Live-read classification P1: G2 call-reachability over fn-arrow skeletons

docs/plans/live-read-witness-classification-design.md

@@ -265,7 +265,19 @@ Phases are ordered; each closes at a named consumer tier.
 
 ---
 
-## 13. Open sub-threads
+## 14. Hand-Rust scaffold receipt (P1 G2 marshal)
+
+**Authority:** `v2.std.fn_index::fn_arrow_skeleton_g2_marshal_host_scaffold_dissolution_trigger`
+
+**Seed-retained site:** `src/v1/stage0/src/coproduct_reflection.rs` — `marshal_string_literal_atom`, `hoist_call_arg_string_literal_edges`, and callee/literal atoms on `marshal_generic` for `ExprCall` nodes. These expand the fn-arrow skeleton corpus-wide so G2 can stat string-literal path arguments and callee chains from `fn_arrow_decl_facts_live()`.
+
+**Dissolution trigger:** fn-arrow body projection becomes a modeled substrate fold (the #5364 self-host corridor for `eval_fn_arrow_decl_facts_live`) emitting equivalent skeleton `Node` facts without hand-Rust marshal expansion in `coproduct_reflection.rs`.
+
+**Witness:** `v2.test.claim.live_read_classification_test::g2_fn_arrow_marshal_host_scaffold_receipt_is_checkable` (Scaffold disposition row is checkable by execution).
+
+---
+
+## 15. Open sub-threads
 
 - **Path pattern static analysis depth** — how many `filesystem_read` path arguments are literal at G2 vs require `Unknown` never-skip.
 - **Namespace-only resolution terminal step** — import edges become `container.member` references; carrier registry and G2 must be edge-source-agnostic (same constraint as `dependency_edge_source_migration_note` in `module_graph.dag`).

src/v1/stage0/src/coproduct_reflection.rs

@@ -618,6 +618,45 @@ fn marshal_skeleton(
     }
 }
 
+// SCAFFOLD (§7 hand-Rust shrink-to-zero): G2 live-read skeleton marshal expansion
+// (`marshal_string_literal_atom`, `hoist_call_arg_string_literal_edges`, callee atoms on
+// `ExprCall`) — see `v2.std.fn_index::fn_arrow_skeleton_g2_marshal_host_scaffold_dissolution_trigger`.
+// Host SOURCE half for P1 G2 call-reachability (docs/plans/live-read-witness-classification-design.md §9 P1 / §14).
+// Dissolves when fn-arrow body projection is a modeled substrate fold (same #5364 corridor as
+// `eval_fn_arrow_decl_facts_live`) rather than hand-Rust marshal in this module.
+fn marshal_string_literal_atom(
+    ctx: &InterpContext,
+    node: &Rc<Node>,
+) -> Option<Value> {
+    match node.expr_data.as_ref() {
+        ExprData::ExprLiteral { value, .. } => match value.as_ref() {
+            crate::std_syntax::LiteralValue::LitStr { value: s, .. } => {
+                Some(edge_positional(ctx, atom_identity_node(ctx, s)))
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+fn hoist_call_arg_string_literal_edges(
+    ctx: &InterpContext,
+    node: &Rc<Node>,
+    edges: &mut Vec<Value>,
+) {
+    if let Some(literal_edge) = marshal_string_literal_atom(ctx, node) {
+        edges.push(literal_edge);
+        return;
+    }
+    if let Some(child0) = node.children.first() {
+        if let Some(literal_edge) = marshal_string_literal_atom(ctx, child0) {
+            edges.push(literal_edge);
+        } else {
+            hoist_call_arg_string_literal_edges(ctx, child0, edges);
+        }
+    }
+}
+
 fn marshal_generic(
     ctx: &InterpContext,
     node: &Rc<Node>,
@@ -629,6 +668,13 @@ fn marshal_generic(
     let mut refs: std::collections::BTreeSet<String> = std::collections::BTreeSet::new();
     if node_references_param(node, &name, param_names) {
         edges.push(edge_positional(ctx, atom_identity_node(ctx, &name)));
+    } else if matches!(node.expr_data.as_ref(), ExprData::ExprCall { .. }) && !name.is_empty() {
+        // G2 live-read call reachability: callee atoms make cross-fn carrier chains
+        // visible in the fn-arrow skeleton (docs/plans/live-read-witness-classification-design.md P1).
+        edges.push(edge_positional(ctx, atom_identity_node(ctx, &name)));
+    }
+    if let Some(literal_edge) = marshal_string_literal_atom(ctx, node) {
+        edges.push(literal_edge);
     }
     if let Some(ref_name) = node_local_reference_name(node, &name) {
         refs.insert(ref_name);
@@ -638,6 +684,11 @@ fn marshal_generic(
         edges.push(edge_positional(ctx, child_skel));
         refs.extend(child_refs);
     }
+    if matches!(node.expr_data.as_ref(), ExprData::ExprCall { .. }) {
+        for child in node.children.iter() {
+            hoist_call_arg_string_literal_edges(ctx, child, &mut edges);
+        }
+    }
     if let Some(inner) = node.body.as_ref() {
         let (inner_skel, inner_refs) = marshal_skeleton(ctx, inner, param_names, si);
         edges.push(edge_positional(ctx, inner_skel));