Fix source atom string projection recursion for #4182

dsl/gunbc/ci_github_actions_workflow.dag

@@ -103,6 +103,7 @@ data gunbc_ci_github_actions_workflow: Workflow = {
     }, {
       id: "affected",
       name: none,
+      continue_on_error: true,
       runner: SelfHosted { labels: ["self-hosted", "linux", "arm64"] },
       steps: [RunStep {
           name: Some { value: "Isolate toolchain dirs (srv1/srv2 shared-$HOME concurrent-rustup race)" },
@@ -179,7 +180,6 @@ data gunbc_ci_github_actions_workflow: Workflow = {
       if_condition: Some { value: "github.event.pull_request.draft != true" },
       strategy: none,
       timeout_minutes: Some { value: 15 },
-      continue_on_error: true,
       concurrency: none
     }, {
       id: "ci_floor",

src/v4/std/target_model.dag

@@ -48,10 +48,12 @@ import v4.std.node {
   Instantiation,
   Named,
   Node,
+  NodeFold,
   Positional,
   Symbol,
   TypeNode,
-  content_hash
+  content_hash,
+  fold_node
 }
 import v4.std.node_query { find_named_child, node_positional_child_targets }
 import v4.std.logic { Bool }
@@ -219,37 +221,93 @@ fn source_atom_char_projection_from_node(source: Node) -> Optional<SourceAtomVal
   }
 }
 
-// 🟡 gated — feature:free-monoid-node-projection — owner:Modeling DFS / std.algebra lane —
-// dissolve-on: std.algebra exports a canonical `Node -> Optional<FreeMonoid<T>>` (or
-// `Node -> Optional<String>`) projection over `free_monoid_type_node`'s encoded surface; replace
-// this local encoded-node projection with that accessor. The local recursion is fail-closed and
-// bounded to TS-ATOM-REALIZATION's String value-template bridge; forbidden: adding another
-// FreeMonoid storage walker outside this receipt.
-fn source_atom_string_projection_from_node(source: Node) -> Optional<SourceAtomValue> {
+// 🟡 coproduct dissolution — local fold state for fail-closed encoded FreeMonoid<Char>
+// projection; dissolve-on: std.algebra exports the canonical string/free-monoid projection
+// named by the `free-monoid-node-projection` receipt below.
+type SourceAtomStringProjectionFold
+  = SourceAtomStringFoldInit
+  | SourceAtomStringFoldHeadSeen
+  | SourceAtomStringFoldTailSeen
+  | SourceAtomStringFoldChar
+  | SourceAtomStringFoldString
+  | SourceAtomStringFoldInvalid
+
+fn source_atom_string_projection_fold_init(source: Node) -> SourceAtomStringProjectionFold {
   match source.kind {
     TypeNode { connective: Atom { identity: id } } =>
       if id == free_monoid_variant_empty {
-        optional_present(source_atom_string(value: source))
+        SourceAtomStringFoldString
       } else {
-        optional_absent()
+        match source_atom_char_projection_from_node(source: source) {
+          Present { value: _ } => SourceAtomStringFoldChar
+          Absent => SourceAtomStringFoldInvalid
+        }
       }
     TypeNode { connective: Conj } =>
-      match find_named_child(root: source, name: free_monoid_field_head) {
-        Accepted { value: head } =>
-          match find_named_child(root: source, name: free_monoid_field_tail) {
-            Accepted { value: tail } =>
-              match source_atom_char_projection_from_node(source: head) {
-                Present { value: _ } =>
-                  match source_atom_string_projection_from_node(source: tail) {
-                    Present { value: _ } => optional_present(source_atom_string(value: source))
-                    Absent => optional_absent()
-                  }
-                Absent => optional_absent()
-              }
-            Rejected { diagnostics: _ } => optional_absent()
+      if count(source.children) == 2 {
+        SourceAtomStringFoldInit
+      } else {
+        SourceAtomStringFoldInvalid
+      }
+    _ => SourceAtomStringFoldInvalid
+  }
+}
+
+fn source_atom_string_projection_fold_step(
+  acc: SourceAtomStringProjectionFold,
+  edge: Edge,
+  child: SourceAtomStringProjectionFold
+) -> SourceAtomStringProjectionFold {
+  match acc {
+    SourceAtomStringFoldInvalid => SourceAtomStringFoldInvalid
+    SourceAtomStringFoldString => SourceAtomStringFoldInvalid
+    SourceAtomStringFoldChar => SourceAtomStringFoldInvalid
+    _ =>
+      match edge.label {
+        Named { name: ename } =>
+          if ename == free_monoid_field_head {
+            match child {
+              SourceAtomStringFoldChar =>
+                match acc {
+                  SourceAtomStringFoldInit => SourceAtomStringFoldHeadSeen
+                  SourceAtomStringFoldTailSeen => SourceAtomStringFoldString
+                  _ => SourceAtomStringFoldInvalid
+                }
+              _ => SourceAtomStringFoldInvalid
+            }
+          } else if ename == free_monoid_field_tail {
+            match child {
+              SourceAtomStringFoldString =>
+                match acc {
+                  SourceAtomStringFoldInit => SourceAtomStringFoldTailSeen
+                  SourceAtomStringFoldHeadSeen => SourceAtomStringFoldString
+                  _ => SourceAtomStringFoldInvalid
+                }
+              _ => SourceAtomStringFoldInvalid
+            }
+          } else {
+            SourceAtomStringFoldInvalid
           }
-        Rejected { diagnostics: _ } => optional_absent()
+        _ => SourceAtomStringFoldInvalid
       }
+  }
+}
+
+// 🟡 gated — feature:free-monoid-node-projection — owner:Modeling DFS / std.algebra lane —
+// dissolve-on: std.algebra exports a canonical `Node -> Optional<FreeMonoid<T>>` (or
+// `Node -> Optional<String>`) projection over `free_monoid_type_node`'s encoded surface; replace
+// this local encoded-node projection with that accessor. The local recursion is fail-closed and
+// bounded to TS-ATOM-REALIZATION's String value-template bridge; forbidden: adding another
+// FreeMonoid storage walker outside this receipt.
+fn source_atom_string_projection_from_node(source: Node) -> Optional<SourceAtomValue> {
+  match fold_node(
+    n: source,
+    algebra: NodeFold {
+      init: source_atom_string_projection_fold_init,
+      step: source_atom_string_projection_fold_step
+    }
+  ) {
+    SourceAtomStringFoldString => optional_present(source_atom_string(value: source))
     _ => optional_absent()
   }
 }