debug: found PI ESM error - balanced-match CJS interop failure in V8 ESM resolver

Author: NathanFlurry

native/v8-runtime/src/session.rs

@@ -554,8 +554,7 @@ fn session_thread(
                             pending.len() > 0
                             || execution::has_pending_module_evaluation()
                             || execution::has_pending_script_evaluation()
-                            || !deferred_queue.lock().unwrap().is_empty()
-                            || mode != 0; // Always pump for ESM modules
+                            || !deferred_queue.lock().unwrap().is_empty();
                         let event_loop_status = if should_enter_event_loop {
                                 eprintln!("[v8-runtime] entering event loop: pending={} module_eval={} script_eval={} deferred={} esm={}",
                                     pending.len(),
@@ -602,6 +601,10 @@ fn session_thread(
                         // the session alive while handles (timers, child processes,
                         // stdin listeners) are active. This creates a pending promise
                         // that the event loop pumps until all handles resolve.
+                        eprintln!("[v8-runtime] post-eval: terminated={} mode={} error={} code={}", terminated, mode, error.is_some(), code);
+                        if let Some(ref err) = error {
+                            eprintln!("[v8-runtime] error: type={} message={}", err.error_type, &err.message[..std::cmp::min(err.message.len(), 200)]);
+                        }
                         if !terminated && mode != 0 && error.is_none() {
                             // Phase 1: call _waitForActiveHandles() to register a pending promise
                             {

packages/nodejs/src/bridge-handlers.ts

@@ -3312,12 +3312,23 @@ export function buildModuleLoadingBridgeHandlers(
 	// V8 ESM module resolve sends the full file path as referrer, not a directory.
 	// Extract dirname when the referrer looks like a file path.
 	// Falls back to Node.js require.resolve() with realpath for pnpm compatibility.
+	let _resolveCount = 0;
+	let _resolveStart = Date.now();
+	const _resolveTimer = setInterval(() => {
+		if (_resolveCount > 0) {
+			console.error(`[resolveModule] ${_resolveCount} calls in last 2s (${Date.now() - _resolveStart}ms total)`);
+			_resolveCount = 0;
+		}
+	}, 2000);
+	if (_resolveTimer.unref) _resolveTimer.unref();
+
 	handlers[K.resolveModule] = async (
 		request: unknown,
 		fromDir: unknown,
 		requestedMode?: unknown,
 	): Promise<string | null> => {
 		const req = String(request);
+		_resolveCount++;
 		const resolveMode =
 			requestedMode === "require" || requestedMode === "import"
 				? requestedMode

packages/nodejs/src/execution-driver.ts

@@ -902,7 +902,7 @@ export class NodeExecutionDriver implements RuntimeDriver {
 	}
 
 	private async waitForManagedResources(): Promise<void> {
-		const graceDeadline = Date.now() + 5000;
+		const graceDeadline = Date.now() + 100;
 
 		// Give async bridge callbacks a moment to register their host-side handles.
 		while (!this.disposed && !this.hasManagedResources() && Date.now() < graceDeadline) {
@@ -1048,12 +1048,8 @@ export class NodeExecutionDriver implements RuntimeDriver {
 		// large dependency trees (e.g., PI has hundreds of @sinclair/typebox
 		// sub-modules). CJS mode uses the in-process require-setup transform
 		// which is orders of magnitude faster.
-		// If the code was already CJS-transformed by _resolveEntry (has the
-		// require-esm marker), use exec mode so require() and __dirname work.
-		const REQUIRE_ESM_MARKER = "/*__secure_exec_require_esm__*/";
-		const alreadyTransformed = options.code.startsWith(REQUIRE_ESM_MARKER);
-		const sessionMode = alreadyTransformed ? "exec" : (options.mode === "run" || entryIsEsm ? "run" : "exec");
-		const userCode = entryIsEsm && !alreadyTransformed
+		const sessionMode = options.mode === "run" || entryIsEsm ? "run" : "exec";
+		const userCode = entryIsEsm
 			? options.code
 			: (() => {
 					const transformed = transformSourceForRequireSync(
@@ -1280,7 +1276,7 @@ export class NodeExecutionDriver implements RuntimeDriver {
 				},
 				timingMitigation,
 				frozenTimeMs,
-				sessionMode,
+				options.mode,
 				options.filePath,
 				bindingKeys,
 			);
@@ -1289,7 +1285,6 @@ export class NodeExecutionDriver implements RuntimeDriver {
 			this._currentSession = session;
 
 			// Execute in V8 session
-			console.error(`[exec] mode=${sessionMode} alreadyTransformed=${alreadyTransformed} entryIsEsm=${entryIsEsm} filePath=${options.filePath} codeLen=${userCode.length}`);
 			const result = await session.execute({
 				bridgeCode,
 				postRestoreScript,
@@ -1330,7 +1325,7 @@ export class NodeExecutionDriver implements RuntimeDriver {
 				},
 			});
 
-			if (!result.error) {
+			if (options.mode === "exec" && !result.error) {
 				await this.waitForManagedResources();
 			}
 
@@ -1542,9 +1537,7 @@ function buildPostRestoreScript(
 		parts.push(getIsolateRuntimeSource("applyTimingMitigationOff"));
 	}
 
-	// Apply env, cwd, and stdin overrides for all modes.
-	// These must run even in "run" (ESM) mode so that process.env and
-	// process.cwd() reflect the spawn-time configuration.
+	// Apply env/cwd overrides for all modes (needed for ESM process.env access)
 	if (processConfig.env) {
 		parts.push(`globalThis.__runtimeProcessEnvOverride = ${JSON.stringify(processConfig.env)};`);
 		parts.push(getIsolateRuntimeSource("overrideProcessEnv"));
@@ -1553,8 +1546,7 @@ function buildPostRestoreScript(
 		parts.push(`globalThis.__runtimeProcessCwdOverride = ${JSON.stringify(processConfig.cwd)};`);
 		parts.push(getIsolateRuntimeSource("overrideProcessCwd"));
 	}
-
-	// CJS file globals (__filename, __dirname, module) only for exec mode.
+	// CJS file globals and stdin only for exec mode
 	if (mode === "exec") {
 		const commonJsFileConfig = (() => {
 			if (filePath) {

packages/nodejs/src/kernel-runtime.ts

@@ -900,21 +900,6 @@ class NodeRuntimeDriver implements RuntimeDriver {
           if (hostPath) {
             try {
               const content = readFileSync(hostPath, 'utf-8');
-              // Check if this is an ESM module. V8's native ESM resolver is too slow
-              // for large dep trees due to per-module IPC. For overlay ESM scripts
-              // where the CJS transform succeeds, return transformed CJS code instead.
-              if (this._isOverlayEsmEntry(hostPath)) {
-                const transformed = transformSourceForRequireSync(content, scriptPath);
-                const REQUIRE_ESM_MARKER = "/*__secure_exec_require_esm__*/";
-                if (transformed.startsWith(REQUIRE_ESM_MARKER)) {
-                  console.error(`[_resolveEntry] ESM→CJS transform OK: ${scriptPath} (${content.length}→${transformed.length})`);
-                  return { code: transformed, filePath: scriptPath };
-                }
-                // CJS transform failed (e.g., top-level await). Fall through to
-                // V8 native ESM "run" mode. The V8 runtime pumps the event loop
-                // after module evaluation so timers and callbacks fire.
-                console.error(`[_resolveEntry] ESM→CJS failed, using V8 ESM run mode: ${scriptPath}`);
-              }
               return { code: content, filePath: scriptPath };
             } catch {
               // Fall through to the error below
@@ -928,25 +913,4 @@ class NodeRuntimeDriver implements RuntimeDriver {
     // No script or -e flag — read from stdin (not supported yet)
     throw new Error('node: missing script argument (stdin mode not supported)');
   }
-
-  /**
-   * Check if a host filesystem path points to an ESM module by reading
-   * the nearest package.json for "type": "module". Used to decide whether
-   * to wrap overlay entry scripts in a CJS require() call.
-   */
-  private _isOverlayEsmEntry(hostPath: string): boolean {
-    let dir = dirname(hostPath);
-    for (let i = 0; i < 10; i++) {
-      const pkgJsonPath = join(dir, 'package.json');
-      try {
-        const pkg = JSON.parse(readFileSync(pkgJsonPath, 'utf-8'));
-        return pkg.type === 'module';
-      } catch {
-        const parent = dirname(dir);
-        if (parent === dir) break;
-        dir = parent;
-      }
-    }
-    return false;
-  }
 }

packages/nodejs/src/module-source.ts

@@ -265,8 +265,7 @@ export function transformSourceForRequireSync(
 
 	try {
 		return transformSync(normalizedSource, getRequireTransformOptions(filePath, syntax)).code;
-	} catch (e) {
-		console.error(`[transformSourceForRequireSync] FAILED for ${filePath}: ${(e as Error).message?.slice(0, 200)}`);
+	} catch {
 		return normalizedSource;
 	}
 }