fix(extraction): a function in an initializer is referenced once, by what the initializer declares (#2743)

PRs #693 and #1802 walk a declaration's initializer under the symbol it declares,
so `const routes = { home }` references `home` from `routes`. The
dispatcher's declaration-wide function-as-value scan then took the same
values again for the enclosing file (or class). Flush-time dedup keys on
the source, so both stayed: a second reference to the same function from
the same spot.

Each initializer walk now records what it walked, and the scan skips it.
PR #2738 added that mechanism for component wrappers, and C#, Scala and Dart
already had their own. The newly covered paths:
- TS/JS module-level constants and variables, owned object literals
  included (#2300), and TS/JS class properties;
- Python assignments, Go var/const specs, Rust const/static items;
- Java fields, and Kotlin properties (walkInitializer takes the property's
  id, so their walk is unchanged).
Mirrored in the kernel: tsjs, python, go, rustlang, java and kotlin.

References no initializer walk takes are unchanged: a module-level call
argument `register(fn)`, C-family tables, Rust's `static CB: fn() = handler`
(the declaration's own value, which the scan still reads).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

codegraph-kernel/src/python.rs

@@ -431,8 +431,10 @@ impl<'t> Walker<'t> {
             self.extract_class(node);
             skip_children = true;
         } else if kind == "assignment" && !self.inside_class_like() {
-            self.extract_variable(node);
-            self.scan_fn_ref_subtree(node, 0);
+            // The right-hand side extract_variable walked under the assigned
+            // name took its own candidates; the scan covers the rest.
+            let walked = self.extract_variable(node);
+            self.scan_fn_ref_subtree(node, 0, &walked);
             skip_children = true;
         } else if kind == "import_statement" || kind == "import_from_statement" {
             self.extract_import(node);
@@ -564,7 +566,9 @@ impl<'t> Walker<'t> {
     }
 
     /// extractVariable's python branch: `left = right` at module scope.
-    fn extract_variable(&mut self, node: Node<'t>) {
+    /// Returns the right-hand side when it was walked under the assigned
+    /// name, for the declaration scan to skip.
+    fn extract_variable(&mut self, node: Node<'t>) -> Vec<usize> {
         let docstring = preceding_docstring(node, self.src);
         let left = node.child_by_field_name("left").or_else(|| node.named_child(0));
         let right = node.child_by_field_name("right").or_else(|| node.named_child(1));
@@ -589,16 +593,19 @@ impl<'t> Walker<'t> {
         // module-level `app = FastAPI()` / `handler = lambda: run()` dropped
         // every call on the right-hand side. A tuple target mints no symbol, so
         // its RHS is walked at the enclosing scope rather than lost.
+        let mut walked = Vec::new();
         if let Some(right) = right {
             match assigned {
                 Some((row, name)) => {
                     self.stack.push(Scope { row, kind: "variable", name });
                     self.visit_function_body(right);
                     self.stack.pop();
+                    walked.push(right.id());
                 }
                 None => self.visit_function_body(right),
             }
         }
+        walked
     }
 
     fn extract_import(&mut self, node: Node<'t>) {
@@ -955,11 +962,15 @@ impl<'t> Walker<'t> {
         }
     }
 
-    fn scan_fn_ref_subtree(&mut self, node: Node<'t>, depth: u32) {
+    fn scan_fn_ref_subtree(&mut self, node: Node<'t>, depth: u32, walked: &[usize]) {
         stack_guard!();
         if depth > 12 {
             return;
         }
+        // Subtrees the body walker has already been through.
+        if walked.contains(&node.id()) {
+            return;
+        }
         // Halts at functionTypes ∪ the fixed arrow/lambda list — python's
         // `lambda` kind is NOT in that list (mirrored).
         if depth > 0
@@ -974,7 +985,7 @@ impl<'t> Walker<'t> {
         self.maybe_capture_fn_refs(node);
         for i in 0..node.named_child_count() {
             if let Some(c) = node.named_child(i) {
-                self.scan_fn_ref_subtree(c, depth + 1);
+                self.scan_fn_ref_subtree(c, depth + 1, walked);
             }
         }
     }