spec: `readable-stream` v2;v3;v4 to `node:stream` v24

Description

We should document and codemod the migration from readable-stream v2/v3/v4 to node:stream v24.

• The migration should be divided by readable-stream v2, v3, and v4.
• The migration should separate import replacement from runtime behavior differences.
• The migration should call out observed output gaps so version-specific behavior is explicit.
• The migration should keep the stream wiring and example structure aligned across all baselines.
• The migration should include compensating patterns for code that depends on legacy timing behavior.

Important points

• readable-stream v2 and v3 share the same legacy timing behavior in the observed gaps.
• readable-stream v4 matches node:stream v24 for the observed gaps.
• Most cases are a straight source-import migration, but a few cases need behavior notes because the output differs at runtime.
• The codemod should prefer built-in node:stream imports for Node.js-only code.
• When runtime timing changes matter, the issue should show a safer migration pattern that avoids the late error.

Examples

readable-stream v2 -> node:stream v24

- import { Readable } from "readable-stream";
+ import { Readable } from "node:stream";

Observed runtime gap:

--- readable-stream v2
+++ node:stream v24
@@
 a
+ERR:boom

Example of potential migration:

 const { Readable } = require("readable-stream");

 const readable = Readable.from(["a"]);

-readable.destroy(new Error("boom"));
+readable.once("error", (error) => {
+  console.error(error.message);
+});
+
+setImmediate(() => {
+  readable.destroy(new Error("boom"));
+});

Example of safer migration for post-data error handling:

 const { Readable } = require("readable-stream");

 const readable = Readable.from(["a"]);

-readable.on("data", (chunk) => {
-  console.log(chunk.toString());
-});
-
-readable.on("error", (error) => {
-  console.error(error.message);
-});
+readable.once("error", (error) => {
+  console.error(error.message);
+});
+
+readable.on("data", (chunk) => {
+  console.log(chunk.toString());
+});

readable-stream v3 -> node:stream v24

- import { Readable, Transform, Writable, pipeline } from "readable-stream";
+ import { Readable, Transform, Writable, pipeline } from "node:stream";

Observed runtime gap:

--- readable-stream v3
+++ node:stream v24
@@
 a
+ERR:boom

Second observed gap:

--- readable-stream v3
+++ node:stream v24
@@
+ERR:readable-err

Example of potential migration for late destroy timing:

 const { Readable } = require("readable-stream");

 const readable = Readable.from(["a"]);

-readable.destroy(new Error("boom"));
+readable.once("error", (error) => {
+  process.stderr.write(`${error.message}\n`);
+});
+
+queueMicrotask(() => {
+  readable.destroy(new Error("boom"));
+});

Example of potential migration for post-data error handling:

 const { Readable } = require("readable-stream");

 const readable = Readable.from(["a"]);

-readable.on("data", (chunk) => {
-  console.log(chunk.toString());
-});
+readable.once("error", (error) => {
+  process.stderr.write(`${error.message}\n`);
+});
+
+readable.on("data", (chunk) => {
+  console.log(chunk.toString());
+});

readable-stream v4 -> node:stream v24

- import * as stream from "readable-stream";
+ import * as stream from "node:stream";

Observed runtime behavior:

--- readable-stream v4
+++ node:stream v24
@@
 (no changes)

Example of the same migration pattern with no compensation needed:

 const stream = require("readable-stream");

 const readable = stream.Readable.from(["a"]);

-readable.on("data", console.log);
+readable.on("data", console.log);

Caveats

• These are runtime timing differences, not API surface differences.
• The migration is usually a simple import swap, but the version split matters when code depends on late destroy() behavior or errors emitted after the first data event.
• v4 aligns with Node core on the observed cases, while v2 and v3 preserve the older behavior.
• If the code relies on the legacy timing, add explicit error listeners before the operation that may fail.
• If the code only needs the stream output and not the timing artifact, prefer the Node core behavior and remove the dependency on the old ordering.

Refs

• Node.js stream documentation: https://nodejs.org/api/stream.html
• readable-stream readme: https://github.com/nodejs/readable-stream/blob/main/README.md
• readable-stream download chart: https://npmx.dev/package/readable-stream?modal=versions&lowUsage=true

Start with the migration examples in the issue and compare the referenced Node.js stream documentation with the readable-stream README. Separate the v2, v3, and v4 import and timing cases, then verify that the codemod guidance preserves the aligned examples and documents compensating error-handling patterns.