diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4573de3..3770c71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,9 +4,16 @@ All notable changes to this project will be documented in this file. See [commit
 
 ## [3.0.3](https://github.com/optave/codegraph/compare/v3.0.2...v3.0.3) (2026-03-04)
 
+> **Note:** 3.0.2 was an internal/unpublished version used during development.
+
 ### Performance
 
 * **ast:** use single transaction for AST node insertion — astMs drops from ~3600ms to ~350ms (native) and ~547ms (WASM), reducing overall native build from 24.9 to 8.5 ms/file ([#333](https://github.com/optave/codegraph/pull/333))
+* **builder:** skip `ensureWasmTrees` when native engine provides complete CFG + dataflow data ([#344](https://github.com/optave/codegraph/pull/344))
+
+### Bug Fixes
+
+* **native:** fix function-scoped `const` declarations being incorrectly extracted as top-level constants ([#344](https://github.com/optave/codegraph/pull/344))
 
 ## [3.0.2](https://github.com/optave/codegraph/compare/v3.0.1...v3.0.2) (2026-03-04)
 
diff --git a/src/builder.js b/src/builder.js
index c5019b4..5eb48d7 100644
--- a/src/builder.js
+++ b/src/builder.js
@@ -1317,16 +1317,47 @@ export async function buildGraph(rootDir, opts = {}) {
   _t.complexityMs = performance.now() - _t.complexity0;
 
   // Pre-parse files missing WASM trees (native builds) so CFG + dataflow
-  // share a single parse pass instead of each creating parsers independently
+  // share a single parse pass instead of each creating parsers independently.
+  // Skip entirely when native engine already provides CFG + dataflow data.
   if (opts.cfg !== false || opts.dataflow !== false) {
-    _t.wasmPre0 = performance.now();
-    try {
-      const { ensureWasmTrees } = await import('./parser.js');
-      await ensureWasmTrees(astComplexitySymbols, rootDir);
-    } catch (err) {
-      debug(`WASM pre-parse failed: ${err.message}`);
+    const needsCfg = opts.cfg !== false;
+    const needsDataflow = opts.dataflow !== false;
+
+    let needsWasmTrees = false;
+    for (const [, symbols] of astComplexitySymbols) {
+      if (symbols._tree) continue; // already has a tree
+      // CFG: need tree if any function/method def lacks native CFG
+      if (needsCfg) {
+        const fnDefs = (symbols.definitions || []).filter(
+          (d) => (d.kind === 'function' || d.kind === 'method') && d.line,
+        );
+        if (
+          fnDefs.length > 0 &&
+          !fnDefs.every((d) => d.cfg === null || Array.isArray(d.cfg?.blocks))
+        ) {
+          needsWasmTrees = true;
+          break;
+        }
+      }
+      // Dataflow: need tree if file lacks native dataflow
+      if (needsDataflow && !symbols.dataflow) {
+        needsWasmTrees = true;
+        break;
+      }
+    }
+
+    if (needsWasmTrees) {
+      _t.wasmPre0 = performance.now();
+      try {
+        const { ensureWasmTrees } = await import('./parser.js');
+        await ensureWasmTrees(astComplexitySymbols, rootDir);
+      } catch (err) {
+        debug(`WASM pre-parse failed: ${err.message}`);
+      }
+      _t.wasmPreMs = performance.now() - _t.wasmPre0;
+    } else {
+      _t.wasmPreMs = 0;
     }
-    _t.wasmPreMs = performance.now() - _t.wasmPre0;
   }
 
   // CFG analysis (skip with --no-cfg)
diff --git a/tests/integration/build-parity.test.js b/tests/integration/build-parity.test.js
index 566d201..d2f2e8a 100644
--- a/tests/integration/build-parity.test.js
+++ b/tests/integration/build-parity.test.js
@@ -35,6 +35,8 @@ function readGraph(dbPath) {
   // Exclude constant nodes — the native engine has a known scope bug where it
   // extracts local `const` variables inside functions as top-level constants,
   // while WASM correctly limits constant extraction to program-level declarations.
+  // TODO: Remove kind != 'constant' exclusion once native binary >= 3.0.4 ships
+  // Fix: crates/codegraph-core/src/extractors/javascript.rs (find_parent_of_types guard)
   const nodes = db
     .prepare(
       "SELECT name, kind, file, line FROM nodes WHERE kind != 'constant' ORDER BY name, kind, file, line",