From e2d4092b16dfdac1879ff01b5893efcc88871f9a Mon Sep 17 00:00:00 2001
From: Malte Ubl <malte@vercel.com>
Date: Mon, 19 Oct 2026 13:18:18 -0700
Subject: [PATCH] Re-export classes through module.exports members that require
 them

`module.exports.Agent = require('./lib/agent')`, where agent.js ends with
`module.exports = Agent`, is the same alias plumbing as
`module.exports.Agent = Agent`: importers resolve to the class declaration
and the class registry applies, instead of storing a class value (which
classes inheriting a runtime-provided constructor, such as EventEmitter
subclasses, do not have). The statement still evaluates the required
module at its position.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../src/frontend/lowering/lower-stmts.ts      |  5 +++-
 .../compiler/src/frontend/lowering/lowerer.ts | 24 ++++++++++++++++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/packages/compiler/src/frontend/lowering/lower-stmts.ts b/packages/compiler/src/frontend/lowering/lower-stmts.ts
index 36abb9130..6feccd5a5 100644
--- a/packages/compiler/src/frontend/lowering/lower-stmts.ts
+++ b/packages/compiler/src/frontend/lowering/lower-stmts.ts
@@ -6168,7 +6168,10 @@ function lowerCjsExportStatement(
     // storage — collectGlobals skipped it; importers re-resolve through
     // cjsMemberExportClassSymbol): the statement lowers to nothing.
     if (lowerer.cjsMemberExportClassSymbol(cjs.expr) !== null) {
-      return { kind: "block", body: [], loc };
+      // An inline require still evaluates its module here.
+      const req = inlineProgramRequireOf(lowerer, cjs.value);
+      const init = req !== null ? lowerer.requireInitStmt(req.spec, req.call) : null;
+      return init ?? { kind: "block", body: [], loc };
     }
     // The tsc VOID-INIT PREAMBLE (`exports.leaf = void 0;` with the real
     // `exports.leaf = leaf;` further down — every tsc-emitted dist file
diff --git a/packages/compiler/src/frontend/lowering/lowerer.ts b/packages/compiler/src/frontend/lowering/lowerer.ts
index 4ecb0176b..aa05b734e 100644
--- a/packages/compiler/src/frontend/lowering/lowerer.ts
+++ b/packages/compiler/src/frontend/lowering/lowerer.ts
@@ -294,6 +294,7 @@ import {
 import { prepareCjsModuleGraph, usesCjsTopLevelThis } from "./lower-node-module.js";
 import {
   cjsNamespaceModule,
+  cjsWholeExportValueOf,
   inlineNamespaceRequireOf,
   inlineProgramRequireOf,
 } from "./cjs-inline-require.js";
@@ -3672,13 +3673,18 @@ export class Lowerer {
         ? d.parent
         : null;
     if (!assign || assign.operatorToken.kind !== ts.SyntaxKind.EqualsToken) return null;
-    if (!ts.isIdentifier(assign.right)) return null;
     const stmt = assign.parent;
     if (!stmt || !ts.isExpressionStatement(stmt) || !ts.isSourceFile(stmt.parent)) return null;
     if (!isJsSourceFile(stmt.parent)) return null;
     const cjs = cjsExportAssignmentOf(stmt);
     if (cjs?.kind !== "member" || cjs.expr !== assign) return null;
     if (cjsExportDiscardReason(stmt) !== null) return null;
+    // `module.exports.C = require('./c')` over a module whose whole export
+    // is a class identifier: the same alias plumbing; the statement keeps
+    // the require's module evaluation at its position.
+    const required = this.memberExportRequiredClass(assign.right);
+    if (required !== undefined) return required;
+    if (!ts.isIdentifier(assign.right)) return null;
     let value = this.checker.getSymbolAtLocation(assign.right);
     if (!value) return null;
     if (value.flags & ts.SymbolFlags.Alias) value = this.checker.getAliasedSymbol(value);
@@ -3686,6 +3692,22 @@ export class Lowerer {
     return isClass ? value : null;
   }
 
+  /** For an inline program `require("./c")`: the class symbol its module's
+   * kept `module.exports = <class identifier>` names, or null when the
+   * whole export is something else. Undefined when `expr` is not such a
+   * require. */
+  memberExportRequiredClass(expr: ts.Expression): ts.Symbol | null | undefined {
+    const req = inlineProgramRequireOf(this, expr);
+    if (req === null) return undefined;
+    const whole = cjsWholeExportValueOf(req.dep);
+    if (whole === null || !ts.isIdentifier(whole.rhs)) return null;
+    let value = this.checker.getSymbolAtLocation(whole.rhs);
+    if (!value) return null;
+    if (value.flags & ts.SymbolFlags.Alias) value = this.checker.getAliasedSymbol(value);
+    const isClass = this.checker.declarationsOf(value).some((decl) => ts.isClassDeclaration(decl));
+    return isClass ? value : null;
+  }
+
   /** The CommonJS JS module a DEFAULT-import binding's declaration loads
    * (`import d from "./lib.cjs"`), or null: Node's ESM-CJS interop binds
    * the default to module.exports — exactly a require binding — so those