diff --git a/CHANGELOG.md b/CHANGELOG.md
index b5c3c9dc3f..34c17aaeae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,49 @@
 
 Detailed changelog for Perry. See CLAUDE.md for concise summaries.
 
+## v0.5.990 — feat(util/stream): util.inherits + stream prototype scaffold (express compile unblocked)
+
+**Symptom.** After PR #983 unblocked `safer-buffer`, `import express from 'express'` advanced one frame further and then crashed at `node_modules/send/index.js:173` with:
+
+```
+TypeError: Object prototype may only be an Object or null: undefined
+    at Object.setPrototypeOf (<anonymous>)
+    at Object.inherits (node:util:14:52)
+    at file:.../send/index.js:356:6
+```
+
+`send/index.js` does the classic pre-ES6 inheritance pattern:
+
+```js
+var Stream = require('stream')             // line 30
+function SendStream(req, path, options) { Stream.call(this); ... }
+util.inherits(SendStream, Stream)          // line 173
+```
+
+`util.inherits(ctor, superCtor)` reads `superCtor.prototype` and calls `Object.setPrototypeOf(ctor.prototype, superCtor.prototype)`. Two coupled gaps converged on the crash:
+
+1. **`node:stream` default export was a plain namespace object.** The V8-fallback `node:stream` shim in `crates/perry-jsruntime/src/modules.rs` ended with `export default { Readable, Writable, Duplex, Transform, ... }` — a literal `{}` object, not the legacy `Stream` constructor Node ships. So `require('stream').prototype` was `undefined`. Even worse, the module had no `__perry_commonjs = true` marker, so the `wrap_commonjs` require() shim took the null-prototype-namespace branch and returned a flat copied object — `Stream.Readable` was preserved but `Stream.prototype` and `Stream` callability were not.
+
+2. **`util.inherits` was minimal.** The V8-fallback `node:util` `inherits` did only `Object.setPrototypeOf(ctor.prototype, superCtor.prototype)` — no `super_` static, no input validation, no useful error message when `superCtor` had no prototype.
+
+**Fix — three coordinated changes:**
+
+1. **`crates/perry-jsruntime/src/modules.rs` (`node:stream` shim):** rewrite the legacy `Stream` value as an actual class with its own `.prototype`, give it the EventEmitter-shaped instance methods (`on`/`once`/`emit`/`off`/`addListener`/`removeListener`/`removeAllListeners`/`pipe`), and re-root `Readable`/`Writable` to extend it. Attach `Readable`/`Writable`/`Duplex`/`Transform`/`PassThrough`/`pipeline`/`finished` as static properties on `Stream` itself, then `export default Stream`. Add `export const __perry_commonjs = true;` so `wrap_commonjs`'s `__perry_require_namespace` returns the class as-is from `require('stream')`. Also splits the old `"stream" | "stream/web"` match arm — they're now distinct, which silences the `unreachable_patterns` warning and lets each module evolve independently.
+
+2. **`crates/perry-jsruntime/src/modules.rs` (`node:util` shim):** harden `inherits(ctor, superCtor)` to mirror Node's contract:
+   - throw `TypeError` on null/undefined `ctor` or `superCtor`,
+   - throw `TypeError` if `superCtor.prototype` is undefined (matches Node's error message format),
+   - `Object.defineProperty(ctor, 'super_', { value: superCtor, writable: true, configurable: true })` so derived classes can chain through `Bar.super_` (the legacy Node pattern several stdlib packages use),
+   - then the original `Object.setPrototypeOf(ctor.prototype, superCtor.prototype)`.
+
+3. **`crates/perry-api-manifest/src/entries.rs`:** add `property("stream", "prototype")` to the manifest so the #463 unimplemented-API gate doesn't reject `Stream.prototype` reads in user TS. (`util.inherits` was already in the manifest.)
+
+**Validation.**
+- `test-files/test_util_inherits.ts` + `test-files/fixtures/util_inherits_v8/inherits_mod.js` — V8-routed fixture mirroring the express/send pattern: `require('util')` + `require('stream')`, two `util.inherits()` calls, and assertions for `Stream.prototype`, `Stream.Readable.prototype`, `super_`, real-prototype-chain `instanceof`, and method resolution through the chain. All eight assertions pass under Perry.
+- Express compile reproducer (`/tmp/perry-express-2/test.ts` = `import express from 'express'; console.log(typeof express)`) now succeeds: prints `function`. Previously this hit the `util.inherits` crash at module-init time and the namespace load failed.
+
+**Caveat.** The native-compile path for `util.inherits` (TS code that imports `node:util` directly without going through the V8 fallback) is still essentially a no-op — Perry's class-id `instanceof` and prototype model don't have a runtime hook for `util.inherits`. That's separate from this fix; users of the express/send chain are in the V8 fallback by definition (those packages are not in `compilePackages` and use CJS internally), so the V8-side change is what matters.
+
 ## v0.5.989 — feat(runtime+jsruntime): expose Object.prototype methods on Buffer instances + plain-object require() namespace
 
 **Symptom.** `import express from 'express'` (and any transitive consumer of `safer-buffer`) threw `TypeError: buffer.hasOwnProperty is not a function` at module-init time. safer-buffer's `safer.js` opens with `for (key in buffer) { if (!buffer.hasOwnProperty(key)) continue; ... }` where `buffer` is the value returned by `require('buffer')`. Two distinct gaps converged on the same error message:
diff --git a/CLAUDE.md b/CLAUDE.md
index b4db67cc31..6122ab6cc0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,7 +8,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 Perry is a native TypeScript compiler written in Rust that compiles TypeScript source code directly to native executables. It uses SWC for TypeScript parsing and LLVM for code generation.
 
-**Current Version:** 0.5.989
+**Current Version:** 0.5.990
 
 
 ## TypeScript Parity Status
diff --git a/Cargo.lock b/Cargo.lock
index 9e3b20642f..75fc08f4a2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4905,7 +4905,7 @@ checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
 [[package]]
 name = "perry"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "base64",
@@ -4960,14 +4960,14 @@ dependencies = [
 
 [[package]]
 name = "perry-api-manifest"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "perry-codegen"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "log",
@@ -4980,7 +4980,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-arkts"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -4989,7 +4989,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-glance"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -4997,7 +4997,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-js"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-dispatch",
@@ -5007,7 +5007,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-swiftui"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5016,7 +5016,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wasm"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "base64",
@@ -5029,7 +5029,7 @@ dependencies = [
 
 [[package]]
 name = "perry-codegen-wear-tiles"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5037,7 +5037,7 @@ dependencies = [
 
 [[package]]
 name = "perry-diagnostics"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "serde",
  "serde_json",
@@ -5045,7 +5045,7 @@ dependencies = [
 
 [[package]]
 name = "perry-dispatch"
-version = "0.5.989"
+version = "0.5.990"
 
 [[package]]
 name = "perry-doc-fixture-my-bindings"
@@ -5056,7 +5056,7 @@ dependencies = [
 
 [[package]]
 name = "perry-doc-tests"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "clap",
@@ -5071,7 +5071,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-argon2"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "argon2",
  "perry-ffi",
@@ -5079,7 +5079,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-axios"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "reqwest",
@@ -5088,7 +5088,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-bcrypt"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "bcrypt",
  "perry-ffi",
@@ -5096,7 +5096,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-better-sqlite3"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "rusqlite",
@@ -5104,7 +5104,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-cheerio"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "scraper",
@@ -5112,14 +5112,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-commander"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-cron"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "chrono",
  "cron",
@@ -5128,7 +5128,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dayjs"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5136,7 +5136,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-decimal"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "rust_decimal",
@@ -5144,7 +5144,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-dotenv"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "serde_json",
@@ -5152,7 +5152,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ethers"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "rand 0.8.6",
@@ -5160,21 +5160,21 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-events"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-exponential-backoff"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-fastify"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "bytes",
  "http-body-util",
@@ -5188,7 +5188,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-fetch"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5199,7 +5199,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lazy_static",
  "perry-ext-http-server",
@@ -5211,7 +5211,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-http-server"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "bytes",
  "http-body-util",
@@ -5230,7 +5230,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ioredis"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5240,7 +5240,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-jsonwebtoken"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "base64",
  "jsonwebtoken",
@@ -5251,7 +5251,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-lru-cache"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lru",
  "perry-ffi",
@@ -5259,7 +5259,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-moment"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5267,7 +5267,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mongodb"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "bson",
  "futures-util",
@@ -5279,7 +5279,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-mysql2"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "chrono",
  "perry-ffi",
@@ -5289,7 +5289,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nanoid"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "nanoid",
  "perry-ffi",
@@ -5298,7 +5298,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-net"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "rustls",
@@ -5309,7 +5309,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-nodemailer"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lettre",
  "perry-ffi",
@@ -5319,7 +5319,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-pg"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "sqlx",
@@ -5328,7 +5328,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ratelimit"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "governor",
  "perry-ffi",
@@ -5336,7 +5336,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-sharp"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "base64",
  "image",
@@ -5345,14 +5345,14 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-slugify"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
 ]
 
 [[package]]
 name = "perry-ext-streams"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "lazy_static",
  "perry-ffi",
@@ -5360,7 +5360,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-uuid"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "uuid",
@@ -5368,7 +5368,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-validator"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "perry-ffi",
  "regex",
@@ -5378,7 +5378,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-ws"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "futures-util",
  "lazy_static",
@@ -5389,7 +5389,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ext-zlib"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "flate2",
  "perry-ffi",
@@ -5397,7 +5397,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ffi"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "dashmap 6.1.0",
  "once_cell",
@@ -5406,7 +5406,7 @@ dependencies = [
 
 [[package]]
 name = "perry-hir"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-api-manifest",
@@ -5420,7 +5420,7 @@ dependencies = [
 
 [[package]]
 name = "perry-jsruntime"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "deno_core",
@@ -5440,7 +5440,7 @@ dependencies = [
 
 [[package]]
 name = "perry-parser"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-diagnostics",
@@ -5452,7 +5452,7 @@ dependencies = [
 
 [[package]]
 name = "perry-runtime"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "base64",
@@ -5476,7 +5476,7 @@ dependencies = [
 
 [[package]]
 name = "perry-stdlib"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "aes 0.8.4",
  "aes-gcm",
@@ -5546,7 +5546,7 @@ dependencies = [
 
 [[package]]
 name = "perry-transform"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "perry-hir",
@@ -5556,7 +5556,7 @@ dependencies = [
 
 [[package]]
 name = "perry-types"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "anyhow",
  "thiserror 1.0.69",
@@ -5564,11 +5564,11 @@ dependencies = [
 
 [[package]]
 name = "perry-ui"
-version = "0.5.989"
+version = "0.5.990"
 
 [[package]]
 name = "perry-ui-android"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "itoa",
  "jni",
@@ -5583,7 +5583,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-geisterhand"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "rand 0.8.6",
  "serde",
@@ -5593,7 +5593,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-gtk4"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "cairo-rs",
  "dirs 5.0.1",
@@ -5612,7 +5612,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-ios"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "block2",
  "libc",
@@ -5627,7 +5627,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-macos"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "block2",
  "libc",
@@ -5645,11 +5645,11 @@ version = "0.1.0"
 
 [[package]]
 name = "perry-ui-testkit"
-version = "0.5.989"
+version = "0.5.990"
 
 [[package]]
 name = "perry-ui-tvos"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "block2",
  "libc",
@@ -5664,7 +5664,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-visionos"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "block2",
  "libc",
@@ -5679,7 +5679,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-watchos"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "block2",
  "libc",
@@ -5692,7 +5692,7 @@ dependencies = [
 
 [[package]]
 name = "perry-ui-windows"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "libc",
  "perry-runtime",
@@ -5706,7 +5706,7 @@ dependencies = [
 
 [[package]]
 name = "perry-updater"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "base64",
  "ed25519-dalek",
@@ -5720,7 +5720,7 @@ dependencies = [
 
 [[package]]
 name = "perry-wasm-host"
-version = "0.5.989"
+version = "0.5.990"
 dependencies = [
  "wasmi",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 2ad86cf858..5194eabd52 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -190,7 +190,7 @@ opt-level = "s"       # Optimize for size in stdlib
 opt-level = 3
 
 [workspace.package]
-version = "0.5.989"
+version = "0.5.990"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/PerryTS/perry"
diff --git a/crates/perry-api-manifest/src/entries.rs b/crates/perry-api-manifest/src/entries.rs
index 4d7ee0accd..a2c5d9d48b 100644
--- a/crates/perry-api-manifest/src/entries.rs
+++ b/crates/perry-api-manifest/src/entries.rs
@@ -1860,6 +1860,12 @@ pub static API_MANIFEST: &[ApiEntry] = &[
     class("stream", "PassThrough"),
     method("stream", "pipeline", false, None),
     method("stream", "finished", false, None),
+    // `require('stream')` returns the legacy `Stream` constructor itself,
+    // which has its own `.prototype` (it extends EventEmitter). The
+    // `node_modules/send` package (express's static-file backend) does
+    // `util.inherits(SendStream, require('stream'))`, which reads
+    // `Stream.prototype` — the gate rejects the access without this entry.
+    property("stream", "prototype"),
     // `Readable.from(iterable)` — Node's static factory. Resolves
     // through the `Readable.foo` -> `stream.foo` route in
     // `lower_call.rs`, so the gate keys off `stream.from`.
diff --git a/crates/perry-jsruntime/src/modules.rs b/crates/perry-jsruntime/src/modules.rs
index 1404b14b2c..9ec85e0057 100644
--- a/crates/perry-jsruntime/src/modules.rs
+++ b/crates/perry-jsruntime/src/modules.rs
@@ -1067,19 +1067,45 @@ export function networkInterfaces() { return {}; }
 export const EOL = '\n';
 export default { platform, arch, cpus, homedir, tmpdir, hostname, type, release, totalmem, freemem, uptime, loadavg, networkInterfaces, EOL };
 "#.to_string(),
-        "stream" | "stream/web" => r#"
-// Stub implementation for Node.js 'stream' module
-export class Readable {
+        "stream" => r#"
+// Stub implementation for Node.js 'stream' module.
+//
+// IMPORTANT: Node's `require('stream')` returns the legacy `Stream`
+// *constructor* (a class) with `Readable`/`Writable`/etc. attached as
+// static properties — NOT a plain namespace object. Packages like
+// `send` / `express` rely on this shape:
+//
+//     var Stream = require('stream')
+//     function SendStream() { Stream.call(this) }
+//     util.inherits(SendStream, Stream)   // reads Stream.prototype
+//
+// If the default export is `{ Readable, Writable, ... }` then
+// `Stream.prototype` is `undefined` and `util.inherits` blows up with
+// "Object prototype may only be an Object or null: undefined".
+// (See: node_modules/send/index.js:30,173.)
+//
+// So we make `Stream` a real class, attach the sub-classes as static
+// properties, and export the *class itself* as default.
+class Stream {
     constructor() {}
-    read() { return null; }
+    pipe(dest) { return dest; }
     on() { return this; }
-    pipe() { return this; }
+    once() { return this; }
+    emit() { return false; }
+    off() { return this; }
+    addListener() { return this; }
+    removeListener() { return this; }
+    removeAllListeners() { return this; }
 }
-export class Writable {
-    constructor() {}
+export class Readable extends Stream {
+    constructor() { super(); }
+    read() { return null; }
+    pipe(dest) { return dest; }
+}
+export class Writable extends Stream {
+    constructor() { super(); }
     write() { return true; }
     end() {}
-    on() { return this; }
 }
 export class Duplex extends Readable {
     write() { return true; }
@@ -1092,7 +1118,25 @@ export class WritableStream {}
 export class TransformStream {}
 export function pipeline() {}
 export function finished() {}
-export default { Readable, Writable, Duplex, Transform, PassThrough, ReadableStream, WritableStream, TransformStream, pipeline, finished };
+// Attach sub-classes as static properties so `Stream.Readable`,
+// `Stream.Writable`, etc. resolve the way Node ships them.
+Stream.Readable = Readable;
+Stream.Writable = Writable;
+Stream.Duplex = Duplex;
+Stream.Transform = Transform;
+Stream.PassThrough = PassThrough;
+Stream.pipeline = pipeline;
+Stream.finished = finished;
+export { Stream };
+// `__perry_commonjs = true` tells the wrap_commonjs() require() shim in
+// modules.rs to return `module.default` instead of the ESM namespace
+// when this module is `require()`'d. Node's `require('stream')` returns
+// the Stream class itself (with `.Readable` / `.prototype` / etc),
+// NOT a namespace object. Without this flag, `var Stream =
+// require('stream')` ends up as a copied null-proto object and
+// `Stream.prototype` becomes undefined → `util.inherits` crashes.
+export const __perry_commonjs = true;
+export default Stream;
 "#.to_string(),
         "repl" => r#"
 // Stub implementation for Node.js 'repl' module
@@ -1157,7 +1201,26 @@ export function format(fmt, ...args) { return fmt; }
 export function formatWithOptions(_inspectOptions, fmt, ...args) { return format(fmt, ...args); }
 export function debuglog() { return () => {}; }
 export function deprecate(fn) { return fn; }
-export function inherits(ctor, superCtor) { Object.setPrototypeOf(ctor.prototype, superCtor.prototype); }
+// `util.inherits(ctor, superCtor)` — Node's pre-class inheritance helper.
+// Real Node semantics:
+//   Object.defineProperty(ctor, 'super_', { value: superCtor });
+//   Object.setPrototypeOf(ctor.prototype, superCtor.prototype);
+// Throws TypeError if either arg is missing a `.prototype`. We mirror that
+// contract so packages like `send` (which derives `SendStream` from
+// `require('stream')`) work transparently.
+export function inherits(ctor, superCtor) {
+    if (ctor === undefined || ctor === null) {
+        throw new TypeError('The constructor to "inherits" must not be null or undefined');
+    }
+    if (superCtor === undefined || superCtor === null) {
+        throw new TypeError('The super constructor to "inherits" must not be null or undefined');
+    }
+    if (superCtor.prototype === undefined) {
+        throw new TypeError('The super constructor to "inherits" must have a prototype');
+    }
+    Object.defineProperty(ctor, 'super_', { value: superCtor, writable: true, configurable: true });
+    Object.setPrototypeOf(ctor.prototype, superCtor.prototype);
+}
 export const TextEncoder = globalThis.TextEncoder;
 export const TextDecoder = globalThis.TextDecoder;
 // util.types — Node's runtime introspection namespace. NestJS / rxjs
diff --git a/test-files/fixtures/util_inherits_v8/inherits_mod.js b/test-files/fixtures/util_inherits_v8/inherits_mod.js
new file mode 100644
index 0000000000..b6db4c3d03
--- /dev/null
+++ b/test-files/fixtures/util_inherits_v8/inherits_mod.js
@@ -0,0 +1,32 @@
+// V8-fallback module exercising util.inherits + the legacy
+// `require('stream')` Stream constructor. Mirrors the
+// `node_modules/send/index.js` pattern that broke express compile
+// before stream.prototype + util.inherits-super_ were scaffolded.
+//
+// This file lives outside compilePackages, so Perry routes it through
+// the QuickJS / V8 fallback module loader — same path express's deps
+// take in production.
+
+var util = require('util');
+var Stream = require('stream');
+
+function SendStream() {}
+util.inherits(SendStream, Stream);
+
+function Foo() {}
+Foo.prototype.greet = function () {
+    return 'hello';
+};
+function Bar() {}
+util.inherits(Bar, Foo);
+
+module.exports = {
+    typeofStream: typeof Stream,
+    typeofStreamProto: typeof Stream.prototype,
+    typeofStreamReadable: typeof Stream.Readable,
+    typeofStreamReadableProto: typeof Stream.Readable.prototype,
+    sendStreamSuper: SendStream.super_ === Stream,
+    barInstanceofFoo: new Bar() instanceof Foo,
+    barGreet: new Bar().greet(),
+    barSuper: Bar.super_ === Foo,
+};
diff --git a/test-files/test_util_inherits.ts b/test-files/test_util_inherits.ts
new file mode 100644
index 0000000000..d7c4971c55
--- /dev/null
+++ b/test-files/test_util_inherits.ts
@@ -0,0 +1,21 @@
+// Test coverage for util.inherits + node:stream prototype scaffold
+// (fix for express → send "Object prototype may only be an Object or
+// null" crash). The actual `util.inherits` exists only in the V8
+// fallback's `node:util` shim, and the bug surfaced via CJS
+// `require('stream') / require('util')` in
+// `node_modules/send/index.js:30,173`. So we route the assertion
+// through a `.js` fixture (V8 fallback) and just import its summary.
+
+import results from './fixtures/util_inherits_v8/inherits_mod.js';
+
+console.log('typeof Stream:', results.typeofStream);
+console.log('typeof Stream.prototype:', results.typeofStreamProto);
+console.log('typeof Stream.Readable:', results.typeofStreamReadable);
+console.log(
+    'typeof Stream.Readable.prototype:',
+    results.typeofStreamReadableProto,
+);
+console.log('SendStream.super_ === Stream:', results.sendStreamSuper);
+console.log('Bar instanceof Foo:', results.barInstanceofFoo);
+console.log('Bar.greet():', results.barGreet);
+console.log('Bar.super_ === Foo:', results.barSuper);