stream.isDestroyed() has been exported from lib/stream.js since v19.9.0 (#45671) but has never been documented, while the sibling helpers exported alongside it — isErrored(), isReadable() and isWritable() — all have entries.

added: was determined by checking lib/stream.js at each release tag rather than from the landing date, since the commit predates the releases that carry it:

v20.0.0 inherited it from main rather than adding it, so it is not listed — matching how isErrored() lists only v17.3.0 and its v16.14.0 backport.

One difference is worth calling out, because it affects the documented types: unlike isErrored() and isReadable(), isDestroyed() bails out on anything that is not a Node.js stream (if (!isNodeStream(stream)) return null), so Web streams are not accepted:

isDestroyed(new Readable({ read() {} }));  // false
isDestroyed(destroyedReadable);            // true
isDestroyed(new ReadableStream());         // null
isDestroyed({});                           // null

The entry therefore lists Readable|Writable|Duplex and reuses the {boolean|null} wording already established by isReadable() and isWritable().

make lint-md and make doc-only both pass locally.