From f5f9ff96ad1c3f0233b2896fb856ba50d7cab0f8 Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 18:41:32 +0000
Subject: [PATCH 1/6] WIP: Optional-return emission fix (05_emit_rust.dag): T?
 fn returns emit bare

---
 src/v1/05_emit_rust.dag                       | 22 +++++++++++--------
 .../src/optional_carrier_signature_test.rs    | 22 +++++++++++++++++++
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/v1/05_emit_rust.dag b/src/v1/05_emit_rust.dag
index fd294b0f617..e9dfa469901 100644
--- a/src/v1/05_emit_rust.dag
+++ b/src/v1/05_emit_rust.dag
@@ -510,10 +510,14 @@ fn render_rust_shared_type_if_needed(type_name: String, rendered: String, shared
   } else { rendered }
 }
 
+fn render_rust_shared_type_with_optional(n: Node, type_name: String, rendered: String, shared_types: Set<String>) -> String {
+  rust_carrier_optional_wrap(n: n, rendered: render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types))
+}
+
 fn render_rust_applied_type_shared(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
   let rendered = render_rust_applied_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   let type_name = authored_name_at(source_indices: source_indices, node: n)
-  render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types)
+  render_rust_shared_type_with_optional(n: n, type_name: type_name, rendered: rendered, shared_types: shared_types)
 }
 
 fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
@@ -535,10 +539,10 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
       } else if n.connective == NoConnective && n.children |> count == 0 && applied_prop == none && set_contains(shared_types, name) {
         let rendered = rust_render_type_leaf_name(name: name, variant_to_enum: variant_to_enum)
-        render_rust_shared_type_if_needed(type_name: name, rendered: rendered, shared_types: shared_types)
+        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: rendered, shared_types: shared_types)
       } else if n.connective == NoConnective && n.children |> count > 0 {
         if !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-          render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+          render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
         } else {
         let base = rust_applied_type_base(name: name, corpus_repr: corpus_repr)
         let peel = is_parametric_opaque_type_by_name(env: env, type_name: name)
@@ -569,7 +573,7 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         } else {
           concat(base, "<", arg_list |> join(separator: ", "), ">")
         }
-        render_rust_shared_type_if_needed(type_name: name, rendered: applied_ty, shared_types: shared_types)
+        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: applied_ty, shared_types: shared_types)
         }
       } else {
         render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
@@ -622,9 +626,9 @@ fn render_rust_fn_sig_type(n: Node, generic_param_names: List<String>, shared_ty
   if n.connective == NoConnective && n.children |> count == 0 && name == "String" && corpus_repr_is_faithful(corpus_repr: corpus_repr) {
     rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
   } else if n.connective == NoConnective && n.children |> count == 0 && name != "" && name != "String" && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: name, corpus_repr: corpus_repr) {
-    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
   } else if n.connective == NoConnective && n.children |> count > 0 && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
   } else if generic_param_names |> count > 0 {
     render_rust_decl_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   } else {
@@ -638,7 +642,7 @@ fn render_rust_fn_sig_type_applied_binding(n: Node, shared_types: Set<String>, c
       if applied.children |> count > 0 {
         let outer_name = authored_name_at(source_indices: source_indices, node: n)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: outer_name, corpus_repr: corpus_repr) {
-          render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+          render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
         } else {
           render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
         }
@@ -3391,9 +3395,9 @@ fn render_rust_type_with_applied_binding(n: Node, shared_types: Set<String>, cor
         let applied_name = authored_name_at(source_indices: source_indices, node: applied)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 {
           if outer_name != applied_name {
-            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else if set_contains(shared_types, outer_name) {
-            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else {
             render_rust_applied_type_shared(n: applied, generic_param_names: [], shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: empty_map(), env: TypeEnv { bindings: empty_map(), str_bindings: empty_map(), ancestry_str_bindings: empty_map(), parents: [], recursive_types: [], recursive_type_set: empty_map(), inductive_fields: empty_map(), source_indices: source_indices, intern_table: empty_intern_table() })
           }
diff --git a/src/v1/tests/src/optional_carrier_signature_test.rs b/src/v1/tests/src/optional_carrier_signature_test.rs
index 177eab13263..7a918b94321 100644
--- a/src/v1/tests/src/optional_carrier_signature_test.rs
+++ b/src/v1/tests/src/optional_carrier_signature_test.rs
@@ -60,3 +60,25 @@ fn non_optional_string_return_stays_bare() {
         "a non-optional `-> String` must NOT be wrapped in Option, got:\n{sig}"
     );
 }
+
+#[test]
+fn optional_shared_type_return_renders_option_rc_signature() {
+    let source = "module optsig.fixture\n\ntype Node = Product { }\n\nfn maybe_node(flag: Bool) -> Node? {\n  if flag { Present { value: Node { } } } else { none }\n}\n";
+    let emitted = emit(source);
+    let sig = return_sig(&emitted, "maybe_node");
+    assert!(
+        sig.contains("Option<") && sig.contains("Rc<"),
+        "a `-> Node?` return on a shared type must render `Option<Rc<..>>`, got:\n{sig}"
+    );
+}
+
+#[test]
+fn non_optional_shared_type_return_stays_bare_rc() {
+    let source = "module optsig.fixture\n\ntype Node = Product { }\n\nfn always_node(flag: Bool) -> Node {\n  Node { }\n}\n";
+    let emitted = emit(source);
+    let sig = return_sig(&emitted, "always_node");
+    assert!(
+        sig.contains("Rc<") && !sig.contains("Option<"),
+        "a non-optional `-> Node` must render bare `Rc<..>` without Option, got:\n{sig}"
+    );
+}

From c0332f42ed025090b9754845380662ff1d48de4f Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 18:53:34 +0000
Subject: [PATCH 2/6] WIP: Optional-return emission fix (05_emit_rust.dag): T?
 fn returns emit bare

---
 src/v1/stage0/src/v1_compiler_emit_rust.rs | 46 +++++++++++++++++-----
 1 file changed, 37 insertions(+), 9 deletions(-)

diff --git a/src/v1/stage0/src/v1_compiler_emit_rust.rs b/src/v1/stage0/src/v1_compiler_emit_rust.rs
index 60155a09595..e0389607b1e 100644
--- a/src/v1/stage0/src/v1_compiler_emit_rust.rs
+++ b/src/v1/stage0/src/v1_compiler_emit_rust.rs
@@ -892,6 +892,18 @@ pub fn render_rust_shared_type_if_needed(
     }
 }
 
+pub fn render_rust_shared_type_with_optional(
+    n: Rc<Node>,
+    type_name: String,
+    rendered: String,
+    shared_types: Rc<std::collections::BTreeSet<String>>,
+) -> String {
+    rust_carrier_optional_wrap(
+        n.clone(),
+        render_rust_shared_type_if_needed(type_name, rendered, shared_types),
+    )
+}
+
 pub fn render_rust_applied_type_shared(
     n: Rc<Node>,
     generic_param_names: Rc<Vec<String>>,
@@ -912,7 +924,7 @@ pub fn render_rust_applied_type_shared(
             env,
         );
         let type_name = authored_name_at(source_indices.clone(), n.clone());
-        render_rust_shared_type_if_needed(type_name, rendered, shared_types.clone())
+        render_rust_shared_type_with_optional(n.clone(), type_name, rendered, shared_types.clone())
     }
 }
 
@@ -992,7 +1004,8 @@ pub fn render_rust_decl_type(
                                     name.clone(),
                                     variant_to_enum.clone(),
                                 );
-                                render_rust_shared_type_if_needed(
+                                render_rust_shared_type_with_optional(
+                                    n.clone(),
                                     name.clone(),
                                     rendered,
                                     shared_types.clone(),
@@ -1005,7 +1018,8 @@ pub fn render_rust_decl_type(
                                 if (!is_container_type(name.clone())
                                     && rust_fn_sig_peel_closed_alias(env.clone(), n.clone()))
                                 {
-                                    render_rust_shared_type_if_needed(
+                                    render_rust_shared_type_with_optional(
+                                        n.clone(),
                                         name.clone(),
                                         name.clone(),
                                         shared_types.clone(),
@@ -1135,7 +1149,8 @@ pub fn render_rust_decl_type(
                                                 }
                                             }
                                         };
-                                        render_rust_shared_type_if_needed(
+                                        render_rust_shared_type_with_optional(
+                                            n.clone(),
                                             name.clone(),
                                             applied_ty,
                                             shared_types.clone(),
@@ -1249,13 +1264,23 @@ pub fn render_rust_fn_sig_type(
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
             && rust_fn_sig_preserves_authored_alias_leaf(name.clone(), corpus_repr.clone())
         {
-            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
+            render_rust_shared_type_with_optional(
+                n.clone(),
+                name.clone(),
+                name.clone(),
+                shared_types.clone(),
+            )
         } else if (n.connective.clone() == Connective::NoConnective)
             && ((n.children.clone().len() as i64) > 0)
             && !is_container_type(name.clone())
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
         {
-            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
+            render_rust_shared_type_with_optional(
+                n.clone(),
+                name.clone(),
+                name.clone(),
+                shared_types.clone(),
+            )
         } else if ((generic_param_names.clone().len() as i64) > 0) {
             render_rust_decl_type(
                 n.clone(),
@@ -1303,7 +1328,8 @@ pub fn render_rust_fn_sig_type_applied_binding(
                             corpus_repr.clone(),
                         )
                     {
-                        render_rust_shared_type_if_needed(
+                        render_rust_shared_type_with_optional(
+                            n.clone(),
                             outer_name.clone(),
                             outer_name.clone(),
                             shared_types,
@@ -8173,14 +8199,16 @@ pub fn render_rust_type_with_applied_binding(
                             && ((n.children.clone().len() as i64) == 0))
                         {
                             if (outer_name.clone() != applied_name) {
-                                render_rust_shared_type_if_needed(
+                                render_rust_shared_type_with_optional(
+                                    n.clone(),
                                     outer_name.clone(),
                                     outer_name.clone(),
                                     shared_types.clone(),
                                 )
                             } else {
                                 if v1_rt::set_contains(&shared_types, outer_name.clone()) {
-                                    render_rust_shared_type_if_needed(
+                                    render_rust_shared_type_with_optional(
+                                        n.clone(),
                                         outer_name.clone(),
                                         outer_name.clone(),
                                         shared_types.clone(),

From 2cf3420e9ae0a4de6dc727f4b196f04c408a2851 Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 19:00:58 +0000
Subject: [PATCH 3/6] Fix optional shared-type signature tests to use recursive
 fixtures.

Empty Product types are type-constants and skip shared_types Rc wrapping;
use a self-referential Node so the witness exercises Option<Rc<T>> emission.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 src/v1/tests/src/optional_carrier_signature_test.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/v1/tests/src/optional_carrier_signature_test.rs b/src/v1/tests/src/optional_carrier_signature_test.rs
index 7a918b94321..55db36b6cf0 100644
--- a/src/v1/tests/src/optional_carrier_signature_test.rs
+++ b/src/v1/tests/src/optional_carrier_signature_test.rs
@@ -63,7 +63,8 @@ fn non_optional_string_return_stays_bare() {
 
 #[test]
 fn optional_shared_type_return_renders_option_rc_signature() {
-    let source = "module optsig.fixture\n\ntype Node = Product { }\n\nfn maybe_node(flag: Bool) -> Node? {\n  if flag { Present { value: Node { } } } else { none }\n}\n";
+    // Recursive struct so `Node` is in `shared_types` and fn-sig emission applies Rc.
+    let source = "module optsig.fixture\n\ntype Node = Product { child: Node? }\n\nfn maybe_node(flag: Bool) -> Node? {\n  if flag { Present { value: Node { child: none } } } else { none }\n}\n";
     let emitted = emit(source);
     let sig = return_sig(&emitted, "maybe_node");
     assert!(
@@ -74,7 +75,7 @@ fn optional_shared_type_return_renders_option_rc_signature() {
 
 #[test]
 fn non_optional_shared_type_return_stays_bare_rc() {
-    let source = "module optsig.fixture\n\ntype Node = Product { }\n\nfn always_node(flag: Bool) -> Node {\n  Node { }\n}\n";
+    let source = "module optsig.fixture\n\ntype Node = Product { child: Node? }\n\nfn always_node(_flag: Bool) -> Node {\n  Node { child: none }\n}\n";
     let emitted = emit(source);
     let sig = return_sig(&emitted, "always_node");
     assert!(

From cfc3ecf6c7a76705560b135cfd7155d9e917c225 Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 19:32:04 +0000
Subject: [PATCH 4/6] ci: re-trigger rust_tests after 15m nextest timeout on
 cold sccache.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

No code change — fmt/clippy/optional_carrier_signature verified green locally.

Co-authored-by: Cursor <cursoragent@cursor.com>

From bf29ebfa7e17862fc3a9e9c0e88bb3328da4fc0c Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 19:38:31 +0000
Subject: [PATCH 5/6] WIP: Optional-return emission fix (05_emit_rust.dag): T?
 fn returns emit bare

---
 src/v1/05_emit_rust.dag                    | 22 +++++------
 src/v1/stage0/src/v1_compiler_emit_rust.rs | 46 +++++-----------------
 2 files changed, 18 insertions(+), 50 deletions(-)

diff --git a/src/v1/05_emit_rust.dag b/src/v1/05_emit_rust.dag
index e9dfa469901..fd294b0f617 100644
--- a/src/v1/05_emit_rust.dag
+++ b/src/v1/05_emit_rust.dag
@@ -510,14 +510,10 @@ fn render_rust_shared_type_if_needed(type_name: String, rendered: String, shared
   } else { rendered }
 }
 
-fn render_rust_shared_type_with_optional(n: Node, type_name: String, rendered: String, shared_types: Set<String>) -> String {
-  rust_carrier_optional_wrap(n: n, rendered: render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types))
-}
-
 fn render_rust_applied_type_shared(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
   let rendered = render_rust_applied_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   let type_name = authored_name_at(source_indices: source_indices, node: n)
-  render_rust_shared_type_with_optional(n: n, type_name: type_name, rendered: rendered, shared_types: shared_types)
+  render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types)
 }
 
 fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
@@ -539,10 +535,10 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
       } else if n.connective == NoConnective && n.children |> count == 0 && applied_prop == none && set_contains(shared_types, name) {
         let rendered = rust_render_type_leaf_name(name: name, variant_to_enum: variant_to_enum)
-        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: rendered, shared_types: shared_types)
+        render_rust_shared_type_if_needed(type_name: name, rendered: rendered, shared_types: shared_types)
       } else if n.connective == NoConnective && n.children |> count > 0 {
         if !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-          render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
+          render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
         } else {
         let base = rust_applied_type_base(name: name, corpus_repr: corpus_repr)
         let peel = is_parametric_opaque_type_by_name(env: env, type_name: name)
@@ -573,7 +569,7 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         } else {
           concat(base, "<", arg_list |> join(separator: ", "), ">")
         }
-        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: applied_ty, shared_types: shared_types)
+        render_rust_shared_type_if_needed(type_name: name, rendered: applied_ty, shared_types: shared_types)
         }
       } else {
         render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
@@ -626,9 +622,9 @@ fn render_rust_fn_sig_type(n: Node, generic_param_names: List<String>, shared_ty
   if n.connective == NoConnective && n.children |> count == 0 && name == "String" && corpus_repr_is_faithful(corpus_repr: corpus_repr) {
     rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
   } else if n.connective == NoConnective && n.children |> count == 0 && name != "" && name != "String" && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: name, corpus_repr: corpus_repr) {
-    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
   } else if n.connective == NoConnective && n.children |> count > 0 && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
   } else if generic_param_names |> count > 0 {
     render_rust_decl_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   } else {
@@ -642,7 +638,7 @@ fn render_rust_fn_sig_type_applied_binding(n: Node, shared_types: Set<String>, c
       if applied.children |> count > 0 {
         let outer_name = authored_name_at(source_indices: source_indices, node: n)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: outer_name, corpus_repr: corpus_repr) {
-          render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+          render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
         } else {
           render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
         }
@@ -3395,9 +3391,9 @@ fn render_rust_type_with_applied_binding(n: Node, shared_types: Set<String>, cor
         let applied_name = authored_name_at(source_indices: source_indices, node: applied)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 {
           if outer_name != applied_name {
-            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else if set_contains(shared_types, outer_name) {
-            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else {
             render_rust_applied_type_shared(n: applied, generic_param_names: [], shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: empty_map(), env: TypeEnv { bindings: empty_map(), str_bindings: empty_map(), ancestry_str_bindings: empty_map(), parents: [], recursive_types: [], recursive_type_set: empty_map(), inductive_fields: empty_map(), source_indices: source_indices, intern_table: empty_intern_table() })
           }
diff --git a/src/v1/stage0/src/v1_compiler_emit_rust.rs b/src/v1/stage0/src/v1_compiler_emit_rust.rs
index e0389607b1e..60155a09595 100644
--- a/src/v1/stage0/src/v1_compiler_emit_rust.rs
+++ b/src/v1/stage0/src/v1_compiler_emit_rust.rs
@@ -892,18 +892,6 @@ pub fn render_rust_shared_type_if_needed(
     }
 }
 
-pub fn render_rust_shared_type_with_optional(
-    n: Rc<Node>,
-    type_name: String,
-    rendered: String,
-    shared_types: Rc<std::collections::BTreeSet<String>>,
-) -> String {
-    rust_carrier_optional_wrap(
-        n.clone(),
-        render_rust_shared_type_if_needed(type_name, rendered, shared_types),
-    )
-}
-
 pub fn render_rust_applied_type_shared(
     n: Rc<Node>,
     generic_param_names: Rc<Vec<String>>,
@@ -924,7 +912,7 @@ pub fn render_rust_applied_type_shared(
             env,
         );
         let type_name = authored_name_at(source_indices.clone(), n.clone());
-        render_rust_shared_type_with_optional(n.clone(), type_name, rendered, shared_types.clone())
+        render_rust_shared_type_if_needed(type_name, rendered, shared_types.clone())
     }
 }
 
@@ -1004,8 +992,7 @@ pub fn render_rust_decl_type(
                                     name.clone(),
                                     variant_to_enum.clone(),
                                 );
-                                render_rust_shared_type_with_optional(
-                                    n.clone(),
+                                render_rust_shared_type_if_needed(
                                     name.clone(),
                                     rendered,
                                     shared_types.clone(),
@@ -1018,8 +1005,7 @@ pub fn render_rust_decl_type(
                                 if (!is_container_type(name.clone())
                                     && rust_fn_sig_peel_closed_alias(env.clone(), n.clone()))
                                 {
-                                    render_rust_shared_type_with_optional(
-                                        n.clone(),
+                                    render_rust_shared_type_if_needed(
                                         name.clone(),
                                         name.clone(),
                                         shared_types.clone(),
@@ -1149,8 +1135,7 @@ pub fn render_rust_decl_type(
                                                 }
                                             }
                                         };
-                                        render_rust_shared_type_with_optional(
-                                            n.clone(),
+                                        render_rust_shared_type_if_needed(
                                             name.clone(),
                                             applied_ty,
                                             shared_types.clone(),
@@ -1264,23 +1249,13 @@ pub fn render_rust_fn_sig_type(
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
             && rust_fn_sig_preserves_authored_alias_leaf(name.clone(), corpus_repr.clone())
         {
-            render_rust_shared_type_with_optional(
-                n.clone(),
-                name.clone(),
-                name.clone(),
-                shared_types.clone(),
-            )
+            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
         } else if (n.connective.clone() == Connective::NoConnective)
             && ((n.children.clone().len() as i64) > 0)
             && !is_container_type(name.clone())
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
         {
-            render_rust_shared_type_with_optional(
-                n.clone(),
-                name.clone(),
-                name.clone(),
-                shared_types.clone(),
-            )
+            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
         } else if ((generic_param_names.clone().len() as i64) > 0) {
             render_rust_decl_type(
                 n.clone(),
@@ -1328,8 +1303,7 @@ pub fn render_rust_fn_sig_type_applied_binding(
                             corpus_repr.clone(),
                         )
                     {
-                        render_rust_shared_type_with_optional(
-                            n.clone(),
+                        render_rust_shared_type_if_needed(
                             outer_name.clone(),
                             outer_name.clone(),
                             shared_types,
@@ -8199,16 +8173,14 @@ pub fn render_rust_type_with_applied_binding(
                             && ((n.children.clone().len() as i64) == 0))
                         {
                             if (outer_name.clone() != applied_name) {
-                                render_rust_shared_type_with_optional(
-                                    n.clone(),
+                                render_rust_shared_type_if_needed(
                                     outer_name.clone(),
                                     outer_name.clone(),
                                     shared_types.clone(),
                                 )
                             } else {
                                 if v1_rt::set_contains(&shared_types, outer_name.clone()) {
-                                    render_rust_shared_type_with_optional(
-                                        n.clone(),
+                                    render_rust_shared_type_if_needed(
                                         outer_name.clone(),
                                         outer_name.clone(),
                                         shared_types.clone(),

From 8634ad953311426c8d1d42510abb532103da7144 Mon Sep 17 00:00:00 2001
From: Brian Searls <briansearls1@gmail.com>
Date: Sun, 5 Jul 2026 19:50:30 +0000
Subject: [PATCH 6/6] WIP: Optional-return emission fix (05_emit_rust.dag): T?
 fn returns emit bare

---
 src/v1/05_emit_rust.dag                    | 22 ++++++-----
 src/v1/stage0/src/v1_compiler_emit_rust.rs | 46 +++++++++++++++++-----
 2 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/src/v1/05_emit_rust.dag b/src/v1/05_emit_rust.dag
index fd294b0f617..e9dfa469901 100644
--- a/src/v1/05_emit_rust.dag
+++ b/src/v1/05_emit_rust.dag
@@ -510,10 +510,14 @@ fn render_rust_shared_type_if_needed(type_name: String, rendered: String, shared
   } else { rendered }
 }
 
+fn render_rust_shared_type_with_optional(n: Node, type_name: String, rendered: String, shared_types: Set<String>) -> String {
+  rust_carrier_optional_wrap(n: n, rendered: render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types))
+}
+
 fn render_rust_applied_type_shared(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
   let rendered = render_rust_applied_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   let type_name = authored_name_at(source_indices: source_indices, node: n)
-  render_rust_shared_type_if_needed(type_name: type_name, rendered: rendered, shared_types: shared_types)
+  render_rust_shared_type_with_optional(n: n, type_name: type_name, rendered: rendered, shared_types: shared_types)
 }
 
 fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_types: Set<String>, corpus_repr: RustCorpusRepr, source_indices: Map<String, NewlineIndex>, variant_to_enum: Map<String, String>, env: TypeEnv) -> String {
@@ -535,10 +539,10 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
       } else if n.connective == NoConnective && n.children |> count == 0 && applied_prop == none && set_contains(shared_types, name) {
         let rendered = rust_render_type_leaf_name(name: name, variant_to_enum: variant_to_enum)
-        render_rust_shared_type_if_needed(type_name: name, rendered: rendered, shared_types: shared_types)
+        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: rendered, shared_types: shared_types)
       } else if n.connective == NoConnective && n.children |> count > 0 {
         if !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-          render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+          render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
         } else {
         let base = rust_applied_type_base(name: name, corpus_repr: corpus_repr)
         let peel = is_parametric_opaque_type_by_name(env: env, type_name: name)
@@ -569,7 +573,7 @@ fn render_rust_decl_type(n: Node, generic_param_names: List<String>, shared_type
         } else {
           concat(base, "<", arg_list |> join(separator: ", "), ">")
         }
-        render_rust_shared_type_if_needed(type_name: name, rendered: applied_ty, shared_types: shared_types)
+        render_rust_shared_type_with_optional(n: n, type_name: name, rendered: applied_ty, shared_types: shared_types)
         }
       } else {
         render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
@@ -622,9 +626,9 @@ fn render_rust_fn_sig_type(n: Node, generic_param_names: List<String>, shared_ty
   if n.connective == NoConnective && n.children |> count == 0 && name == "String" && corpus_repr_is_faithful(corpus_repr: corpus_repr) {
     rust_carrier_optional_wrap(n: n, rendered: render_rust_text_carrier(shared_types: shared_types))
   } else if n.connective == NoConnective && n.children |> count == 0 && name != "" && name != "String" && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: name, corpus_repr: corpus_repr) {
-    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
   } else if n.connective == NoConnective && n.children |> count > 0 && !is_container_type(name: name) && rust_fn_sig_peel_closed_alias(env: env, n: n) {
-    render_rust_shared_type_if_needed(type_name: name, rendered: name, shared_types: shared_types)
+    render_rust_shared_type_with_optional(n: n, type_name: name, rendered: name, shared_types: shared_types)
   } else if generic_param_names |> count > 0 {
     render_rust_decl_type(n: n, generic_param_names: generic_param_names, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: variant_to_enum, env: env)
   } else {
@@ -638,7 +642,7 @@ fn render_rust_fn_sig_type_applied_binding(n: Node, shared_types: Set<String>, c
       if applied.children |> count > 0 {
         let outer_name = authored_name_at(source_indices: source_indices, node: n)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 && rust_fn_sig_peel_closed_alias(env: env, n: n) && rust_fn_sig_preserves_authored_alias_leaf(name: outer_name, corpus_repr: corpus_repr) {
-          render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+          render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
         } else {
           render_rust_type_with_applied_binding(n: n, shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices)
         }
@@ -3391,9 +3395,9 @@ fn render_rust_type_with_applied_binding(n: Node, shared_types: Set<String>, cor
         let applied_name = authored_name_at(source_indices: source_indices, node: applied)
         if outer_name != "" && n.connective == NoConnective && (n.children |> count) == 0 {
           if outer_name != applied_name {
-            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else if set_contains(shared_types, outer_name) {
-            render_rust_shared_type_if_needed(type_name: outer_name, rendered: outer_name, shared_types: shared_types)
+            render_rust_shared_type_with_optional(n: n, type_name: outer_name, rendered: outer_name, shared_types: shared_types)
           } else {
             render_rust_applied_type_shared(n: applied, generic_param_names: [], shared_types: shared_types, corpus_repr: corpus_repr, source_indices: source_indices, variant_to_enum: empty_map(), env: TypeEnv { bindings: empty_map(), str_bindings: empty_map(), ancestry_str_bindings: empty_map(), parents: [], recursive_types: [], recursive_type_set: empty_map(), inductive_fields: empty_map(), source_indices: source_indices, intern_table: empty_intern_table() })
           }
diff --git a/src/v1/stage0/src/v1_compiler_emit_rust.rs b/src/v1/stage0/src/v1_compiler_emit_rust.rs
index 60155a09595..e0389607b1e 100644
--- a/src/v1/stage0/src/v1_compiler_emit_rust.rs
+++ b/src/v1/stage0/src/v1_compiler_emit_rust.rs
@@ -892,6 +892,18 @@ pub fn render_rust_shared_type_if_needed(
     }
 }
 
+pub fn render_rust_shared_type_with_optional(
+    n: Rc<Node>,
+    type_name: String,
+    rendered: String,
+    shared_types: Rc<std::collections::BTreeSet<String>>,
+) -> String {
+    rust_carrier_optional_wrap(
+        n.clone(),
+        render_rust_shared_type_if_needed(type_name, rendered, shared_types),
+    )
+}
+
 pub fn render_rust_applied_type_shared(
     n: Rc<Node>,
     generic_param_names: Rc<Vec<String>>,
@@ -912,7 +924,7 @@ pub fn render_rust_applied_type_shared(
             env,
         );
         let type_name = authored_name_at(source_indices.clone(), n.clone());
-        render_rust_shared_type_if_needed(type_name, rendered, shared_types.clone())
+        render_rust_shared_type_with_optional(n.clone(), type_name, rendered, shared_types.clone())
     }
 }
 
@@ -992,7 +1004,8 @@ pub fn render_rust_decl_type(
                                     name.clone(),
                                     variant_to_enum.clone(),
                                 );
-                                render_rust_shared_type_if_needed(
+                                render_rust_shared_type_with_optional(
+                                    n.clone(),
                                     name.clone(),
                                     rendered,
                                     shared_types.clone(),
@@ -1005,7 +1018,8 @@ pub fn render_rust_decl_type(
                                 if (!is_container_type(name.clone())
                                     && rust_fn_sig_peel_closed_alias(env.clone(), n.clone()))
                                 {
-                                    render_rust_shared_type_if_needed(
+                                    render_rust_shared_type_with_optional(
+                                        n.clone(),
                                         name.clone(),
                                         name.clone(),
                                         shared_types.clone(),
@@ -1135,7 +1149,8 @@ pub fn render_rust_decl_type(
                                                 }
                                             }
                                         };
-                                        render_rust_shared_type_if_needed(
+                                        render_rust_shared_type_with_optional(
+                                            n.clone(),
                                             name.clone(),
                                             applied_ty,
                                             shared_types.clone(),
@@ -1249,13 +1264,23 @@ pub fn render_rust_fn_sig_type(
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
             && rust_fn_sig_preserves_authored_alias_leaf(name.clone(), corpus_repr.clone())
         {
-            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
+            render_rust_shared_type_with_optional(
+                n.clone(),
+                name.clone(),
+                name.clone(),
+                shared_types.clone(),
+            )
         } else if (n.connective.clone() == Connective::NoConnective)
             && ((n.children.clone().len() as i64) > 0)
             && !is_container_type(name.clone())
             && rust_fn_sig_peel_closed_alias(env.clone(), n.clone())
         {
-            render_rust_shared_type_if_needed(name.clone(), name.clone(), shared_types.clone())
+            render_rust_shared_type_with_optional(
+                n.clone(),
+                name.clone(),
+                name.clone(),
+                shared_types.clone(),
+            )
         } else if ((generic_param_names.clone().len() as i64) > 0) {
             render_rust_decl_type(
                 n.clone(),
@@ -1303,7 +1328,8 @@ pub fn render_rust_fn_sig_type_applied_binding(
                             corpus_repr.clone(),
                         )
                     {
-                        render_rust_shared_type_if_needed(
+                        render_rust_shared_type_with_optional(
+                            n.clone(),
                             outer_name.clone(),
                             outer_name.clone(),
                             shared_types,
@@ -8173,14 +8199,16 @@ pub fn render_rust_type_with_applied_binding(
                             && ((n.children.clone().len() as i64) == 0))
                         {
                             if (outer_name.clone() != applied_name) {
-                                render_rust_shared_type_if_needed(
+                                render_rust_shared_type_with_optional(
+                                    n.clone(),
                                     outer_name.clone(),
                                     outer_name.clone(),
                                     shared_types.clone(),
                                 )
                             } else {
                                 if v1_rt::set_contains(&shared_types, outer_name.clone()) {
-                                    render_rust_shared_type_if_needed(
+                                    render_rust_shared_type_with_optional(
+                                        n.clone(),
                                         outer_name.clone(),
                                         outer_name.clone(),
                                         shared_types.clone(),