4/compiler/06_translate.dag
+++ b/src/v4/compiler/06_translate.dag
@@ -33,9 +33,9 @@ import v4.std.diagnostic {
   Accepted,
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
-  PortLocus,
+  port_locus,
   Rejected,
   Unavailable,
   bind_outcome,
@@ -78,7 +78,7 @@ data translate_child_reattachment_not_realized: Symbol = translate_child_reattac
 fn translate_target_bundle_malformed_diagnostic(target: TargetModel) -> Diagnostic {
   Diagnostic {
     reason: translate_target_bundle_malformed,
-    at: NodeLocus { node: target },
+    at: node_locus(node: target),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
@@ -88,7 +88,7 @@ fn translate_target_bundle_duplicate_edge_diagnostic(
 ) -> Diagnostic {
   Diagnostic {
     reason: translate_target_bundle_duplicate_edge,
-    at: NodeLocus { node: target },
+    at: node_locus(node: target),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
@@ -125,14 +125,14 @@ fn target_bundle_child_lookup_step(
 fn translate_target_source_not_realized_diagnostic() -> Diagnostic {
   Diagnostic {
     reason: translate_target_source_not_realized,
-    at: PortLocus { port: translate_stage_locus_port },
+    at: port_locus(port: translate_stage_locus_port),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn translate_child_reattachment_not_realized_diagnostic(parent: Node) -> Diagnostic {
   Diagnostic {
     reason: translate_child_reattachment_not_realized,
-    at: NodeLocus { node: parent },
+    at: node_locus(node: parent),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/compiler/self_host.dag b/src/v4/compiler/self_host.dag
index 3756c570a58..0ae9edc63da 100644
--- a/src/v4/compiler/self_host.dag
+++ b/src/v4/compiler/self_host.dag
@@ -10,9 +10,9 @@ import v4.std.collection { List }
 import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
-  PortLocus,
+  port_locus,
   Rejected,
   Unavailable,
   diagnostics_singleton
@@ -76,7 +76,7 @@ data fixed_point_not_realized: Symbol = fixed_point_not_realized
 fn self_host_runner_not_realized_diagnostic() -> Diagnostic {
   Diagnostic {
     reason: self_host_runner_not_realized,
-    at: PortLocus { port: self_host_runner_port },
+    at: port_locus(port: self_host_runner_port),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
@@ -106,7 +106,7 @@ fn bootstrap_roundtrip_scaffold(
   Violates {
     diagnostic: Diagnostic {
       reason: bootstrap_roundtrip_not_realized,
-      at: NodeLocus { node: expected_stage },
+      at: node_locus(node: expected_stage),
       correction: Unavailable { reason: ExternalContractUnknown }
     }
   }
@@ -120,7 +120,7 @@ fn fixed_point_scaffold(
   Violates {
     diagnostic: Diagnostic {
       reason: fixed_point_not_realized,
-      at: NodeLocus { node: reference_stage },
+      at: node_locus(node: reference_stage),
       correction: Unavailable { reason: ExternalContractUnknown }
     }
   }
@@ -134,7 +134,7 @@ fn stage_emission_equality_scaffold(
   Violates {
     diagnostic: Diagnostic {
       reason: stage_emission_equality_not_realized,
-      at: NodeLocus { node: reference_stage1 },
+      at: node_locus(node: reference_stage1),
       correction: Unavailable { reason: ExternalContractUnknown }
     }
   }
diff --git a/src/v4/lens/affected_set_examples.dag b/src/v4/lens/affected_set_examples.dag
index a0eee16d1c3..11b4ee3e87c 100644
--- a/src/v4/lens/affected_set_examples.dag
+++ b/src/v4/lens/affected_set_examples.dag
@@ -8,7 +8,7 @@ module v4.lens.affected_set_examples
 
 import v4.std.diagnostic {
   Diagnostic,
-  NodeLocus,
+  node_locus,
   Unavailable,
   ExternalContractUnknown,
   diagnostics_singleton
@@ -52,7 +52,7 @@ data affected_set_example_edit: Edit = Edit {
 
 data affected_set_example_invalid_edit_diagnostic: Diagnostic = Diagnostic {
   reason: affected_set_example_reason,
-  at: NodeLocus { node: affected_set_example_node },
+  at: node_locus(node: affected_set_example_node),
   correction: Unavailable { reason: ExternalContractUnknown }
 }
 
diff --git a/src/v4/lens/cost.dag b/src/v4/lens/cost.dag
index c63171569c3..889ad69edd2 100644
--- a/src/v4/lens/cost.dag
+++ b/src/v4/lens/cost.dag
@@ -47,7 +47,7 @@ import v4.std.cardinality { NonZeroNat }
 import v4.std.diagnostic {
   AmbiguousIntent,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   Unavailable
 }
 import v4.std.node {
@@ -176,7 +176,7 @@ fn unknown_cost(reason: String) -> SymbolicCost {
 fn symbolic_cost_diagnostic(n: Node) -> Diagnostic {
   Diagnostic {
     reason: cost_reason_unmodeled_symbolic_cost,
-    at: NodeLocus { node: n },
+    at: node_locus(node: n),
     correction: Unavailable { reason: AmbiguousIntent }
   }
 }
diff --git a/src/v4/std/coercion.dag b/src/v4/std/coercion.dag
index 71fa4215af3..b56a407698a 100644
--- a/src/v4/std/coercion.dag
+++ b/src/v4/std/coercion.dag
@@ -17,7 +17,7 @@ import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
   None,
-  NodeLocus,
+  node_locus,
   Outcome,
   Rejected,
   Unavailable,
@@ -82,7 +82,7 @@ fn coercion_not_realized_diagnostic(
 ) -> Diagnostic {
   Diagnostic {
     reason: coercion_mismatch_reason(kind: kind),
-    at: NodeLocus { node: source.node },
+    at: node_locus(node: source.node),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
@@ -116,7 +116,7 @@ fn declared_inhabitant_candidates(inhabitants_root: Node) -> List<Node> {
 fn coercion_candidate_set_not_closed_diagnostic(inhabitants_root: Node) -> Diagnostic {
   Diagnostic {
     reason: coercion_mismatch_candidate_set_not_closed,
-    at: NodeLocus { node: inhabitants_root },
+    at: node_locus(node: inhabitants_root),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/std/constraints.dag b/src/v4/std/constraints.dag
index 67b719af4e7..bd449c84ddf 100644
--- a/src/v4/std/constraints.dag
+++ b/src/v4/std/constraints.dag
@@ -15,7 +15,7 @@ import v4.std.diagnostic {
   Accepted,
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -65,14 +65,14 @@ type CanonicalGroundingWitness {
 fn constraints_not_realized_diagnostic(graph: ConstraintGraph) -> Diagnostic {
   Diagnostic {
     reason: constraints_not_realized,
-    at: NodeLocus { node: graph.root },
+    at: node_locus(node: graph.root),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn constraints_ill_formed_root_diagnostic(graph: ConstraintGraph) -> Diagnostic {
   Diagnostic {
     reason: constraints_ill_formed_root,
-    at: NodeLocus { node: graph.root },
+    at: node_locus(node: graph.root),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/std/diagnostic.dag b/src/v4/std/diagnostic.dag
index 9391a79110a..510c9d34457 100644
--- a/src/v4/std/diagnostic.dag
+++ b/src/v4/std/diagnostic.dag
@@ -18,11 +18,16 @@ import v4.std.node { Node }
 type Extent
   = WholeFile
   | ByteRange { start: Int, end: Int }
+// 🟢 coproduct dissolution — L1.4.b Pattern B: Node/Port payload tags
+// are recoverable from the parameterized anchor type.
+type LocusAnchor<T> {
+  at: T
+}
 // 🟢 coproduct dissolution — CP-3229-GREEN-TERMINAL.
 type Locus
   = Textual { file: Symbol, extent: Extent }
-  | NodeLocus { node: Node }
-  | PortLocus { port: Symbol }
+  | NodeLocus { anchor: LocusAnchor<Node> }
+  | PortLocus { anchor: LocusAnchor<Symbol> }
 // 🟢 coproduct dissolution — CP-3229-GREEN-TERMINAL.
 type NoCorrectionReason
   = UserInputBoundary
@@ -59,6 +64,12 @@ type StageDiagnosticPolicy {
 fn diagnostics_singleton(d: Diagnostic) -> NonEmptyDiagnostics {
   NonEmptyDiagnostics { head: d, tail: [] }
 }
+fn node_locus(node: Node) -> Locus {
+  NodeLocus { anchor: LocusAnchor { at: node } }
+}
+fn port_locus(port: Symbol) -> Locus {
+  PortLocus { anchor: LocusAnchor { at: port } }
+}
 fn outcome_accepted<T>(value: T) -> Outcome<T> {
   Accepted { value: value, diagnostics: None }
 }
@@ -81,18 +92,18 @@ fn locus_eq(a: Locus, b: Locus) -> Bool {
   match a {
     Textual { file: fa, extent: ea } => match b {
       Textual { file: fb, extent: eb } => (fa == fb) && eq(a: ea, b: eb)
-      NodeLocus { node: _ } => false
-      PortLocus { port: _ } => false
+      NodeLocus { anchor: _ } => false
+      PortLocus { anchor: _ } => false
     }
-    NodeLocus { node: na } => match b {
+    NodeLocus { anchor: na } => match b {
       Textual { file: _, extent: _ } => false
-      NodeLocus { node: nb } => na == nb
-      PortLocus { port: _ } => false
+      NodeLocus { anchor: nb } => na.at == nb.at
+      PortLocus { anchor: _ } => false
     }
-    PortLocus { port: pa } => match b {
+    PortLocus { anchor: pa } => match b {
       Textual { file: _, extent: _ } => false
-      NodeLocus { node: _ } => false
-      PortLocus { port: pb } => pa == pb
+      NodeLocus { anchor: _ } => false
+      PortLocus { anchor: pb } => pa.at == pb.at
     }
   }
 }
diff --git a/src/v4/std/find_witness.dag b/src/v4/std/find_witness.dag
index d9de5053750..36cf188cf60 100644
--- a/src/v4/std/find_witness.dag
+++ b/src/v4/std/find_witness.dag
@@ -16,7 +16,7 @@ import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
   None,
-  NodeLocus,
+  node_locus,
   Outcome,
   Rejected,
   Unavailable,
@@ -63,28 +63,28 @@ type MultiplicityPolicy
 fn find_witness_no_candidate_diagnostic(source_facts: Node) -> Diagnostic {
   Diagnostic {
     reason: find_witness_reason_no_candidate,
-    at: NodeLocus { node: source_facts },
+    at: node_locus(node: source_facts),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn find_witness_ambiguous_candidate_diagnostic(source_facts: Node) -> Diagnostic {
   Diagnostic {
     reason: find_witness_reason_ambiguous_candidate,
-    at: NodeLocus { node: source_facts },
+    at: node_locus(node: source_facts),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn find_witness_not_realized_diagnostic(source_facts: Node) -> Diagnostic {
   Diagnostic {
     reason: find_witness_reason_not_realized,
-    at: NodeLocus { node: source_facts },
+    at: node_locus(node: source_facts),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn find_witness_invalid_witness_diagnostic(source_facts: Node) -> Diagnostic {
   Diagnostic {
     reason: find_witness_reason_invalid_witness,
-    at: NodeLocus { node: source_facts },
+    at: node_locus(node: source_facts),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/std/float.dag b/src/v4/std/float.dag
index b9df9f1ce6e..29737100875 100644
--- a/src/v4/std/float.dag
+++ b/src/v4/std/float.dag
@@ -11,7 +11,7 @@ module v4.std.float
 
 
 import v4.std.algebra { Ordering, Less, Equal, Greater }
-import v4.std.diagnostic {Diagnostic, Outcome, PortLocus, Unavailable, UserInputBoundary, Accepted, None, diagnostics_singleton}
+import v4.std.diagnostic {Diagnostic, Outcome, port_locus, Unavailable, UserInputBoundary, Accepted, None, diagnostics_singleton}
 import v4.std.logic { Bool }
 import v4.std.machine { Bit, Word32, Word64 }
 import v4.std.nat { Nat, nat_compare, is_zero }
@@ -164,7 +164,7 @@ fn float_body_compare_ieee_ordered_outcome(a: FloatBody, b: FloatBody) -> Outcom
 fn float_ordered_compare_nan_rejected() -> Outcome<Ordering> {
   Rejected { diagnostics: diagnostics_singleton(d: Diagnostic {
       reason: float_totalizer_reason_ieee754_nan_unordered,
-      at: PortLocus { port: float_totalizer_port_ieee754_nan_totalizer },
+      at: port_locus(port: float_totalizer_port_ieee754_nan_totalizer),
       correction: Unavailable { reason: UserInputBoundary },
     }) }
 }
diff --git a/src/v4/test/claim/algebra_laws/nat_semiring.dag b/src/v4/test/claim/algebra_laws/nat_semiring.dag
index 47b8af2eeec..03e6e223b15 100644
--- a/src/v4/test/claim/algebra_laws/nat_semiring.dag
+++ b/src/v4/test/claim/algebra_laws/nat_semiring.dag
@@ -12,7 +12,7 @@ module v4.test.claim.algebra_laws.nat_semiring
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -160,7 +160,7 @@ data claim_nat_add_wrong_identity_falsifies_law: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: algebra_law_violation_reason,
-        at: NodeLocus { node: falsification_nat_add_wrong_identity },
+        at: node_locus(node: falsification_nat_add_wrong_identity),
         correction: Suggested { node: nat_add_left_identity_input }
       }
     ),
diff --git a/src/v4/test/claim/diagnostic_correction/show_correct_code.dag b/src/v4/test/claim/diagnostic_correction/show_correct_code.dag
index 5f31dd00486..95494f40afe 100644
--- a/src/v4/test/claim/diagnostic_correction/show_correct_code.dag
+++ b/src/v4/test/claim/diagnostic_correction/show_correct_code.dag
@@ -14,9 +14,9 @@ import v4.std.diagnostic {
   ByteRange,
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
-  PortLocus,
+  port_locus,
   Rejected,
   Suggested,
   Textual,
@@ -117,7 +117,7 @@ data claim_complexity_diagnostic_suggests_correct_code: TestClaim = DiagnosticCl
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_complexity_reason,
-        at: NodeLocus { node: falsification_complexity_diagnostic_without_correct_code },
+        at: node_locus(node: falsification_complexity_diagnostic_without_correct_code),
         correction: Suggested { node: complexity_correction_expected_node }
       }
     ),
@@ -132,7 +132,7 @@ data claim_transport_diagnostic_suggests_shared_contract: TestClaim = Diagnostic
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_transport_reason,
-        at: NodeLocus { node: falsification_transport_diagnostic_without_correct_code },
+        at: node_locus(node: falsification_transport_diagnostic_without_correct_code),
         correction: Suggested { node: transport_correction_expected_node }
       }
     ),
@@ -147,7 +147,7 @@ data claim_ambiguous_boundary_diagnostic_names_no_correction_reason: TestClaim =
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_ambiguous_boundary_reason,
-        at: NodeLocus { node: falsification_ambiguous_boundary_without_unavailable_reason },
+        at: node_locus(node: falsification_ambiguous_boundary_without_unavailable_reason),
         correction: Unavailable { reason: AmbiguousIntent }
       }
     ),
@@ -192,7 +192,7 @@ data claim_port_diagnostic_carries_port_locus: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_port_reason,
-        at: PortLocus { port: correction_port_symbol },
+        at: port_locus(port: correction_port_symbol),
         correction: Suggested { node: transport_correction_expected_node }
       }
     ),
@@ -207,7 +207,7 @@ data claim_external_contract_diagnostic_names_no_correction_reason: TestClaim =
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_external_contract_reason,
-        at: NodeLocus { node: falsification_external_contract_without_reason },
+        at: node_locus(node: falsification_external_contract_without_reason),
         correction: Unavailable { reason: ExternalContractUnknown }
       }
     ),
@@ -222,7 +222,7 @@ data claim_user_boundary_diagnostic_names_no_correction_reason: TestClaim = Diag
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: correction_user_boundary_reason,
-        at: NodeLocus { node: falsification_user_boundary_without_reason },
+        at: node_locus(node: falsification_user_boundary_without_reason),
         correction: Unavailable { reason: UserInputBoundary }
       }
     ),
diff --git a/src/v4/test/claim/impossible_bug/idempotency_contract.dag b/src/v4/test/claim/impossible_bug/idempotency_contract.dag
index c4f585942ce..18213ce61da 100644
--- a/src/v4/test/claim/impossible_bug/idempotency_contract.dag
+++ b/src/v4/test/claim/impossible_bug/idempotency_contract.dag
@@ -38,7 +38,7 @@ module v4.test.claim.impossible_bug.idempotency_contract
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -109,7 +109,7 @@ data claim_repeated_append_in_idempotent_position_caught: TestClaim = Diagnostic
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: idempotency_repetition_reason,
-        at: NodeLocus { node: falsification_repeated_append_in_idempotent_position },
+        at: node_locus(node: falsification_repeated_append_in_idempotent_position),
         correction: Suggested { node: idempotent_inhabitant_input }
       }
     ),
@@ -124,7 +124,7 @@ data claim_nonidempotent_in_idempotent_position_caught: TestClaim = DiagnosticCl
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: idempotency_violation_reason,
-        at: NodeLocus { node: falsification_nonidempotent_in_idempotent_position },
+        at: node_locus(node: falsification_nonidempotent_in_idempotent_position),
         correction: Suggested { node: idempotent_inhabitant_input }
       }
     ),
diff --git a/src/v4/test/claim/impossible_bug/nested_optional_flatten.dag b/src/v4/test/claim/impossible_bug/nested_optional_flatten.dag
index 7d42273f9e3..4060819a297 100644
--- a/src/v4/test/claim/impossible_bug/nested_optional_flatten.dag
+++ b/src/v4/test/claim/impossible_bug/nested_optional_flatten.dag
@@ -24,7 +24,7 @@ module v4.test.claim.impossible_bug.nested_optional_flatten
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -101,7 +101,7 @@ data claim_optional_double_unwrap_rejected: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: double_unwrap_reason,
-        at: NodeLocus { node: falsification_optional_double_unwrap },
+        at: node_locus(node: falsification_optional_double_unwrap),
         correction: Suggested { node: flattened_optional_input }
       }
     ),
@@ -116,7 +116,7 @@ data claim_nested_optional_collapses: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: nested_optional_reason,
-        at: NodeLocus { node: falsification_nested_optional },
+        at: node_locus(node: falsification_nested_optional),
         correction: Suggested { node: flattened_optional_input }
       }
     ),
diff --git a/src/v4/test/claim/impossible_bug/suboptimal_complexity.dag b/src/v4/test/claim/impossible_bug/suboptimal_complexity.dag
index 97e1a5bde32..65816adbea4 100644
--- a/src/v4/test/claim/impossible_bug/suboptimal_complexity.dag
+++ b/src/v4/test/claim/impossible_bug/suboptimal_complexity.dag
@@ -42,7 +42,7 @@ module v4.test.claim.impossible_bug.suboptimal_complexity
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   NonEmptyDiagnostics,
   None,
   Outcome,
@@ -93,7 +93,7 @@ fn expected_complexity_rejection(input: Node, reason: Symbol, correction: Node)
   diagnostics_singleton(
     d: Diagnostic {
       reason: reason,
-      at: NodeLocus { node: input },
+      at: node_locus(node: input),
       correction: Suggested { node: correction }
     }
   )
diff --git a/src/v4/test/claim/impossible_bug/transport_type_drift.dag b/src/v4/test/claim/impossible_bug/transport_type_drift.dag
index d37a8f7ac81..f4202e3b1ab 100644
--- a/src/v4/test/claim/impossible_bug/transport_type_drift.dag
+++ b/src/v4/test/claim/impossible_bug/transport_type_drift.dag
@@ -24,7 +24,7 @@ module v4.test.claim.impossible_bug.transport_type_drift
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -103,7 +103,7 @@ data claim_target_contract_drift_impossible: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: target_transport_drift_reason,
-        at: NodeLocus { node: falsification_target_contract_drift },
+        at: node_locus(node: falsification_target_contract_drift),
         correction: Suggested { node: shared_wire_contract_input }
       }
     ),
@@ -118,7 +118,7 @@ data claim_wire_contract_drift_impossible: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: transport_drift_reason,
-        at: NodeLocus { node: falsification_wire_contract_drift },
+        at: node_locus(node: falsification_wire_contract_drift),
         correction: Suggested { node: shared_wire_contract_input }
       }
     ),
diff --git a/src/v4/test/claim/impossible_bug/unenumerated_effects.dag b/src/v4/test/claim/impossible_bug/unenumerated_effects.dag
index 6d145bb8051..8ddf833d9e2 100644
--- a/src/v4/test/claim/impossible_bug/unenumerated_effects.dag
+++ b/src/v4/test/claim/impossible_bug/unenumerated_effects.dag
@@ -27,7 +27,7 @@ module v4.test.claim.impossible_bug.unenumerated_effects
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -125,7 +125,7 @@ data claim_redundant_read_caught: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: redundant_read_reason,
-        at: NodeLocus { node: falsification_redundant_read },
+        at: node_locus(node: falsification_redundant_read),
         correction: Suggested { node: explicit_reread_input }
       }
     ),
diff --git a/src/v4/test/claim/impossible_bug/unhandled_diagnostic_paths.dag b/src/v4/test/claim/impossible_bug/unhandled_diagnostic_paths.dag
index f8a62c4378c..99640fa5041 100644
--- a/src/v4/test/claim/impossible_bug/unhandled_diagnostic_paths.dag
+++ b/src/v4/test/claim/impossible_bug/unhandled_diagnostic_paths.dag
@@ -26,7 +26,7 @@ module v4.test.claim.impossible_bug.unhandled_diagnostic_paths
 import v4.std.diagnostic {
   Accepted,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   None,
   Outcome,
   Rejected,
@@ -121,7 +121,7 @@ data claim_unproven_division_rejected: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: unhandled_division_reason,
-        at: NodeLocus { node: falsification_division_by_zero_unhandled },
+        at: node_locus(node: falsification_division_by_zero_unhandled),
         correction: Suggested { node: total_division_input }
       }
     ),
@@ -136,7 +136,7 @@ data claim_unproven_oob_index_rejected: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: unhandled_index_reason,
-        at: NodeLocus { node: falsification_oob_index_unhandled },
+        at: node_locus(node: falsification_oob_index_unhandled),
         correction: Suggested { node: checked_index_input }
       }
     ),
@@ -151,7 +151,7 @@ data claim_force_unwrap_count_zero: TestClaim = DiagnosticClaim {
   expected_rejection: diagnostics_singleton(
       d: Diagnostic {
         reason: force_unwrap_reason,
-        at: NodeLocus { node: falsification_force_unwrap_survives },
+        at: node_locus(node: falsification_force_unwrap_survives),
         correction: Suggested { node: total_unwrap_input }
       }
     ),
diff --git a/src/v4/test/claim/manual/diagnostic_assert_eval.dag b/src/v4/test/claim/manual/diagnostic_assert_eval.dag
index 2cd3b5b90ec..8f063435f69 100644
--- a/src/v4/test/claim/manual/diagnostic_assert_eval.dag
+++ b/src/v4/test/claim/manual/diagnostic_assert_eval.dag
@@ -20,7 +20,7 @@ import v4.compiler.eval {
 import v4.std.diagnostic {
   AmbiguousIntent,
   Diagnostic,
-  NodeLocus,
+  node_locus,
   NonEmptyDiagnostics,
   Outcome,
   Accepted,
@@ -55,7 +55,7 @@ fn diag_assert_node() -> Node {
 fn diag_assert_d() -> Diagnostic {
   Diagnostic {
     reason: diag_assert_reason,
-    at: NodeLocus { node: diag_assert_node() },
+    at: node_locus(node: diag_assert_node()),
     correction: Unavailable { reason: AmbiguousIntent }
   }
 }
@@ -64,7 +64,7 @@ fn diag_assert_d() -> Diagnostic {
 fn diag_assert_other_d() -> Diagnostic {
   Diagnostic {
     reason: diag_assert_other,
-    at: NodeLocus { node: diag_assert_node() },
+    at: node_locus(node: diag_assert_node()),
     correction: Unavailable { reason: AmbiguousIntent }
   }
 }
diff --git a/src/v4/test/claim/manual/eval_runtime_mvp.dag b/src/v4/test/claim/manual/eval_runtime_mvp.dag
index 0b05dd9815a..c76838cac33 100644
--- a/src/v4/test/claim/manual/eval_runtime_mvp.dag
+++ b/src/v4/test/claim/manual/eval_runtime_mvp.dag
@@ -28,7 +28,6 @@ import v4.std.diagnostic {
   Accepted,
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
   None,
   Outcome,
   Rejected,
diff --git a/src/v4/test/claim/manual/infer_emit_compile_anchor.dag b/src/v4/test/claim/manual/infer_emit_compile_anchor.dag
index ede13f686ee..a40011a7f62 100644
--- a/src/v4/test/claim/manual/infer_emit_compile_anchor.dag
+++ b/src/v4/test/claim/manual/infer_emit_compile_anchor.dag
@@ -23,9 +23,9 @@ import v4.std.collection { Map }
 import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
-  PortLocus,
+  port_locus,
   Unavailable
 }
 import v4.std.node { Conj, Node, Symbol, TypeNode }
@@ -78,7 +78,7 @@ data anchor_stub_inferred_facts: InferredFacts = InferredFacts {
   descent: Violates {
     diagnostic: Diagnostic {
       reason: anchor_stub_descent_not_derived,
-      at: NodeLocus { node: anchor_stub_empty_conj },
+      at: node_locus(node: anchor_stub_empty_conj),
       correction: Unavailable { reason: ExternalContractUnknown }
     }
   },
@@ -91,7 +91,7 @@ data anchor_stub_empty_facts_map: Map<Node, InferredFacts> = Map {
     Violates {
       diagnostic: Diagnostic {
         reason: anchor_facts_map_lookup_not_realized,
-        at: PortLocus { port: anchor_facts_map_lookup_not_realized },
+        at: port_locus(port: anchor_facts_map_lookup_not_realized),
         correction: Unavailable { reason: ExternalContractUnknown }
       }
     }
diff --git a/src/v4/test/claim/manual/outcome_diagnostics_eq.dag b/src/v4/test/claim/manual/outcome_diagnostics_eq.dag
index 1f4b68918ff..112c7ceda8a 100644
--- a/src/v4/test/claim/manual/outcome_diagnostics_eq.dag
+++ b/src/v4/test/claim/manual/outcome_diagnostics_eq.dag
@@ -10,7 +10,7 @@ module v4.test.claim.manual.outcome_diagnostics_eq
 
 import v4.std.diagnostic {
   Diagnostic,
-  NodeLocus,
+  node_locus,
   Unavailable,
   ExternalContractUnknown,
   NonEmptyDiagnostics,
@@ -34,14 +34,14 @@ data diag_eq_reason_y: Symbol = diag_eq_reason_y
 fn diag_eq_x() -> Diagnostic {
   Diagnostic {
     reason: diag_eq_reason_x,
-    at: NodeLocus { node: stub_empty_conj },
+    at: node_locus(node: stub_empty_conj),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
 fn diag_eq_y() -> Diagnostic {
   Diagnostic {
     reason: diag_eq_reason_y,
-    at: NodeLocus { node: stub_empty_conj },
+    at: node_locus(node: stub_empty_conj),
     correction: Unavailable { reason: ExternalContractUnknown }
   }
 }
diff --git a/src/v4/test/claim/manual/process_numeric_refinements.dag b/src/v4/test/claim/manual/process_numeric_refinements.dag
index afda5f0724f..7574a2748be 100644
--- a/src/v4/test/claim/manual/process_numeric_refinements.dag
+++ b/src/v4/test/claim/manual/process_numeric_refinements.dag
@@ -19,7 +19,7 @@ import v4.extdeps.posix {
 import v4.std.diagnostic {
   Accepted,
   Rejected,
-  NodeLocus
+  node_locus
 }
 import v4.std.node { Node }
 import v4.std.verification {
@@ -37,21 +37,21 @@ import v4.test.claim.manual.connective_anchors {
 
 
 fn witness_exit_code_256_rejects() -> Bool {
-  match make_exit_code(value: 256, at: NodeLocus { node: stub_empty_conj }) {
+  match make_exit_code(value: 256, at: node_locus(node: stub_empty_conj)) {
     Accepted { value: _, diagnostics: _ } => false
     Rejected { diagnostics } => diagnostics.head.reason == exit_code_out_of_range
   }
 }
 
 fn witness_process_id_zero_rejects() -> Bool {
-  match make_process_id(value: 0, at: NodeLocus { node: stub_empty_conj }) {
+  match make_process_id(value: 0, at: node_locus(node: stub_empty_conj)) {
     Accepted { value: _, diagnostics: _ } => false
     Rejected { diagnostics } => diagnostics.head.reason == process_id_out_of_range
   }
 }
 
 fn witness_signal_num_zero_rejects() -> Bool {
-  match make_signal_num(value: 0, at: NodeLocus { node: stub_empty_conj }) {
+  match make_signal_num(value: 0, at: node_locus(node: stub_empty_conj)) {
     Accepted { value: _, diagnostics: _ } => false
     Rejected { diagnostics } => diagnostics.head.reason == signal_num_out_of_range
   }
diff --git a/src/v4/test/claim/manual/validate_then_compile_public_terminal.dag b/src/v4/test/claim/manual/validate_then_compile_public_terminal.dag
index cc8abb31bae..c8c1fa4b35c 100644
--- a/src/v4/test/claim/manual/validate_then_compile_public_terminal.dag
+++ b/src/v4/test/claim/manual/validate_then_compile_public_terminal.dag
@@ -30,7 +30,7 @@ import v4.std.diagnostic {
   Accepted,
   None,
   Outcome,
-  PortLocus,
+  port_locus,
   Rejected,
   outcome_accepted,
   outcome_rejected
@@ -72,7 +72,7 @@ fn claim_symbol_node(s: Symbol) -> Node {
 fn always_reject_lens_gate(_tree: InferredTree) -> Outcome<Witness<Node>> {
   outcome_rejected(
     compile_lens_gate_rejected_diagnostic(
-      at: PortLocus { port: rejecting_lens_gate_at }
+      at: port_locus(port: rejecting_lens_gate_at)
     )
   )
 }
diff --git a/src/v4/test/claim/workflow/pipeline_rejections.dag b/src/v4/test/claim/workflow/pipeline_rejections.dag
index 7e00e6e9295..399b9ad4e61 100644
--- a/src/v4/test/claim/workflow/pipeline_rejections.dag
+++ b/src/v4/test/claim/workflow/pipeline_rejections.dag
@@ -38,7 +38,7 @@ import v4.std.node {
 import v4.std.diagnostic {
   Diagnostic,
   ExternalContractUnknown,
-  NodeLocus,
+  node_locus,
   Outcome,
   Accepted,
   None,
@@ -187,7 +187,7 @@ fn workflow_inferred_facts() -> InferredFacts {
     descent: Violates {
       diagnostic: Diagnostic {
         reason: inferred_descent_not_derived,
-        at: NodeLocus { node: resolved },
+        at: node_locus(node: resolved),
         correction: Unavailable { reason: ExternalContractUnknown }
       }
     },