fix(cfg): harvest all names of a Dart multi-variable declaration (#2195)

`var a = 1, b = 2;` is one initialized_variable_definition whose first binding
is the name/value field pair and whose subsequent bindings are trailing
initialized_identifier children. Both prescan (declareInitializedVar) and the
walkValue case read only the name/value fields, so every name after the first
was never declared or def'd — `b` resolved to a synthetic module binding and
its REACHING_DEF/taint flow was lost. Iterate the trailing initialized_identifier
nodes in both phases. (Dart-3 record/list pattern declarations `var (a,b)=pair`
remain a separate follow-up.) dart suite 35 passed, tsc + grammar gate green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gitnexus/src/core/ingestion/cfg/visitors/dart-harvest.ts

@@ -212,10 +212,18 @@ export class DartHarvester {
     }
   }
 
-  /** Declare the `name:identifier` of an `initialized_variable_definition`. */
+  /** Declare every name of an `initialized_variable_definition` (`var a = 1, b = 2`). */
   private declareInitializedVar(node: SyntaxNode, kind: BindingEntry['kind']): void {
     const name = node.childForFieldName('name');
     if (name) this.declare(name, kind);
+    // Trailing comma-separated bindings: each `initialized_identifier` (`b = 2`)
+    // names another local that the `name` field alone misses.
+    for (let i = 0; i < node.namedChildCount; i++) {
+      const c = node.namedChild(i);
+      if (c?.type !== 'initialized_identifier') continue;
+      const id = c.namedChildren.find((g) => g.type === 'identifier');
+      if (id) this.declare(id, kind);
+    }
   }
 
   /**
@@ -367,6 +375,16 @@ export class DartHarvester {
         if (value) this.walkValue(value, acc);
         const name = node.childForFieldName('name');
         if (name) this.def(name, acc);
+        // Trailing comma-separated bindings (`var a = 1, b = 2;`): each
+        // `initialized_identifier` is an `identifier` + its own value expr.
+        for (let i = 0; i < node.namedChildCount; i++) {
+          const c = node.namedChild(i);
+          if (c?.type !== 'initialized_identifier') continue;
+          const id = c.namedChildren.find((g) => g.type === 'identifier');
+          const val = c.namedChildren.find((g) => g.type !== 'identifier');
+          if (val) this.walkValue(val, acc);
+          if (id) this.def(id, acc);
+        }
         return;
       }
       case 'assignment_expression': {

gitnexus/test/unit/cfg/dart-visitor.test.ts

@@ -387,6 +387,15 @@ describe('Dart CfgVisitor — def/use harvest', () => {
     // `obj` is used (it is the assignment target's root); no scalar `x` binding.
     expect(usesBinding(cfg, bindingIdx(cfg, 'obj'))).toBe(true);
   });
+
+  it('multi-variable declaration `var a = 1, b = 2;` defines BOTH names (#2195 P2)', () => {
+    const cfg = dart.cfgOf(`void f() { var a = 1, b = 2; use(a); use(b); }`);
+    // The bug dropped every name after the first — `b` became a synthetic
+    // global. Both must be real locals defined by the declaration.
+    expect(definesBinding(cfg, bindingIdx(cfg, 'a'))).toBe(true);
+    expect(definesBinding(cfg, bindingIdx(cfg, 'b'))).toBe(true);
+    expect(usesBinding(cfg, bindingIdx(cfg, 'b'))).toBe(true); // use(b)
+  });
 });
 
 describe('Dart CfgVisitor — functionStartColumn', () => {